Power Loss and Engine Wear - A Detailed Study

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Sunny Devon
I have always wanted to start a thread saying that I have searched and found nothing, but the truth is that I found at least a dozen threads full of random musings, unsubstantiated rumours, incomplete data and even misinformation but very little reliable fact or reproducible data. So now I present to you my detailed findings.

PREPERATION

To assist in obtaining reliable figures with minimal rounding errors I required a high powered vehicle, and the Nissan R390 Race car seemed perfect with exactly 800BHP (actually PS, but that is a topic for another thread) at the garage list screen. A used version was also available as one of the Black Beauties, so I had a minimum power figure to work towards.

I took a new, unmodified R390 and proceeded directly to the test track at the driving park. This car was exactly as it arrived from the dealership - stock tyres, stock gear ratios, even stock oil. I selected Free run, and handed the keys to B-spec Bob instructing him to push hard. I exited the race as soon as he passed under the start/finish line and returned to view the car in my garage. The odometer read 1.2 miles. I then returned to the test track and repeated the run taking the odometer total to 2.5 miles. After another two runs the odometer was reading exactly 5.0 miles, so I concluded that a free run at the test track has a 1.25 mile run-up before the start line.

The test track is advertised as being 6.43 miles in length. A quick session in excel suggested that 1.25 miles run-up + 37 laps + 1350 metres would equal 240 miles - a nice round number. However in practise this turned out to be incorrect. The odometer reading was over by 1.8 miles!

A few more tests, and a little more time in excel and I came up with;
1.25 miles run-up + 46 laps (@ 6.48 miles) + 1050 metres equals 300 miles - another nice round number.

It now occurred to me that I did not know how hard the engine was working, so I took the car for a few laps in A-spec. I found that the car was nudging against the 7000rpm red line for most of the lap with a top speed of 229mph, and there was a ~7400rpm rev limiter. This seemed perfect as it meant the car was running on a knife edge with a reasonable red band before the fuel cutoff.

INITIAL TEST

1. New (Stock) Car Without Oil Change

After resetting the console to return the car to 0 miles I returned to the test track. Again I selected Free run, and again B-spec Bob was given the keys and told to push hard. I then left him to run for exactly 300 miles as earlier calculated. At the end of the run I returned to the car view at the garage to check the odometer before selecting change car as a quick way to save progress. This took me back to the garage list screen where I noted the power figure and entered the data into excel before sending Bob off again for the next 300 miles. Rinse and repeat forty times until the odometer reads 12,000 miles.

Sometimes at the end of a run the odometer would read over or under by 0.1 miles, and occasionally by 0.2 miles. If this occurred I would adjust the length of the following run by a hundred or so metres to return the reading to exact numbers. If the reading was over by 0.3 miles or more (as would happen if I was not paying attention), then I would reset the console and repeat the last run. This kept my mileage readings correct to within 0.1% - about as accurate as the power figures where the margin of error due to rounding is +/- 0.5 BHP.

A graph of the results (blue line) was plotted, and the car returned to the test track overnight in the capable hands of Bob to ensure no additional power was lost.

SUBSEQUENT TESTS

2. Used Car With Fresh Oil.
A used (Black) R390 was obtained and the mileage increased to 24,000 miles. The oil was then changed and this car handed over to Bob who again ran multiple sessions of 300 miles. 25 data points were recorded taking the mileage up to 31,500 and a graph plotted (purple line).

3. New Car With Fresh Oil.
A second new R390 was bought, the oil changed and the experiment repeated. 20 data points were recorded taking the mileage to 6000 and a graph plotted (pink line).

4. New Car With Regular Oil Changes.
Another new R390 was obtained and the oil changed. After each 300 mile session the oil was again changed before the data was collected. 35 data points were recorded and a graph plotted (orange line).

RESULTS

A table containing 120 data points was collected but not presented as this post is getting long enough already. A graph was plotted, and this is shown below. The data table can be supplied if enough people request it, but it is really not that interesting.

R390 - Oil Changes.gif

ANALYSIS

Although four tests were carried out, only three lines stand out.
The orange and purple lines display two different types of power loss with the blue line combining them. A third type of power loss is also signified by the pink spike.

The orange line represents power lost due to engine wear. This begins somewhere between 600 and 900 miles - some undocumented testing in steps of 20 miles narrows this down to somewhere between 780 and 800 miles. It follows an almost but not quite straight line, with the rate of power loss lessening towards the end. A final figure of 798BHP is observed at 7500 miles, equating to a power loss of exactly 5% from 840BHP.

The purple line represents power lost due to dirty oil. This occurs suddenly between 3300 and 4500 miles, and is again exactly 5% (760BHP -> 722BHP)

The blue line combines these with a 5% drop from 800BHP to 760BHP for engine wear, and a further 5% drop from 760BHP to 722BHP for dirty oil. Note that this does not give a total drop of 10% as these losses are multiplied rather than added giving a total power loss of 9.75% from 800BHP.

Also, closer examination of the graph shows that the sudden drop due to dirty oil occurs earlier with the new car than it does with the used one, and maximum power loss occurs later in the unmaintained car that it does with the well maintained one.

The pink spike represents power loss (or gain) due to maintenance. An oil change gives a gain of 5% from 800BHP to 840BHP, but this is very short lived lasting for less than 300 miles. The power then returns to the original level of 800BHP before following the blue line exactly.

CONCLUSIONS

There is no difference between stock oil and GT Auto oil. Although an oil change seems to give you a 5% power boost, this is very short lived and is most likely down to the engine being in peak condition due to having just been serviced. The engine being more highly strung will rev more freely and possibly accelerate engine wear over time, but will quickly settle back down to stock power.

