Problem with the stage 4 turbo?

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A7X

A7X

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Sorry if this is a n00b question but it has me confused.
I have searched for this but couldn't find anything on it so here goes.....

I was driving my Golf GTi IV, fully tuned up and i noticed the turbo meter was running virtually opposite too how it usually does. It was starting at 0 bar pressure and then working its way up as normal until around 4250 rpm when it would start to decrease in pressure, although i could still cleary hear the "whine" of the turbo getting louder and higher as if pressure was still building? I was wondering if this was a "bug" or if it was meant to happen because it does not appear on any of my other cars? or none that i've noticed.

The turbo and tuning parts were all bought from HPA motorsports apart from the tyres, i also added new wheels from the "used" section, changed the oil and had a car wash done. it was fully lowered and nos was running at 100 percent power, i also had all driving aids off. I dont know if that makes any difference what so ever but thought i might add it just incase. I'm also running the PAL version.

Thanks and i'd be interested too here what your responses are.

A7X
 
no its deffinately not lag as the pressure builds up but as the revs get higher instead of the pressure going up like it should it decreases. turbo lag is where the turbo takes a little while to kick in as the pressure builds up. As it works off the exhaust when your revs increase it doesn't instantly increase the turbo pressure. I may be wrong but im pretty sure thats what it is. maybe someone could explain a bit more. But it still doesn't explain why the pressure decreases. I'm confused

A7X
 
It's no glitch guys.

I have an AmD remapped Audi A4 1.8 Turbo Sport (in the real world), and I know a fair bit about forced induction.

What happens is that turbos get to a point where peak efficiency is passed. This is because of heat build up and the volume of the turbo itself. Basically, it cannot spin any faster, and all the energy it creates translates as heat, which has a negative effect on the density and charge-properties of the air. A result of this is the boost (air pressure) slowly dropping. On my Audi, the turbo loses efficiency at about 5200 rpm. The boost pressure drops noticably at this point - if you watch my boost gauge you'll notice it drop from roughly 14.7psi (1 bar), down to about 11 psi at 6000 rpm. This is totally normal.

If I were to fit a larger capacity turbo, like an IHI roller-bearing design or Garrett GT28, the turbo would not lose effeciency until much later on in the rev-range. Granted, there will be more time before the turbo spools up, due to the larger volume of air required to 'fill' the turbo. These modern roller-bearing turbos can hold boost well past an engine's peak torque - think of them as the 'Original' turbos offered in the Tuning Village (or whatever you want to call it).


Simple rule:

Small turbo = fast spool-up and little turbo-lag; but loses effeciency early and trails boost early.

Large turbo = slow spool-up and more turbo-lag; but loses efficiency much later and holds full boost longer.


Keep an eye on the boost gauge on GT4, I'm pretty sure the values are quite accurate. Compare the boost-drop between cars fitted with small (or standard) turbos and cars fitted with large 'Stage 4' turbos. Also look when the turbo pressure builds.

Hope this makes sense.
 
hi guys.

I think its a bug not a big one but it is.
in real life boost is slamming at once when you push the pedal.
at least whit my car Ford Escort RS Turbo S1 whit 1.2 bar pressure

im going to buy that car and going to check it out later, i once saw that boost is building up but i didnt remember if it was whit the gt3 or gt4 .
 
Hmmmm. Not quite sure what you're trying to get accross to us, jtc+racer. However, I will forgive you as you obviously wouldn't have read the post I made simultaneously.

I have answered the original question anyway.
 
it's not a glitch it's real life ;] As AJP400 wrote- big turbo = higher rpm on wchich it gives a maximum boost. If anyone of you watched Top Gear in which clarkson was testing Evo 8 FQ400 accelerating from about 80 km/h on highest gear he lost vs fiat palio ;] It's the same thing here ;]
 
AJP400
Hmmmm. Not quite sure what you're trying to get accross to us, jtc+racer. However, I will forgive you as you obviously wouldn't have read the post I made simultaneously.

