Thread: Flat spot after 6000rpm after C2 cam install

Hi guys, some of you may remember the problems I had with a recent S3 cam install, in the end I got some JWT C2 cams and springs and because of some bent valves, had to take the car to another list members' place (he has a lift and all and did a great job on short notice)

I have a '91 SE-R with a JDM SR20DE engine transplant (about 50k on it) and the following engine mods:

JWT C2 cams & retainers
JWT ECU (standard POP program)
Custom CAI
Custom exhaust
Hotshot G3 header
Z32 fuel filter
SR20DET valves

Here's the problem: when I messed up the S3 cam install, we believe the chain skipped at the crank. Don't know how many. Therefore, the car ran like crap until some adjustments were made with the cam timing to compensate which lets it run better now, BUT it still feels like the acceleration falls flat at about 6000rpms, it honestly felt faster with the stock cams before. Now its MUCH better than before when it wouldnt even rev past 5000rpm, but it seems it should be better. It just feels flat at WOT and takes too long to move between 6000 and 7800rpm.

So here is the question: should I try adjusting the cam timing again (perhaps advancing one of the cams by a tooth or so) - the problem is the cam timing markers may now be off since it skipped, and while it runs better than it did initially, it still seems like something's up. have no idea what adjustments to make (advance or retard which cam and by how many teeth)

uhm did you put a stick in the #1 cylinder? I usually use one of those collapsing magnet things. That will tell you if you're cams are in sync w tdc.
That header could hold you back w C2 cams.

Yep I remember it being at TDC. Interesting, you think it could possibly be correct, just the engine being choked?

If you skipped a tooth on the crank you most likely stretch the chain. Its tough to tell tdc after that sometimes.

start from scratch. i'd pull the front cover and vc make sure the chain and crank and cam gears are timed properly. "compensating" with cam gear only timing is just asking for trouble.

^^^truth, u dont want to advance too much on a stock and kiss ur valves good bye, yeah if i would u ill retime it the right way, front cover off

Thanks guys. I wonder how the JWT cam gears would apply in this situation (help or do nothing at all)

Did you get the ecu reflashed for the C-series cams? What's the ecu even tuned for?

You know what, in all thats been going on the past week or two, I didn't even think of that. Let me tell you guys, I lost my dad just a couple weeks ago. I've found some solace in distraction the car has given me. So it sort of helps.

Anyways, the ECU currently has the standard JWT POP program with the S3/S4 cam program on it, but I was going to get rid of it because I thought it wasn't helping.

I didn't even think of needing a reprogram for the C cams. I suppose I could give JWT a call and check? Unless someone else knows. The listmember who helped me with the car is very experienced and does great work, so I thought it was less likely that the timing was off, but he did what he could considering the situation. That would be great if an ECU retune is what it actually needs, because the car runs fine otherwise, idles well, pulls hard until and just flattens out around 6000rpm.

Well, Ben from JWT replied to my email:

"You should be using the JWT C2 cam program which improves the low to mid power area and the idle quality, not as much of the top end power is effected.* The header design is very important with helping these cams make their best power.* You should be running a header with at least a 1 3/4" primary and best to do a 3" collector and 3" low restriction exhaust system.* If not, then the top end power will not be much more than the JWT S3 or S4 cams.* You should also check your base ignition timing and ensure that it is correct and the cam timing settings as if this is off, it can definitely effect the power curve."

So my question is, who makes a header with a 3" collector?