Darren

Who has dynos they can post along with modifications? The reason I'm asking is that I'm preparing my car for NASA GTS and I'm wondering whether chipping (as currently is being discussed in another thread) or other mods will help me increase my rwhp so I can run closer to the limit of GTS4

Currently my car is making 294 rwhp, as seen below. The GTS4 limit, 8.5 or 9.0, lbs per hp that at current power I need to weigh either 2499 lbs (impossible probably) with me and DOT tires (impossible probably), or 2646 lbs with me and full slicks. I'd rather not run slicks, so trying to figure out how to increase power.

Hopefully there are more people with dynos -- if you have the ability please post uncorrected charts with smoothing factor 4, as per GTS rules.

Mods:
Sachs lightweight flywheel
Fabspeed cold air intake
Fabspeed muffler delete

Darren

BTW -- look how straight the hp line is until it starts going rich! I can see getting power there with an ecu reprogram, but I don't know how much!

onefastviking

315 RWHP is possible without pulling a valve cover off, more if you'd like to pull a valve cover , even more if you go X51. What tracks will you be running GTS4 on ?

Darren

Mostly Summit Point, VIR, Watkins Glen, Thunderbolt/Lightning....

FLY996

EVOMS Intake
RSS Plenum
Maxspeed Headers & 200 Cell Cat's (Maxspeed Headers and Cat's are for sale)
Cargraphic Exhaust
Revo Stage 2 Software

AudiOn19s

Still have the stock cats on the car? Those would be the next thing I'd be gone with. You shouldn't mind sacrificing low end power to drop some more lbs from the car and free up some hp in the rev range where you'll be using it.

I remember JimB talking about how he gained 14-17hp on the top end with his X-51 car by running no cats. Said it was completely dead below 4500rpm though.

It's a win / win for what you intend to use the car for.

One of your best possible resources has already posted in this thread (onefastviking). I had the opportunigy to look over a car he built in the past and it was rather impressive.

Andy

Darren

I think I'll probably pull the cats -- I got a price from the dealership wondering what I can sell them for and they said they are $1600 each! Ouch! I'll probably pull them off to sell and get the Fabspeed cat bypass pipes.

Onefastviking -- I don't want to do the X51 at this point but I'm all for doing whatever to this motor. What cams are the hot ticket?

Paul 996

Darren,

Definitely delete the Cats. I am 299RWHP on the NASA dyno at Summit. X51 headers, No Cats, Fabspeed Mufflers, EVOMS intake and a non stock ecu flash.

What times do you turn at Summit? GTS4 is a tough pack to run with, we drop in at the low end of the HP/Weight limits and also there aren't that many racers in our neck of the woods. GTS3 would be much more competitive for our cars and better racing

-Paul

Darren

GTS3 was my original intent but my car is very light, I'd have to run with 400 lbs of ballast!

The car was previously a street car with PSS9 suspension, full interior and all and the best I could run was 1:24.4-1:24.5. Now I'm 300-400 lbs lighter, Moton Motorsports suspension (3x higher spring rates), all solid bushings, etc...I think I should be in the 1:20-1:21 range without too much trouble.

That is if I don't bounce off the track on the T6 bumps

onefastviking

There are some Grand Am cams floating around, although I'm not sure they are what you want since those motors were built more for power and less reliability. The X51 cams and heads are a great add although it seems almost cheaper/easier to just buy a complete X51 motor when it comes time.

With stock cams you can still see some pretty good jumps from where you are at. Toss the cats, if you drive at tracks that check sound you will need to have some mufflers built for it or do some 90's that turn the sound away from the meter. Reprogram the ECU, call Mike at AWE-Tuning (site sponsor here), explain to him what you are doing with the car and what you want and he will know what you need. Tell him I said hi also.

The hot rod (we won't mention specific names) Plenums don't help anything significant, the underdrive pulley helps the P/S from overheating but doesn't help hp anything significant, I presume you already removed AC compressor drag and weight. Other than that just remember that the engine is just an airpump and it's really pretty simple.

That should buy you a pretty good jump in power and then I would drop weight out of the car to get where you need to be.

We are still running in GTS3 although we have to carry a hefty amount of ballast and also we restrict the car to make less hp. For us when we decide to make the jump to GTS4 it will be easy, just drop the boat anchor remove the restrictor and change the decals !

onefastviking

From what you have posted I would guess you could easily do 2800lbs / 310rwhp which puts you at 9.03 power to weight and then you could run slicks, or get to 2700 / 315 hp and then run DOT's which puts you at 8.57 . Both would seem pretty easy to do from where you currently are.
Get an X51 and then you don't need to loose as much weight.

Paul 996

A 1:20 is working it in a 996 and what you would need to be in the mix in GTS4, I think 1:19 to podium consistently. Remember in 4 you run with Cups.

Last month I got down to a 1:21.4 on R6s with full interior. My best so far.

My plan would be to carry the weight and aim for GTS3 turning 1:22-21. Should put you at the top of the heap.

Darren

What hp and weight are cup cars that run in GTS4?

karlooz

huh? around here cups run in GTS5. 2700/360wHP so that's 7.5. GTS5 is 6.5 - 9 with slicks.

i am at the top end of the GTS4 performance range with my weight and slicks.

karlooz

they'd have to add 500 lbs with 360wHP to be in GTS4.