The Drag Tuning Bible -- v4.1 - September 2012

[GT350GT]

It's pretty simple, not too much obviously, when I've added you, I'll ship one over for you to see

 

[dr_slump]

Just deleted someone from my friend list, the 100 friends limit is annoying, you know.

You'll ship one over? Oh that would be excellent! 👍

 

[Slash]

Great work on the guide slump.

 

[Rotary Junkie]

I'm so confused.

Dampers do nothing to the Aventador I decided to toy with... It's still full weight but running automatic for consistency's sake (every run will be the same) no change in damper settings, front or rear, made even 0.001s difference anywhere through a full mile run.

Oh, and yes. I was wrong, we do have a full mile run, and the 1/4 mile is an actual 1/4 mile/402m. Driving options has a switch between miles and kilometers, which switches from 400m/1000m to 1/4 mile/1 mile.

 

[dr_slump]

I'm so confused.

Dampers do nothing to the Aventador I decided to toy with... It's still full weight but running automatic for consistency's sake (every run will be the same) no change in damper settings, front or rear, made even 0.001s difference anywhere through a full mile run.

Oh, and yes. I was wrong, we do have a full mile run, and the 1/4 mile is an actual 1/4 mile/402m. Driving options has a switch between miles and kilometers, which switches from 400m/1000m to 1/4 mile/1 mile.

Always thought that dampers don't make a big difference on a super flat track.

But maybe it's just the car? Did you try another one?

 

[Rotary Junkie]

Every car I've tried so far has changed by, at most, one thousandth of a second.

 

[dr_slump]

Hmm, it could mean that dampers don't affect the max. traction.
They only come into play when the car drives over bumps. The faster you go the more dramatic it is. So I guess you'll only notice a big difference, if at all, when tuning for a longer distance, like tunnel was/is.
Because the tarmac of these tracks is so damn even.

 

[articzap]

Hmm, it could mean that dampers don't affect the max. traction.
They only come into play when the car drives over bumps. The faster you go the more dramatic it is. So I guess you'll only notice a big difference, if at all, when tuning for a longer distance, like tunnel was/is.
Because the tarmac of these tracks is so damn even.

Dampers in real life effect the 60 foot heavily. I've noticed the Dampers effecting my 0-60 mph times.

 

[Rotary Junkie]

Dampers in real life effect the 60 foot heavily. I've noticed the Dampers effecting my 0-60 mph times.

Indeed... But the change is extremely small even then from what I've seen so far.

Actually there's something...

If I drop the spring rate on my GT-R, it will launch "harder" (higher max. G-force) but by 60mph it's down a few thousandths, and by the traps it's down about a hundredth.

Makes zero sense considering the higher g-force indicates stronger acceleration at launch due to greater traction... At minimum one would expect the 0-60 to improve.

 

[savage388]

Indeed... But the change is extremely small even then from what I've seen so far.

Actually there's something...

If I drop the spring rate on my GT-R, it will launch "harder" (higher max. G-force) but by 60mph it's down a few thousandths, and by the traps it's down about a hundredth.

Makes zero sense considering the higher g-force indicates stronger acceleration at launch due to greater traction... At minimum one would expect the 0-60 to improve.

Well if there is a little bog from more traction then it'll launch hard initially then the rpms aren't high enough to keep the car accelerating like that.

 

[Rotary Junkie]

Well if there is a little bog from more traction then it'll launch hard initially then the rpms aren't high enough to keep the car accelerating like that.

That's the thing though, it pulls higher Gs but seems to spin more if anything.

 

[ReVoLuT1oN]

From testing at Route X, I found toe actually made me slower... at least from the cars I tested.
At the 1/4 mile.

 

[savage388]

That's the thing though, it pulls higher Gs but seems to spin more if anything.

Hmmm, the g meter seems kind of tricky. My ACR sees highest g's in 2nd gear of 1.29

 

[Beastcochito]

Great update slump +1

 

[Rotary Junkie]

From testing at Route X, I found toe actually made me slower... at least from the cars I tested.
At the 1/4 mile.

Same... In fact, it had a similar effect to the softer springs I've tried on my GT-R; higher launch Gs but slower to 60 and onward.

Hmmm, the g meter seems kind of tricky. My ACR sees highest g's in 2nd gear of 1.29 while my stock zo6 pulls 1.57! On sports softs.

