Rotary Car Club - Dispelling Myths: Using RX-8 internals in a 13B-REW

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Quote:

Originally Posted by neit_jnf (Post 36102)

how about the seals?

I've read elsewhere that:

-rx-8 apex seals can't stand a peripheral exhaust port and warp/wear down; also read that they eat up the non-rx-8 rotor housing chrome
-corner seals with metal plugs eat up non-rx-8 side plates

anyone here with some insight?

It's far from ideal to have stock renesis apex seals travel over peripheral ports. The metal plugs shouldn't touch the irons.

You also would want to avoid putting non-renesis rotors into a renesis due to seal vs port locations.

All the above have been done but are not smart or suggested.

Paul.

Good right up, I've used rx8 shafts in rew's due to the weight and price difference. Good to see all the info in one place and properly displayed.

Brent

[QUOTE=WE3RX7;47141]I planned on using these parts for the 13B RE build in my FC. Mainly because the 13B RE from the cosmo stationary gears don't support more than 6500RPM (seeing as how they were built for an automatic luxury car) and the price of the MSP gears and e-shaft are much less than that of an REW.

You have any facts to back your statement?

Quote:

Originally Posted by WE3RX7 (Post 47141)

I planned on using these parts for the 13B RE build in my FC. Mainly because the 13B RE from the cosmo stationary gears don't support more than 6500RPM (seeing as how they were built for an automatic luxury car) and the price of the MSP gears and e-shaft are much less than that of an REW.

You have any facts to back your statement? Good write up :icon_tup:

I am sure it has been discussed elsewhere, but I was hoping to get it added to this thread:

What about using RX-8 rotors in the 13B-REW?

If one wasn't looking for more than 7-10 lbs of boost, and used water injection, and wasn't looking for peak numbers, but wanted lots more on the low end.... wouldn't these be a good option?

Aside from machining the apex seal groove out deeper (I am unsure of the validity of this) what else would be required?

RX8 rotors are 10:1 aren't they? Isn't that a bit heavy on a turbo car?

Quote:

Originally Posted by NoDOHC (Post 93385)

RX8 rotors are 10:1 aren't they? Isn't that a bit heavy on a turbo car?

There are plenty of turbo-charged RX-8's out there. My question pertains to the compatibility. If someone wanted the most low-end they could get and then run 6-8 lbs of boost... the curiosity becomes whether or not the RX-8 rotors are drop in for an REW.

I don't necessarily plan on doing it, just curious if it is possible. I might build my backup engine this way just for S&Gs if there are no fitment issues.

Quote:

Originally Posted by jamespond24 (Post 82194)

You have any facts to back your statement? Good write up :icon_tup:

The msp e-shaft is less than $200. The REW e-shaft is closer to $500 if I recall correctly.

Very true. One of the reasons that I went with the RX8 E-shaft. My memory says closer to $150 for the shaft.

So... my original question still stands

No, the Apex seals are different requiring milling of the rotor itself. And I believe there are some descrepancies with the rotor side landing clearances that need to be addressed

Missed the question the first time, sorry

Hmmmm...

What do you mean by side landing clearances? Did they move the side seal location to a point where it would cause a problem with the stock REW port?

Quote:

Originally Posted by Racing Beat

Rotor Clearancing

A second concern for rotors used near or above 8,500 RPM is the clearance between the sides of the rotor and the side housings. The construction and assembly of the rotor and rotor gear is such that both sides of the rotor have a portion, referred to as the “land”, that protrudes out from the rotor “side” several thousandths of an inch. For measuring purposes, detailed below, the “land” on the side of the rotor containing the rotor gear is the face of the rotor gear itself. The “land” on the opposite side of the rotor is the circular portion of the rotor surrounded by the inner oil seal. These features need to be taken into consideration when clearancing the rotor.

The first step in preparing a rotor for clearancing is to measure the thickness of the rotor housing being paired with the rotor at eight evenly spaced points to determine the minimum or narrowest point of thickness of the rotor housing. This minimum thickness becomes the “base line” for the calculation process.

Now, measure the thickness of the rotor and rotor gear assembly at three different points from the “land” on one side to the “land” on the other side. Select the maximum, or widest, thickness of this assembly and subtract this number from the base line number previously obtained. We have found that the following clearances work well:

Clearance between side housings and rotor maximum “land” width:
12A Engines (.009” +/- .001”)
or 13B Engines (.010” +/- .001”)

“Land” protrusion from rotor side: .0055” +/- .0005” (each side). This “land” clearance is obtained by machining away material from the “side” of the rotor, thus leaving the “land” extending from the rotor “side” by the specified amount.

It is entirely possible, based on the production tolerances we have seen over the years that you may need to remove as little as .001” to. 002” from each surface to achieve the recommended clearance. In other words, some of the clearance required already exists.

There is also the portion between the oils seals and the side seals that need to be addressed as well as the portion of the rotor from the side seals out.

This is all very OLD knowledge to me as I decided years ago that I was going to turbo charge my 13B-RE as opposed to build a high-revving n/a engine using the renni rotors.

What are the differences between the REW clearances and rotors sizes compared to the MSP? If there is a small amount of additional clearance, it seems it might actually be better suited for high rpm power levels?

Check the FSM's, I'm sure someone has the RX8's FSM up by now