Thinking of adding some goodies to the engine I'm about to build. Just trying to consolidate a list of parts to buy.

Engine being built is 90TII 13BT with mint housings rotors, and plates. Want to run 9 psi stock and try to lower the boost threshold (minimize turbo lag) as much as possible. In the class of racing I do, time trial events like ones run by NASA I'm required to submit a dyno plot showing peak horspower of the car, they do not care when and how long you can sustain this. So i want to have low rpm max boost and be able to hold it across most of the RPM band

See attached.

In addition I would like to add:
rx8 eshaft
rx8 stat gears
Competition rotor bearings from Mazdacomp

Will the rx8 eshaft and rx8 stat gears work in the engine? I read what mazdatrix had to say. Use hylomar between the stat gear flange and the rear plate. As well they said to check the clearance between the rx8 eshaft and the rotor bearings if using the rx8 eshaft. What is the required clearance? Also the rx8 eshaft is tapered where the lands / journals are? Why? and will it work?

 

Increasing compression ratio isn't going to change your boost threshold or spool at all. All increasing CR does is improve the off-boost response of the engine, which makes it seem to most people that spool-up is improved. In reality, it's just taking your engine less time to make the same amount of revs to produce the same amount of boost as before.

Whether or not that is good enough for your situation though, I don't know.

 

I DO NOT plan on running the rx8 rotors. I'm sticking with the S5TII 13BT rotors. I'm not interested in increasing compression. The only rx8 parts I plan on using are: rx8 eshaft, rx8 stat gears.

 

I'm following along here.
One question though:
Is it possible to use the rx-8 shaft with Rx-7 stationary gears? Im thinking oilfeed holes and such?

 

Somone over at nopistons.com had mentioned that the oil feed holes don't line up. Meaning the rx8 and previous rx7 eshafts oil feed holes are slightly different. That person said he was running rx8 stat gears with an older rx7 eshaft, He took ovalized the holes on the stat gears such that oil would get to where it needs to go. I would assume that the position of the oil feed holes are not drastically different.

 

The taper is there so when the e shaft flexes it doesn't wipe out the journal or bearing. Its an old racing trick that Mazda has built into the new stuff. Just like the hardened stat gears.

 

Actually it will increase spool. With higher compression you have more exhaust energy at any given rpm range when compared to the same engine with lower compression. Extra energy will spool the turbo faster.