I'v desided to go with the 8.5 s4 T2 rotors in my 20B. I alright have 3 D stamped rotors which are only 1 pound heaver then The 9.0.1 Stamped E. By the time i get them lightened, and balanced they should weigh the same as a E series rotor or less. Now i need to find a Cosmo 13B RE front Iron. Anybody have one for sale??????

 

Call mazdatrix. ~$500. Or get a FD iron and machine it out.

 

I bet Japan2LA has one right now.

 

I have it..

I quoted you a price already...

 

I can personally attest to the strength of the casting in the s4 T2 rotors. I have detonated the crap out of mine and they were fine when I tore the motor down.

As far as the compression ratio argument goes, I was simply suggesting 8.5:1 because it allows more room for error. And error on a 20B could get really expensive.

 

Vaguely related to this...

Am I right in saying 8.5:1 13B rotors are all stamped D and 9:1s are all stamped E?

As I want to run 8.5 max, hell, id prefer more like 7.5-8 as want to run a ton of boost and pump gas...

 

NO.

All rotors (at least from 1986 and up) are stamped with letters from A to E.

 

Yes KNONFS is rite you can find S4 Turbo to motors from letters A threw D and D being the lightest out of all S4 Turbo rotors. I myself have S4 Stamped C in my 13B REW but they were lightened and balanced. And For the 3 rotor i bought 3 S4 rotors Stamped D. It took me awile to find them (all 3) but worth the effort i guess.

 

turbo rotors not turbo motors sorry had to fix that

 

And from S5 and up All the rotors were stamped E with 9-0-1

 

Chohakai....................if you want larger horsepower you have to increase your volume in the cylinder, if you use low comp rotors 8.5 you do 2 thing,right 1 is to inrease the cyl size for more and safer boost as well ,lower your chance for knock if you size your turbos properly you should not experience any lag,if you are looking for better street performance try using a t3 exaust and a t4 or larger intake turbine fast spool big Hpor if you can stand the small delay go t4 all the way,Its good for 420rwhp done right with bigger injectors 550 primarys,1600 seconds hope it helps ps check my page for some eng picks

 

You have no clue. You don´t adding displacement, spool-up is worse than high compression, off-boost responsive is worse...everything is worse. difference in compression between S4 turbo rotors and S5 N/A rotors is 12,4%, not much IMHO. High copression turbo engines are tuned with less timing, thats it... The myth that you can´t turbocharge high compression engines is fallacy

 

to no clue'.......displacement is volume ,lower compression is an increase in cyl size, or displacement lower compressoin allows way more boost ,try reading about second ww2 air craft turbios and superchargers i have also read about a p51 mustang that ran a 16cyl packard car engine that had 6.5 comp pistons that can boost 60 lb during a race and, can take 100 psi for i minute if they have to push it the engine makes 6to8,000 HP try that in your high compressio rotary see how long it lasts,I would not usually respond to your insults but in this case i am willing dont be afraid to read, its good for the brain,Ps I have worked on rotarys for 30 years so try not to tell anyone how smart you are just show us with facts or pics

 

so what, some F1 turbo engines were running 60+ psi and much more than 6.xx compression ratio, and mainly far higher dynamic compression than WW2 aircraft engines-on gas, no alcohol. High compression isn´t what breaking wankel engines-missfires, pre-ignitions, detonations do... Yes, lower compression will give you larger room for error, but never cure the reason of it-bad tune... I don´t know power limits of "low" vs. "high" compression rotors, probably no-one know, but everything being equal, higher compression-more power, better BSFC, lower EGTs win win situation. There are some members who done it, and I´m sure they keep it for good reasons. I didn´t want to insult you, but I was shocked with suggesting T3 housing for 20B... "TURBODREAMS04" already decided on rotors, so nothing to talk about. Stick with what works for you and be happy with it

 

Considering the amount of high and low compression engines I've played with over the years, I'm really not sold on this high comp business if we talking the limits of pump gas and holding cars at WOT for long periods.

Sure a high comp engine can run XXpsi boost, but can it do it at the same ignition timing? No, and unless rotaries are magically different to the piston engines im used to, the extra ignition timing you can run at the same boost from lower compression yealds much better performance results than anything you lose from lowering the comp.
And on piston engines dropping the comp .5 a point never noticably changes performance aside from at low revs totally off boost anyhow, and no car, esp not a rotary, is quick there anyhow, and it doesnt change where the boost threshold starts...

So, is the 8.5:1 and 9:1 rotors easily distinguished from each other then?

