Corvette C4 questions about TT3

[jimbow]

I'm going to be specific, please help me out to make sure I haven't mis-read anything.

Using the 2012 weight tables:

3500 lbs = +.3 mod factor

3400 lbs = +.15

3300 lbs = +.05

 

Using the 2012 tire tables:

275 DOT = +.4 mod factor

 

Now here is where I need the help

TT3 = 9.0 lb/hp

 

3500

9.0 -0.7 = 8.3

3500/8.3 = 421 rwhp

 

3400

9.0 -0.55 = 8.45

3400/8.45 = 402 rwhp

 

3300

9.0 - 0.45 = 8.55

3300/8.55 = 385 rwhp

 

Did I do the calculations correctly?

 

On my TTA sheet I have a 1pt mod for a cut air filter cover - do I need to find an OEM replacement to keep me out of the aero penalty box?

 

TT3 means I can go coilovers, fix some of the suspension "anomalies" with no mod points?

One of the suspension fixes is to go to different dogbones (basically strut rods) and camber beam (replaces with a rod as well). I'll find a link to it. http://banskimotorsports.com/C4_Rear_Suspensioin.html

 

Good news none of this requires cutting, or otherwise changing mounting points.

 

Now for the big question:

The stock C4 is one of the strangest animals when it comes to front camber.

You can get eccentric busings/bolts for the lower control arm, but once you remove all the shims from the upper control arm mount there is no more adjustment.

 

There are adjustable upper control arms available - would these also be usable with no mod factor?

 

TIA!

Edited October 11, 2012 by Guest

[kbrew8991]

Looks good to me on the calcs. You might want to not cut it quite so close with just a 0.01 buffer but that's up to you

 

Suspension and alot of other things become pretty wide open with an ST type ruleset.... some limitations but usually takes a sawzall to exceed them in most cases.

[jimbow]

I was looking for max numbers, just in case me and my car get a lot lighter over the next few months.

3300 is probably my target race weight, but I won't be there anytime soon.

 

Before I blew the engine it was 3400lbs and 318 rwhp.

The rebuild is going to come nowhere near 402rwhp, more in the 350 range.

 

I was more concerned with the suspension cause stock and all the 0 pt mods gets me to -0.5 camber on the front. Yes that is not a mis-type - less than ONE degree of negative camber. For less than $400 I can get the SPC adjustable front A-arms and get that elusive -2 to -3!

I have the coilovers in the shed cause I was sure I was going to TTS next year.

Its been a bummer being down most of the year, and the v6 Camaro is only fun for HPDE instructing.

[Aardwolf]

I thought of putting those SPC arms on mine too. For much less cost I put poly in the stock arms for bushings and cut the conical spacers where the alignment shims go (free!). That setup is working well for now. I made a thread on it:

 

http://forums.corvetteforum.com/c4-tech-performance/2845104-uneven-camber-per-side.html

 

My car is 3075 completely full of fuel and me on board. I believe it to be around 2735 with no fuel and no driver, stock glass still and a passenger seat. It's 360 rwhp so I have to keep it heavy a lot for these pw/wt classes.

[jimbow]

My spacers are cut down as far as they can go.

Driver side is the main issue, thats the max of -0.5

I've found the SPC arms from just over 150 to 225 each.

So for about 400 and no points I can solve my problem and might actually be able to drive it harder in the turns.

Cheap since big brakes become real expensive.

 

So next year will be sorting out the suspension and hoping the new engine lives.

Thinking ahead will be big brakes, finish the cage, get over my "never" w2w, get comp license, etc.

 

Probably will not go past the T/PT3 level though.

Now if I hit the lottery all bets are off

[Varkwso]

Points no longer matter.

[jimbow]

Points no longer matter.

 

Its starting to sink in

Especially when I can get rid of a wart.

[kbrew8991]

so can everyone else you'll be running against - it'll be a raised bar for sure

[Kubs]

Jim,

 

When I was building for PTA/TTA I used points for adjustable upper control arms, Banski heim jointed rear parts, and solid bushings. ST rules allow anything you want suspension wise while maintaining the stock frame rails so yes you can use all of them.

[jimbow]

Yep, now all I'm waiting to see is if I need to fund a stock air filter cover.

Mine was cut open when I bought the car many years ago.

[Kubs]

Yep, now all I'm waiting to see is if I need to fund a stock air filter cover.

Mine was cut open when I bought the car many years ago.

 

No you don't. There are no points anymore so you can do whatever you want from the engine section. Hood vents and facia mods for brake cooling and engine air intake were approved as not being aero mods.

 

From the ST rules (now the same for the new TT3):

 

7.3.1) Aerodynamic modifications are unrestricted with the following exceptions:

 

a.) Active aerodynamic devices or modifications (including, but not limited to, computerized, cockpit adjustable, self-adjusting, and OEM) are not permitted.

b.) ST1, ST2, and ST3 only (not applicable to STR)

A rear wing (or rear spoiler for wagon-style bodies) may not exceed a height of eight ( inches above the roof-line (or OEM windshield height for convertibles).

c.) ST1, ST2, and ST3 only (not applicable to STR)

Modification of the OEM roof line is permitted, but will be assessed via a Modification Factor in the “Adjusted Weight/Power Ratio”.

d.) ST3 only

The addition of non-OEM aerodynamic aides or modification of OEM body lines (unless specifically stated otherwise in these rules), will be assessed a Modification Factor to the “Adjusted Weight/Power Ratio”. In this case, non-OEM is defined as any part that does not come from the vehicle manufacturer either as a standard feature, a factory option, or on a factory optional trim model/package of that generation of the street-legal (in the U.S.A.) version of the vehicle.

 

3) The inner/inboard side of the fender well may have holes cut specifically for the purpose of the passage of brake ducts, external shock reservoirs, and brake lines/ABS wires. Plastic fender liners may be modified and/or removed. The front, top, and rear aspects of the fender well may have modifications to allow vent holes for aero and/or cooling purposes.

 

C. The following are additional permitted exceptions to 7.3.1(d) above:

1) Undertray/belly pan forward of the centerline of the front axle.

2) Removal of a convertible soft top/frame and/or adding a hardtop to a convertible provided that the hardtop uses a sealed rear window and is either OEM, an OEM option, or the same shape and size of an OEM/OEM option top.

3) Lexan front, rear, and rear side windows without uncovered holes.

4) Front wing window/frame removal and replacement with Lexan.

5) Hood replacement/modification for venting and/or weight reduction (“aero” hood pins are permitted).

6) Removal/cutting/drilling of the fascia for engine cooling, air intake, and brake ducting purposes.

7) Removal of rain gutters/drip edges and mirrors

8. Flared and/or rolled fenders

9) NACA ducts, air ducts, or air hoses placed in a side window frame solely for the purpose of driver cooling.

10) Headlamp, headlight covers, and fog lights may all be removed. The holes may be left open, used for brake ducts, or must be covered with material that replicates the shape of the OEM light/cover, leaving the shape of the OEM fascia intact.