boosthappy

how much more rpm's do you think i can get out of a stock head while beenin boosted ..thankz

2_much_tc

0.... And I'm assuming by this you mean raising the RPM limiter? It ain't gonna happen. You need a standalone to do this to my understanding...

torqueTc

iTrader: (11)

yup, the correct answer is 0, boost adds NO rpm's, but will cycle up through them much faster.

I also wouldnt go raising the rev limit either, overboost can be a major problem without proper tunning if you bypass your rev limit.

SePaTc

Yeah, i don't think he meant boost will add rpms...i think he meant whats teh highest he can raise the rev limiter on a boosted setup without blowing up the head.

and while you have pretty much gotten your answers already, theres only one real way to find out.

Mightygnu

like they all said, zero!

brett561tc

i will let you guys know here in the next few weeks. i should be getting my stand alone pretty soon. i plan on raising the rev-limiter to 7k.

engifineer

Its not just the head... it is the bottom end that will go blam when you raise the average piston velocity too high. 7k may last a while, but I wouldnt do it very much personally. I figured it up a long while back (cant find my numbers and am too lazy to do it right at the moment), and I believe our engine is running at piston velocity of approx 24 m/s at redline. I dont think you want to go much higher than that.

To properly raise safe redline on a car, you de-stroke it.

Mr_Meaty

but your on a built block, Brett.

He posted this in the other thread that no one watches, so I told him to start a new thread.

He is going to be boosted and want's to raise his rev limiter (I think the greddy ultimate let's you do it). He want's to know how high he an raise it on the stock block and still see improvements.

I told him not to riase it on the stock block, and he wanted more input. I think everyoen here pretty much agrees that you should NOT raise the rev limiter unless you build the motor.

Mightygnu

I agree!

OuterHeaven

The truth is no one (well at least to my knowledge) has blown an engine due to revving too high. I think someone has but it was a miss shift and probably was well over 8k rpm (also people have mis shifted before and logged in excess of 8k rpm). Enqifineer there is still some head room especially with a street car that does not red-line every shift. I believe the mean piston velocity is safely recommended at 25 m/s (for a race engine) if I remember correctly but you also have to realize that our cranks are offset by 10mm. So I think the pistons have different velocities depending if they are going up or down. Personally with a street car I would not be afraid to rev it a little higher if I could but I can't and even if I could I would not net any more power with my 05 engine the way it is now. This would only be beneficial for an 07+ engine due to the power curve and I bet even 7k rpm would be even a little too high for an 07+ engine. Also if I were raising the rev limit I would want a fairly large turbo and a tubular turbo exhaust manifold at the lest.

boosthappy

i dont think im goin to get more rpm's from boost i said how much more do you think i can get on a stock head bein boosted and im goin to be tuning on a greddy ulimate im thinkin atleast 6500 for a redline..let me know

engifineer

Total stroke and rpm determine average piston velocity. If something moves X mm (stroke) in X amount of time (given by rpm), then regardless of anything else, its average velocity will be derived from those two numbers.

Comparing to the max recommended velocity for a race engine is a moot point. And the rev limiter is not a "Safe" point to hit all the time, so running above it regularly will not be safe either. It may not come apart right away on you, but you can expect a much shorter life on this engine if you push it much higher, especially with boost.

torqueTc

iTrader: (11)

you can easily over rev a motor (missed shift, slamming wrong gear) and bend valves. The celi GT-S motors are infamous for floating valves and causing them to unseat when people miss shifts and "force" the motor to hit past the limit briefly (they are already operating at a higher rev then us).

By you taking away a factory setting like that, the power gain would be so minimal on a "larger" displacement 4, that youll never see it. This isnt a high revving honda engine, its a docile, low rev 4, thats geared to make (i use this loosely) "gobs" of torque at a low RPM.

If it was me (and I just got this, so it is kinda me) Id work more on traction, I just got a TRD LSD a little back, and its not installed yet. A car that can hook up, will always out perform a car that can "rev" higher by 750rpms (then boom!)

bigAL

iTrader: (1)

Mine is set at 6600rpm on a stock block and stock head with a turbo setup. I definately wouldn't live up there though, I've only hit the limiter twice. BTW - I have a standalone.

Mightygnu

Jeff(318_tC) could rev out his engine to 7500...

But he was fully built as well

aen

i dont' know about you, but i don't want to drive a been boosted car.

brett561tc

7k rpms will be fine on a stock head. the only thing im woried about is the oil pump.

Mightygnu

yea. I hope it doesn't fail!

Mr_Meaty

What do you mean by a "been boosted car" aen?

boosthappy...you want to raise it to 6500rpm? Isn't the rev limiter right now at 6250? What woudl be the point? Just so you can get up there and not bounce off the limiter?
that doesn't sound like to bad of an idea to me. My mine revs up there so quick that it wouldn't matter!

bloody_mess

awww no fun