Safely raising rev limit?

[Zentec]

Originally Posted by CTB727

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

Did you change any internals springs? or headers? How reliable has it been that high? Any oil or temp problems?

[dowroa]

Originally Posted by 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.

I am not sure of your statement in (B).

Changing the valve springs puts you into Prepared in autoX, which almost instantly not viable for competition of full-on race cars.

Was that just a separate curiosity having nothing to do with autoX classing?

[guybo]

Originally Posted by 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.

Cams may not be possible without MAJOR work to make them fit.

https://www.revvolution.com/blog/201...he-fa20-4u-gse

Speaking of the camshafts, SCR noted they have nice big fat lobes, so they may not be something we need to worry about swapping out. Couple that with the near infinite adjustability of the cam timing, and there may not be much need to put big aftermarket cam shafts in to get the power.
As SCR stepped into the combustion chamber, they noticed there is not a whole lot of clearance between the valves and the pistons. If you’re trying to go with cams that have higher lift and/or duration, you could potentially have interference issues.

[Teseo]

Originally Posted by dowroa

I am not sure of your statement in (B).

Changing the valve springs puts you into Prepared in autoX, which almost instantly not viable for competition of full-on race cars.

Was that just a separate curiosity having nothing to do with autoX classing?

Sorry for my rubbish question, but how the fuck they will know if my car have springs for higher rpms or any internals upgrades?

[Zentec]

Originally Posted by Teseo

Sorry for my rubbish question, but how the fuck they will know if my car have springs for higher rpms or any internals upgrades?

They use the force. These are not the valve springs you are looking for move a long move along.

[nico_rsx]

Originally Posted by Spartarus

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.

This.
You can get the full explanation here:
[ame="https://www.youtube.com/watch?v=zZBqb0ZJSwU"]When To Shift Gears For The Fastest Acceleration - YouTube[/ame]

[gtengr]

Originally Posted by SCR

Cams may not be possible without MAJOR work to make them fit.

https://www.revvolution.com/blog/201...he-fa20-4u-gse

Speaking of the camshafts, SCR noted they have nice big fat lobes, so they may not be something we need to worry about swapping out. Couple that with the near infinite adjustability of the cam timing, and there may not be much need to put big aftermarket cam shafts in to get the power.

As SCR stepped into the combustion chamber, they noticed there is not a whole lot of clearance between the valves and the pistons. If you’re trying to go with cams that have higher lift and/or duration, you could potentially have interference issues.

As Spartarus noted, the duration is fairly short for high rpms. VVT moves the duration forward or backward in the combustion cycle, affecting timing and lobe separation angles, but it doesn't extend the duration. It helps a lot, but pure duration is also extremely valuable at high rpm.

Piston to valve interference is a big consideration that would take some work to figure out. But if you're into the motor far enough to change cams, you may be able to do pistons with valve reliefs to get around that problem.

[Keenercarguy]

Originally Posted by dowroa

I am not sure of your statement in (B).

Changing the valve springs puts you into Prepared in autoX, which almost instantly not viable for competition of full-on race cars.

Was that just a separate curiosity having nothing to do with autoX classing?

I don't AutoX with SCCA or NASA usually. The classing where I run is different. My suspension wouldn't technically be STX legal either anyway. I also literally drive tight epic mountain roads to and from work everyday. So it'd also be for that.
I totally forgot this thread existed lol

[Zentec]

Originally Posted by nico_rsx

This.
You can get the full explanation here:

Love EE he dose good work.