I've always been told that the head can start to lift from the block once you start boosting around 25-26psi. I just said that he'll need them soon if he keeps modding and/or raises the boost. ---I think.

 

1 Flames I was told are normal.
2 Your cylinder head is what limits your RPM range mainly not your block. (That statement is incorrect when talking about an Evo) Evos rod bolt fail first. I searched and found 2 cases where people have spun bearing before destroying valvetrains, haven't found a single case of destroyed valvetrain yet.
3 You don't need head studs yet
4 8000 rpms is just a rev limit, you don't have to rev that high.
5 after about 7000 rpms you car doesn't realy make much more power than it did at 6000 rpms

 

I have accidentally rev'd to 8000 and bounced off my rev limiter...was kind of scary to hear my engine running that high. The valvetrain is not the issue here, I think the stock valvetrain can handle 8000 perfectly fine. Its the rod bolts that will fail. Many people have experienced rod bolt failure in stock engines. If you want to reliably rev that high all the time, put in a set of ARP rod bolts, forget about the head studs. I run 25 psi on stock headstuds daily, no problems.

 

for what it's worth I ran around on stock headbolts at 24psi without issues, but I wasn't getting any detonation either.. I did go ahead and replace them when I put cams in since I was in there so I could sleep better.

 

i run 23-24 peak (92 gas) with absolutelly zero knock. but that is only peaking and im not in that boost for a really long time. I say its ok to do so without head stud replacement, but thats just me.

 

And 94 octane is readily available at most NJ Sunoco stations.

 

Yeah, don't bring it there tooo too often. you can shift 7000 for daily driving, and try for 7500 when racing....but it will end up flaring higher.

 

8k? This isn't a Honda.

 

Put this in your car and it will become a honda.

 

Youl probably start to lose power around 7300ish and wouldnt benefit taking it any higher. But personally i wouldnt take it up to 8 just for the fact that unless some internal aftermarket work was done cams etc...there would be no reason to subject the block to that extra stress.

 

Okay, so everyone is saying that the vavletrain will not float at 8k rpms. Where does it begin to float? I know on SR20DEs before the 1999, they start to float just past 8k.

However, you guys are saying the rod bolts are weak on the 4g63 and revving to 8k as opposed to the stock fuel cut of ~7600 will cause premature failure of the rod bolts. Hmm... well, that sucks. As for not making any more power at 8k and therefore not needing to shift that high, that's not the case on a road course. It's called 'over rev capability/capacity' and it's often spoken of on 600cc sportbikes where momentum is critical on corner entry. Being able to stay in gear another couple hundred revs instead of having to shift (even though your power is dropping off) is invaluable to cutting quick lap times.

Like Mellon mentioned, having an few extra hundred revs really helps out on an auto-x/road course. On my nissan, I had my rev limit increased from 7100 to 7800 and I was often near 7800 rpms before entering a corner. If I didn't have the ability to rev that high, I would've either bounced off the rev limiter at 7100, or shifted to the next higher gear to only downshift back down a split second later, neither of these things being good for lap times.

 

To me, it is not the amount of power available in the last 600 or so RPM, but it is what those extra revs do to engine life. Revs are probably the biggest contributing factor to engine issues. The piston speeds and forces just get really high. I have actually turned down my rev limit at the track to stock because I almost always bounce the limiter, and I am sure my laptimes have more to do with my driving than the extra revs anyway.

Marek

 

To the OP: Two things...
- get the car onto a dyno, that way you will know what your power curve is and you can figure out your shift points from there.
- unless you absolutely MUST have an 8000 RPM fuel cut for racing purposes, I'd set fuel cut for around 7800 RPM. The extra 200 RPM gain you nothing for street driving and will just cause extra wear and tear.

l8r)

 

does anyone rev higher with cams and valve spring, retainers without the conrod bolts

 

15,600 miles of reving to 8500 all the time draging and autocross! Stock block- no issues. I do however have cossie cams and supertech valvetrain - 3076.

I do it cause i like the scream at those high revs.

A