nice engine VEST RACING

 

Run your stock shaft turbo PP to 11k under boost and see what happens...

 

since we're on the subject, what is a good redline for a non-balanced rotating assembly with a stock shaft on a 13bppt?

 

Chaotic_FC -

It doesn't matter what ports you are using.. but i have read somewhere that mazda balanced the shafts to 9000rpm (i could be wrong - I read it in a sae technical paper somwhere?) Power around 700hp mark is where they start to bend. I have seen a methanol 13b bp turbo pushed to 930hp with dowels and ceramic seals however that motor only lasted a couple of runs.
From your build thread it's not going to be a race motor so I wouldn't worry too much about pushing it to the limit with your set up, depending on the power band of your setup 8000rpm to 8500rpm should be enough to make you happy and a safe limit for the bearings and seals from wearing out rapidly.

 

ok, thank you.

 

What stock shaft???

 

If you use RX-8 internals they are balanced to like 11k. The engine revs to 9250 in stock form and in mis-shifts I have seen 10k...no issues....



Chris

 

I dont know what you guys are on about? I ran my PP NA (NOT TURBO) to 11000 and had no issues with my shaft/....rebuild for next year and ran all year..
we usually shift at 9800 with a start cut seinz gearbox....with just 200 rpm drop in every gear
so that means 9800 constantly all day long..not no 1/4 mile one off...raod course in trinidad and tobago..jamaca, puerto rico, guyana , barbadoes......all year long. from island to island...
so if you guys are breaking shafts at 9000 something seems wrong....the only issue I ever have run into is bearing spin usually due to imbalance....or wrong internal match up...not rpm...of course this being said I will say that there is of course a point at which harmonics will come into play and cause issues...

 

i believe thats because your setup was NA.

 

i can see tht to be true Chaotic FC......as i said my whole time has been NA, jus getting to learn turbos...lol
i will get it though

 

My comment wasn't directed towards your ungodly beautiful engine vest. I'm saying that there is a big difference in combustion pressures that come in to play at very high rpm's when you go turbo as opposed to N/A. Just for a small example (that may not be relevant, it seems to be to me though) check out this compression ratio calculator. With FD rotors at 18 lbs of boost, the effective compression ratio is 20:1 (or nearly 300 psi of pressure BEFORE combustion factors in), compared to even the Renesis rotors @ 10:1, tell me that doesn't make a difference when revving the snot out of it.

 

looks like a lot of invested. how much hp do you have?

 

https://www.rx7club.com/showthread.p...34#post9472434

 

thats only a semi-pp too!

thats how extreme this kind of porting is with a turbo.

hence why im doing it

 

hope you can handle that racecar sound. loud as hell! & dont even let me mention the gas mileage. and few can tune pp13b's it isnt easy AS YOU THINK


btw if your really serious about a PP 13b i would of advise you to go for a gt47 or bigger. reason being is the power on a pp doesnt start till after 3500-4000rpm. and it starts dying close to 10,000rpm which is perfect for a big turbo

 

300 psi isn't **** compared to pressures in the chamber after combustion. However forced induction doesn't really create as much more wear and tear as you think. it mostly allows the combustion event to last longer, with more air fuel mixture, so the engnie is gererating torque for a longer period of time which makes more HP since HP is a measure of torque/factor of time. yes forced induction will degrade your engine faster i agree. but raising the redline will kill the engine much faster... especially on a piston engine.

 

Wow that engine looks amazing!

 

Yes I know, that is what I said. However if you put twice as much air into the combustion chamber (read: boost) your combustion pressure is that much higher.

You're completely contradicting yourself. yes, it does create more wear and tear. if that wasn't the case, carbon seals would work in a turbo application. they don't.


I'm not sure what any of this has to do with anything. raising the redline creates a lot more stress on your rotating assembly, especially when your combustion is much more powerful with forced induction.