Highest RPM stock motor can be rev'd to... ??

[all4bspinnin]

Just wondering what the guys / builders with more experience say about rpm with these cars....

With a GT30R / 35R you will need as much RPM as possible, especially with our short 1st, 2nd, etc...

So what is the max you can rev this motor past redline (if at all)...

I know from my subaru days, redline was @ 7000 but you could safely stretch it out to 7500 if you needed to... anything past that was stressful

Opinions, comments?

[Sacrilicious]

very few people have actually played with redline on our car, but there's actually no point if you don't get upgraded cams, because you're getting held back by that anyway. with the cams, you'll just have to fool around and find out yourself...

[taf0422]

yeah I have no idea what the benefit of getting into the red line would be on this car without the needed upgrades...

my brothers svt went from a redline cutoff of 6500 to be able to go to 8k with no problem even made a little more hp with a tunerbut no idea on these cars

[rodrigo]

uhmm , i'll ride out 7k sometimes....if im feeling lazy on the shifting......but if this car makes its peak hp at 6100 or so with ap tuning...u aint gonna see anything exciting at 7k.... u need to change either the timing of the cams or the duration of the lobes themselves (different cams) to see anything worthwhile at that rpm

[xxandrossxx]

i think i saw 7-8k on an amazing downshift blunder from my first time at the track with this car...

[gsrtype1]

Ive ive hit the rev limiter just for fun a few times its like 7200 rpm if I remember.

[Buildabong]

I just take it to 5,500. Stock turbo poops itself past that.

[predapio]

Never been over 6k....it's like beating a dead horse, there's no use.

[all4bspinnin]

Here's basically what im getting at...

We all know the stock turbo, even with a good tune is basically done after 6000 rpms... but what about the big turbos? I know that a 35R isnt going to lose steam until past 7k rpms... to get the most of these expensive turbo's and our cars gearing, we need more rpm. The stock camshafts im sure will start to die out, but the car should still make power up top... With some custom ground cams, it should see a lot more.

Just looking to see if any big turbo guys have pushed the limit...

and for builders that have cracked these motors open...

How tight are the clearances on this motor?
Does the oil pump push enough volume/have enough pressure?
Is the crank capable or this many rpms without modification to oil?

[phantom3]

you can't inject enough gas at those speeds without using port injection. You don't have enough time.

Have you even measured the injector cycles at that RPM? (inside joke)

[all4bspinnin]

No i havent.

So are you saying the the stock injector will max out or the duty cycles will?

[phantom3]

Have you even measured the injector cycles at that RPM? <-- joke.

The problem is not the duty cycle... its that on a DI engine you only have an extremly small window to squirt in. Unlike a PI engine where you can start squirting long before the valve opens. the faster the engine goes the smaller the window becomes, the less you can squirt.

[all4bspinnin]

Oh... ok. But how far can we stetch this window? 8k?

[phantom3]

doesn't work like that. You would need massive DI injectors for the engine that don't exist. You have to go to PI in order to get the gas into the engine.

Let me see if I can find the numbers for you.

[all4bspinnin]

so basically, if i understand you correctly... there is a specific window that the injector can spray. The higher the rpm, the less the window. What you are essentially saying is that engine speed increases so much that the injector cannot keep up. You would need a huge injector to spray a good bit of fuel for a millisecond (probably shorter than that) in that super super small window to make it work... which is highly unlikely...

I remember seeing some prototype fuel rails for port injection. With those we could use direct injection until the rpms climb too high... then switch to PI?

[phantom3]

Originally Posted by all4bspinnin so basically, if i understand you correctly... there is a specific window that the injector can spray. The higher the rpm, the less the window. What you are essentially saying is that engine speed increases so much that the injector cannot keep up. You would need a huge injector to spray a good bit of fuel for a millisecond (probably shorter than that) in that super super small window to make it work... which is highly unlikely... I remember seeing some prototype fuel rails for port injection. With those we could use direct injection until the rpms climb too high... then switch to PI?

You got it! Bang on!...

Vivid Motor sports is currently working on a PI spacer kit for our engine. Should be good... there's also a CF intake rumored to be in the works that should work with the vivid kit as well

[all4bspinnin]

cool..

that vivid kit was kind of pricey but for the R&D involved, its a small price to pay.

I guess for the sake of this thread, around 7k is the max before the window for the stock fuel injector closes

thanks for the knowledge phantom!

[06Speed6]

DI injectors have a theoretical max of ~415 crank hp @ 7000rpm iirc.

The stock engine bottom end has a theoretical max rpm of ~7500rpm due to piston velocities since we have what amounts to a stroked 2.0l engine.

The valvetrain is good to about 9000rpm.