forkedroad

im very curious...
how much psi can you put into a stock rotary engine? maybe in the years from '05-present... i was thinking of adding a turbo, but i just dont know how much a rotary can take.

maybe telling me the maximum psi and what is good enough for an rx8.


thanks.

TeamRX8

iTrader: (25)

1st post and you're already out of your league ...

mysql101

I like to start at 14 psi and go up from there.

kartweb

I recall what someone who blew their turbo motor after 40,000 miles told me;

Take 120,000 miles and divide it by the average PSI you'll run over atmospheric and plan on it failing before that number of miles. Above 14 psi detonation is unavoidable. Detonation breaks things in a hurry. Cuttng back timing and richening it up will minimize detonation to a point but it won't really make any more power. So I've been told.

mysql101

^ sounds like someone made up random stuff - boosting to 2 psi wouldn't shorten your engine lifespan to 60,000 miles...

kartweb

Read it more carefully;

Take 120,000 miles and divide it by the average PSI.....

Personally I doubt the motor would last 60,000 miles if the AVERAGE boost was only 2 PSI.

A few months ago I bought 3 low km Renesis motors during a trip to Japan, all low mileage. Was planning on giving one to my son for his 914 and selling the other 2 to break even. 2 have been sold to folks with turbos, the 3rd I'll hang onto. Both had very well tuned motors.

mysql101

how do you figure out average? Average in boost? Average pressure ever? How about when in vacuum, do you subtract from it?

Your doubts appear to be unfounded. I'm 43,500 miles now, turbocharged for 11,000+ miles at a minimum of 9 psi most of the time.

kartweb

Read it carefully my friend.

Take 120,000 miles and divide it by the average PSI you'll run over atmospheric and plan on it failing before that number of miles.

Bottom line, the more miles of boost the shorter the life. The candle that burns twice as bright lasts half as long. It sounds like you disagree with that. I recall one other person who posts here prominently that commented he never had a problem with his turbo - except he's been through 2 motors so far. I really don't care what the excuses are, the fact is it happens excuses and all.

One day I'll probably put a supercharger on mine with 6-7 PSI. Already have a nice rebuilt unit from a Mercedes. Brackets are easy, plumbing is easy, tuning is easy, and no I won't be intercooling it. Nor do I expect it to last 50,000 miles before it blows the seals. I don't have anything against FI, but I sort of laugh when people try to give the illusion that a turbo will give magical powers with no loss of longevity.

I'm not the most experienced with modern rotaries, most of my endurance experience only dates back to about 1983-1989. #07 GTU class.

mysql101

Okay, so back to my first reply - if you run just 2 psi of boost, you're claiming a 60k lifespan on the engine. Which is why I said it sounds like someone's pulling stuff out their ***.

If you want me to read carefully, you might want to consider doing the same - I never once said the engine lifespan would not be effected. I am simply stating that your claim is invalid and will rarely, if ever apply to any real life numbers

MazdaManiac

iTrader: (3)

Agreed.

Everything in this post is utter nonsense.
The stupidity of which is only surpassed by this bit of drivel:

Are you really that clueless?

forkedroad

wow... tough crowd, huh?
i was just wondering how much psi you can put into a 2 rotor engine.
this is my 1st post cause i am quite new to this club... i havent been on for a while cause i was busy with school.

im still kind of new to all this too.

btw.. wat type / brand of turbo is good and reliable? i researched a lot, but i dont really know what is good or reliable. i may not necessarily get a turbo, but if not i was thinking of an intake, exhaust, and manifold... again, what is good?

i need some easy tips of performance...

ChrisRX8PR

iTrader: (1)

I have seen a Two rotor at 40psi+ (13bREW) running on alcohol. Its all about fuel/ignition management. You can break your engine at 6-7psi if it is badly tuned but you can have a reliable engine at 20plus if it is perfectly tuned and not break for years...

Chris....Esmeril

kartweb

When you get your Ph.D. in Physics from Duke University and win a few 24Hr races with a Mazda ask me again.


28 years ago I worked for Champion Spark Plug doing research in Toledo Ohio analyzing combustion propogation at 2000 frames per minute. I'm guessing you were still filling your diapers with dinner from the night before about then.

mysql101

hehe.

At 8 psi*, that means my engine can only last 15,000 miles by kartweb's calculation. I'm about 12,000 miles under boost now. I'll let you know in a month if my car still runs



* I actually run 9-11 psi most of the time...