Engine wear reduces power permanantly by up to 5% depending on mileage. It begins within 800 miles and starts at a steady rate. The rate of wear lessens over time, and is noticeably slower after the sudden drop in power due to dirty oil. This suggests that when trying to wear a car out for increased A-spec points it may be beneficial to perform an oil change after the first 3000 miles.

Dirty oil reduces power by a further 5% and occurs suddenly. In this case it begins at around 3000 miles, but there is sufficient evidence to suggest that this can vary significantly depending on engine power and/or RPM.

The Nissan R390 Race car whilst perfect for this set of tests is a costly proposition. It will have to be exchanged for something more affordable in future tests.

ADDITIONAL WORK

A closer look at the power spikes due to fresh oil is already underway.
Further tests looking at the effects of engine revs, engine type (V8/rotary/boxer etc), aspiration type (NA/turbo/supercharged) and vehicle type (road/race/tuner/concept) are also planned, and Bob is currently running in circles around the test track in a VW Nardo Concept to get these underway. However, with the original (blue line) test requiring some 20 hours of Bob's time punctuated with regular stops for data collection, this may take some time.
 
EXTRAPOLATED CURVES

The data from the graphs was extrapolated out to 15,000 miles. As I already knew the power figures at 12,000 miles, and the exact same figures were recorded after leaving Bob driving all night it was safe to assume that these had remained the same the entire time. Also knowing that power change due to each of the three factors was exactly 5% it was a simple job to create the theoretical teal and cyan curves. The pink and purple (oops, it looks to be brown now) curves were then overlaid in appropriate positions.

R390 - Projected.gif

The teal line represents base power and starts on the left showing the power of any new car as it arrives in your garage. On the right, it shows the power at your disposal after maximum engine wear and reasonable oil condition. Everything else is related to it.

The orange line, as explained in post 1 is the maximum power curve, only obtainable after regular oil changes. It is exactly 5% above the base power. Note how 800BHP (new car) * 1.05 (fresh service) * 0.95 (worn engine) = 798BHP. Multiplying the percentages results in a 0.25% drop, so a used car with fresh oil is still not quite as good as one straight from the showroom but without an oil change.

The cyan line represents minimum power, and the leftmost part is impossible to achieve without blackened oil at 0 miles - highly unlikely. At the other end it shows the power you will have in any used car when it arrives in your garage. As shown in post 1 the minimum power is 800BHP (new car) * 0.95 (worn engine) * 0.95 (dirty oil) = 722BHP, a 9.75% drop.

The pink curve is the power loss measured in a new car with an oil change before first use. The purple curve shows the power loss measured in a used car, again with an oil change before use. This time it has been moved to the right as this car already had many thousands of miles on the odometer before testing. These two curves are the same data points as measured in the first post, only now presented alongside each other rather than above/below each other.

To calculate the power gained by changing oil in a used car you have to divide by 0.95 to return to base power, then multiply by 1.05 for the service boost. Likewise to calculate the return to base power when the service boost wears off you divide by 1.05 - Multiply away from base, divide to return.

RECOMENDATIONS

For maximum performance runs regular oil changes may be just the boost you need. However you will likely need to replace your car within 800 or so miles to maintain maximum power levels.

For longer endurance races, taking a new car with fresh oil would be foolish. The initial power boost would disappear within two hours, engine wear could also cost 2% with another 5% dirty oil drop in the closing stages. Your best bet would be a used car that had its oil changed 300 miles previously. You would then suffer no power loss for the next 3000 miles!

I think I'll stop for now as I seem to be making this more complicated than it needs to be.

R390 - Closeup.gifNardo - Closeup.gifTuned 2CV - Closeup.gif
 
Excellent research, if Only i can ever go this indepth with my school work and presentations, that'd be a miracle.

I didn't read everything because I lost attention since I'm not dealing with such a problem, but have you mentioned that Bob himself can alter these results simply because he's gotten better with the car and track?
 
I'm confused about the part where you say that stock oil is no different to GT oil, of course it is. A 5% increase is an increase nonetheless. My Monaro would be making far less than 690hp (without exhausts) if it were not for the oil. Every time its power drops a little (from oil going bad) I change the oil and back to 690hp. Anyway, good work and good effort on doing this. Cudos.:cheers:
 
I'm confused about the part where you say that stock oil is no different to GT oil, of course it is. A 5% increase is an increase nonetheless. My Monaro would be making far less than 690hp (without exhausts) if it were not for the oil.

I think the context was the speed at which the oil degrades. If I'm not mistaken, in this case his tests show that a car running with the oil in it at the time of purchase loses power at the same rate as a car that's had its oil changed for GT Oil, when both cars begin the loss from the same point, when that point is at stock power levels or below.
 
I most certainly don't agree with those figures on the first 1000km of ANY NEW CAR + OIL CHANGE. I've seen this with my Spec-C's, Integra Type-R and several of my circuit/rally cars. The first instance of any decrease of power, regardless of whether it's had the oil change done or not is 250km or 155miles.
After that point, the rate of power loss between both the new stock and new oil changed cars stays constant until around the 5,000km mark where the stock car balances out and the oil changed motor then continues to lose power UNTIL it's equalled with the stock car at around the 10,000km mark, not at 250 miles (400km) like I'm seeing in the graph.

Mafs!!
 
Nice bit of research. It'd be interesting to see if this remains true for other cars or if it's been set differently for different cars.

I'm not sure that it translates well to real life. In my experience production cars go better after a few thousand miles, not worse. I can't comment on super cars but I've seen it with all of my production cars.

In F1 the performance doesn't seem to degrade either, well not for two races anyway. The engine seems to have a life of so long at so many revs, it doesn't really lose power after that, it just starts to break (or to be precise the chance of component failure becomes much higher).