I have answered the original question anyway.
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Your facts are dead on, but this happens with a larger turbo (stage 4) rather than a smaller one "running out of breath".
 
LandoAWD
Your facts are dead on, but this happens with a larger turbo (stage 4) rather than a smaller one "running out of breath".
Click to expand...

Yeah, I see what you're saying.

Maybe A7X could try taking the Stage 4 turbo off, and see when the boost starts dropping on the standard (KKK03) turbo. In theory it should start dropping much earlier on in the rev range than the Stage 4.

The boost-dropping issue is not a glitch, that's for sure. But if Stage 4 boost drops off in an identical fashion to standard or Stage 1 (or 2 or 3 for that matter) then yes, I suppose we do have a (little) glitch.

A7X - Give it a go and let us know what you find out.
 
AJP400
Yeah, I see what you're saying.

Maybe A7X could try taking the Stage 4 turbo off, and see when the boost starts dropping on the standard (KKK03) turbo. In theory it should start dropping much earlier on in the rev range than the Stage 4.

The boost-dropping issue is not a glitch, that's for sure. But if Stage 4 boost drops off in an identical fashion to standard or Stage 1 (or 2 or 3 for that matter) then yes, I suppose we do have a (little) glitch.

A7X - Give it a go and let us know what you find out.
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It's a glitch, PD did not put things like turbo efficiency or intercooler heat soaking into the game. Another possibility is that TCS or ASM is kicking in, try turning those off and see what happens.
 
jtc+racer
hi guys.

I think its a bug not a big one but it is.
in real life boost is slamming at once when you push the pedal.
at least whit my car Ford Escort RS Turbo S1 whit 1.2 bar pressure
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Turbocharges should NOT be on any Escorts unless they are Cosworths. Too many images of rude-boys in badly modified Mk3 escorts spring to mind... the car is naff as hell anyway, and they somehow manage to make it worse :crazy:

And if you have boost coming on instantly, that must be the worlds smallest turbo... turbo lag exists in real life for sure. You just need to be driving something other than an Escort to notice. And I hope that's 1.2bar ABOVE normal atmospheric pressure... (atm pressure is 1.01325 bar in standard conditions)
 
ChicagoGSX
It's a glitch, PD did not put things like turbo efficiency or intercooler heat soaking into the game. Another possibility is that TCS or ASM is kicking in, try turning those off and see what happens.
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Sorry, you're wrong.

They DID put this feature in the game. It was also in GT3. It varies from car to car (as it would in real life), but you can see the boost pressure dropping off slowly in the high RPMs. It is VERY subtle - you need to keep an eye on the needle. The only turbos that don't seem to lose any boost in the game are the 'Original' turbos.

Take your time, do some research, and get your facts right before making such a bold statement of disagreement. Play the game a bit more, then come back and tell me what you found out. You won't have to apologise if you don't want, that's ok with me.

Oh, and intercooler heatsoak is something completely different, and was never mentioned, so don't get the wrong end of the stick.

RenesisEvo,

Completely agree about Escort RS Turbos, however you may have missed the fact that jtc+racer's car (allegedly) is a Series 1 RS Turbo, which is infinately more rare and desirable. But yeah, it's still an Escort.

And why oh why are there no Cossies in the game??!!! :lol:
 
il check too see what happens when i take the turbo off or fit a normal one so expect a reply soon. i always run with tcs and asm off. AJP400 i you said you can notice a slight drop but with the GTi it is very sudden often dropping down to around zero again. Should have some more details soon.

thanks for the help
A7X

UPDATE: ok i tried all the other turbo's and it appears that they all loose boost at around 4250rpm i think it might be a glitch in this case? also the highest turbo you could put on this little machine was a stage 3 so my bad, but it shouldnt make too much difference right?

A7X
 
Turbo gremlins, maybe?

