Im spanking new at rotaries. I know how everything works in a rotary, but when it comes down to technical poo, i wanna know all i can learn. So heres my question 's, how do you lower the compression in a rotary, if this isnt possible, how do you run large amounts of boost without the engine detonating or somthing like that. What mods do people tend to do on these engines, does the engine have to be pretty modified to aim for larger HP levels. like 300-400Hp. If anyone could answer these it would save me a lot of time. Id apprectiate anyones help oh and heres a question every newbie asks, whats the diff between the s4 and the s5? which is better for like 400HP applications -alex

 

Turbo rotary engines have lower compression rotors in them than what the n/a enignes do.

 

If you want to learn about rotaries I would strongly recommend taking some time and reading as much as you can from this forum. Just skim the titles of the posts until you see something interesting and then read it because there have been a ton of posts about modifying your Rx. You can also do a search for specific topics in question.

Here are some quick answers to your questions.

Lower the compression? Don't bother. You can get plenty of power safely from a turbo motor. If you want you could make a hybrid engine using S4 rotors which are 8.5:1.

High HP? Fuel and tuning.

S4 and S5? Series 4 and Series 5, 86-88, 89-91.

Which can make more HP? Whichever you put more money into The S4 did crack easier so get an S5 or newer engine.

 

S4 Turbo rotors are the best for high boost/horsepower applications because they have the lowest compression out of them all, people usually use the later models blocks though like s5/6/7/8 and cosmo ones especially s6+ and cosmo because they come with huge ports out of the factory.

Also if you get your motor rebuilt and your aiming high horsepower, dowelling is always good for extra strength, aswell as 3mm seals (this is an argued topic 2mm vs 3mm) aswell as getting it balanced and extend ported.

In my Opinion this is the ideal setup:

Start with an S6+ or Cosmo block, get it rebuilt using S4 Turbo rotors, get them machined to accept 3mm seals, get it dowelled, balanced and Extend ported, and you are at a start for some serious figures...

just my 2c