Still, as I say it's b interesting to see if, for example, a Clio or Mini behaves the same.
 
Nice work...what happened to the Quality Posts system??? :grumpy: This is one that surely woulda deserved some +rep from all of us.

It's too bad GT oil is no different from stock. That doesn't represent reality at all...i was hoping your research would indicate perhaps GT oil is = to synthetic...and that a car with non-synthetic oil from the dealership is getting "souped up" with synthetic at the GT tune shop. :grumpy: Oh well.
 
My results so far can only be guarunteed for the Nissan R390 Race car. Things may be different for road cars etc. Hopefully I can also clarify a few things when I get a chance to writeup the second post later tonight or sometime tomorrow.
 
My results so far can only be guarunteed for the Nissan R390 Race car. Things may be different for road cars etc. Hopefully I can also clarify a few things when I get a chance to writeup the second post later tonight or sometime tomorrow.

That's exactly what I think...your results will vary from car to car.

Off-topic: a public apology to the board members from me for misquoting facts (in the now closed Where's LeMans? thread). I'm in the habit of coming here and posting without doing any research, and I make mistakes--most of my posts nowadays are off the top of my head...as if I'm talking to someone I work with and don't have time to consult an encyclopedia about everything I say. Usually nobody catches them but me, so I apologize to daan and others. How embarrassing.
 
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Great research Car-less (or Carlos as us LANers called you...), especially useful given I've done 1,800 miles in my 120i with bob driving.
 
My results so far can only be guarunteed for the Nissan R390 Race car. Things may be different for road cars etc. Hopefully I can also clarify a few things when I get a chance to writeup the second post later tonight or sometime tomorrow.

I'll be eagerly awaiting the results of the road car you test.

Like I said however in another thread about buying the best valued new & 2nd hand cars, I've seen identical results between different cars (Spec-C, Integra Type R) from their oil changes.....the actual number of Kw/hp/ps gained between cars is always going to be different, but on a percentage scale, it's absolutely identical....5% from a new car + oil change, and then it's on a sliding scale depending on k's travelled and how dirty the oil is. You can get up to 12% increase from the current levels of that particular car's current power from the oil change when bought 2nd hand and still a couple of percent over the factory claims.

Mafs!!

P.S. I'm loving the effort you are putting into this however. A+ for that. :D
 
I'd just like to address the comments so far before writing up the second series of tests.

Excellent research, if Only i can ever go this indepth with my school work and presentations, that'd be a miracle.

I didn't read everything because I lost attention since I'm not dealing with such a problem, but have you mentioned that Bob himself can alter these results simply because he's gotten better with the car and track?

It seems that as in depth as my work was, I still managed to miss out a few important points!

I failed to mention that Bob already had maximum skills long before I started this series of tests. I also failed to observe his consistency before the first test, but I did do so this morning.

After leaving him running all night I observed Bob for 20 laps in a used car. His lap times were all within 0.03 seconds of each other - in an 18,000 mile used car with black oil and a warped chassis. I then gave him a new car and again observed him for 20 laps. This time his laptimes were all the same to within 0.01 seconds - consistency that I could never dream of achieving myself.

I'm confused about the part where you say that stock oil is no different to GT oil, of course it is. A 5% increase is an increase nonetheless. My Monaro would be making far less than 690hp (without exhausts) if it were not for the oil. Every time its power drops a little (from oil going bad) I change the oil and back to 690hp. Anyway, good work and good effort on doing this. Cudos.:cheers:

A new car with oil change does give you a 5% increase in power. I am suggesting that this power boost is not due to a better blend of oil, but rather is down to the car being in peak condition due to having just been serviced. The oil filter will be clean and dry, the drain plug nice and secure, and the HT leads properly seated on the spark plugs.

Within a few hundred miles the filter will be wet and a little dirty and bolts/leads may have worked loose. My experiment showed that within 300 miles your freshly oiled car will have the exact same power as it would have had had you not changed the oil to begin with. From 300 miles until at least 6000 miles a new car with GT Auto oil has the exact same power figure as a new car with stock oil. If GT auto supplied a different blend of oil I would expect the pink and blue curves to show different rates of wear over time - not to be an exact match.

I think the context was the speed at which the oil degrades. If I'm not mistaken, in this case his tests show that a car running with the oil in it at the time of purchase loses power at the same rate as a car that's had its oil changed for GT Oil, when both cars begin the loss from the same point, when that point is at stock power levels or below.

Sort of. They both lose the exact same power at the exact same rate. The only difference was that the freshly oiled car had a 5% power boost for a few miles before returning to the stock power figure.

I most certainly don't agree with those figures on the first 1000km of ANY NEW CAR + OIL CHANGE. I've seen this with my Spec-C's, Integra Type-R and several of my circuit/rally cars. The first instance of any decrease of power, regardless of whether it's had the oil change done or not is 250km or 155miles.
After that point, the rate of power loss between both the new stock and new oil changed cars stays constant until around the 5,000km mark where the stock car balances out and the oil changed motor then continues to lose power UNTIL it's equalled with the stock car at around the 10,000km mark, not at 250 miles (400km) like I'm seeing in the graph.

This is exactly the sort of anecdotal evidence I am trying to prove/disprove. Your first paragraph suggests all cars lose power within 200 miles. What if I told you I have seen claims of cars gaining power from being driven carefully for the first 200 miles!
You then claim that a stock car will reach minimum power in just 3000 miles while the oil changed one continues to lose power at the same rate until also reaching minimum power after just 6000 miles. I think everyone in the 100,000 A-spec club will disagree with that.

If you have documented and verifiable proof of these claims, or if I have misunderstood what you wrote, please let me know.

