ltborg

I completely agree that a good PT car set up is much different from a TT car.

For exclusively time trials, does this mean a TTB* C5 would not be as good a starting point for TTA as a C5Z?

I am looking to have a car that could be nationally competitive in either TT or PT simply with different prep. That way if I move to another region or choose to go TT to PT or vice versa, I don't have to worry about selling a race car and buying another one, just changing some parts and the set up.

96CollectorSport

I think I can verify that for you! Yep it's verified.

The thing about the 255 is that the sidewall is smaller than the 275 so it makes the car twitchy. They work ok for TT but I wouldn't want to run them for 20 - 40 min. No way they would last.

Like Mark said the way you build a TT car is way different than the way you would build a PT car. Gotta bring the right tool for the job.

I think the C5Z is a better starting point for a TTA car it's just easier to get to the min hp/wt with the LS6. I think with the exception of the SE you will do just fine with a C5 in TTA, there are very few TTA cars that are as fast as those SE "Corvette Mafia" guys. If it were me I'd just start off wit the C5 so you can run wheel to wheel, if you really think about it a PT car makes for a less than ideal TT car because the cage adds weight up high - obviously it's a trade off most of us are willing to make. But if everything was the same and one car had more of it's weight lower (around the beltline) and one had weight higher, you know which one would be better.
You may think we're splitting hairs but in TT it can come down to .001 of a second, but that's what makes TT/PT so interesting - you can pick where you want to take the points.

Heck you could add the 255 A6's and use the rest of your points for loosing weight and run at 2942!

sperkins

1. My LS1 only makes 346RWHP, but with the headers it makes decent torque at 359.

2. 1 point for CAI. The Vararam is not the best choice anyway.

3. Haven't tried 255's yet, but it's only 2 more points for me to run a 275 which I know works well.

4. Less weight and less power is better than more power and more weight. I use 8 points to get down to 3122 comp weight.



A TTB* C5 is a great choice for TTA even with minor/affordable mods (the way I have mine). If you can afford to build it to the max rules, I think it could be better than a C5Z - easily.

The benefit to the C5Z is that it's an outstanding package right out of the box. A really good driver would do very well with a "mostly" stock ZO6. Other than a higher initial cost, it's the cheaper option.

drivinhard

also if you really get into nitty gritty, different tracks will have different set-ups

do the later LS1's have the same rod bolts as the LS6's? ie, can you twist the 01-04 LS1's to 6900?

scott really gets hurt by the low revs of his 99, it wouldn't hurt as bad if 5th was usable, but he's gotta use 5th with only 6300 revs on the fast tracks, and 5th just lays over like a pig. his peak mph is way down on the LS6 cars (with no more torque, slightly more power, but 500 more revs)

The m6 would be a good box with 6900 revs. with 6300, I'm not sure it really has much advantage over the M12/LS6. maybe on a few tracks in a few spots, but the M12 probably has advantages in other areas of the same track.

in the end, it's fun picking your "array of weapons" (points). I'm still on the fence of trying something off the wall at RA Dec

ltborg

Would something like a Breathless or Callaway intake (where you cut the radiator shroud) be legal?


That's what I think too (probably all my work on FSAE in college), but it seems like it would be hard to get to the power levels needed with minimal mods. That's why I thought a big power car might be an option.


A built bottom end is a no points mod so I would think if the LS1 bolts couldn't take it, you could just replace them under that rule.


Do people think that either car will be a good option, going forward for several years? I know that's impossible to know for sure but if any of you who are more familiar with past rules changes have any input, it would be appreciated. I hate to spend the money on either at this point and have something happen to make them obsolete. I know it will happen at some point but as long as I can get some good time out of it, it'll be fine.

drivinhard

are you asking about the C5 vs C6, or C5Z vs C6Z51?

I think a TTB* coupe would make a fine TTA/PTA car for years to come, unless the rules totally change or something.

AU N EGL

duct taping shut the fog light screens for better aerodynamics far offsets the any advantage for air intakes.

varkwso

I agree. My built bottom end LS1 spins easily to 6900.

TTA will be spec C5 for a while I think.

