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Thanks for that. I spoke to Mazdaspeed, they are a longer seal made for mazdaspeed by mazda japan. The part number is N3H1-11-C11C. This is a proper mazda part number but it does not work in NZ, which explains why I was told there is no such seal available, although mazda NZ are now ordering these seals in bulk, as of today.

In light of this, the info in my top post about fitting oversize cornerseals can be ignored.

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I've heard of a couple of race n/a PP engines here in NZ using the factory RX8 apex seals with no problems. There is also a local bridgeported engine using them.

The next engine I build for myself I'm going to try them, I'm fairly sure they'll work, half the height means half the weight. Remember the 2mm 3 piece seals in 13b turbo engines? The upper half of those seals are the same height as the RX8 apex seals and they didn't seem to have a problem running over peripheral ex ports.

Mr. Midas

I had no clue they were that short. That shows how much I know about the renesis.





I was thinking the same thing almost. That short piece handles the heat stress fine(150,000-200,000 miles was good enough back then). But you have to remember, the upper half doesn't have the springs pushing on it. It's backed up by the inside piece; although, I really don't know how much extra pressure the spings produce compared to the outward pull of the seals own weight. If people are running/testing them, hopefully they are good for more than a few passes at the strip. I would really like to find out more, and definitely hope you can fill us all in when you build your engine.



Thanks!

mazdaspeed7

The warping is from the seal not having enough surface area to transfer the heat it builds up passing over the exhaust port into the rotor.

Ariel

Can you elaborate on this? I somehow got the impression that those who have tried the rx8 rotors also used the rx8 counterweight.

mazdaspeed7

I read it as he used the S5/S6 front counterweight with the renesis rotors because the renesis counterweight wont clear the oil pump chain in the earlier engines.

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Correct. Although it seems just about any pre-renesis front counterweight will work as earlier counterweights are heavier so material is removed during balancing to match up to the renesis rotors.

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For those interested I ordered an RX8 crank from Mazda and compared it to an FD crank. There are only 2 visual differences:

1) Rotor journals are 1 thou smaller

2) RX8 crank is lighter by 170 grams



All other dimensions, journal sizes, oil gallery sizes & position are the same as FD. This includes the stepped front & rear main bearing journals. Oil jets are the same, 2.5mm.



I would like to hardness test but I don't think Mazda would like their crank back with dents in it.



NOTE: this crank was the high power model. Here in NZ high power is manual trans and low power is auto. The low power crank possibly has less bearing clearance, I don't know I havn't seen one yet.



Cost is about 270NZD (190USD).

Mr. Midas

Just wondering. Could you just use the MT balanced flywheel instead of the rear counterweight? Would there be any problems getting the clutch to work on an NA tranny?

diabolical1

great information here. i guess some of it will make more sense whenever i get my hands on a pair of Renesis rotors, but at least this will provide a solid reference source for me when i do.



thanks,

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