I would bet they programmed in the efficiency. I would be very interested in an answer to this. But does the performance of the car change at all? like a slow down in acceleration, or is it just a problem with the gauge?
 
read the description under stage4 turbo when you're trying to apply it- it's something about top end rpm power despite loosin tons of tourque in the low and mid range, it's all written there :]
 
We kind of need more information. In what gear are you seing this. Ok, here. Go to the test course with a manual transmission, and put it in a gear where it will at no point spin the tires. from a roll with the revs at about 1500 rpm, punch it and watch your boost guage while it climbs to redline, then PM me or post here what it does. Make sure your tires aren't chirping in the least!

Like you said, with a stage 4 turbo you shouldn't be losing presure at high rpm unles it's regulating the boost for some reason. Which this engine is known to do.

[EDIT]
The "whine" your hearing is coming from the transmission.
 
i remember a couple of cars in gt3 that that would drop extremely fast from 2 to 1bar of boost in about 1.5 - 2 seconds.i think 1 of them was the yaris(pink prize car:))
 
i think he means he turned it up to 100 shot in the options not that he was using it at 100%:)
 
taking the regular stance of regulars against noobies (mind you I hate this particular attitude):

use the search function!!!

gt3 had quite a few cars that did the exact same thing and it was covered extensivly there. try searching gt3's forum and you will find the answer to your problem. :)
 
inferno
We kind of need more information. In what gear are you seing this. Ok, here. Go to the test course with a manual transmission, and put it in a gear where it will at no point spin the tires. from a roll with the revs at about 1500 rpm, punch it and watch your boost guage while it climbs to redline, then PM me or post here what it does. Make sure your tires aren't chirping in the least!

Like you said, with a stage 4 turbo you shouldn't be losing presure at high rpm unles it's regulating the boost for some reason. Which this engine is known to do.

[EDIT]
The "whine" your hearing is coming from the transmission.
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You read my mind! I actually did a little test just now before reading your post, and it was much the same as you suggested:


The test was carried out with 2 different vehicles, and both with the different sizes of turbo offered.

All tests were done on the straight of the Test Course, starting from tickover in third gear at full throttle through to the rev limiter.


Firstly, I started with the Mazda RX7 02 (the one you can buy new). I started with the standard turbo, and found that full boost was reached almost immediately after tickover. The boost dropped VERY SLIGHTLY just before the redline.

Then I tested the Stage 4 turbo. Surprisingly, I found that the gauge indicated full boost being reached at the same point as the smaller standard turbo. However, the boost didn't seem to drop off at all in the higher revs.


The other car I used was a Peugeot 106 Rallye. I first did the test with the largest available turbo - the Stage 3. Full inicated boost was reached at about 2500 rpm, and it dropped off at about 7000 rpm.

Then I tested the smaller Stage 1 turbo. Full boost was reached at an indicated 3000 rpm, and dropped off at about 6000 rpm. Again, surprising.


However, do bear in mind that although the boost gauge may have indicated full boost, there was definately more lag to the larger turbos. Also the torque did noticably decrease in the high rpms with the small turbos.

I strikes me that while the principle of turbo-lag and turbo-efficiency (boost drop) have definately been included in the game, perhaps the values displayed on the boost gauge are not entirely accurate. What does seem accurate (thankfully) is the fact that regardless of what the gauge tell us, different capacity turbos have an accurate effect on the torque curves and power curves of the vehicles.

Granted, this was not an entirely thourough test, so you must consider that it is possible for the vast majority of the vehicles to display accurate boost levels on their gauges.

Maybe the Golf Mk IV Turbo, RX7 and Peugeot 106 Rallye are just an example of the inaccurate handful.