Now that is very odd.

My Aventador pulled the same launch Gs with bolt-on power mods only at almost full weight (1565kg) as it did fully tuned... So it's 99% traction... Unless your Z06 is being a little funny with how it actually launches, in which case drag tuning will be a game of figuring out who can duplicate that for as long as possible.

Edit: You pulled the bit about the Z06, why?

 

[savage388]

Same... In fact, it had a similar effect to the softer springs I've tried on my GT-R; higher launch Gs but slower to 60 and onward.

Now that is very odd.

My Aventador pulled the same launch Gs with bolt-on power mods only at almost full weight (1565kg) as it did fully tuned... So it's 99% traction... Unless your Z06 is being a little funny with how it actually launches, in which case drag tuning will be a game of figuring out who can duplicate that for as long as possible.

Edit: You pulled the bit about the Z06, why?

I tested it again and saw more normal results. Either it was a fluke or I was thinking of the wrong car. Memory jumble I guess.

 

[ReVoLuT1oN]

I tested it again and saw more normal results. Either it was a fluke or I was thinking of the wrong car. Memory jumble I guess.

I noticed some "flukes" too. Racing on Auto transmission in AWD cars, I saw difference in times of up-to 0.50ms - on same setups. Not sure what's causing this.

 

[dr_slump]

Dampers in real life effect the 60 foot heavily. I've noticed the Dampers effecting my 0-60 mph times.

I'm not talking about real life.

Indeed... But the change is extremely small even then from what I've seen so far.

Actually there's something...

If I drop the spring rate on my GT-R, it will launch "harder" (higher max. G-force) but by 60mph it's down a few thousandths, and by the traps it's down about a hundredth.

Makes zero sense considering the higher g-force indicates stronger acceleration at launch due to greater traction... At minimum one would expect the 0-60 to improve.

The g-force value only shows the peak. If there were a graph (isn't this a great idea?) you could see why.

I noticed some "flukes" too. Racing on Auto transmission in AWD cars, I saw difference in times of up-to 0.50ms - on same setups. Not sure what's causing this.

Because you rarely launch at the same rpm.

Hmmm, the g meter seems kind of tricky. My ACR sees highest g's in 2nd gear of 1.29

Now that is very odd.

My Aventador pulled the same launch Gs with bolt-on power mods only at almost full weight (1565kg) as it did fully tuned... So it's 99% traction... Unless your Z06 is being a little funny with how it actually launches, in which case drag tuning will be a game of figuring out who can duplicate that for as long as possible.

Edit: You pulled the bit about the Z06, why?

The mistake you make is to think that the g-force in starting gear is constant (or at least almost). The g-force only shows the peak, the absolute maximum.
The average g-force in first gear is actually much lower.

 

[Rotary Junkie]

The mistake you make is to think that the g-force in starting gear is constant (or at least almost). The g-force only shows the peak, the absolute maximum.
The average g-force in first gear is actually much lower.

I realize perfectly well that it's a measure of peak Gs.

However, a higher peak indicates, at minimum, the possibility of holding a higher average.

 

[dr_slump]

I realize perfectly well that it's a measure of peak Gs.

However, a higher peak indicates, at minimum, the possibility of holding a higher average.

Possibility.......yeah, lots of things are possible.

 

[bigbear]

Very interesting write up dr_slump. I've been doing a lot of testing lately and would like to share some findings. My tests were performed using a Chev Camaro Z/28 '69 at S.S.R.X. The car has 565 supercharged HPs and full weight reduction.

First: It seems you can achieve consistent results with automatic transmission for developing your setup. When the screen is black (loading) hold full throttle and keep it there. I was able to run the exact same times run after run this way. If it works for you it can help take the guess work out of tuning.

Second: I made 15 passes with 3 Diff setups (stock, custom5/5, custom60/60) and each run was exactly the same.
0-60......3.036
0-100....6.127
1/4Mile.10.816
MaxG.....1.04
My feeling with GT5 is that the Diff only effects traction when turning. In a straight line it seems to have no effect. So on S.S.R.X the Diff setting doesn't matter.

Third: My fastest run was with both Front and Rear ride height at +45. Lowering the front ride height should put more weight on the front axle and decrease traction for a F/R car. I'm not sure how this effects in-game performance but setting the ride height all the way up worked for me.

