The only number I have seen for lost HP was less than three with the splitters. Exhaust design will be much easier with them.

 

The tubes for your Pport should be thick walled and a light press fit, in the inner wall in order to support the edges of the housing when the stack is torqued up. Keeps the chrome from cracking. Fill in the water void between inner and outer housing with an aluminum filled mechanical epoxy. If there is no water, it can't leak. Devcon Plastic Aluminum if you can find it. http://www.freemansupply.com/DevconEpoxyPlastic.htm

 

The putty. Not the liquid.

 

Use a milling machine. Practice on a junk housing or two. Paul Yaw did up a nice Pport and had the pictures on his web page. www.yawpower.com. I'm on dial up until the 6th, so I didn't look through his stuff to see if any of that was still there. Leave at least 1/2" of chrome on each side to support the apex seal.

 I built one for a guy who ran it through two passes at an autocross and never developed oil pressure.

Said it ran real good. It was in a Mini Cooper woody wagon. The engine had set in his shop for two years before he ran it. (10 inch tires were not enough)

 

Keep runner (tube) ID about the same as the combined area of both stock runners. High velocity is what you want. Bigger is not better until you get closer to 10,000 RPM. 

 

Cover all of the chrome you don't want ruined with three layers of duct tape.

 

Look for 200+ HP

 

Lynn E. Hanover

 

Lynn,

I had be agonizing over runner diameter for a long time now and never prescribed to PL's 2" runners for our use. I think I originally came to my conclusions by doing a lot of surface area measurements on the standard manifolds.

 

Anyhow there is a chap from the old Powersport who has a wealth of experience on PL's site who has given some very useful info on their developments, it would seem their final ( and current) inlet manifold sizing is 1 11/16" ( 43mm) ID is almost exactly what my calculations indicate for my single rotor development. Naturally I want the most out of the single and am aiming for 125hp.

 

The Powersport engine is claimed to produce 200hp at 6,000 rpm - pretty good and not an outrageous claim. Extrapolating that to 7,500 one would expect to see 250hp for the 2 rotor and therefore 125 seems doable for the single. I have also opted for the RX8 high compression rotor and cut it for 3mm apex seals - this should help me get there and that's at 100 VE. If I get more VE with a tuned manifold , all the better.

 

On tuned lengths, PL has tested an engine and got 240 hp ( I think) with a 24" manifold, by working out the volume of the 2" OD tube and dividing by the smaller tube I get a length of  30 "approx.

 

The bottom line is, my approach is in line with your thinking and agrees with Powersport, in regard to manifold tube diameter. I hoping with a little more information I can tie down a more accurate guesstimate on the length before I start putting it all together.

 

I have put this up as 'grist for the mill' for other to consider in line with PP sizing.

George (down under)