What's that increase of power at 5500rpm?

[ryback]

I have a stock 91 240SX 5spd, and usually feel (and hear) an increase of power at 5500rpm when flooring it. Was wondering what does this? Like a dual stage intake manifold?

[MaineExport]

Actually 5500 rpms is where the powerband drops off on the KA. Strange that you would feel more pull then. But no, there is no 'dual stage intake manifold' kicking in. Usually the KA starts to pull hard from 3800 until 5500.

It's pretty much a bare bones engine, no fancy variable valve timing or what not.

[ryback]

Hmmm... that's odd. Well, I'll try to take a video of it tomorrow and post it.

[240 or die]

I believe that there is a slight surge in power at 4500-5500, and i cant remember what causes it but it was broken down in an older post. If you look really hard you may find it. But there is an increase of power at that range.

[Nismo_Freak]

no he's not talking out his ***... look at the intake dynos for the KA24DE on the Injen website. Notice the VTEC like engagement at 5500. For some reason on those vehicles earlier S13s the car picks up power at that rpm.

[nismokid]

i have a 91 5 spd as well and it is supposedly the quickest dohc model but a 5500 - 6000 rpm thats when the power dies off. when i race my friend in his 95 i pull on him a little when we get to the higher rpms but nothing drastic. i think the 91's have the most aggressive cams or something like that

[SSDwellah]

Do the secondary butterflies open at this point?

[MaineExport]

no he's not talking out his ***...

I didn't say he was.... just thought it was curious.

[Perfectd3]

I have a 93 and I too feel a good kick in th epants around 5500rpm

[APEXi240]

I feel no kick anywhere. 155hp creates more of a breeze than a kick.

[ryback]

Well this is weird. I thought someone would know what it is.

Nismo_Freak, you're right about that intake dyno, but it looks like it happens at 5000rpm. Still, an increase of 20hp happens in a matter of 100rpm.http://www.injen.com/webpages/...0.jpg

[ryback]

Here's a couple of videos I took a minute ago...

http://www.tps-racing.com/240/2ndgear.mpg (watch the tach around 5300rpm)

http://www.tps-racing.com/240/3rdgear.mpg (notice the camera shakes at 5500rpm)

By the way, I am 100% stock. 109k miles, stock filter, stock exhaust (just a big exhaust leak :oface).

[SSDwellah]

I believe you, I have a 91 and it happens to me too! Somewhere between 4500-5500 at WOT but then it starts to fall off. It's not noticable at part throttle. I'm wondering if anyone with 95+ w/ 91-94 cams has this effect too. If not, then it is probably intake manifold related (when do the secondary butterflies which aren't on 95+ work)