wickedrotary

can someone explain wich is the simplest way to find out how much to take away from the rotors for high

rpm, im building a peripheral motor , the housing are almost done but i want to do the race clearance on the rotors, so if any one has done it and can expalin to me

on the timing some people have told me to run 10btc on L 0 on trailing thisis from a guy from pr who runs pp motors

thanks for the info

Lynn E. Hanover

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None off if you stay under 8,500 RPM. If you plan to go to 9,000 RPM on every shift, then, .010" off each side. Above 9,000 on every shift, then very light rotors and .012" off each side. Be sure to press the rotor gear in solid during build up.



For NA engines, 24-27 BTDC is plenty. Based more on how much cooling you have. This is set at 4,000 RPM.



My timing on a 12A is fixed with no advance curve at all. No springs on the advance weights. Car starts and runs at 27 degrees. No split timing. Both leading and trailing running off of the leading pickup. For street driving, 20 to 22 degrees would be less drama starting out in low gear, and better torque in lower RPM.



You can drive the race car around with a 1.96:1 first gearand a 7 pound flywheel. It would do just fine with a street 3.25:1 first gear.



That 10 and zero sounds like it is for slower street driving. The cylinder filling is so poor at slow speeds the timing changes don't seem to have effect.



Picture is of an aluminum end plate with an iron wear surface. Half the weight of the stock iron. For a single rotor airplane engine.





Lynn E. Hanover

wickedrotary

i never seen side housings withouth the intake port,in aluminum i know racingbeat sells the aluminum ones , but they r expensive

how much for a set, even though i probably will go with steel way cheaper to build, well on the motor build up i plan to use atkins apex seals , what kind of clearance should i use in the apex to rotor groove, i dont plan to run lightned rotors im runing a 90 gtu 9.7 internals and plan to run them in the stock weight,nobody in las vegas that i know can do the balancing so i might go with them the way they are unles u know what machine to do it on and i can call around see if any machine shop has and if they can do it

thanks julio

thanks julio

Maxt

I would suggest to get the best rotor weight and clearance you can get without getting into sometimes questionable aftermarket balancing, order 2 new rotors and the counterweights at the same time. They will be both C's, and the batch numbers will be matched to the counterweights, and the new rotors are already side clearanced enough to take to 10k rpm.. Your rotors are over 16 years old now anyway....

I am running a s5 based p-port in my FC currently, they are a great motor..

Maxt

I just happen to have a set of new versus old rotors sitting right here , there is . 012 total difference in width between old and new..

wickedrotary

i plan to use my old set of rotors i dont believe in buying eveything new ,my set of 9.7 rotors are i good condition and i do ha ve the front balance and flywheel, on the clearancing .012 total clearance or on each side of each rotor, meaning remove .012 from both side of the rotor?

on the ignition if u can help me again with this one 0 slpit meaning i will be running both coils , msds from the same igniter wich will be the leading runiing at 24-27btc with the dizzy locked, i know ive read alot about 0 slpit some people runn it that way some dont can u runn 0 split on a turbo motor??and what timing to run on a monter 6 port with a jaytech manifold using probably 9.4 rotors on a garret gt 45

any info on this set up is apreciated this will be my next project

thanks again julio

Lynn E. Hanover

I know enough about turbo engines to know that I don't know enough to tune one.



First, you want far less compression than any NA engine, so you want 8:1 rotors from a turbo engine.



Just a few pounds of boost gets you back to a 9:1 effective compression ratio, and it gets higher as the boost goes higher. (More volume is being compressed into the same head space).



The correct timing is a function of trying to get the highest cylinder pressure at the ideal crank angle (40 to 50 degrees ATDC in a rotary). So when the boost is up (and so then is the effective compression ratio) the burn rate will be much higher and very little advance is required to get full cylinder pressure at the right crank angle.



So the management system would be retarding timing as the boost increases. I suspect that a mid range timing might be zero BTDC or close to it, depending on the total boost. Then at very high RPM there might be less cylinder filling due to shorter open times, and some additional timing may be put back in.



Keep in mind that the rotor is turning in slow motion, at one third the crank speed. Very little timing is needed to get everything burned in the closing chamber. Put the rotor at TDC and rock the crank. Note that the rotor hardly moves. It spends a lot of time around TDC in every cycle. It is called dwell, in both piston and rotary engines. Smokey did it with longer rods. The rotary does it as a function of design.



For off throttle operation, and just off idle, where there is no boost at all, timing might be up to 35 degrees.

Nearly no mixture and 8:1 rotors makes this possible.



The NA engine is difficult to detonate. Because cylinder filling decreases as the revs go up. Less mixture volume in the same head space. So it can use more advance with higher RPM.



The turbo engine is easy to detonate. And you can do it with faulty tuning.



So get real good at looking at the management profiles of succesfull engines, and stay on the conservative side of every tuning point. Lest a bunch of important parts turn up in the muffler.



This advice may be worth what you are paying for it.



Lynn E. Hanover

j9fd3s

thats a good one!



i'm not expert either, but the timing usually ends up between 10-15 BTDC L, less timing = higher egt's, unless you're running that much boost.



it would also seem that having the trailing fire ATDC a couple of degrees is a good thing too.

j9fd3s

you can see the machining is different on the "new" rotors. seems like its a recent thing too, within the last couple years

wickedrotary

how much is suppose to be removed .012 total or .012 from both sides of rotor??

the clearance from the apex seal to the rotor groove is supposed to be diferent on a race motor thoes anyone know what should be the clearacnce be?