Like I said however in another thread about buying the best valued new & 2nd hand cars, I've seen identical results between different cars (Spec-C, Integra Type R) from their oil changes.....the actual number of Kw/hp/ps gained between cars is always going to be different, but on a percentage scale, it's absolutely identical....5% from a new car + oil change, and then it's on a sliding scale depending on k's travelled and how dirty the oil is. You can get up to 12% increase from the current levels of that particular car's current power from the oil change when bought 2nd hand and still a couple of percent over the factory claims.

I suspect that my testing will agree with a blanket 5% increase for ANY new car - but only for a short while as I explained for nd 4 holden spd.

Used cars however, I thought fell into two categories. 10km (6.2 mile) specials that are essentially new cars, and fully worn cars with greater than 12,000 miles. All fully worn cars I expect to give a 10.525% power increase, but again only for a short while before settling on a 5.25% increase from fully worn. Any sliding scale you have observed I suspect only applies to the cars value or price - not to how much power they will gain from an oil change.

The factory power claims can probably be ignored as very few cars will ever agree with the factory claim anywhere else in the game - just look at the 'gentlemans agreement' Japanese cars that all claim to have the same 276BHp. It is for this reason that all my power measurements come from the same garage list screen.

Again, if you have documented and verifiable proof, or if I have misunderstood what you wrote, please let me know.
 
Well thats some good research/ Analysis; I was almost waiting for a Powerpoint Presentaion... lol
Good job!

So, either change the Oil often, or just keep buying new cars often. Keep the oil, just change the car, it's only money...lol
 
Quick question: Did you truly see a couple cars gaining power from a break-in period?

And if so, how did you go about it? (IE what were the conditions?)
 
Quick question: Did you truly see a couple cars gaining power from a break-in period?

And if so, how did you go about it? (IE what were the conditions?)

I have not seen it happen myself, but I have seen others claim to have observed it. I'm going to run a few more cars for 800 miles before posting my results, but I suspect that they were confusing GT4 with GT3.
 
Same here. In GT3, if you kept the stock oil in the car, you'd gain power right up until the oil light came on, then gain MORE when changing the oil.
 
I had typed for about an hour to give my retort to your comments then my DSL went down for a minute as I was posting, but I'll give a detailed explaination to your replies tomorrow car-less, needless to say, there's still a few points I'm going to be debating with you. ;)

Mafs!!
 
PART 2. THE EFFECTS OF ENGINE SPEED (RPM)

The VW Nardo Concept was observed to be easily obtained, and to have a nice round figure of 600BHP at the garage list screen so this was chosen for the next series of tests. A new car was obtained and a few test runs made to find the 300 mile marker. This time it was at;
1.25 miles run-up + 46 laps (@ 6.48 miles) + 450 metres = 300 miles. The VW Nardo appears to run a 2 metre shorter lap, possibly due to tighter racing line. This car was also observed to be nudging against the redline for most of the lap, at 8000 RPM with a 8500 RPM cutoff.

INITIAL TEST

TEST 1. New (Stock) Car @ 8000 RPM
(Exactly the same as Part 1, Test 1).
After resetting the console to return the car to 0 miles I returned to the test track. Again I selected Free run, and again B-spec Bob was given the keys and told to push hard. I then left him to run for exactly 300 miles as earlier calculated. At the end of the run I returned to the car view at the garage to check the odometer before selecting change car as a quick way to save progress. This took me back to the garage list screen where I noted the power figure and entered the data into excel before sending Bob off again for the next 300 miles. Rinse and repeat forty times until the odometer reads 12,000 miles.

A graph of the results (blue line) was plotted, and the car returned to the test track overnight in the capable hands of Bob to ensure no additional power was lost.

SUBSEQUENT TESTS

2. New Car @ 8500 RPM
Another new VW Nardo Concept was obtained, and the Auto setting of the (stock) fully custom gearbox adjusted from 15 to 13.The car was handed over to Bob who again ran multiple sessions of 300 miles. 40 data points were recorded and a graph plotted (red line).

3. New Car Bouncing Off The Rev Limiter
Another new VW Nardo Concept was obtained, and the Auto setting of the (stock) fully custom gearbox adjusted from 15 to 9. The car was handed over to Bob who again ran multiple sessions of 300 miles. 40 data points were recorded and a graph plotted (brown line).

4. New Car @ 7000 RPM
Another new VW Nardo Concept was obtained, and the Auto setting of the (stock) fully custom gearbox adjusted from 15 to 21. The car was handed over to Bob who again ran multiple sessions of 300 miles. 40 data points were recorded and a graph plotted (light green line).

5. New Car Using The Full Rev Range
Another new VW Nardo Concept was obtained, and the gearbox left at the stock setting of 15.
The car was handed over to Bob who again ran multiple sessions of 300 miles, but not at the Test Track. This time the Nurburgring was used as a test of normal driving/racing conditions. 40 data points were recorded and a graph plotted (yellow line).

Note: Before starting this final test Bob was sent out on a few runs to find the 300 mile marker. This was discovered to be on lap 24 at the bottom of the dip just before Adenour Forst (between T2 and T3). During these pre-runs Bob was observed to leave the road on occasion if pushing hard, so to prevent any accidents Bob was asked to take it easy running at Medium pace(3) for the measured runs. The console was then reset before starting the measured runs.

RESULTS

A table containing 200 data points was collected but is not presented. A graph was plotted, and this is shown below. Again, the data table can be supplied if enough people request it, but it is really not that interesting.