 

Its not about can it do it, it doesn´t have to and properly ported wankel engines with right supporting mods for given combination even with low compression ratio runs with very low advance, less than 10° at full power.... If engine is gaining power with much further advance, something is wrong in given setup-engine doesn´t breathe very well... for example PRO STOCK motors, they run stupidly high CR, VE of these engines is over 124% and ignition advance is only around 11-13° BTDC, more advance-loss of power, torque... also these engines have extremely low BSFC, as low as .34 whereas rotary in its state of art form full PP have at best around .46

 

There is no arguing that, but race engines sure as hell dont run pump fuel though.

Thats the main reason for lower compression, it's the only real way (water/alcy injection aside) you can have the two vital components for power on PUMP fuel, lots of boost and lots of ignition.

High compression= Big boost, big ignition advance, pump fuel. Pick two.

 

Tell that people who has reliable turbo rotary on pump gas, lots of boost, lots of fuel(10,8 AFR seems like magical number) and smallish timing-rotarys really don´t need as much timing, I don´t know if 5% power increase from further advance is worth a trouble and rebuild... I really don´t know why you wrote "big boost, big advance, pump fuel"... As fas as I know high octane race fuels rather need more timing for max power...

 

o man this is too funny!!! people please stop arguing!!!!! everybody has there opinion. Some might be wrong some might be right but please stop the arguing. As far as Turbo im going with a GARRETT GT55R and the 20B is getting full bridge ported so i can drive it on the street. Any yes im going with meth injection like iv been but this time im going with 2x pumps and prob 3 to 6 extra Fuel injectors. and im going to be running it with pump gas and race gas im going to have 2 different map settings. and yess im going to boost it anywere from 30-to-40 psi just worried about the iron since im pritty sure they start braking around 33psi and up

 

I would use the 8.5 rotors.. Not so much for the compression but for the fact that's it's a stronger rotor.. The 9.0 seems to get beat up pretty easily..

 

33psi,GT55 and 20b means 1300whp, do you really know what your getting yourself into, I mean if you are going to that extreme surely your engine builder or yourself should know what parts to use??
If not then you are taking a very big risk in learning with a 1300hp 20b

 

They break at lower boost levels then 30psi. Mainly on 2 steps. Dont usually break for no reason.


But the above is correct. You will make 1200rwhp+ on 30psi with 20b and gt55. If the engine is ported right power band will be ok but still high up.

 

The stupidity these forums provide is amazing. Look. It's really simple. Lower compression ratio on forced induction engines.
I'll take an industry leader with a supercar.

Corvette Z06 compression ratio is 11.0:1
Corvette ZR1 supercharged compression ratio is 9.1:1

Woah! Go figure!
Diesel engines are even dropped a few points when turbocharged.

If you need a full explanation, maybe another industry leader in turbocharger manufacturing can explain it. Honeywell Garrett, who builds turbochargers and jet engines...

Go to section 4
Turbocharging and engine compression ratios 101

"a stock Honda S2000 has a compression ratio of 11.1:1, whereas a turbocharged Subaru Impreza WRX has a compression ratio of 8.0:1."

Now go be a tuning GOD and run N/A rotors running 30 PSI and let us know how you do.

 

Thing is, you will get somebody who does and then proclaims to be the king of the world and anyone running lower are retards.

But they are missing a huge point, ignition timing.
Dont know about rotaries, but on piston engines you generally get a lot better performance at a given boost pressure from lower comp and advanced timing than higher comp and less timing.
Of your if you got the octane for it you can have it all, but on pump fuel without AI, well...

Or you get the "well my high comp engine has just at much power as your low comp engine but at much less boost" people. But to get that they have bigger laggier turbos and bigger ports, ******* up the power delivery, not to mention the masses of missing torque from the lower boost.

Its the never ending internet argument.
But I know what ive tried in the past and works for me (albeit on piston engines, but same basic principle), and no end of internet experts whos never actually tried both will tell me otherwise.

 

Thing is, you will get somebody who does and then proclaims to be the king of the world and anyone running lower are retards.

But they are missing a huge point, ignition timing.
Dont know about rotaries, but on piston engines you get a lot better performance at a given boost pressure from lower comp and advanced timing than higher comp and less timing.

Or you get the "well my high comp engine has just at much power as your low comp engine but at much less boost" people. But to get that they have bigger laggier turbos and bigger ports, ******* up the power delivery, not to mention the masses of missing torque from the lower boost.

Its the never ending internet argument.
But I know what ive tried in the past and works for me (albeit on piston engines, but same basic principle), and no end of internet experts whos never actually tried both will tell me otherwise.