midnightsunset

There seems to be a taboo about going beyond the factory redline of 9,000 rpms.

Some say there is no power beyond 9k.....

Some say the F series cannot handle the higher redline....

Some say that no one has stepped up with the right products to achieve such a feat....


Many a tuner have upped the redline even after stroking the motor to 10k+

Higher lift/duration cams are supposed to allow for a movement of the power curve to allow for a broader powerband.


"Why" is the question of the day. Would like more tech than opinion and the premise for this discussion is for a race motor, not street.

-Joshua

21337R

Seems to me that the main limiting factor is piston speed.

terahertz

i agree. the f20 and f22 are almost identical except the stroke is longer. this results in higher piston speed per revolution and honda lowered the redline themselves.

midnightsunset

"Race" is the key word. I haven't heard of anyone trying to surpass the factory rev limit, N/A or turbocharge, race or street trim. Yet I have seen 1.6 liter hachi's and 2.0 ltr Evo's pushing 10k+ without a rev limit close to the F series from factory.

With the means to build an engine to handle it, ASM, BC, J's, all keep the redline close to 9k

terahertz

what we're saying is the piston speed is the limitation we think. if you notice the spoon ctr i believe has a 10k redline but its a b18 engine. theoretically the bore could be the same size as the f20, but the stroke will be shorter, resulting in shorter distance the piston must travel during one revolution = lower piston speed. if you destroked the f20 to a f18 (lol) then you could most likely run 10k speeds as well with a beefed up valvetrain

iDomN8U

It's been done. Hytech will build you cams for your application. Talk to Inline if your serious

If you decide to do it, be prepared to empty your pockets and sell off any non-vital organ.

Voodoo_S2K

Almost anything is possible on a race motor, it's just a matter of budget. Do you want to rebuild the motor after every session, every weekend, every season?

street_ruler

i dont think poiston speed is an isue....we have a short stroke. the 4g63 has been revved to 9300 daily in some race motors....why not a car wiht a 9K stock redline.

i think the issue is valve float and retainers cracking.


i did see a viedo of the J's s2K blowing the motor by mmissing a shift but thats like a 9K + 6K revvs accident.

i think with the right cams, springs and retainers espicaly 10K-11K could make power

Voodoo_S2K

There a lot of barriers to higher redline. Piston speed, piston side loading, valve floating, cam profile.

Once again, it's all a question of how long you want the motor to last.

revmatch

my car revs to 11k daily /ricer