Nardo - Engine Revs.gif

ANALYSIS & CONCLUSIONS

Five tests were run, and five seperate lines plotted. They all follow a very similar line with almost no deviation in the first 3000 miles. The sudden drop due to dirty oil started at 3300 miles for all cars except the one running at the Nurbugring. This started 300 miles later. It is at this point that the greatest difference in power is noticed with a 15 BHP (2.5%) difference between the hardest driven car, and the sunday driver at the 'Ring.

At 4500 miles with fully dirtied oil the lines again convereged. They then followed similar but not the same line until 10200 miles where the last car was finally fully worn out. Although quite difficult to see, there is a significant difference in the mileage needed to fully wear out each car. The first to reach minimum was the car bouncing off the rev limiter (brown line), at 8400 miles. The last to reach minimum was the car lapping the Nurburgring (yellow line) at 10200 miles - a more than 20% increase in mileage required! The other three cars all reached minimum at exactly 9000 miles.

The most surprising (and totally unexpected) result was that the car driven at the lowest constant RPM (light green line) was the first to begin losing power due to dirty oil. The car bouncing off the rev limiter (brown line) was very close behind, and this car did lose power quicker after the sudden drop. This leads me to believe that the two types of power loss (dirty oil and engine wear) are modelled seperately, and are affected by different things.

Bouncing off the Rev limiter causes more engine damage, but is not the deciding factor for dirty oil. Rather I suspect that the oil is dirtied quicker in cars the more they are altered from factory spec. This appears to be determined by how close you are running to the peak power output as suggested by Power Drifter in Post 27. The stock ratios (blue line) seems to last the longest, with the slightly altered (-2 Auto gear setting) (red line) occuring slightly earlier. The significantly altered (light green) and (brown lines) (+/- 6 auto gear setting) dirty the oil significantly earlier.

Also, note how the minimum power reached is 600 * 0.95 * 0.95 = 541.5 rounded up to 542 BHP - the same 9.75% loss as noticed in the Nissan R390 Race Car.
 
Just a thought, maybe as you collecting your data points, figure out percentages. You may notice more of a trend in the HP numbers across certain engine types. Anyway, if the HP numbers work in GT4, like it does in GT3, then it is based more on % than actual HP 'numbers'. I realized that while hybridding in GT3. If you ever did any hybridding, check-out my excel spreadsheet at: https://www.gtplanet.net/forum/showthread.php?t=99714
 
This is exactly the sort of anecdotal evidence I am trying to prove/disprove. Your first paragraph suggests all cars lose power within 200 miles. What if I told you I have seen claims of cars gaining power from being driven carefully for the first 200 miles!

There is one example I completely forgot about that this had happened to but it wasn't from being driven carefully!! :mischievous: That was the Pontiac GTO (Monaro shape). Stock, it was 260Kw....after around 300km of racing (through the stars and stripes series), it went up to 262Kw. However, I notice from your second study graph that you didn't get a power increase from the Nardo. :cool:

car-less
You then claim that a stock car will reach minimum power in just 3000 miles while the oil changed one continues to lose power at the same rate until also reaching minimum power after just 6000 miles. I think everyone in the 100,000 A-spec club will disagree with that.

Well, I'm at 94,257pts myself so while I'm not in that hallowed club (yet!), I think I know a little bit about the game too.

car-less
I suspect that my testing will agree with a blanket 5% increase for ANY new car - but only for a short while as I explained for nd 4 holden spd.

Used cars however, I thought fell into two categories. 10km (6.2 mile) specials that are essentially new cars, and fully worn cars with greater than 12,000 miles. All fully worn cars I expect to give a 10.525% power increase, but again only for a short while before settling on a 5.25% increase from fully worn. Any sliding scale you have observed I suspect only applies to the cars value or price - not to how much power they will gain from an oil change.

Not correct, and this is where I did a bit of research on this, in Engine Rebuilds in Tuning Section. It was originally designed to find powerful 2nd hand cars for cheap and work out the best power for each category of car. I'll cut and paste to save the page hopping:

mafia_boy in Engine Rebuilds Thread
The key is to keep your cars as low mileage as possible with regular oil changes. I know that the Spec-C can do 300km straightaway then shows signs of wear, but an oil change will bring it back to full power, but this will only continue until you hit the 1000km mark, then any power loss you experience can't be brought back.

Same goes with 2nd hand cars, buy as close to the price limit changes as possible. For example, a 40000km-41000km car will perform better than an equivalent car with say 48000-49000km due to the fact it's had 8000km less of wear and tear on it. My guide is this and while it's not 100% foolproof, it helps me get the best priced used cars for the mileage done and the most power from each class of used car. For example:

Anything Pre '97 - More than 64000km - After oil change, less power than factory claims.

Anything Pre '97 - 60000km-62000km for the cheap examples, when oil change is done, it's brought back to what the factory would claim.

Anything Pre '97 - 40000km-42000km for the decent examples, when oil change is done, it's brought back to about 3% above factory claims.

Anything Post '97 - 40000km-42000km for the cheap examples, when oil change is done, it's brought back to about 5-7% above factory claims.

Anything Post '97 - 20000km-22000km for the best value examples, have about 30-40% off their new price tag and after oil change, it's brought back
to 5-12% above factory claims.

Any 10.0km (6.2mi) examples after oil change get an easy 5% increase.

Anything brand new after oil change gets an easy 5% increase aswell.

car-less
The factory power claims can probably be ignored as very few cars will ever agree with the factory claim anywhere else in the game - just look at the 'gentlemans agreement' Japanese cars that all claim to have the same 276BHp. It is for this reason that all my power measurements come from the same garage list screen.

