the 20b rotors are bigger then 13b rotors right. So I guess going by rotor count is not a good way to estimate hp on a rotary. While on this what is the hp on a 20b?



And how much hp is the 13b?

The rotors are the same between the Cosmo 20B & the FD 13B-REW.

yah theres 3 rotors in a 20b and 2 in a 13b.



mike

how much hp does 13b make? 20b?

Asking stock numbers for 13b and 20b?

Which 13b, and remember 20bs have smallish twins like 13brew's do and were auto only.

I meant on the 13b and 20b engines alone stock with no turbos, how much hp do those engines put out?

you need to refine your question



a 76 13b makes 128hp stock

an 89 13b na makes 160hp stock

the na 20b makes 450ps stock but the only non turbo 20b there ever was is the race motor



mike

[/QUOTE]but the only non turbo 20b there ever was is the race motor[QUOTE]



lol, I wouldnt want an na 20b, no turbo is no fun ^^



I am planning on doing a swap to a 20b and wondering if it will justify the cause, 400+ hp stock justifies it VERY MUCH. That and a nice turbo and you are rolling 600-700hp, that and and insane turbo and you can probably hit 1000+ hp. I know it wont be cheap but it feels to me the beast is worth it ^^

but the only non turbo 20b there ever was is the race motorOK, now I see what your getting at.



The 20B twin turbo did make a bit more HP stock then the 13B-REW, but not by much.



The 20B also has a 2 piece e-shaft which means it will flex more at high RPMs & high boost. This can be compensated for but that means a full rebuild with machine work.



600HP from a stock 20B is asking for broken apex seals IMO. 450 should be easily attainable for someone who knows what their doing.



The 13B-REW is a nice engine, & IMO can support 450 crank horse power as well. You wont get as much low end torque, but it's a direct fit & is less to build...

Actually the 20B has a extra main bearing on the thick intermediate plate to support the joint in the e-shaft and provide a stationary gear for the middle rotor so it can run the same rpms as the 13B with out e-shaft flex... On the stock 20b block you are limited by the little ex port sleeves so trying to get over 500 hp is REALLY hard on a stock block unless you put in 13b rotor housings or put 13B ex sleeves in the 20B rotor housings. you can also run a 20B at 600hp fairly reliably since your basicly pushing 200hp out of each rotor and that would be about the same stress as 400hp on a 2 rotor. You would however be better off just running the 2 rotor for a while first and building it up with parts that you can change over to the 20B later on like a really good clutch, intercooler, beefed up drive line and good fuel system. If you try to build a 20B to make that much power all at once you will find your self very poor very fast with lots of broken parts.. https://www.nopistons.com/forums/pub...IR#>/boink.gif

j9fd3s - Aren't you talking about the 13G used in the 757? I've read that it was renamed to the 20B name. But in it's race form as a n/a engine, it was the 13G.

Actually the 20B has a extra main bearing on the thick intermediate plate to support the joint in the e-shaft and provide a stationary gear for the middle rotor so it can run the same rpms as the 13B with out e-shaft flex... On the stock 20b block you are limited by the little ex port sleeves so trying to get over 500 hp is REALLY hard on a stock block unless you put in 13b rotor housings or put 13B ex sleeves in the 20B rotor housings. you can also run a 20B at 600hp fairly reliably since your basicly pushing 200hp out of each rotor and that would be about the same stress as 400hp on a 2 rotor. You would however be better off just running the 2 rotor for a while first and building it up with parts that you can change over to the 20B later on like a really good clutch, intercooler, beefed up drive line and good fuel system. If you try to build a 20B to make that much power all at once you will find your self very poor very fast with lots of broken parts.. https://www.nopistons.com/forums/pub...IR#>/boink.gif [/quote]

you can always switch the sleeves like you said, port the thing OF COARSE!! By asking what hp does it make stock I did not mean i would KEEP it stock. Its rather stupid to try to push it to 600ph stock. I was thinking a nice porting job, good clutch is one of the 1st's in my to buy first list. I really just want to get the fd in my garage and work on it and do it once and do it right sort of plan. I though to buy a cheap non running one for 3-4 grand and use the rest of the money to work on it, but to go straight to 20b as to not waste money on the 13b which will come out eventually anyway.... maybe you are right though, I see where you are comming form with that. i have been reading this forum for about a year, (I only started posting recently), i learned alot about working on rotaries. I have a talent with all mechanical things too, I have no experience though so I can see it would be smart to start slow... this might waste more noney in the long run though, then on the other hand it can be worth it, get experience, get parts, I will loose a few grand in to the 13b though, because its going to come out eventually. Experience vs money... lol... I think I should take experience///

The stock 20B in the JC Cosmo made 206 KW (what's that in HP- 250-300?). Apparently. Probably made a little more but not much as they are limited by Japanaese laws regulating the max power of their locally produced cars to 206KW. So about the same as the 13B, but with so much more potential- a friend of mine has a 20B in his car and it is awesome! Love the sound...and... https://www.nopistons.com/forums/pub...#>/BURNOUT.gif

I didn't realise we were friends Andy https://www.nopistons.com/forums/pub...IR#>/smile.png

The big motor is less frantic in it's delivery and has a mountain more torque than a 13B. It will last longer at the 450hp output too, thanks to lower boost/rpm needed to achieve that power.

Realistically though in most street car situations you can make a 13B do what a 20B will, often for less money too!



But once you do three, two just ain't enough