side seal clearance
 

Question for those of you who drag race..

What kind of side seal clearance are you running on race engines???

Stock is .05-.15mm I usually set mine at .15-.20mm since I do a lot of high rpm street racing..

What? nobody builds there own engines?
or is this some kinda rotory secret?

No secret !

I run mine at 0.04mm and this is a tight slid fit when pulling through the "feeler gauge" .... I polish the tips on both ends so all have a consistent feel on the gauge.

THIS IS A BIG POWER SECRET !!!!!

Take time and you will reap the rewards, tip the ends are no square, hence I cut & polish both ends.

Taking the extra time blueprinting everything will always reward you with maximum power!

crispeed
87TII
9.20@150mph

Ok I understand cutting the ends at an angle so they will sit flat with the corner seal, is that what your saying, or is there somthing else?

Yes exactly, there is nothing else...

If you have lots of time on your hands like I used to, you would find that the clearance you put on the side seal by trimmin one end only as Mazda suggest is well over the tight clearance in no time at all, due to the seal not sitting square on the corner seal.

All this is very pedantic indeed, but when you are chasing the max HP possible then you can gain a fair bit through "tight" side seals.

In my engines the clearance is more like 0.02mm cause the seal does distort in the groove when forced by the feeler gauge, the idea is to get a nice tight sliding fit of your 0.05mm or 0.04mm gauge and this clearance will be optimum. Just make sure that the selas do not stick when pushed "square" by hand to check movement, also allow seal to cool to rotor temp after handling or clearancing as this increases the length of the seal (more than you might think) and one you put in tight, in 30min will be over clerance ! (but well within Mazda Limits) With regards to people worring about such a tight clearance ? there is nothing to worry about as the seal runs at the same or lower temp than the rotor housing holding it, I have NEVER had a side seal stick in it's slot when it has been properly machined and clearanced.

Turbo rotaries are very hard on side seals, in the way that the clearance QUICKLY increases, use a good quality premix on it's own or in conjunction with the OMP and make sure you have combustion temps under control via correct af ratio (whole topic on it's own for these two points).

On a side note, I freshen my engines more than regularly (compared to some others) to regain lost power due to side seal clearance increase over time.