Trying to build a TTB C5. I even have base model sways and springs due to generosity of a forum member!

geerookie

What did you do to the bottom end?
Mine is a stone stock LS1 with 113k+ miles and never been apart. I've been turning 6500 for two years now but would like to spin 6900 or 7k. I spend too much time on the rev limiter.
This winter I'm putting in LS6 valve springs and chrome moly push rods.
I'm wondering what I should do to the bottom end.
I'm running ST2 so I can't add any horsepower...my car is too light and I want to keep it that way I need more rpm not power.

geerookie

I made some aluminum plates to cover the holes in the nose and riveted them on. A little more rigid than duct tape.

ltborg

C5Z vs C5 Base Coupe.

It sounds like there is really no reason to run a C6 since any tiny benefit would be offset by the added cost and potential LS2 reliability problems.

RX-Ben

My TTB C5 is a lot of fun. Finally had my first sessions with 275 R6s all around. The suspension softness takes a little getting used to (delayed response/communication). Coming from an S2000, it took a bit to get comfortable. I'd like it stiffer up front, but I don't think there is much to do for that other than play w/tire pressures.
But, the car is fast and the build is affordable if you wrench, though takes a while (poly bushings, hardbar shock tops, oil cooler, I did a custom seat/harness install, harness bar, no carpets/center console (gets in my way while shifting), no A/C compressor/condensor (I hate A/C), SKFs, camber kit). It came in at 3090lb with street tires/wheels and 1/4 tank. Not sure how much lighter with the R6s and C5Z front wheels all around, but they feel a bit lighter. I spent +11 on the 275 R6s and +1 on 20lbs lighter. I think it will be light enough to run without having to uninstall the pass seat.
There is not much TT competition in the NE (yet), but my first NASA event will be at NJMP-Tbolt next weekend.
I was about 1sec/lap slower than a GTS4 996 Carrera (wing, real slicks, etc) at NJMP-Thunderbolt but still have some time to pick up in a couple turns (3, 14) and I hope to have my abs working by then as well.

I really like the R6s vs the 305 R888s (too big for TTB) that I also have. The R6s give a lot of feedback at the limit (self-aligning torque?) and still have some grip if pushed too hard which helped my confidence.

Also - anyone know if taping up the front caverns (where the fog lights are) counts as "modifying the front fascia" (+3pts) or it is no pts?

Regarding spinning to the upper 6s - this is just done to avoid a shift? My understanding is the stock cam (LS1 or 6) takes a nose dive in that area and stronger springs are a really good idea.

drivinhard

tape is pts.

if we could do it, we would be

varkwso

LS6 rods, ARP rod bolts, forged pistons plus B&B rotating assembly. The later LS6 blocks (and probably LS1s) have some mods to help oil scavenge and return. LS2 timing chain and CTS V lifters with comp cams springs. I would do restricted flow pushrods if I did it again I think. I forget which year LS1 cam I am running. 2000 maybe. They are not all the same I hear.

varkwso

Tape is definitely points. Higher rpm is nice with MN6 trans. I love its third gear and hate its fifth.

TTB C5 base wt is 3246 with driver...

mrc24x

Be careful here. Engine parts are not allowed to be swapped. Even within a year range that's in the same classification.

Fwiw, I think the Corvettes are classed close enough that any of them can be a front runner with the right prep and driver. The tire rule hurts the C4 (26 points if I choose to run 295 a6's) but it's still a solid platform.

varkwso

LS1 went from 97-04. I am pretty sure anything in that range is acceptable. I know almost no race car has an engine that matches it vin after a few years - for that matter the 99 FRC we run in ST2 has very little of the original car left.

That would mean all the crate replacement LS6s in 2001 C5Zs are illegal.

AU N EGL

tape is points ? how about installing the coupes fog light holders ? that would close things off.

Jason

Also points. We've already asked.

mrc24x

I've been told many times that is the rule. The L98 was used from '84-'91 and the cars are based together but Greg G. would not allow the cams to be swapped or the heads, etc. Bottom end parts are ok to change because of the rebuilding rule but a cam change would be 6 pts.

Not trying to be a pain but you may want to clarify before Nationals.

Motors and engine parts cannot be swapped under the update/backdate rule without specific approval.