Sorry if the following is jumping from topic to topic...and for the what appears to be long enough for someone's final thesis on rambling and confusion...but please bear with me...

Ok, here's the deal. I put a smaller pulley on my comptech supercharger (4.25") and went to get it tuned today. I've got an even smaller pulley on my other S2000, tuned it...no problems whatsoever...pushing 366 to the ground. I lived in another state, so I guess the guy at the dyno there knew more about tuning S2000's? Anyhow...I threw a comptech SC on this one, dyno'd at 273 to the ground in the winter. I put comptech 4-1 headers and testpipe on it, got it dyno'd at 252 to the ground (granted it was much warmer). Now, I've got V-AFC, intercooler and a smaller pulley, and the top run was 267 to the ground. We had a loose wire earlier on, causing it not to take any fuel out....we played with the wires and it worked fine after that. Now before I put the smaller pulley on, I installed an intercooler. After the install, the car sounded funny and the gas pedal felt a little different from 4000-5000 rpms. The noise seemed to be coming from the SC, like the air was struggling to get in from the filter. After 5000, it was fine again...and it didn't matter what gear I was in. (...back to the dyno) After we figured out the V-afc wiring problems, the car would just cut power (hp) at 4400-4800 rpms...major drop off, and then it'd go right back up. It would do this 2 out of 3 runs I would say. The car hesitated, then jumped right back into sync. My question is: how could the intercooler possibly cause this? It started when I got the intercooler installed. I can't figure any reason why the intercooler would affect this in anyway. If not the intercooler, any other ideas? Also, any ideas on why only 267hp? I'm going to try and take my other S2000 to get dnyo'd to see how much the heat takes off of it.

The 366 hp S2000 has a built engine, smaller pulley than the other S2000, and a different intercooler. Those are the only differences...both are 2001, and have the same 'other' mods.

One thing though, do you think the ecu is causing the major dropoff at 4400 rpms and why only 4400-4800rpms? Do you think it would help if I reset it (of course I didn't think about that at the dyno).

Again, I appologize for the length of this post. I will also try to get some charts posted on here tomorrow when I can get them on the computer. I'd like to have a general idea of 'something' to try and fix, before I go back to the dyno and sit there scratching my head.

Thanks for any help if anyone read this far!
Dave

 

how big is your intercooler, if you are running a big ass front mount it could be a pressure drop, because even turbo cars boosting 21 PSi like my beater has a pressure drop once a FMIC is installed on a stock turbo. The Comptech Supercharger Does NOT require a FMIC for sufficent cooling.

 

it's I want to say 20X10, 3 inch piping.

 

I dont think 3" piping is really needed. I would go with 2.5". Im sure there is a lot of pressure loss there. Have you looked at your V-AFC? Check and see if the tuner is using positive numbers. The guy I went to used positive numbers and at a certain point the power would just drop by 40hp and then slowly pick up again. It looked like the V-AFC and the ECU were fighting back and forth. If he is using positive numbers I would have him go adjust the fuel pressure so that he can lean it out using the V-AFC instead of try to add fuel and conflicting with the ECU.