The Panther

Anyone ever set up a C4 for TTB? I am looking for some info from people who have played around with different setups and found something that works. I want to start setting my car up to run by the end of the year. It looks like my current points would be

TTC + 7
Shocks 3
Sways 2
Exhaust 2
Brakes 2
A6 13

I need to find about 5 seconds at Road Atlanta to be in the ballpark(1:45 now, want to get under 1:40). I am running 315 NT01s right now and want to switch to A6s. 275s preferebly or 255s and use the other 4 points for tire size increase somewhere else. Anybody been down this road before?

ScaryFast

I can offer some help, but my car is set up for TTA/PTA. Hoosiers have been the tire of choice, but now the A6 comes with a steep +13 penalty. V710's may creep into favor here.

Obvious questions first, have you done all of the free mods allowed? What's your current power to weight ratio? Can you remove weight?

jaa1992

Why are you taking 2 pts for brakes? (+7 tells me you have a 92 & up, j55 became stock so use the update rule for 0 pts)

The car will work fine with 275 square!
What shocks are you using?

I assume the 2 pts for exhaust is catback? If so return to stock - it doesn't help much on an LT1
OR
Headers, relocated/deleted cats, cat back is 5pts, then add a good dyno tune (0 pts for a piggy back chip), use a high flow air filter (0 pts) - don't cut the air lid

Have you replaced all the suspension bushings with poly yet?

I just need bigger marbles now that I went to TTA. I can do a 1:40 if I had the marbles.

The Panther

I don't know my power to weight ratio right now. I took out about 250 pounds but then put in a cage. No mods to the engine and it has 100k miles on it, so I doubt it is making much power. Can you give me a rundown on the free mods?

ooldguy

its listed on the main NASA site. NASA CCR as I recall. TT Rule set.

I ran an LT4 in the NASA Midwest Region that was reasonable until the Evo's and STI's showed up.

Robert Dudek

The Panther

Car came with C5 calipers on the front when I got it. I have straight pipes running out the back which saved about 30 pounds when the mufflers were cut off. I could put them back on though if the two points can be use somewhere else.

Shocks are Bilsteins about 4 years old and it has poly bushings.

The Panther

Just looked up the free mods and have done most of the weight saving ones. Still have the headlights for now.

sperkins

I definitely wouldn't take 2 points for the C5 crap clam calipers. Put the stockers back on or get some real brakes.

jaa1992

I have c5 caliper brakets for a conversion - never used the darn things.
Have to get my crap together and sell them. My brake upgrade will be a big brake kit for the front - only $1700

My j55's are sufficient for 120-130 down to 50ish for 10A at Road Atl. I am running xp12/10.

I had to have mine wieghed and a dyno done because I swapped in a 383 - Balanced Peformance has a good deal for us guys. It was around $100 for both.

Your engine is where mine was last year. If you don't run NCCC events a lightweight flywheel and new clutch would help getting power out of the old engine.

ScaryFast

Yeah but be careful, bigger marbles is a 2 point mod.



You can send your Bilsteins in and have them custom valved and not take points for them...something like $55 apiece.

I agree with jaa, I ran (run) 275 square when I drive TTA. Helps with the p/w ratio. I'm not sure I'd take points for sway bars in a car that close to stock. A little roll is nice.

I think the two places I'd go to use my points are brakes and power on a C4. I never thought I'd say that, but some juice under the hood will help in TTB. Maybe a set of longtube headers to get some torque.

And you ABSOLUTELY need to optimize your p/w ratio. This is completely free and the best mod you can do. What is it in B, 10.5:1?

The Panther

10.25:1. The weight listed for a C4 is 3203. I would guess I would dyno about 250. So I could use points for power or weight.

96CollectorSport

Are you sure about that Jon? I would take custom valved Bilsteins as this -
Also remember in TTB that if you run 275's you have to take +1 for going +10mm over 265's (Base tire for TTB is 265)

From the mods listed above the OP still has 16 points to play with to stay in TTB. At 3201 lbs you will have to get to around 310 rwhp to get to 10.25/1. So if you're really around 250 rwhp, I'd try to figure out a way to get closer to 310. Because once you start going below 3201 you will have to use points for weight reduction and you will take a hit on the power to weight.

The Panther

I am assuming I would have to take +4 since my base class is TTC. Anybody ever compare an A6 255 vs 265 vs 275?

The Panther

+50 rwhp doesn't seem like an easy task. It looks like a cam and roller rockers would be +6 but I don't know where that would get me in terms of rwhp with no other mods.

ScaryFast

There is a 255 tire that is a bit "wider", but I think it's only available in 18". I know Carlyle was experimenting with this but bailed when we moved to ST2.

Keep in mind that 3201 is with the driver, so you can get the car to about 3000 - 3050 depending on how much you weigh wearing all your gear, helmet, etc. So...to get us to 310 RWHP with 16 points. Hmmm...

+2 Headers
+2 Throttle body
+6 Cam
+1 Remove cats
+2 3" exhaust
+0 1.6" Roller rocker

For +6 Heads would be a big jump in HP. Maybe ditch the TB? But this is starting to cost lots of money. TTB seems to be a nasty middle ground for a C4. TTC* + A6's may be the place to go

The Panther

Or back to a C5 non z51. It would be so easy if I didn't want a cage.

96CollectorSport

That "special" 255 is as wide as the 275's, and only availible in an 18", but it also has a very skinny sidewall and doesn't communicate very well. So basically you have lots of grip then bye bye.

Also remember 1.6 Roller rockers are only +0 if you are already taking +6 for the cam. If you shoot for a target # you may also be able to get a dyno reclass and see where you end up.

Another option is just to use all your points on weight reduction.
13 points gets you 199 lbs so you could weigh in at 3005 lbs and then you could dyno up to 287 rwhp.
- or use all 16 points for 244 lbs so you could weigh 2960 and dyno at 280 rwhp.
I'm not sure how light you can get the car, but weight reduction is cheaper than hp -to a certian point. One thing that sucks about cutting weight though is that you take a hit on points and on your hp/weight.
This is what makes NASA so cool there are probably 100 different ways for you to use the points given to you, how to best use them is a matter of trial and error.

drivinhard

The great thing about weight though, is as a general rule, 100 lbs is 1-1.5 sec/lap virtually guaranteed!

jaa1992

If you do ANY engine mods get a Dyno reclass! It may save you from having to take the points!
My 383 is NOT tuned very well, it put down 315 rwhp and Greg gave me three options at 3500 lb comp weight, TTB, TTB* and TTB**
I'm using TTB** in the hopes I can get a better tune and get to 350rwhp. Any higher and I'll have to bug him for another reclass.

ScaryFast

It's pretty tough to get a C4 much lower than 3000lbs (no driver). Mine is right there, almost 3000 on the nose. I have (but have not installed) a lexan rear window, I've read that's about 30 lbs. I could get a lighter hood for another 20 or 30 lbs. I could ditch the ZF trans and save another 20. And that's about it, short of rifle drilling the fasters. So I could probably get to 2900, which means 3100 race weight, which means 302 HP.

That's 8 points in weight reduction, leaving 6 for a cam and 2 for an exhaust.

Maybe?