Rotary Engine Failure due to Side Rotor/Side Rotor Housing Clearance..

rx4ur7 · 07-07-2009, 03:33 PM

Just saw this thread show on top.

I have been building these things since 72 and have never seen this as a failure point, street or race. The IT motors spent their lives near 8 and the GT motors at 10K.

Resulting damage from bad bearings and or bad build or gear walking, yes, many.

Here are my 2CS.

I do not see the necessity or any cost benefit. Mazda does not include it as one of their build hints, and it is not in my copy of the Mazda RX7 Competition Preparation and Service Manual. I do not have the latest versions though so I will stand corrected if that modification is recommended. (remember I am the factory freak) I do not know of any of the top builders that do.

But I will not dismiss it completely either. Who knows what the future and innovative experimentation may result in. I will leave this one to those with deep pockets. I’m having enough to do with flat bottoming the open road car and working on this buggy.

When a rotary is built properly to spec with new parts or parts that meet spec it will perform and be reliable. It is then to the client to take care of it. A good build isn’t anything if the oil isn’t changed or it is run out of water. (but the light wasn’t on that long, just until it stopped.) They may come in the shop that way, but they leave knowing the proper care and feeding of their investment.

Side seal clearance was not increased drastically. There is no difference between SS and CS. The clearance of SS in the rotor is different because of the design of the new SS.
Rotor to side housing clearances are less .12-.21mm for FD, .05-.19mm for Renesis.

If you are inducing any blow by it will shorten the life of the motor. First by contaminating the oil and building up combustion gases in the oil containment system. Beside loss of power.

***Herblenny*** · 07-08-2009, 02:13 PM

Thank you for your input Rx4ur7!

Quote:

Originally Posted by rx4ur7

Side seal clearance was not increased drastically. There is no difference between SS and CS. The clearance of SS in the rotor is different because of the design of the new SS.
Rotor to side housing clearances are less .12-.21mm for FD, .05-.19mm for Renesis.

That's interesting.. I was looking for that information about FD vs Renesis clearance.. Thanks for posting that.

Quote:

Originally Posted by rx4ur7

If you are inducing any blow by it will shorten the life of the motor. First by contaminating the oil and building up combustion gases in the oil containment system. Beside loss of power.

Same thing was also told by another very experienced builder.

07-07-2009, 03:33 PM	#1
rx4ur7 Rotary since 1972 Join Date: Nov 2008 Location: Tucson Posts: 231 Rep Power: 17	Just saw this thread show on top. I have been building these things since 72 and have never seen this as a failure point, street or race. The IT motors spent their lives near 8 and the GT motors at 10K. Resulting damage from bad bearings and or bad build or gear walking, yes, many. Here are my 2CS. I do not see the necessity or any cost benefit. Mazda does not include it as one of their build hints, and it is not in my copy of the Mazda RX7 Competition Preparation and Service Manual. I do not have the latest versions though so I will stand corrected if that modification is recommended. (remember I am the factory freak) I do not know of any of the top builders that do. But I will not dismiss it completely either. Who knows what the future and innovative experimentation may result in. I will leave this one to those with deep pockets. I’m having enough to do with flat bottoming the open road car and working on this buggy. When a rotary is built properly to spec with new parts or parts that meet spec it will perform and be reliable. It is then to the client to take care of it. A good build isn’t anything if the oil isn’t changed or it is run out of water. (but the light wasn’t on that long, just until it stopped.) They may come in the shop that way, but they leave knowing the proper care and feeding of their investment. Side seal clearance was not increased drastically. There is no difference between SS and CS. The clearance of SS in the rotor is different because of the design of the new SS. Rotor to side housing clearances are less .12-.21mm for FD, .05-.19mm for Renesis. If you are inducing any blow by it will shorten the life of the motor. First by contaminating the oil and building up combustion gases in the oil containment system. Beside loss of power.