Renesis in 9A

While wrestling with engine choices and changing my focus for the zillionth time, I am again considering the Renesis engine.
In searching the web for salvage cores, I am finding plenty of RX-7 13b's around but the Renesis appears rare. Have any of you found a source or do you have to buy a new "short block" to consider this (anyone have the price handy?)

I priced a Bruce Turrentine build and, while his prices did not seem outrageous, I think I would like to do the building myself.

Thanks for any info/leads.

-Mike

Im in the same boat. I also prefer to go Renesis, because it is newer, a bit more economical at low rpm, and tuned better for top end. The only real difference is the lcoation of the ports which provide less exhaust and intake charge overlap.

The Renesis is a new engine, only installed in 1 high end sports car (Mazda RX-8) at this time, so I don't see it becomming too common in the near term. It is undoubtedly a slightly improved design over the older 13B, but not a big deal because you do not really need the extra HP and the higher rpm required in a 9A.

I see three ways to go (assuming you want approx 180-200 HP)- turbocharge a 13B, go to the 3-rotor 20B, or wait a few years for the Jap used engine market to find a supply of engines. The Renesis is very close/same as the 13B with most parts, but as you noticed, the 13B's are much more common and AVAILABLE. Ill probably go the turbocharged 13B route (quieter, better high altitude performance, probably better economy at cruise).

Decided on a redrive and prop yet?

mlw450802 said:

While wrestling with engine choices and changing my focus for the zillionth time, I am again considering the Renesis engine.
In searching the web for salvage cores, I am finding plenty of RX-7 13b's around but the Renesis appears rare. Have any of you found a source or do you have to buy a new "short block" to consider this (anyone have the price handy?)

I priced a Bruce Turrentine build and, while his prices did not seem outrageous, I think I would like to do the building myself.

Thanks for any info/leads.

-Mike

Click to expand...

Mike,
The only real difference between both engines is the exhaust port style. The high RPM used on any aircraft negates the differences. Tracy Crook makes about 200 HP with a 13B and a renesis, both N/A. Exhaust slightly quieter with a renesis, but water temps slightly higher. (The energy has to go SOMEWHERE) So either engine will work fine. Rotaries LOVE RPM so get a 2.83:1 PSRU. Tracy's is the RD-1C. The advantages are correct prop rotation, for more selection (of props) and operation around 6000 RPM. That RPM might be a problem for pistons, but a rotary has almost no load on the bearings at that RPM. (Mazda tested it) Plus the rotary is a bit more efficient at higher RPM, depending on tuning of course. There were some good sources of Renesis engines in Austrailia but the shipping could break you!
Rotary10-RV
Bill Jepson

The choice between a 13B and Renesis is a really tough call now, but given the choice, I'd go for the Renesis. The ports are already set up to breath well at higher rpms than you're going to run, and it's done without compromising the low end.

You can get essentially the same HP out of a 13B, but enlarging the ports increases the overlap, and becomes a problem at lower rpms. The amount of problem depends on how much you work the ports, particularly if you do something silly like PP (peripheral port) it

The next problem comes with deciding if you want a 4 port, or 6 port Renesis.