I dyno'd my Formula 6/14/03 at FLP in Naperville,IL.

Since the last time I dyno'd the car, I added the following:

-SLP 1 3/4" headers
-custom y-pipe into 3" in/out single converter
-SLP stage II chip
-aluminum driveshaft
-MSD 8.5mm wires
-Bosch platinum plugs

It dyno'd 236RWHP and 299RWTQ. My last dyno results are in my sig along with my mods. The temp was about 20 degrees warmer and a little more humid than last time in October '02.

I ran against a couple LS1 and LT1 cars a week or so ago and it was about 2-3 tenths faster half track, after that the car hits a friggin' wall more than it did before the headers.

I am stumped why the car runs slower at the track (the conditions were not all that great) and dynos lower.

 

Because the TPI is choking your motor. Do you know how much air you need to flow at 5000 RPM with a TPI? More than you can.

Story: Last year with the mods in the sig, I gained 8mph at halftrack from the factory motor. But I only gained 5mph by the end. If I would have had a TOPEND (dyno results = topend) gain like I did down low, I would have seen some 102-103 mph passes on a relatively stock motor. All I did was new pistons and cam inside the motor. EVERYTHING else was stock.

 

Same dyno each time? Did you have the numbers corrected back to standard temp and pressure each time you ran? Weather conditions alone could account for the difference.

Any chance that the new exhaust is contacting the body giving an indication of false knock?

Another possibility is that the tuning of the SLP chip is generating more knock counts causing the ECM to pull out timing relative to your previous runs. Getting knock after the 2-3 shift is pretty common due to the lack of tq multiplication in third. That alone could kill your third gear pull/MPH. May want to experiment with initial timing and fuel pressure. A scan tool is highly recommended.

 

Those 1 3/4" headers are WAY overkill for most street 350's. Especially ones with TPI's on them. My setup runs fantastic with 1 5/8" primaries. No track times unfortunately, and though I'm loath to admit it, I have had a few run-ins with various "fast" cars here and there (freeway on-ramps, side roads, etc.). Always to their dismay, shall we say.

When I had the TPI setup, I put catalytic converters on it thinking I'd have to get it smogged. To my amazement, the car ran harder all over the rpm range. I chalked it up to the possibility that TPI's like some back pressure. So I'm not sure what effect going to such a large primary tube did to the operating characterstics of your engine. It appears to have had detrimental effects unfortunately.

 

Try your original chip over the SLP chip. I have a bunch of so called performance chips and the SLP chip that I have slows my car down 2 to 3 tenths over my stock chip. The SLP chip that I have does not advance my timing to more then 29 degress at full throttle, according to my scanner. This lack of timing slows my car down. Maybe your SLP chip doesn't have this problem but I would swap it out and take the car for a spin. I do not believe your 1-3/4 headers are hurting your performance. The 1-3/4 headers will work fine on a 350.

 

I agree. Toss the chip, and go back to the track. Most shelf chips, even from companies named SLP, suck ***.