Drag Racing Mythbusters Edition

[jezboosted]

So I'm sure you guys have heard it all, certain things slow you down and other things are better.
Well here is the thread where I (and others if the testing is thorough) will aim to put those theories to rest.

Mythbusting Part 1

My test car is a Audi RS6 Avant 08'. My drag tune uses an automatic transmission which isn't the fastest but after 10 runs back to back giving exactly the same time I am happy to use it as the test mule.

So here is its time running automatic trans with stock wheels, stock body and no wing.



Next test is running the car with its premium bodykit which some people have claimed increases downforce and will therefore slow the cars down.



Next test is still with the bodykit on and now those expensive rims (eg; Boyd Coddington F-09) that cost twice as much as the others and apparently have a performance benefit.



Now this test includes all of the above bodykit, wheels and now the custom wing set to minimum downforce level of 5



So there you have it - Myths Busted!

Next up I will be looking at chassis stiffening, the myth that a painted carbon bonnet is quicker than a raw carbon bonnet and more.

Stay tuned !

Mythbusting Part 2


Now chassis stiffening is something I will have to explore in more detail at a later date as information from the community suggests that this feature might be something that works on older chassis based cars, not the unibody type we have today. It's possible that it mainly affects the cornering capabilities and that it serves no purpose in drag at all. So I fitted the raw carbon bonnet which made no difference and neither did the chassis stiffening.



Next in the test cue is the Centre differential torque distribution between front and back. Generally 45:55 is the rule of thumb but it shows that there are differences even 1 click away. This was set at 44:56.



I tried everything from 40:60 to 50:50 and 44:56 and 42:58 were the only two settings that actually improved the time by .001 of a second. Nothing to get excited over but it shows there is definitely an improvement.

This next one really surprised me.

Generally you would just assume that the triple plate clutch kit being the most expensive and the last option is the best way to go. Well, the cake is a lie !! This test was ran with the Twin Plate Clutch Kit.



WTF right ? yep ! I ran multiple passes and switched back and forth from the twin to the triple and the results are solid. For this vehicle in this circumstance, a Twin plate clutch is the faster option. It must have a higher rotational mass as what I saw against my ghost is that I pulled away from the line faster till about midtrack and then the ghost was slowly crawling its way back. It wasn't enough to catch the twin plate though !

 

[Simple Matt]

Interesting about the twin plate clutch..

 

[jdiaz092009]

Excellence job bro!!!

 

[Mikeybc]

Nice, the down force thing has me stumped though, on my NASCAR's it does affect handling and top speed. Maybe try a premium car ?

I tested the torque split and 50/50 was the best option, but just like you said. .001. Interesting enough I too used the RS6

Good find on the twin plate clutch, should to run them online with the same tune.

 

[jezboosted]

Audi RS6 Avant 08' is a premium car. I think the reason why it is not noticeable over the drag distance is that its only going from 0 downforce to 5 whereas a Nascar might have a minimum of 200-300.

Your finding on the torque split could be to do with running a different tune with manual. I guess you are doing a 1-2 quickshift whereas my auto rides out 1st on a longer gear. The important thing is now its all open for accurate testing per tune.

The twin plate clutch could be something that is only noticeable on a BSL.

 

[Mikeybc]

Audi RS6 Avant 08' is a premium car. I think the reason why it is not noticeable over the drag distance is that its only going from 0 downforce to 5 whereas a Nascar might have a minimum of 200-300.

Your finding on the torque split could be to do with running a different tune with manual. I guess you are doing a 1-2 quickshift whereas my auto rides out 1st on a longer gear. The important thing is now its all open for accurate testing per tune.

The twin plate clutch could be something that is only noticeable on a BSL.

What the hell was I thinking ? yeah of course it premium

Think I was running an auto trans using BSL when trying torque split. Though a manual trans will walk away from the auto up the track.

I see your point on the downforce thing too 👍

It would also be interesting to see what peoples cars currently run before fine tuning on the test track.

 

[jezboosted]

👍 The 3 examples I posted are just straight from Indy except for the RS6 which I did the mythbusting on.

Would be great to get people to post their indy times first and then begin the tuning.

