Hey guys,

I am in process of building my A4 C5 for track, aim is to hit low tens

440 ls7 short block
Ls7 CNC Peted heads (11.7 compression)
Cam is 248/260 660/672 on 111lsa
102mm fast intake
102mm throttle body
Haltech super bee CAI
60# fast injectors
AR-long tube headers & off road x-pipe
Electric exhaust cut-outs
QA1 18 way adjustable shocks

I wanted experts advice/opinion on the fallowing

-Rear Tire/wheels size
-Rear end diff ratio size
-Best shocks adjust/setting in order to get the best track results
-Torque convertor stall (I've been recommended to go with the 4200 stall)


Appreciate your feed back
Thanks

 

My car is similar, but I have a 427. Runs 9s

3.73 rear. 4500 stall

28" M/T bias with skinnys up front.

If you don't hit low 10s, you should burn your car to the ground.

Good luck and have fun.

 

Automatics like radial tire more then a stick does.

You have to decide what size tire/wheel you want to run. Capthuff and I are both running a 15" wheel on Bogart rims I have 26 and 28" tall tires the taller one I haven't tried as of yet, I plan on spraying with them and haven't gotten to the track yet to test them out.. I am running Hoosier drag radial tire and cut a decent 60'.

373 gears in both the 346 and 382 Ci motor...

Both of my cars (10 sec street), I am running a stock shock.

The 382 car has 1.34 - 60's
The 346 car has multiple 1.36 - 60's

3600 and 4000 stalls here.

******************************8

I think you can run 9's N/A with that setup in good conditions - have fun!

 

Sir I have an 04 C5 6 speed 373 rear, slight street & a good tune, a DD
12.0s-1250s consistantly, with slicks 1190s. First learn how to drive your car. with some left seat time 950s would be norm.at that speed stuff happens quick. if you feel anything abnormal first thing pull foot off go pedal brakeing can destroy you & car

 

Lol, agree on that
I was kinda hesitant to say.. I wanna hit 9's
But I'll be more than happy if I'll be hitting low tens

Btw, have you reduced the weight?

 

I haven't decided which wheels/tires to go with, I used to use the stock F-body wheels 16"
Now am leaning towards the new weld's due to their reasonable price, look and weight.
Now I wanna know.. What size wheels and tires of I wanna go with the weld!

 

Definitely a 9 second car.

 

9 second requires a lot more than HP & torque
It's a lot of rims/tire to rear end ratio calculation that is driving me crazy lol

I need experts recommendation on which wheel/tire size to use that woks the best with the ratio

 

My car is pretty light. 3150 with me in it.

There's guys having good success with the M/T 275/40/17 drag radial, but I'd still suggest something s bit different.

With a bit of messaging, you can get the 16" wheels to fit. Weld does sell a 17" front and rear wheel set up that's certainly good enough. Although, 16" rears are a better option.

Your tire diameter will be determined by your rear ratio.

I would suggest 3.73 and a 28" tire.

Will your car see a lot of street time? If so, I wouldn't go any higher than a 4000 stall converter.

If you go with a dedicated drag pack (which I highly suggest) look at the 28x16 Hoosier QTP for the rear and a 17" bias ply front skinny. That'll be one of the lightest combos available.

Best of success with your project.

 

 

A lot of useful info's... Thank you
Will try to get the 16's welds for the rears
What about the width of the wheel?

Btw, that's an amazing pic

 

I think 16x10 is pretty standard.

 

I think you have to buy new spindles if you want to run 15" wheels. I run 16" CCW classics. The 15" are better as there are more bias-ply tire options. On the 16" Im stuck with the MT ET Street tires. They are great, but I'd love to get a set of ET Drag ties on someday. Need 15" rims for those.

Tires, gears, and stall, along with the supporting mods to handle the power will play a more important role than all that power you will be making. You will want at least 3.73 gears, a minimum of 4000 stall, and some real bias-ply tires like the Micky Thompson ET street. I dont know why anyone would want to run a radial tire??? The ripple effect of a bias-ply is hands down a better launching tire. Radials inherently have a stiffer sidewall don't they? The ET street on a 16" is weak, but far better than a radial tire will do. The 15" and lower wheels allow tires with some real ripple potential. But the stock C5 spindles only allow so much.

I have taken to using Pfadt's drag specific coilovers. The adjustability allows a lot of front end lift and rear end squat. Consider looking into them or the like.

I highly recommend solid mounts and a trans to diff brace. Auto's are generally easy on the drivetrain, but, that is getting into serious power and a high stall like that is still going to hit hard. Ive never had a problem with wheel hop since I installed a solid tans mount. Im sure you are aware of the need for stronger shafts in the differential and maybe even trans.

 

Yeah, agree that the power is not the only thing that will take me to my goal. As for now..
Tranny will be converted to the 4L80
Will use the 4.10 rato
Shocks are adjustable QA1 and I don't know how to adjust them lol, stiff the rear or...
I don't wanna go 15's, Id rather stick to the 16's from weld wheels.
What is your exact tire size?
Any suggestion to reduce weight? I don't wanna go crazy as others
Am looking for normal weight reduction.

 

My ET's are 26"x11.5". The fronts are 5x5.25? Not sure what that means.. thats what they say. But they are skinnies. I think they are a motorcycle tire to be honest.

You want to loosen the front suspension for lift, and go fairly tight in the rear for stability.

For weight reduction I do go a little crazy. Here are some ideas. All are simple to remove and replace, and the process gets quick as you get use to it.
I run without interior. I leave it out even though its my street car. But all pieces are easily replaceable. I remove both stock seats and put in the one Sparco racing seat I have. The CCW's I swap on are a 3-piece light weight design. I run Borla straight pipes from the axleback to remove the 40+ lbs of mufflers (they stay on). I remove the front swaybar as its not needed, things like the widow wash reservoir, hoodliner, rubber seals, etc, etc. The torque converter I chose is a billet one weighing 20 lbs lighter than stock! Even the solid trans mount deletes the heavy vibration damper on the diff and stock mount.

There are tons of things you can do for reduction. The K&N intake, crappy BBK shorties I have on there, and other modifications all add up in weight reduction too. The Pfadt coilovers are light, reduce unsprung weight further, and remove the leafsprings. I could go on with all the areas that I have reduced weight.

 

WAW!
That's what I call useful info..
Thank you NUKE C5, now am almost done with my set up. I was stuck with the wheels/tires thingy.
The sway bar idea is cool. I'll be tuning with no muffler (just the headers and X-pipe)

 

I have QA-1s on my car front and rear. single adjustable.

In the pic I posted, I had the fronts on 6 and the rears on 4. That was a 1.40 60' ran 9.90@130 lifting in order not to break out on a 10.0 dial... didn't work out too well...

My front sway bar is removed.

It's a track only car, so I have a lot of other stuff removed too. A/C and ABS - no power steering - manual brakes.

The front sway bar is not heavy at all - mostly it's removed to allow more front end travel.

I wouldn't worry about getting the car really light this early in the game. Run the car a few times and figure out what it wants. Then on a good DA day, pull everything out and let-r-rip!!

 

How do the QA1's adjust? Do you count the clicks from full stiff? Or from full soft? Pfadt calls for adjustments from full stiff to soft. For example in the front they recommend 20 clicks down from full stiff and rear 16 clicks from full stiff. I usually go the full 26 clicks in the front and around 10 in the rear though. That lets the front lift more and the rear stays a lot more stable.

Just wondering if the 6 and 4 means you are that many clicks away from full stiff or from full soft? I would imagine soft correct?

 

Yeh. Starting at full soft.

 

So you run even softer in the rear. Interesting. I have to give that a try.