With a decent stand alone fuel management and injectors upgrade, and a good IC, what is the maximum boost I can get on the stock engine without blowing it ?

I dont know much about rotaries, I dont know if stuff gets forged in it like pistons do in regular engines, etc.. so basically I'm wondering how much boost the stock engine can take with a good A/F ratio

Thanks.

 

The rotary isn't as limited in that manner like piston engines. There is no documented "limit". Many guys have put large single turbos on stock engines without issues. Your main limitation will come from the port sizes, not really anything mechanical.

 

Its all about tunning and proper maintnance. Oil changes after 2500, Spark plugs every 7000, never boost untill car is warm, keep boost spike to a minimum, upgrade radiator to keep heat down.

Chris

 

change spark plugs every 7000 kms? does that apply to the stock 10 psi setup too?

 

A turbocharged rotary tends to foul plugs fairly quickly. You can get a little more use of them if you have a spark plug cleaner and clean them on a regular basis.

 

Then basically, a Rotary with well tuned fuel maps and good injectors/spark plugs, a good radiator, good intercooler, oil cooler and an efficient hood scoop for engine bay ventilation could take like 40 PSI without melting or blowing?

 

wow, 40 PSI! You're trying to build a rocket ship aren't you!?

 

Boost is limited by a few things: Fuel system (injectors, regulator, pump), ignition, standalone ECU & tuning, intercooler and turbo choice. This is what will enable a stock (internals) engine to survive higher then stock (10psi) boost levels.

 

Well, that is a gross over simplification, but in general, yes. You don't need "forged" internals to run higher boost. However, PSI rating is arbitrary when it comes to turbos (i.e. 10 PSI on a large single turbo is not the same as 10 PSI on the stock twin turbos). Airflow is what matters. At some point, you will be limited by the ports on the engine as far as airflow.

 

actually i was mostly thinking about seals that might break off or something. Since there is no parts moving back and forth in a rotary (like valves, rods, pistons etc that might decide to go fly through the block), I was actually wondering how a rotary can blow. does a rotor pops outta the hood or something?

 

Basically, when or if detonation happens, it can/will crack an apex seal. With that crack, it can either lower compression or cause the seal to completely break into pieces and exit the engine. Since it will exit the exhaust ports, those pieces can damage/ruin a turbo compressor.

 

alright thats what I thought, thanks for the quick answer and sorry for my noob-ness

would replacing apex seals (and put on brand new ones) reduce the chance of this happening?

 

Not necessarily. Everyone would like to say that if you put new ones on that it would reduce the risk but the fact is that there have been guys to put a good hard 70,000 miles on the original ones straight from the factory and then have a rebuild done and blow the new seals after 3,000 miles.

I would venture to say that proper tuning and maintenance are more key essentials to keeping a motoring from popping. ie. if you're going to run 20psi then you better have the right setup (air, fuel and electronics) and the right tune to run 20psi. Or 10psi, 15, 40 or whatever.

 

of course I wouldnt boost over 15 psi without a perfectly tuned stand alone fuel and ignition management device, I mentionned it in the first post

 

Not really. The seals press and rub against the housings as the motor turns. By nature, they will wear and become weaker over time. The real goal is to know when to say when. It's not a question of *if* you will need a rebuild, it's *when*. The question at that point will be is it a rebuild from low compression due to wear, or low compression due to damaged seals?

If you blow a seal, it typically takes out the rotor, rotor housing and possibly a turbo. Does that mean you should rebuild sooner to save parts? Not necessarily. If the apex seals are rubbing on the rotor housings, they are also taking wear. So it's possible that even without blowing a seal, the rotor housings are out of spec and need to be replaced on a rebuild.

You next question is probably going to be about stronger/better apex seals. Yes, they do exist. However, detonation is detonation. There is no Superman Unbreakable seal. They will all break under the "wrong" circumstances.

 

To be sure. I was merely stating that if anyone (not you specifically) is going to run whatever psi they need to be sure their setup can effectively handle that psi.

 

Getting back to the intial question u could run up to 12-14psi on the stock twins (i run 11psi and its safe) and u can have good power at that level. On an aftermarket turbo i want to say 15-20psi, but remember that at any level u can blow a motor, its all about proper tuning and taking care of your engine. And if u REALLY want to do a rebuild u can put in ceramic seals that will take more damage before they break, or 3mm apex seals (i recommend ceramic seals). Also remember that u dont need alot of boost to make good power in a rotary, for example theirs a guy hear at the shop that runs 23psi in his Evo8 and he makes the same power as i do at 11psi with all bolt-ons and stock ports and seals.

 

wow either your making a lot of power at 11, or that evo isn't tuned for beans.

You really don't have to forge anything, have you ever looked at a rotor, I don't think you could break it with a ballping hammer. And the apex seals by comparison are much thicker and stonger than any piston ring. Like others have said its not really boost that is going to limit your motor but other things like detonation, compression, and heat as these motors tend to run a little on the hot side, mainly the weaker link apex seals. I'm not sure about maximum boost but I think there is a couple of people on here that have gotten in to the 10s with the stock engine and stock turbos.