BrandonS

I've been out of the loop for some time, so please forgive me on this question. First, i don't need to be told that it already revs high, or that you'll only loose power by redlining higher..... i know that. Also, i already know 9k is twice as much stress as 8k... ect. My question is this. If you rais the redline to 9.5k, what else SHOULD be done to help hold the engine together?
I'm not the type of person who runs their car hard, and I really only want the added 500 rpms to increase my power bandwith, and for the awe of it. I figure if i reduce the vtec by 400rpms with my vafc2, and raise the redline 4 or 5 hundred rpm's i'll have gained nearly 1000prm's of good power. Also, with the higher rpms, when i shift, i'll be downshifting to a higher rpm, which means more power. Maybe i'll be faster, maybe slower, but i think it would make a semi decent experiment. And if not 9.5k... maybe 9.4 or 9.3. Any thoughts on this. Also, i can use the VAFC 2 to raise the max RPM as well, correct?

Brandon

Oh yea, as far as monitering the rpms, i'll simply use my apexi RSM. The digi dash won't go above 9k, but the RSM is set to read from 0-10k.

Sideways

Brandon,

I'm running a 9500 redline.
I have good news and bad news. The F20C engine is on the back side of the powerband and the torque and hp numbers are falling sharply at 8900 rpm. Going higher will lead to so much less power you will be forced to shift.
To overcome the drop off in power you need to run forced induction. With FI you can extend the powercurve up somewhat. I measured mine increasing in hp beyond 9000 rpm where as the NA peaked at 8300 rpm.

The F20C will turn 9500 rpm as it sits. I decreased the valve train weight in mine by 10% so I could be comfortable with the higher redline. I don't want any stinking valve float. IMHO, you don't want to spend much time above 9000 rpm as the rod bolts tend to stretch .

You mentioned monitoring the rpms. I use one of Modifry's shift beepers set all the way to the top with 300 rpm spacing. It goes off at 8300 rpm, 8600 rpm & 8900 rpm and goes to a long beep at 9200 rpm. I've been using 9200-9400 rpm as my maximum shiftpoint. The tach is worthless and there isn't time to look at one anyway with rpms climbing to fast.


Oh, the good news, I switched my car insurance and saved 1700 dollars.

alex s

you just completely contradicted yourself there.



nope. the VAFC is a piggy back. all you can really do with it is take away fuel and change the vtec engagement point. it wont raise or lower your redline.

AusS2000

The only way to increase redline is to replace the ECU. I doubt the maps in the stock ECU even extend above 9200. the obvious option stateside is the AEM and with it you can set a higher cut off and tune for it.

It sounds like an interesting experiment but I expect it would be expensive and the ultimate conclusion will be "Don't bother". Still, I'm grateful there are people like you willing to go to this trouble to come to this conclusion at absolutely no expense to myself.

Hyper-X

If you want to increase your power bandwidth, the easier and less costly approach is to beef up the midrange of the car, since you're not planning to run the car hard, which is contradictory to your 9500rpm goals. Correct me if I'm wrong, but anyone with goals of running their engine to 9500 rpms definitely has plans to run their car super hard.

The guys are right. There's a lot more involved that what you may realize in achieving that extra 500 rpms. The least you'll need are improvments to the valvetrain components like stiffer springs to counteract any risk of valve float as Sideways mentioned. Reducing valvetrain weight also helps reduce valvetrain inertia, however the cams and head may be the limiting factor. The high cams are already running near the limit for lift and more duration may spell your intake charge getting blown out the exhaust ports. The ECU would need to be re-tuned in addition to having the rev limiter removed/disabled, improved cooling and lubrication are a must and since your car is a MY02, I wouldn't think about doing this until you make sure you're running the 4 hole banjo bolts also.

Then there's the rest of the engine parts like the throttle body, intake, exhaust and such. Can they hold up (without causing restrictions) to the theoretical airflow demands that're put at 9500 rpms?

I would agree with AusS2000. It's a lot of work, a lot of money and may as well be one of those "not worth the time and effort and funds" kind of deal. Forced induction is an easier approach to gaining a more powerful powerband. If you're planning to stay with NA, look to improving your midrange, you'll find it more useful for day to day demands and feels great during competition.

Random1

An extended rev limit could help in autocross? As already said, probably not worth the investment, but to have extra range on the red line could help on those autocross courses where you hit the rev limiter frequently but don't shift because the turn is close. Although you probably won't gain much in 1st or 2nd gear (most time spent here while autocrossing).

Just a thought.

dhayner

The plot below shows that you could gain something in the 1-2 and 2-3 shifts, but not the other shifts, by upping the rev limit. The plot and the subject in general is discussed in this thread.