If you only need 220 HP then the side port is quick and easy also.

 

 

Evening Lynn,

 

Thanks for the comments.  It's always a pleasure to hear numbers that are based on experience.   

 

I'm curious about that 220 figure for the side port though.  What vintage housings are you talking about, and which form of porting?  Surely that's not a bridgeport on REW or Cosmo housings.  What would you expect to see with a mild/street port on a set of REW housings? 

 

Thanks,

Rusty

 

The SCCA just altered the rules on street ported engines for "E" production engines so as to curtail the short lived high HP engines and reduce their power. Both Daryl Drummond and

Stan Lizauskas were saying 228.5 to 229 HP from street ported engines before that rule change. I do not know what size chokes they get to run in those. Some are now getting that from 12A engines for the lighter weight they get to run. This year power is up some more but the engine builders are tighter lipped about the details. 

 

My experience with 13Bs is just one with a very mild bridgeport and a day on the dyno ended with 259 HP at 9,000 RPM. It did like a lot of advance. WE went up to 36 degrees and the power kept going up as well but the heat went up also. So about 29 degrees was best power from a practical view..

I would liked to have done it with lower octane fuel and less lead to see how that ran but it wasn't my engine my dyno or my money. The port was so small as to be vestigal. No cut into the rotor housing at all.

So, a mild bridgeported 13B would do it easy. Very little work involved. With a lot of work, a bridgeported 12A would do it but favors higher RPM. Just 7,000 might be a tad too slow.

 

A Pported 13B would do it easy.

 

The big port runners of the turbo or Cosmo irons are not required, for tuning to a low RPM.

Great for big boost drift cars but perhaps too low in the runner velocity area. The stronger engines need high runner velocity to provide a wide power band to cover the RPM drop on gear changes. Using the 12A center iron is good as it has the biggest runners. So if you want big, 12A center irons with Cosmo ends would be good. I am not famillier with anything but 12As so you have to stay with all of the "O" rings in the rotor housings. You will not be limited by choke size as we are. So the power should be a no brainer for aircraft use.

Cooling will be a bigger problem than power.

 

Lynn E. Hanover