That's for new cars. If you go to the used car lots you will see their ACTUAL power rating, not just the gentlement agreement figure. Go check an R33 GT-R for example.....40000-60000km range is fine. Click on buy ONCE, and when it shows the finer stats like weight, dimensions and whether you want to buy or cancel, you will see the true power figures before you buy it. Note: THIS WILL NOT WORK FOR CARS IN THE NEW CARS/LEGENDARY CARS AREAS, THIS WILL ONLY WORK IN THE USED CAR LOTS!! For new cars/legendary cars you need to use the garage screen like you're saying to get the true power. :)



Now, onto your 2nd set of tests..........very very interesting read and great work there dude. A great time studying this one and I have nothing to say on this one, it's watertight. :) The problem is trying to apply that to real racing conditions, because we don't stay at 6th gear @ 340km/h+ at 8000rpm for 300km that often. ;)
Nonetheless, bravo for all the work you've done so far, even though I'm debating some of the 1st study's work, it's giving us an insight into what we can do to maximise the power of the car and to be honest....if I can get another Spoon Civic, and warm the motor up a little in distance, maybe I can get a couple of hp more for it and drop my ET's for the 1/4.

Mafs!!. :)
 
I most certainly don't agree with those figures on the first 1000km of ANY NEW CAR + OIL CHANGE. I've seen this with my Spec-C's, Integra Type-R and several of my circuit/rally cars. The first instance of any decrease of power, regardless of whether it's had the oil change done or not is 250km or 155miles.

So nothing like this then?

Spec C - Closeup.gif

I now officially Hate the Subaru Impreza Spec C - the car favoured by many for 'not being like the other cars'. After 5 hours and 1500 miles all it managed to do was prove that I had been right all along.

The car with GT Auto oil lost all of its 5% power advantage between 126 and 189miles like all the other cars I have tested. The car with stock oil neither lost or gained a single BHP until 1032 miles had been driven, and yes, every single point on that graph was actualy measured. 15 * 21 miles with GT auto oil, and 40 * 21 miles plus 6 * 60 miles in the middle when I got bored for the car running manufacturers oil.

Not correct, and this is where I did a bit of research on this, in Engine Rebuilds in Tuning Section. It was originally designed to find powerful 2nd hand cars for cheap and work out the best power for each category of car. I'll cut and paste to save the page hopping:

Originally Posted by mafia_boy in Engine Rebuilds Thread
The key is to keep your cars as low mileage as possible with regular oil changes. I know that the Spec-C can do 300km straightaway then shows signs of wear, but an oil change will bring it back to full power, but this will only continue until you hit the 1000km mark, then any power loss you experience can't be brought back.

Same goes with 2nd hand cars, buy as close to the price limit changes as possible. For example, a 40000km-41000km car will perform better than an equivalent car with say 48000-49000km due to the fact it's had 8000km less of wear and tear on it. My guide is this and while it's not 100% foolproof, it helps me get the best priced used cars for the mileage done and the most power from each class of used car. For example:

Anything Pre '97 - More than 64000km - After oil change, less power than factory claims.

Anything Pre '97 - 60000km-62000km for the cheap examples, when oil change is done, it's brought back to what the factory would claim.

If you go to the used car lots you will see their ACTUAL power rating, not just the gentlement agreement figure. Go check an R33 GT-R for example..... 40000-60000km range is fine. Click on buy ONCE, and when it shows the finer stats like weight, dimensions and whether you want to buy or cancel, you will see the true power figures before you buy it.

On day 5894 (day 294, cycle 9) I bought;
Nissan Skyline GT-R Vspec (R33) '95 (Silver) with 36678.0 miles (58684.8km) for $26,450.
Factory claims 276BHP, Seller claims 289BHP, Garage shows 293BHP.
After Oil change, Valuation screen shows 319BHP, Garage shows 324BHP.

On day 5895 (day 295, cycle 9) I bought;
Nissan Skyline GT-R Vspec (R33) '95 (Dark Blue) with 43049.6 miles (68879.3km) for $18,514.
Factory claims 276BHP, Seller claims 289BHP, Garage shows 293BHP.
After Oil change, Valuation screen shows 319BHP, Garage shows 324BHP.

Previously bought and sitting in my garage already I had;
Nissan Skyline GT-R Vspec (R33) '95 (Black) with 6.2 miles (10km).
Factory unknown, Seller unknown, Valuation shows 320BHP, Garage shows 324BHP.
After Oil change, Valuation screen shows 336BHP, Garage shows 341BHP.

$8,000 and 10,000km makes no difference to the claimed or actual power figures, before or after an oil change - if you are looking at the exact same model of car. They both gained 10.525% from an oil change, and if I could be bothered to test them, they would most likely lose around 16BHP (4.75%) of this new figure after just 200 miles of use.

The 6.2 mile special gained 5% from an oil change, a gain that would also no doubt be lost within 200 miles if I could be bothered to test it.

Although the used cars with oil change show the same power figure as the 6.2 mile special without oil change in the garage list screen, there is a 1BHP defecit in the used cars at the valuation screen. This will be due to the actual 0.25% defecit being rounded up in one case, and rounded down in the other.

Just a thought, maybe as you collecting your data points, figure out percentages. You may notice more of a trend in the HP numbers across certain engine types. Anyway, if the HP numbers work in GT4, like it does in GT3, then it is based more on % than actual HP 'numbers'. I realized that while hybridding in GT3.

I am deliberately using the exact power figures as shown in the garage list screen (where you choose from the list of 10 cars per page) as these will be the same for everyone no matter what units you are using for power. These are already slightly error prone, being rounded to the nearest whole number. This error that would be magnified as soon as I tried to calculate anything from it, and generate nasty figures to work with...

The Nissan R390 loses 1BHP at 900 miles.
The VW Nardo loses 1BHP at 900 miles.
The Impreza loses 1BHP at 1200 miles.
*The 2CV loses 1BHP at 2700 miles. *(made up number)*

Or...

