Hi everyone! New to the forum. I am looking at building a high rpm NA 13B out of an 85 rx7. I have been researching the porting aspect and there is a lot of info out there on that, but not much on other engine components. What I am trying to find out is what problems do people face when running these engines at high rpm's. Seal problems from to high a velocity, rotor contact with the rotor housing, bearing problems....??? If there is anything that can be done to address these problems, I would like to do that up front before I get too crazy.



Thanks for the help!

 

Well, you're in the right section to research this information, there is a wealth of information and many links to even more information and pictures to help, both in this and the FAQ section.



Your question is actually pretty general however as there are many combinations and configurations of N/A applications, all having corresponding pros and cons respectivly.



Welcome to Nopistons!

 

yeah do a little searching...



briefly though, it depends a little on how long you need/want the thing to last. also it depends on where the powerband is, stock peaks around 6500, you can rev it higher, but it just makes noise and wears faster...



so generally its accepted that 8500 is the limit, although a big heavy rotor 13B might be happier around 8.



as the rpms go up the forces on the seals, and gears go up exponentially. to rev higher we use hardened gears (factory issue from 89+). also most people are using the 2mm apex seals, or the racing carbons. the stock 74-85 3mm seals are really heavy



as far as bearings go, we generally bump the oil pressure from the stock 71 to FD pressure 100psi. mazda also has lightened the 13b rotors with each series of engine which helps

 

Thanks for the reply's. So take a look at reducing the rotor weight, rotor gears, seals and bump the oil pressure, anything else to look for?



Thanks

 

dynamic balancing of whole rotating assembly-gold...