s2kboii

wil this set up work?

ap1's head with ap2's block?

and if it does will i be able to take it up to 9k with ap1 ecu?

and will i still have the same amt of torque as ap2's motor or less?

thanks in advance

CrazyPhuD

Lower end is the limit for 9K the head IS NOT the limit....AP2 head is perfectly fine to rev to 9K. It's the rods that will give out.

azrael

The problem for high-revving on an AP2 block is mean piston velocity. When you lengthen stroke, the mean piston velocity (as well as peak piston acceleration) goes up. At 9k on the 2.0L, Honda was already pushing the bounds of what is acceptable and reliable on a street motor. When they lengthened the stroke on the 2.2L, the rev limit needed to drop to maintain reliability. In theory, with the proper engine management, you could run the engine up to whatever speed you want, but in all likelihood, you're looking at breaking rod bolts or scoring cylinder walls due to extra side-loading.

Wildncrazy

And yet lots of people are doing it without failure.

It isn't the head that is different on the AP2 it's the cam.

Wisconsin S2k

yet. it's not a question of IF it's WHEN. BIG BIG difference.

LUVNMBRS

IMHO, pushing the bottom end of the AP2 to 9K rpm is not entirely unreasonable.

There are many people reving B20/B16 hybrids (CRV engine with VTEC head - 89mm stroke) to 9.5K rpm, H22 Prelude motors (90.7mm stroke) to 9K and K24/K20 hybrids (TSX block with RSX head - 99mm stroke) to 8K. All of these motors have similar or longer strokes with worse rod/stroke ratios than an AP2 block (90.7mm stroke), and they are still able to easily survive the abuse.

A risk adverse manufacturer like Honda want a cushion/margin of safety re. the max. rev. limit for their engines. Their engines can actually rev. higher than the preset limit. However, if you don't feel you need this cushion of safety, then go for it.

The stock rods on the S2K are already very good pieces. They are forged, carburized and shot peened from the factory. There are many people running 15 psi boost and 400+ wheel hp on these stock rods in the FI forum. They should be able to hold up to an extra 1K rpm. Just make sure you use a good "real" synthetic oil like Redline and cylinder scoring should not be an issue.

If you want to be safe, then just swap in some aftermarket rods. There are many available now (Cunningham, Crower) at reasonable prices, so just think of it as cheap insurance if you don't want to take the risk.

Wisconsin S2k

none of those cars has anything to do with the S2000. the S2000 is a completely different engine. in case you missed it, honda specifically lowered the rpm of the ap2 because of the piston speed, rod angle, and piston deceleration. in case you're wondering, the ap2 spinning at 9000rpm, is like the ap1 spinning at almost 11,000rpm.

so, know any of those honda engines you mentioned that can spin to 11,000rpm on the stock block and not blow up?

the rods are actually not the concern. the rod bolts, however, are. and higher horsepower has ZERO to do with piston deceleration rates, and piston speed. where on earth did you get your information from? lol, and a "real" synthetic oil? please read our oil journals before you say such things.

more terrible advice. the bolts are one of the main things that need to be changed. not the rods.

*spoon*

i dont post here often, but i was going to do this set-up.. Please advise me on what to change and what not to change on this set-up.. or is this set-up even safe for my AP2. thanks for the help

Jakup

People can do it and not have any problems, but I'm sure with as many redlines as some people do a day over a prolonged period something would give.
Due to increased stroke of the F22, piston speed at any given RPM is going to be greater than in the F20C. In theory, though, this should be offset by the greater torque, as you'll be able to shift at lower revs while having the same power. The piston speeds of the F22 at 9k RPMs would be too much (at least Honda thought so) to remain reliable. Some people manage to pull it off, but as soon as any little thing goes wrong (and it could happen at any time while revving that high) it's going to be a very expensive fix (e.g. broken rod).

azrael

WisconsinS2k covered all of the big points, but just to reiterate -- a few pounds of boost and added horsepower don't hold a candle to the forces created by an increase in the rev limiter. Peak piston acceleration on the F2xC is through the roof for a street engine. If you compare and contrast with other high-performance engines, you'll realize what an engineering feat 8300 RPM already is on the F22C.

If you want more power, look to forced induction. If you want a higher redline, just get an F20C long block and be done with it.