The Nissan R390 loses 0.125% power at 7.5% test distance.
The VW Nardo loses 0.167% power at 7.5% test distance.
The Impreza loses 0.306% power at 10% test distance.
*The 2CV loses 1.961% power at 22.5% test distance. *(made up number)*

I'm sure the game does work in percentages, but I cannot measure 0.125% of 51BHP. I do however sometimes talk in percentages once each set of tests is completed.
 
This is getting a) weird & b) annoying....your graph and mine aren't aligned from the 100-200mile mark (car + oil). Like I said, the 155 mile mark (250km) was when I saw a drop in any figure, not 126 like you have.

Are you running PAL or NTSC there Car-Less..........I'm trying to break this down rationally as at the moment I can't explain why I get 30 miles further than you before any drops occur. :dunce:

Part 2 though:
On day 5894 (day 294, cycle 9) I bought;
Nissan Skyline GT-R Vspec (R33) '95 (Silver) with 36678.0 miles (58684.8km) for $26,450.
Factory claims 276BHP, Seller claims 289BHP, Garage shows 293BHP.
After Oil change, Valuation screen shows 319BHP, Garage shows 324BHP.

On day 5895 (day 295, cycle 9) I bought;
Nissan Skyline GT-R Vspec (R33) '95 (Dark Blue) with 43049.6 miles (68879.3km) for $18,514.
Factory claims 276BHP, Seller claims 289BHP, Garage shows 293BHP.
After Oil change, Valuation screen shows 319BHP, Garage shows 324BHP.

Previously bought and sitting in my garage already I had;
Nissan Skyline GT-R Vspec (R33) '95 (Black) with 6.2 miles (10km).
Factory unknown, Seller unknown, Valuation shows 320BHP, Garage shows 324BHP.
After Oil change, Valuation screen shows 336BHP, Garage shows 341BHP.

Before oil change, yeah, I'd believe the discrepancies.......but if you have already bought it and done the oil change, it should show the same specs on both the garage screen and the valuation/selling screen.

I've got time this morning so I'll chase this up right........now. bbl with some more info on this from my end + photos.

Mafs!!
 
Well, after 90 minutes of buying Skyline's like crazy to get more indepth with my own study of used cars & oil changes and also to compare against car-less's notes I've come to the following conclusions.

1. We measure differently, so we are coming up with different results. You are using hp (& ft/lb's for torque I assume too), and I use Kw & Nm for my measurements, and that is what is bringing up the discrepancies. Now I went by your method aswell and discovered where your results are coming from and WHY they are identical, but in my method it is showing the more minute differences in power & torque. ;)

2. I'm changing my range-gaps for power differences aswell, 60000+ is no longer my limit, it's a hell of a lot less, but I'm still looking at where that difference is for the higher km examples.

3. THERE IS NO DIFFERENCE FROM THE BUY SCREEN TO YOUR GARAGE!!

Now, to the results.

Car 1: (Baseline) '96 Skyline GT-R V-Spec LM Edition = 60175.0km + oil change already done, just sitting in garage.
Power: 238Kw@6800rpm
Torque: 417.87Nm@4400rpm

Car 2: '96 Skyline GT-R V-Spec = 10.0km version, no oil change
Power: 239Kw@6800rpm
Torque: 418.85Nm@4400rpm

Car 3: '96 Skyline GT-R V-Spec = Bought from late 90's lot w/42380.4km on clock.
BEFORE BUYING ON THE VALUATION SCREEN:
Power: 215Kw@6800rpm
Torque: 378.08Nm@4400rpm
AFTER BUYING, NO OIL CHANGE:
Power: 215Kw@6800rpm
Torque: 378.08Nm@4400rpm
AFTER BUYING, OIL CHANGE PERFORMED
Power: 238Kw@6800rpm
Torque: 417.87Nm@4400rpm

So, there you go. Pictures of results are as follows too.
Baseline - GT-R V-Spec LM Limited - 60175.0km model


GT-R V-Spec 10.0km model


GT-R V-Spec - 42380.4km model, BEFORE AND AFTER BUYING, NO OIL CHANGE





You're more correct on the issues than I was Car-less, but not 100% and that's the point of this debate, to get conclusive proof of everything.
I'm not against you, I'm eager to work this thing out myself and if that means blowing every theory I used to have out the window, so be it. :mischievous: But I knew something wasn't quite right with what you said, and vice versa. :)

Mafs!!
 
Car-less:

I think the reason why the VW Nardo in your recent test lost power so quickly when ran at 7000 rpms is, that it's peak power output is at 7000 rpms!
I've always been suspecting this fact and now it seems it's true.

I've been doing my own mileage tests with absolutely stock Subaru 360 (:D), and so far I'm at 3900 miles, having lost just 1.92% of the original power without oil change.
That would translate to about 12HP of loss in the Nardo, and it actually matches your graph. I'm at the point where the power figures should start dropping quickly.

I've been driving the car only myself without Bob's help, usually on the Ring, carefully keeping it at the rev limit without bouncing it at all or coasting down the hills on neutral :D

Just pointing out that the power figures or a tuning stage of a car aren't likely effecting the power loss rate.
 
1. This is getting a) weird & b) annoying....your graph and mine aren't aligned from the 100-200mile mark (car + oil). Like I said, the 155 mile mark (250km) was when I saw a drop in any figure, not 126 like you have.

2. Are you running PAL or NTSC there Car-Less..........I'm trying to break this down rationally as at the moment I can't explain why I get 30 miles further than you before any drops occur. :dunce:

3. Before oil change, yeah, I'd believe the discrepancies.......but if you have already bought it and done the oil change, it should show the same specs on both the garage screen and the valuation/selling screen.

