Help Me Lower My Short Time

[Scoobum]

Thot this would be a good thread for advice and tips from guys like SW, PACECARTA, Joebuick and Nocooler who have been at it with these cars for eons.

I managed to get my short times down into the high 1.5's. I'd like to lower it to low 1.5's to high 1.4's...off the footbrake.

Here's what I have to work with:

Stock front sway bar
Line lock
All long rear pads
90\10 front shocks
Stock front/rear springs
QA1 single adjustable rear shocks...curre ntly on the number 2 setting
ATR rear bar
Metco billet LCA's
Choice of 28x9 and 28x10.5 slicks...and I'm open to suggestions for tire pressures on the 9 and 10 inch slicks.

[Scoobum]

There's a pair of air bags in the rear coils that are coming out...and a new pair of UMI non adjustable rear upper control arms that have arrived with new bushings to be installed as well.

[TexasT]

All i  have is pull the front sway bar and maybe go to a 70/30 front shock to see how the car acts. If it is unloading the rear with too much front lift and the front coming back down the 70/30 or something adjustable might keep rear planted. Have you considered moving the battery to trunk? Or a light battery in the front? Any other nonessential weight you can remove?

[Scoobum]

Front weight removed has been the air con...with the heater box left intact. Front rims weigh in at 9.5 lbs each. F body rad swap. ATR front fiberglass bumper. LT1 starter.

[Steve Wood]

First...it takes horsepower to make a good short time better.   Second, you have to get the hp to the rear tires as quickly as possible.  I am probably wrong, but I still think that converter is a bit "soft" for your turbo/combo.  Seems like a bit tighter converter or a size bigger turbo would help. 

Battery in the trunk, lighter front end, skinnier driver...all that stuff helps because it is simply physics.

Speaking of physics, a set of drops on the lower bars will make it hit the tires a lot harder...make you launch like a '60's super stocker..but a set of these will make the launch more controllable allowing you to feed more hp to the tires without getting crazy off the line.   http://www.baselinesuspensions.com/kits/chevy.htm

What most forget is the part that it takes hp to leave fast and physics to control it.

You are fast enough that good two way shocks and some patience to dial them in will help dial the "hit" in.  You need a launch pad where you can play with it...

[Scoobum]

The 6466 turbo is the next step up...but it's only available in a DBB version...whic h chimes in at $2500 Canadian after exchange rate...shippin g etc. I noted that the convertor is around 3400 to spin it...which is another $1500 Canadian for a PTC unit from Dusty...after exchange rate, shipping etc. If you wonder why I'm the only one racing one of these cars up here every weekend...you're getting the idea why. I have cash set aside to get the transmission 'toughened' up...and for the fuel upgrades. I'm gonna have to work with the suspension I have.

[Joe Buick]

How much Boost can you hold at the line! I remember back in the 90's I start using the Hand Brakes to Launch. Damn... it was crazy launching at 15 - 20 psi..
How much are you launching at?

[Scoobum]

I'd have to check. Convertor flashes to 3800 leaving the line. I can hold any RPM I want.

[good2win22]

I installed the baseline pro kit, ordered the door slammer book and went to the scales.  I'm not making near as much power as you and I'm launching in the high 1.5's now.  The key with the baseline kit is the bracket that moves the upper control arm attaching point rearward.  It shortens the length of the upper control arm allowing for a lesser angle thus moving the instant center closer to the CG. 


I am still running stock length lowers with poly bushings from UMI.


http://www.ihadav8.com/forum/index.php?topic=4694.msg66519#msg66519

[Scoobum]

I'm gonna drop the front sway bar and pull the rear air bags...for a start. I pretty much have the track to myself on Mix N Match evenings...so we'll try different things...and report back to make adjustments for the next outing. I won't be making an all out assault till our Thanksgiving weekend...so there's plenty of time to dial it in.

[TexasT]

I mulled it a bit and I think 28x9 is plenty of tire. The larger one just takes more power to haul it on the top end. Really a 26 tall might get some in the sixty but give up some at the big end so I'd stay with taller, especially at your power level. The taller loads the turbo up. Have you considered a 3.23 or 3.08 gear? Might be something to play with on one of the desktop dyno programs.

[good2win22]

My next purchase is a pair of 28x9's

[Steve Wood]

the length of the patch is often more important than the width of the patch..thus the taller tire provides more grip.  Once our cars are well into the twelves, the taller tire will usually give better short times and better mph.  The additional loading provided by the effectively taller gearing will load the turbo better making more heat and better spool.

[motorhead]

You need to work on your instant centre.

[Steve Wood]

You need to work on your instant centre.

into Zen, eh?