Lynn,

 

   Does Rob use any special tricks we have not heard about before to make his

12A's live above 10,000 rpm ??...............Also what are you 12A racers doing

When I took one of his apart he was just doing huge ports and really big bridgeports. He hosed a rotor bearing at the Mid Ohio championship race, and Mazda slipped him a complete rotating assembly already lightened and balanced for free. I stripped the engine. Crew chief Mike Bashem cleaned and laid out the parts, and 2 hours later he made the next session. Nothing really dramatic other than operating above 10,000 on every shift. He could do it because he had the trans out every weekend changing ratios for each track. He was weak below 9,000 but he was seldom there.

 

12 rotor housings can be manufactured from any 13B rotor housing except for Renisis parts. Early 13B irons through the twin turbo FD (1995) can be used to build a 13B or 12A. If you cannot make the coolant seal grooves in the cut down rotor housings, just use the irons that have the grooves in them. Turbo irons have huge ports and runners already installed, so less porting is required. He is on the phone to Daryl Drummond a lot, so he is making some really big power. When we quite you needed 270 plus to compete. There was a faster 12A on the pole, but he collided with another car and pinched his exhaust pipe a bit and he had to pit it slowed him so much. Maybe 285 to 290 HP now.

 

About .012" off the rotor sides outboard of the oil scraper grooves to allow the rotor to tip a bit when the crank bends into a sine wave shape. Reduced rear half of the rear main bearing, same reason.

 

About .004" on the rotor bearings, about .003" on the mains. 100 to 120 pounds of oil pressure. No balls or springs. 180 to 200 Weber main jets in the holder, to limit oil into the rotors.

 

Oil the crank from both ends, ceramic or carbon one piece apex seals. Dual MSD6als. usually 27 degrees of advance, no split. $25.00 spark plugs (Free from Mazda) pump gas 93 octane no alcohol. One ounce per gallon of Redline racing 2 cycle oil as a premix. 40 wt. Synthetic Redline in the sump (Or reserve tank).  

 

Not any secretes. You can download the Mazda Competition manual from the No pistons web site for free.

 

I have it as a PDF at about 4.8 meg.

 

The last new set of 12A rotor housings I have seen I built into a showroom stock engine last fall. It ran fine of course but stock they had like 115 HP, so it isn't really racing is it? 

 

Lynn E. Hanover