Sticky2k

my guess is header design

prancer

It might be the mods, but it looks like your AFR is all out of whack to me. Most factory S2Ks can get a damn near perfect line all the way through the dashed portion until the very end.

Elistan

I assume by "more of less are" you mean air? The VFAC can not adjust the amount of air going into the engine. That's determined by the throttle plate and valve timing. Maybe you're thinking about how VAFC works by tricking the ECU into thinking there's more or less air entering the engine, which produces a corresponding change in the amount of fuel actually entering the engine? In other words, as I said, the VAFC can only adjust fuel. (And VTEC transition, obviously. ) My point being, it cannot adjust ignition timing.

And sure, you can set the transition to 4000 rpm, even 3000 rpm if you'd like, it'll just run like crap and loose a ton of power below about 5500 rpm. From what I've read on the boards, only people running an AEM EMS or similar, which can adjust both fuel and ignition, can realize any gains from setting the VTEC transition below 5500 rpm or so.

Grant B

Thanks, I'm guessing this is what the issue is with the blue trace. An inertia Dynojet is a pretty simple machine and I don't see how it could malfunction like this, but it seems more likely than the car suddenly making more low-end than any S2000 does on one pull, then a normal amount on another. Header and intake design is not going to do that.

The blue dip isn't noticeable when driving, but I'm used to cars that are quite a bit faster than this one. I'm not entirely sure I could feel it unless I was trying to notice it.

A pic of the exhaust manifold:


The intake is a ram-air box in the driver's side headlight:

The length of the intake from the start of the TB to the end of the pipe is 14.5". I don't know what the optimal length is here.

The car looks quite a bit different now than it did in the above pics, but the intake and exhaust are the same. I can't decide if I should adopt my Megan header to fit this chassis, or build a 4->1 header. I'm also considering permanently putting the car into VTec since I don't really have any need for low-end. From what I'm reading you really need something that will tune timing too, like an AEM or an E-Manage.

BTW, the car ran 13.8 @ 102 with me hitting the rev limiter twice (the tach had stopped working so I was having to base my shifts off of my PerformanceBox's MPH readout).

TJ01s

I agree with the header being the culprit in that tq curve. the f20c is really picky with headers. if you still have an oem one, i suggest using that one if you can make it fit.

Elistan

Do you have your Dynojet run files? If you send them to me, I can put them on a chart with some other S2000 runs with nearly the same torque, but more hp, so you can see where you're winning and loosing.

camuman

header sucks and while your at it get an aem ems and get that tuned. vafc will not be worth it in the long run for you.

no need to mill/build head for 230whp. can do that with stand alone and CAI/header/exhaust.

its all in the tune, well that and a way better header design that that bastard child you have on there.

bgoetz

A miata with a F20 should do better than 102mph at the end of a 1/4. You still have some sorting to do IMO.

Grant B

[QUOTE=Elistan,Oct 31 2009, 05:49 PM] Do you have your Dynojet run files?

Mor.gan

Here:

https://www.s2ki.com/forums/index.php?showtopic=417646

Guy on here already did this. Helped him a little bit and he made decent power.