MazdaManiac

iTrader: (3)

So why do you say such stupid and incorrect stuff?
Was your "education" really that worthless?
Really. I am amazed. I know plenty of folks that went to Duke and their grasp of even basic stuff exceeds the value of your every worthless post.

That formula you threw out there is worse than wrong and who told you that building a supercharger system is easy? It certainly isn't easier than building a turbo system or we would be flooded by them right about now, rather than watching Petit use their customers as beta testers.
The tuning is identical in all forms of forced induction.

Just stop.

You are either a liar or a fool (or both) and you are just making these poor folks even more confused with your crap.

No. I was 12. So you are old and dumb?

maxxdamigz

iTrader: (1)

28 years ago? Fuel injection wasn't even standard. I should think you would have learned many times over in the last 28 years the amount you actually knew 28 years ago. Anyone with a PhD worth a damn should A) know by that point that they don't know everything and B) not need to mention they have a PhD to establish credibility for the arguments they post. Even an idiot can have a stroke of genius so all arguments from all sources must weighed, considered, and tested.

We've all had professors who somehow got PhDs but were basically idiots. Your argument has some logic behind it - more power = more stress/heat = more fatigue - but your arrogance doesn't help.

StealthTL

iTrader: (1)

Champion - that brings back memories! 28 years ago was the last time I ever used Champion plugs in a rotary, after having one drilled out of my 12A.
Broke off clean, leaving just it's threads, and the Mazda mechanic just laughed "....don't tell me!...it was a Champion, right?!!"

I've been wanting to meet the designer of those plugs for a LONG time......

S

TeamRX8

iTrader: (25)

Champion = lawn mower plug

that's about it

mysql101

thats what a rx8 is, right? a lawn mower with rear seats.

MazdaManiac

iTrader: (3)

Here, try this little bit of bench-logic:

150,000 - 150,000 / ((Pr - (Pt - Pr))) = ELe

where Pr is OEM rated power, Pt is the target power level in Hp and ELe is expected engine life in miles.

Equally bullshit, but at least it produces "believable" numbers.

staticlag

lol. isnt atmospheric like 14 psi? maybe its the ratio over atmospheric

SmokeyTheBalrog

Michael

I'm only 20 and at least I know that driving ability doesn't mean dick about your knowledge of automobiles. Hell, if I had a dollar for every guy at a DE that simply pays to have a shop maintain his vehicle, trailer it to the track, just so he can hop in his GT3 for a fun ride, I'd be the one in the GT3RS.

I'm currently doing research/publishing a paper on TMJ and IVRO. That doesn't mean I can perform the surgery.

I know a lot about fish. Does that make me an expert fisherman? An expert chef?

Do you think that the guy (back before assembly lines were automated) that screwed the spark plugs in on an assembly line knew how the rest of the engine worked?

In essence, and please, don't take offense, as I like to respect my elders:

You could be the next Jesus, but noone here will care if you present yourself as the omnipotent omniscient RX-8 owner. We already have one rotarygod. , and he's nice to us.

kartweb

You know the really funny part of all this....

The poster originally asked:

"how much psi can you put into a stock rotary engine?"

You of all people who've blown what, 2 motors now, should have been able to answer him. If memory serves me correctly the last one was something on the order of 21 lbs of boost.

But no, rather then answer the question, you think being a smartass is cool. Typical street racer kid. Look at your avatar - gay ****, a new one every week. By golly you're an internet guru of street racers aren't you?

Someone like you will NEVER be in a position to offer someone like me a job. Thats OK, I really don't care what a gay **** street racer punk thinks anyway.

nycgps

iTrader: (1)

I dont have a phd, not even masters. but I think I know history.

Lets not go back in time way too far, lets talk about 13B-REW for a bit

there was a time that 30 psi was a dream. but its possible now. So something thats impossible now, does not mean its not possible in the future. I dont need a phd to know that.

and I can tell, the reason why *someone*'s engine blew at 21 psi simply because his car had a malfunction. and before the malfunction happens his car's tune was NOT tune for 21 psi. What do you expect to happen when the tune was not for 21 psi of boost? I dont need a phd to understand the results.

So does that mean Renesis cannot handle 21 psi ? Now, could be. Future. Nope

And I seriously think you should try to get a new phd degree, simply bcecause I think your old phd is seriously out of date.

Champion plugs .... rofl

Its just funny that a phd degree holder said some irresponsible stuff like yours.