Safely raising rev limit?

[Keenercarguy]

What, realistically, would it cost to purchase valve springs and have them installed to safely raise the rev limit? What else (reasonable) can be done to raise the rev limit and what safe rev limits are realistically possible?

[Silver Cervy]

What exactly would you be trying to accomplish by raising the rev limit? Max power is around 7000 rpm so all you'd be getting is some more noise.

With a lot of cars you can raise the limit with a tune but idk if it works for these.

[EAGLE5]

The rev limit can be safely raised some. OFT makes it easy. They also put a soft rev limit, so it's not like hitting a wall with the stock one. Makes mistakes less punishing. Realistically, going over 7000rpm is either because of poor technique or wanting to stay in gear at a track. If you add a turbo, the game changes because then you may be able to make more power up high.

[phrosty]

Originally Posted by Silver Cervy

What exactly would you be trying to accomplish by raising the rev limit? Max power is around 7000 rpm so all you'd be getting is some more noise.

It is power at the wheel that matters, not power at the crank. A lower gear will always give significantly more torque than a higher gear on this car, so you should be shifting at redline.

If you could do it without blowing the engine, I'd not be surprised to find sufficient power 300-500rpm higher than current limit.

[churchx]

Originally Posted by Silver Cervy

What exactly would you be trying to accomplish by raising the rev limit? Max power is around 7000 rpm so all you'd be getting is some more noise.
With a lot of cars you can raise the limit with a tune but idk if it works for these.

Even if engine produces less power at very high rpms:
1) due gearing ratio there is still more torque going to wheels then at "more optimal" rpms/power curve peak but in higher gear
2) wider usable rpm range/ability to go longer at certain gear without upshifting or downshifting at many tracks may give extra advantage of loosing less time on gear shifts

But at the end it's all upto reliability of very high-reving engine. And for that .. imho just valve springs might be insufficient. Fully built engine might be outside of budget of most though.

[8RZ]

Won't gain much with aggressive cams either.

[Stang70Fastback]

FYI, autocross is an example of a situation where a slightly increased rev limit would be useful.

[Spartarus]

Ok, bickering aside, the upper limit of this engine is around 8200. It varies a little, but that's slightly below the point where the oil pump quits moving oil.

Some have done 7600-7800 on stock valve springs, after that you are on borrowed time until you upgrade them. Plan on paying $1200 to a good shop for parts and labor to swap the springs.

Some have "solved" the oil pressure issue by fitting a massive Accusump accumulator to move oil after the pump quits doing it. They go to 9000 RPM... In short bursts. Their motors don't last.

The oil pressure limit is a wall. You can't get past it with a "built" engine, don't waste your money. All proper high-revving engines use an underdriven oil pump that sits in the sump. This one settles with a direct-drive pump that sits on the crankshaft. Limitations are limitations.

Cams will absolutely help. Stock advertised duration of 252/252 is not conducive to high RPM operation, regardless of what you do with VVT. Duration at .050 is even less. That's why the VVT angles are so wide... Not like the valves are gonna collide or anything.

Higher redline is beneficial until the flywheel torque drops by the percentage gear ratio drop from one gear to the next. In short, it is beneficial on the FA20 to keep revving it.

Get an equal length header with the shortest available runners, like the ACE / 150, if you want to actually make power up to redline. There is an intake manifold with shortened runners available, which has been tested, but it is very expensive.

E85 will also help.

UEL headers will choke the engine up high.

[Keenercarguy]

Right, A) I'd be moving to an Ace Clubsport (EL) if I decided to raise the rev limit, B) I'd be doing so for autocross because staying in a gear longer is quite valuable. I'm really curious to hear from people that *have* swapped the valve springs and are running a redline north of 7850.

[kiichiro]

I havent been on the forumz in a while...
has anyone figured out how to put a FA20DIT and WRX ecu into a 86 yet? I'd come back to the platform for that.

[GsxrMe]

Originally Posted by kiichiro

I havent been on the forumz in a while...
has anyone figured out how to put a FA20DIT and WRX ecu into a 86 yet? I'd come back to the platform for that.

At that point people are jumping over to Motec

[Keenercarguy]

Originally Posted by kiichiro

I havent been on the forumz in a while...
has anyone figured out how to put a FA20DIT and WRX ecu into a 86 yet? I'd come back to the platform for that.

Honestly at that point there are numerous forced induction options that are cheaper, plus FA20DIT's have had compression problems even on the stock tune/boost in WRX's… So I wouldn't even want to go that route at this point, personally.

[wbradley]

Originally Posted by kiichiro

I havent been on the forumz in a while...
has anyone figured out how to put a FA20DIT and WRX ecu into a 86 yet? I'd come back to the platform for that.

But why? It would cost way more than a well designed bolt on kit. Maybe even with lower compression pistons, forged bottom end, etc.

And, a twin scroll with low end torque that tapers off up high goes against maintaining traction on a light rwd drive. Trust me on this, look at both my vehicles. The FA20DITdoes not have the ideal power curve for the twins.

Oh, and the location of the turbo makes it not fit the engine bay.

[CTB727]

Originally Posted by Stang70Fastback

FYI, autocross is an example of a situation where a slightly increased rev limit would be useful.

This. I have my rev limit set to 8,000 RPM. Those extra few MPH are worth valuable tenths of seconds.