l98 torque
Thread Starter
4th Gear
Joined: Oct 2025
Posts: 4
Likes: 0
l98 torque
Hello everyone, new here and to the c4 world. I'll just get to it. This question has been probably ask a million times and I did some light research. I have a l98 c4. I know that the tpi is super restrictive for high HP numbers. Im okay with that, I want a torque monster stop light to stop light car. I read that long tube headers/exhaust, gears, torque convertor is a must. What cam is best for a good loppy sound and low end torque? and should i port the heads/intake and plenum or just find some used afr 195 cc? does anyone have a great set up for 400-420 ft lbs? Thank you for everyone's advice. or if anyone can post a thread for me to look at, that answers my question.
Racer
Joined: Nov 2006
Posts: 379
Likes: 7
Hello everyone, new here and to the c4 world. I'll just get to it. This question has been probably ask a million times and I did some light research. I have a l98 c4. I know that the tpi is super restrictive for high HP numbers. Im okay with that, I want a torque monster stop light to stop light car. I read that long tube headers/exhaust, gears, torque convertor is a must. What cam is best for a good loppy sound and low end torque? and should i port the heads/intake and plenum or just find some used afr 195 cc? does anyone have a great set up for 400-420 ft lbs? Thank you for everyone's advice. or if anyone can post a thread for me to look at, that answers my question.
Racer
Joined: Nov 2006
Posts: 379
Likes: 7
That was just what I did - does not mean that is the right solution for you. Before I put in a new 383, I just put headers and true dual exhaust on the original L98 with 113 heads from '87, opened up the filterbox and adjusted everything well, including the tune. The vette ran 14 seconds straight on the 1/4 mile with this setup (150.000 miles on the engine) and ran very healthy up to around 4500-5000 RPM. It was faster than a 350 hp Supra on the 1/8 mile, but not on the 1/4 mile. I have 3.07 rearend gears and auto. If you do not optimize or change out the original TPI intake, then I would not bother with much more else internal in the engine, as it has a lot of torque as it and has a very low 1. gear on the TH-700 (if you have an auto).
Thread Starter
4th Gear
Joined: Oct 2025
Posts: 4
Likes: 0
That was just what I did - does not mean that is the right solution for you. Before I put in a new 383, I just put headers and true dual exhaust on the original L98 with 113 heads from '87, opened up the filterbox and adjusted everything well, including the tune. The vette ran 14 seconds straight on the 1/4 mile with this setup (150.000 miles on the engine) and ran very healthy up to around 4500-5000 RPM. It was faster than a 350 hp Supra on the 1/8 mile, but not on the 1/4 mile. I have 3.07 rearend gears and auto. If you do not optimize or change out the original TPI intake, then I would not bother with much more else internal in the engine, as it has a lot of torque as it and has a very low 1. gear on the TH-700 (if you have an auto).
Racer
Joined: Nov 2006
Posts: 379
Likes: 7
Stock TPI intake limits power above approx. 4400 rpm if I remember correctly, which is why I would not use much time on camshaft or heads if the intake is not adressed. The FIRST TPI manifold just looks like the stock TPI (just bigger) but is a whole new intake and no parts interchange with the stock TPI.
Everything from rearend ratio, camshaft, heads, compression ratio, intake etc. etc. should be matched closely together to what you want to accomplish.
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