1. Whilst running my latest close-up test a thought occurred to me. 126 miles is the last point at which the car still has full power. 147 miles is the first recorded instance of reduced power. (I really must get round to writing the close-up test results).

If you are running 50km sessions between points on the graph then 200km (124 miles) is slightly before the point of power loss. 250km (155 miles) is about half way through the drop, and 300km (186 miles) is just as the power returns to the stock level. Perhaps we are just not quite understanding each other here?

2. PAL (uk) here, and another thought - the Nissan R390 has 800 BHP, so a 1BHP drop is just 0.125% loss. Measuring a 0.125% loss in a 200 BHP Civic would not be possible as it would be just 0.25 BHP. Do you have a $4.5million race car you can test?

3. The Garage List screen (where you choose from a list of cars) does not agree with the valuation screen when using BHP, HP or KW as units of power. The reasons for this are discussed in the thread I linked to near the top of my first post. If you are using KW and getting the same power figure in the Garage list as you do at the valuation screen then you must have an updated (bug fixed?) version of the game - mine is from the first month after release.

Well, after 90 minutes of buying Skyline's like crazy to get more indepth with my own study of used cars & oil changes and also to compare against car-less's notes I've come to the following conclusions.

1. We measure differently, so we are coming up with different results. You are using hp (& ft/lb's for torque I assume too), and I use Kw & Nm for my measurements, and that is what is bringing up the discrepancies. Now I went by your method aswell and discovered where your results are coming from and WHY they are identical, but in my method it is showing the more minute differences in power & torque. ;)

2. I'm changing my range-gaps for power differences aswell, 60000+ is no longer my limit, it's a hell of a lot less, but I'm still looking at where that difference is for the higher km examples.

3. THERE IS NO DIFFERENCE FROM THE BUY SCREEN TO YOUR GARAGE!!

4. You're more correct on the issues than I was Car-less, but not 100% and that's the point of this debate, to get conclusive proof of everything.
I'm not against you, I'm eager to work this thing out myself and if that means blowing every theory I used to have out the window, so be it. :mischievous: But I knew something wasn't quite right with what you said, and vice versa. :)

1. You are getting more accurate figures for Torque as I am not measuring it, but I am getting more accurate figures for power. 1BHP from 800 is more accurate than 1KW from 589 for my first test. The rounding error (+/- 0.5) will still affect your figures as you don't get any extra decimal places for your power figures.

2. I have not looked at your studies beyond what you quoted here and don't intend to, but I suspect you will eventually find there are only two types of used car despite there being up to four different prices.

3. No difference from Buy screen to Valuation screen. When I say Garage screen I am refering to the first screen you come to when you click on Garage at Home.

4. It's good to have someone else keeping a close eye on this, and even better that we have different points of view. It keeps eveything honest and should we eventually agree, it makes the results more accurate and worthwhile.

1. I think the reason why the VW Nardo in your recent test lost power so quickly when ran at 7000 rpms is, that it's peak power output is at 7000 rpms!
I've always been suspecting this fact and now it seems it's true.

2. I've been doing my own mileage tests with absolutely stock Subaru 360 (:D), and so far I'm at 3900 miles, having lost just 1.92% of the original power without oil change.
That would translate to about 12HP of loss in the Nardo, and it actually matches your graph. I'm at the point where the power figures should start dropping quickly.

3. I've been driving the car only myself without Bob's help, usually on the Ring, carefully keeping it at the rev limit without bouncing it at all or coasting down the hills on neutral :D

4. Just pointing out that the power figures or a tuning stage of a car aren't likely effecting the power loss rate.

1. I had not considered that. Thanks for bringing it to my attention - something else for me to try and test out.

2. At first I thought your sudden power drop was overdue, then I discovered you were running at the 'Ring so it should be imminent. It is nice to know that proper racing is less wearing to the oil than constant full throttle autobahn driving ;)

3. Rather you than me! Much as I enjoy driving regular cars at the ring, 300 laps at a snails pace would get boring.

4. Looks like I have more testing than I thought yet to do.

Edit:- @ mafia boy, I forgot to ask about your figures for the first 300 miles in a new car with the manufacturers oil, no oil change. Originaly I thought you were saying it too lost power at 250km, but now I am thinking it was only the point when power loss began for the car with oil changed that you are disagreeing with?
 
In spite of all of this data, I've got no plans to change my driving habits, oil change frequency, nor choice and frequency of driving any particular car. But it's good to know.
 
Did you know that you can measure even 0.001% power loss in a 15 HP car by looking at the power to weight ratio?
Only problem is that GT4 internally uses the PS unit, so you have to convert the power/weight ratio results:
1 PS (metric HP) = 0,9863185781 HP/BHP

Just write down the original ratio, divide the vehicle weight with it and check that the power readings match when you're doing it first time.
i.e.:
24,522 P/W ratio, 385kg weight.
385 / 24,522 = 15,70018758 = 15,4853866896 HP :D

Car-less
2. At first I thought your sudden power drop was overdue, then I discovered you were running at the 'Ring so it should be imminent. It is nice to know that proper racing is less wearing to the oil than constant full throttle autobahn driving

3. Rather you than me! Much as I enjoy driving regular cars at the ring, 300 laps at a snails pace would get boring.
Sorry, I didn't mean it suffered a sudden power drop. It's been dropping constantly after the first 200 or so miles, just like your Nardo graph shows.
I just don't know yet if the power will start dropping more quickly from now on. It's a shame I've only got the current power reading and didn't do any graph plotting this far..

What do you know, driving Subaru 360 is.. BORING! :lol:
Sometimes I even start to fall asleep if I'm doing three laps in a row for example. It's even more boring than driving a real car constantly for 300 miles :dunce:
 
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