95firehawk

My car just does not feel like it used to. At its peak it went 13.2 @ 107 with these mods:
HPP, 4.10's, airfoil,!cat, pro 5.0, centerforce DF, DD sfc, lca, lca reloc., springs, shocks, and that's pretty much it (street tires and full weight).
A couple of years ago I grenaded the clutch and cracked the bellhousing at the track. I then replaced the bellhousing and the clutch with a Spec stage 2. While I was in there I also threw on a set of edelbrock shorties. Since then the car has only gone a best of 13.4 @ 103. But is not what really bothers me. Since the 13.4's (which were also attained a couple of years ago) I have:
Replaced engine (7,000 miles), rebuilt the tranny with the kit from gearbox.org plus steel fork and billet sliders (5,000 miles), new 10 bolt out of LS1 car with 4.10's (4,000 miles on it total), new opti, plugs, wires with engine, all synthetic fluids, new injectors, and walbro fuel pump with upgraded wiring harness. I also got some datalogging software off the net and according to Injuneeer's website all sensors are reading fine (no knock and all sensors reading within parameters).
Problem is that it is still not as strong as it used to be. Since all of this began around the time of the header/clutch install I have checked numerous times for exhaust leaks and watched to see if the clutch was slipping. No apparent problems there. Unfortunately I haven't been back to the track because its a noticeable difference in the way it feels.
Basically I am hoping that someone suggests something that I have overlooked. I have to believe that it is something minor since I have essentially replaced every major mechanical component in the car. Sorry for such a long writeup.

jsetzer

Did the firehawk come with a different cam or something? There were not enough mods on the old motor to justify 107mph trap. 103 maybe.

What did you replace the engine with? 4 mph could be nearly a 40hp difference.

95firehawk

No different cam or anything like that. It dynoed 287 hp and 317 torque to the wheels the summer before the 13.2/ 13.3's (only mods were 4.10's and lca reloc. between dyno and runs). It's best was a 1.94 60' with a 13.29 @ 106.99 mph. Actually I guess I should probably say 13.3 at 107 but that's not what concerns me now. Back then the car would push me into my seat up until 5k or so and then it would feel like it felt like it push me back just a little bit harder until I shifted at 6200. Now it doesn't really push me back into the seat at all and feels like it takes longer to reach my shift point. I am out of ideas of what I could look for. Can the stock 2OTL exhaust be rotting out from the inside? It's stainless and doesn't look bad on the outside. Any help would be appreciated.

HardcoreRM125

Different motors run ... well, different.

My LT1 is a heavy *** convertible, and it felt (When stock, other than a CAI ) significantly stronger than my friends 94 Z28 that had a CAI and catback. This is especially odd since my car is a vert. and weighs 100 lbs more. But it definatly, without question, was stronger. And his was in good running condition.

95firehawk

I know there is no consistency between LT1's but my car feels exactly the same as it did before I changed the motor. I think that I am going to do a leak down test on the engine to make sure that it was built properly. Thanks for the replies so far.

HardcoreRM125

couple other things to check before you go through all that work, get the car on a scanner that can do datalogging. Most shops will have one. Take it out for a spin and see if all the readings are normal.

Take a look at your O2's, TPS, MAF/MAP, and Temp Sensors ... Any of these can affect your mixture and make it run rich/down on power. O yea, and the IAT.

Make sure the car isnt stuck in open loop, etc. Check everything fast and easy before you pull do a compression test. Thats a major pain in the *** if you dont have to do it.

95firehawk

I have already done a couple of datalogs and everything looks on par. I am going to check over everything AGAIN this weekend and if nothing seems out of the ordinary then I will do a leak down check. If that doesn't show anything then I will drive it off a cliff.