 

[FastFurious77]

Twin plate clutch. Damn usually 3 is better than 2 but we're not talking about girls here sooo sure I'll jump on and test my RS6 now and post it. 0.001 for the torque split. This is interesting as my cars were already usually set to 42:58, 48:52 or 45:55. Yeah their probably is't enough down force to cause a big effect unlike racing cars which have huge amounts.

 

[The Chosen One]

Could your try and see if it's faster having an FR with CH/RS than with RS/RS?

 

[levitt1991]

Could your try and see if it's faster having an FR with CH/RS than with RS/RS?

It used to be, pretty sure it got patched a few updates ago though

 

[Mikeybc]

I tried CH on front, times being the same or a little slower , but only by a couple thousandths of a second or so IIRC, I do remember going back to RS immediately after.

 

[jezboosted]

CH tires really just help keep a car straight is all I have found.

 

[Denezin]

Def gonna try the twin plate. Thanks!

 

[jezboosted]

Def gonna try the twin plate. Thanks!

Only works on some cars and only when doing a Bsl

 

[Denezin]

Only works on some cars and only when doing a Bsl

It worked for the Shelby 350R im gonna run through and see which ones it does and does not work on, I wonder what other things would help. Gonna test that next! Thanks again!

 

[DolHaus]

On the subject of twin vs. triple plate I suspect the key factor is power (and weight to an extent).

Good testing structure though, gives easily repeatable results which is the nearest we can get to proof. I think you might need to do some further testing/isolating of factors to get completely indisputable results but you're on the right track 👍

 

[jezboosted]

On the subject of twin vs. triple plate I suspect the key factor is power (and weight to an extent).

Good testing structure though, gives easily repeatable results which is the nearest we can get to proof. I think you might need to do some further testing/isolating of factors to get completely indisputable results but you're on the right track 👍

Thanks alot @DolHaus, it's nice to have some feedback from a tuner with your expertise. I have been too focused on running the GT6 drag leaderboards but will endeavour to continue on with testing.

 

[eran0004]

Is the flywheel heavier with the double plate clutch than with the triple plate?

If it is, then perhaps the increase in energy from the heavier flywheel could explain the improved acceleration from a standing start?

 

[jezboosted]

Is the flywheel heavier with the double plate clutch than with the triple plate?

If it is, then perhaps the increase in energy from the heavier flywheel could explain the improved acceleration from a standing start?

What is interesting is that you can take another high powered AWD car and it has no benefit at all from the twin plate clutch. The other thing too, is that the benefit is only there if you do a black screen launch (holding the accelerator down during the black loading screen and not releasing it at all through out the run).

Note: For those that are not seeing any form of consistency or repeatable results, try doing a BSL.

 

[DolHaus]

Is the flywheel heavier with the double plate clutch than with the triple plate?

If it is, then perhaps the increase in energy from the heavier flywheel could explain the improved acceleration from a standing start?

It is described as heavier than the triple plate (both are lighter than stock)

A heavier flywheel maintains its kinetic energy better due to the increased mass so less rpm is lost during shifts but it takes more energy to make it spin in the first place so reduces the amount of energy that is transferred to the wheels.

What is interesting is that you can take another high powered AWD car and it has no benefit at all from the twin plate clutch. The other thing too, is that the benefit is only there if you do a black screen launch (holding the accelerator down during the black loading screen and not releasing it at all through out the run).

Note: For those that are not seeing any form of consistency or repeatable results, try doing a BSL.

Try limiting the power until you find a changing point

 

[eran0004]

A heavier flywheel maintains its kinetic energy better due to the increased mass so less rpm is lost during shifts but it takes more energy to make it spin in the first place so reduces the amount of energy that is transferred to the wheels.

Indeed, during the latter part of the acceleration when rpm is climbing, the flywheel is absorbing some of the energy produced by the engine. But when you start from standstill you get to charge up the flywheel (by revving the engine) before you actually set off, so some of the energy used to accelerate the car is produced already while the car is stationary. And the heavier the flywheel, the more energy it stores.

Basically, whenever the rpm drops, the flywheel is pushing the engine. Whenever the rpm climbs, the engine is pushing the flywheel.