 

[kennyblanco]

I had the same results with the lsd settings. There were no changes between using different settings. I plan to test more thoroughly, but for right now I have to agree that lsd has no effect on drag set ups.

 

[dr_slump]

Very interesting write up dr_slump. I've been doing a lot of testing lately and would like to share some findings. My tests were performed using a Chev Camaro Z/28 '69 at S.S.R.X. The car has 565 supercharged HPs and full weight reduction.

First: It seems you can achieve consistent results with automatic transmission for developing your setup. When the screen is black (loading) hold full throttle and keep it there. I was able to run the exact same times run after run this way. If it works for you it can help take the guess work out of tuning.

True, but I often see 4 different types of consistant times. A rare super fast one; one that looks as if it's fast, but it's not; a slow one; and a super slow one.
It really depends on your tune.

Second: I made 15 passes with 3 Diff setups (stock, custom5/5, custom60/60) and each run was exactly the same.
0-60......3.036
0-100....6.127
1/4Mile.10.816
MaxG.....1.04
My feeling with GT5 is that the Diff only effects traction when turning. In a straight line it seems to have no effect. So on S.S.R.X the Diff setting doesn't matter.

Seems so.

Third: My fastest run was with both Front and Rear ride height at +45. Lowering the front ride height should put more weight on the front axle and decrease traction for a F/R car. I'm not sure how this effects in-game performance but setting the ride height all the way up worked for me.

Did you use downforce?
I guess you did.

 

[Rotary Junkie]

True, but I often see 4 different types of consistant times. A rare super fast one; one that looks as if it's fast, but it's not; a slow one; and a super slow one.
It really depends on your tune.

I'm noticing that depending on what point in time you hit the gas after starting the run, your launch is affected.

WFO from the moment you press the start button will always run the exact same time, playing with it from there will either make you quicker or slower.

Seems so.

It doesn't actually affect traction per-se either. It only changes how much of a difference in wheel speed is allowed by the diff. For SSRX and SSR7, you generally won't run into noticeable loss of grip with the diff maxed out (60/60/anything) due to how slight the turns are, and will be able to hold a higher speed through said turns with said maxed diff.

Did you use downforce?
I guess you did.

So downforce is the deciding factor as to whether nose-down provides more traction or not? Or is it that the higher front only works with downforce?

Certain cars I've played with don't seem to care where the front suspension is set at all in terms of launch grip... They only care about spring rates and rear ride height.

 

[dr_slump]

So downforce is the deciding factor as to whether nose-down provides more traction or not? Or is it that the higher front only works with downforce?

Certain cars I've played with don't seem to care where the front suspension is set at all in terms of launch grip... They only care about spring rates and rear ride height.

A car with 0 downforce usually works best with front down.
He said that max/max gave the best result, so my thought was that he used downforce.
Of course, it could be something special, but this above is in the most cases true.

Downforce and front ride height play hand in hand.

 

[Rotary Junkie]

Ah, hmm.

Stop making me test so much stuff.

 

[dr_slump]

Ah, hmm.

Stop making me test so much stuff.

That's the reason why every good tunnel ACR has front up (as example).

 

[Rotary Junkie]

That's the reason why every good tunnel ACR has front up (as example).

Well I know front-up helps top-end but the question was whether nose-down helps launch by enough to make it worth it without downforce.

Answer is yes, kinda. It results in a net gain over the 1/4 with a downforceless car but from 60mph out it's losing to max/max. I'd say over pretty much any distance over 1/4 mile, max/max > min/max.

 

[dr_slump]

Well I know front-up helps top-end but the question was whether nose-down helps launch by enough to make it worth it without downforce.

Answer is yes, kinda. It results in a net gain over the 1/4 with a downforceless car but from 60mph out it's losing to max/max. I'd say over pretty much any distance over 1/4 mile, max/max > min/max.

Depending on speed, downforce number, springs and rear/front height difference.
👍

 

[bigbear]

I don't have any additional downforce on the car.

Just to reiterate: During acceleration testing,if you go full throttle before the car shows up (any time while the screen is black) you should run consistent times. The car will launch at the same rpm because it revs up the same everytime.

After further tuning I was able to get Min/Max ride height to work well on the '70 Charger and '71 'Cuda. I had to use very different spring rates between the two (no downforce on either). But I still can't get Min/Max ride height to work on the Camaro.