I know its a good Idea for you to run new head studs for higher boost or higher redline, but which is it mainly for? If I am shifting at 7100 or so, is it ok to run 23-24 psi spike on 110 oct. on the stock head bolts? is that pushing it?

 

I'd say your pushing it...

However your going to have these people come here and say they have pushed x amount of boost for x amount of time and never had any problem. Well, I've also heard people say that they "...don't ever recall marijuana effecting their memory..." if you get my drift. Just because you can "get away with it", doesn't mean it may not bite you in the *** sooner or later.

 

May as well stay stock then Zeus. I run my street tune from the dyno (375 whp dynapack AWD dyno) every day of the week back and forth to work with no head studs, rod bolts, or main studs.

It don't hurt the car to upgrade early.... just your wallet, and it isn't expensive at all. Nobody I know of has blown a headgasket on the stock head bolts because it seems like everyone is switching to upgraded hardware as one of the first few things they do. I personally will put in headstuds when I get headwork done.

Keith

PS: Like I said above, it won't hurt to put in the head studs and they are cheap.

 

hmmm.. good stuff.. but still, is it moreover for rpm or boost reasons that you upgrade?
I ask because I wanna take her to a track event and run ohhh about 22 or 23 psi.. heck maybe spike to 24 if its not too stupid, however I won't rev too high, I always stop before 7500, so is this still an issue? is this much boost too much for stock bolts to handle for such a short period? or do they need more punishment than that? again..rpm or psi?

 

It's both and either. It's about moving CFM through the motor. A lower boost level with a bigger turbo will still move more CFM than a high boost small turbo so boost is irrelevant. Higher RPMs mean more CFM through the motor as well but a stroked or higher displacement can move more CFM and lower RPM so RPM is irrelevant.

Therefore if we are talking about CFM then we are talking about a horsepower level.

So you should ask at what HP level do you need headstuds. My educated guess is 400 AWHP. I have heard from pro tuners that there is no need at all and a lot of people here think you need them for 275 AWHP. It's up to you. I say why replace what works fine. I'll upgrade my motor hardware when I build the motor and not before.

 

Ok, first of all headstuds have absolutely nothing to do with RPMs, zero The main and only purpose of upgrading the studs is to protect against possible stretching of the factory studs when running high boost (stock turbo). The combustion chamber seal needs to be held at check when at high boost, therefore upgrading to a heavy duty fastener will only afford you a better chance of not breaking this seal. Sure you can go on with the stock bolts, but I always change to studs whenever I do a cam install, this is just for safety of course.

Maybe someone was mistaken when they thought about RPMs having to do anything with headstuds, maybe they were thinking about ARP rod bolts Those may protect when revvving up high

 

Exactly! Rod bolts and main cap studs need to be upgraded when going for very high RPM setups, or just as a "why not" if you have the oil pan off anyway. I think anything over 8000 RPM I would start worrying about rod bolts and main cap studs.

Keith

 

Looks like you guys have never lifted a head on a naturally aspirated motor.

 

Lets see, I ran a Type R at up to 9000rpms, 2.2 Prelude at 8500rpms, both with upgraded springs and retainers a couple years back, never "lifted" a head I haven't heard of a head lifting off due to high rpms, it just doesn't make any mechanical sense, not unless someone didn't properly torque the headbolts down. Then again im sure I havent seen everything out there yet, weird s-hit happens everyday

 

You would not believe what some NA Honda engines have done to OE headstuds. Then again, your talking to someone who believes "high compression" only starts at 12.5:1 on a Honda street engine... and the bottom end of a "Honda turbo engine" should never go below 9:1.

It only takes one good "ping" on a bad tank of gas (depending on tune) to "break the seal" on most Japanese four cylinder engines depending on cylinder pressure. Hell, depending on who you use to tune the car, a little generous dose of timing in the mid-range can stretch OE head bolts without said "ping". I've only personally seen it once on an Evo, but seen it none the less. I had the (dis)pleasure of replacing that head gasket and installing studs on that car.

This is not a "must do" thing (as you hear so many people "getting away with it"), but a "damn I wish I had done that..." kind of thing.

 

Guys please just get this supporting mod out of the way early in the game. I have 44k on my car, around 32k or so, yep you guessed it, the stretch bolts stretched and bye bye Mr. head gasket. As Zeus stated this job SUCKED, keep in mind we had to do it outside because I did not want to risk driving the car after the failure but never the less earlier is better with this particular mod in my opinion.

Josh

 

ok, so its rod bolts that need to be replaced for higher redline... what are cap studs? Al reccomended somewhere on here to replace the headstuds when raising the rev limiter, thats where I got that Idea. so someone list it out in a table type format for me, giving me which stud/bolt should be replaced at which cfm/hp/milage/whatever you think is impt.
btw:I really appreciate all you gurus and mods, and seasoned evo owners helpin out.

 

hi guys ,,,,,heres my bit....its never been to dyno,,,,no head studs, i run 23 psi daily driver.......i run 33 psi 8500 rpm at the track on c16......every 2nd tuesday of every month....for our import shootout.... been doing it for 3 months.... i had to put in 1200cc rc injectors ....sparkplugs have just a tad of detonation on em....i just did a leak down today i got 2.5% ALL the way across the board.....im changing out turbos to a 780 fwhp unit AND IM GONNA SEE IF ITLL HOLD 35 PSI WITH GOOD TUNING....if you dont detonate it, itll hold...with good tuning this engine is incredibly strong....with caution dont be scared to push it....
regards rick

 

Dude, it's a $97 safety. It's not hard to do. Rick I met you at the track I guess about a month ago, you're a cool guy but the way you and MZM are so prowd of pushing these stock head bolts makes no sense to me. I agree that with good tuning your chances of stretching the stockers are significantly lessened but still, it is just so rediculous to me not to spend the little bit of time and money to cover your ***.

 

Sounds simple enough, will be one of the first mods I do when i get my evo.

Maybe its the same reason my dad always drives untill he has about 2 miles left of gas in his car. He justl ikes to see how far he can push it befor he runs out. Haha one time he actualy did run out and called me while he was on the freeway and enough ADD for one post.