Ok obviously on stock internals and intake/exhaust you don't need to allow for a higher redline. But say I get something like an individual throttle body setup and a race tuned exhaust for a certain RPM range. How would I go about preparing the engine for a higher redline? Other than a balanced assembly, lightened/clearanced rotors and stronger stationary gears what do you do? And how do you know what RPMs it will run safely? Is there some method of testing the engine to KNOW what RPM it is safe to?


Santiago


PS- This is out of curiousity and please no BS about how stock it won't make any good power at high RPM's I am talking about something like a bridge or peripheral port for racetrack only and zero street use. Scattershield inplace for the flywheel/clutch not to kill/hurt anyone.

 

hardened stationary gears for a start. i wonder if anyone has tried cryo treating e-shafts? oh clearanced/lightened rotors. higher pressure oil pypass. im sure theres more.

 

good question, i never thought about that, im gonan build a S5 1320 motor

 

My interest isn't HOW to get there. But WHERE your at. I am wondering how exactly you figure out what is the highest safe RPM for an engine with better internals.

 

RB catalogue is a great place to read up on what is needed for a high revving rotary as NA power has been their staple for a long time.

Stock unmodified internals are pretty good to 8,500 rpm.

Over that balancing, clearanceing, oil mods, ligher apex seals and to get really crazy maybe even the custom e-shaft w/ needle bearing intermediate housing.

 

My interest isn't HOW to get there. But WHERE your at. I am wondering how exactly you figure out what is the highest safe RPM for an engine with better internals.

Ah, by slowly increasing the redline and measuring carefully for unusual wear on engine tear down between races.

 

Ok now what is an acceptable amount of wear? how would I know/descide?

 

Ok now what is an acceptable amount of wear? how would I know/descide?

I imagine that would depend of the type of racing and the budget.

Maybe in drag racing anything short of total catastrophic failure is acceptable wear, since it just has to go 1/4 mile before the engine is changed out.

Conversely, in endurance racing one may have to set it up so that there is NO measurable wear since in the course of the race there will be so many unexpected/uncontrollable circumstances the engine will have to operate under.

 

Well, with my old 90 n/a car, Rob@Pineapple said to not worry about taking it to 9,000. But the revlimiter stepped in at 8,600. That was a motor that had some mild work done to it. What he told me to do was put it on a dyno, and find where it made peak power, and shift it around a 1k rpms higher. Sucks that my car made peak at 8k.

On my even older very large streetported 86 engine (was in a 74 repu.) with a 48mm dcoe, dual exhaust, it still only made peak power at 8,600. So unless you're doing some bridge motor, chances are if you keep it below 8,500 it should be allright. Unless you're apex seals/bearings, etc. are out of spec/to short. CJ