Please feel free to carry out further tests, as this is quite interesting!
(Oh jeez, I am sad!). :lol:
 
i did the test on the test course and it appears that it does it in all gears at exactly the same revs and there was no slipping of the tyres. godzilla gtr was right i didnt use nos it was just turned up to 100 i thought i'd give you all the settings i could as it may help. it isnt a little drop it rises to the highest in the "plus" area (don't know how many bar that is and drops very quickly back down to zero bar boost as in by red line it is at zero boost. There is absolutely no change in the acceleration of the car as it may had the turbo boost dropped, it appears to just be the guage. i havent tested any other cars although when i was looking through the gt4 bugs page someone mentioned opels and volkswagons doing this but no one answered. im just curious as to whether it is a glitch or it is supposed to happen

Thanks all for your reply's and il keep investigating

A7X
 
A7X
...
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Droping back to zero presure? Hmm, this is starting to sound like a bug. Not only because you would notice a significant drop in performance, but you have to figure this is a game. everything is supposed to work properly. I cant think of any reason for a properly functioning turbo setup to behave that way, so I'm leaning more and more towards "glitch". See, my origional thought was that some how the standard boost characteristicts got carried over to the stage 4 turbo, because the 1.8t engine is known to regulate boost. thats how the torque curve runs so flat. it's a relativly large turbo for the amount of boost it makes, which isn't much. Peak boost is reached about 2500 rpm. then the waste gate opens and holds the boost at that level even as the turbo continues to spool more. the result is peak torque available from 2500 rpm to 4500 rpm. A similar phenomena occures in the high rev region with peak hp available through a wide spread, which would indicate a droping torque curve and fast droping boost to cause it...

wait, the mk IV golf. Is that the new one or the old one? Umm, ok I feels stupidid nows.

[EDIT]
Anyway if it is the new golf were talking about, That was my origional theory but the boost would never taper that much for any reason unless something was wrong. So I'm saying it's a glitch with the boost guage.
 
Funny I thought that higher gas temperature led to higher pressure, according to some physical law or another (something like Pressure = Volume x Temperature).

I would think that turbo pressure would be more likely to decrease at higher revs because the engine is draining the inlet charge faster and the turbo can no longer maintain maximum pressure. The Volvo T4 I drove for a while 9not in the game) sure felt like the torque dropped off as the rev peak was approached, and turbocharged engines are rarely high revving screamers.

Then again I'm no expert on turbocharging. It's all just conjecture.
 
I noticed this also with the Opel Speedster turbo. Put the biggest turbo (stage 2 or 3 i think) on it and it loses all boost by redline :P seems fairly pointless having a turbo if it's not making masses of air at engines peak power, especially if it's a modified one, but the Audi TT did the same thing in GT3 (i assume it also does it in 4)

Edit - No, hot air = less dense
Cold air = more dense
u will notice (in real life) that your car runs smoother on a cool night or morning than a hot one (less detonation etc) even if it's naturally aspirated :)
Thats also why u use an intercooler to cool the air :P
 
I would think that turbo pressure would be more likely to decrease at higher revs because the engine is draining the inlet charge faster and the turbo can no longer maintain maximum pressure.
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Yes, this is verry true. thats why hp usualy drops off in the higher rev region with turbo cars. but as mentioned, he's running a stage four turbo. So no shortage of breath there.
 
inferno
the 1.8t engine is known to regulate boost. thats how the torque curve runs so flat. it's a relativly large turbo, for a 1.8
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Not true.

Your other points about the 1.8T engine are close enough, but to say the standard turbo on these engines is 'relatively large' is a bit far from the truth, to say the least.

I have the same 150 BHP (Well now it's 203BHP after a remap 👍 ) in my 96 Audi A4 1.8 Turbo Sport. They use Borg-Warner KKK03 turbos in the 150 BHP models, such as the Golf mk IV GTI Turbo. Trust me these turbos are TINY! Even the K03S, or K04 turbos (used in S3, TT) are small.

Maybe they are relatively large, but only in comparison to a yo-yo!!!

(For anyone who doesn't know, the 1.8T is used by Audi, VW, Skoda, Seat, etc etc).

Trust me (and yes, I'm being very big-headed here), I know alot more than most of you about the 1.8T. I spend my life (and my life savings!) tuning these engines.
 
Have we got any data on the power / torque curve or anything like that off this problem car?

If the power curve in game indicates a late peak in power and quite a norrow power band then its totally at odds with the boost gauge.

Press start in the settings menu for the car, and take a piccy.
 

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