In a message dated 6/22/2005 8:57:55 PM Pacific Daylight Time,=20 13brv3@bellsouth.net writes:

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

Evening Lynn,

Thank= s for the=20 comments. It's always a pleasure to hear numbers that are based on=20 experience.

I'm curious about that 220 figure for the side port though.&= nbsp;=20 What vintage housings are you talking about, and which form of porting?&nb= sp;=20 Surely that's not a bridgeport on REW or Cosmo housings. What w= ould=20 you expect to see with a mild/street port on a set of REW housings? =20

Thanks,

Rusty= =20

The SCCA just altered the rules on street ported engines for "E" produc= tion=20 engines so as to curtail the short lived high HP engines and reduce their po= wer.=20 Both Daryl Drummond and

Stan Lizauskas were saying 228.5 to 229 HP from street ported engines=20 before that rule change. I do not know what size chokes they get to run in=20 those. Some are now getting that from 12A engines for the lighter weight the= y=20 get to run. This year power is up some more but the engine builders are tigh= ter=20 lipped about the details.

My experience with 13Bs is just one with a very mild bridgeport and a d= ay=20 on the dyno ended with 259 HP at 9,000 RPM. It did like a lot of advance. WE= =20 went up to 36 degrees and the power kept going up as well but the heat went=20= up=20 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 s= ee=20 how that ran but it wasn't my engine my dyno or my money. The port was so sm= all=20 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= .=20 With a lot of work, a bridgeported 12A would do it but favors higher RPM. Ju= st=20 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=20 tuning to a low RPM.

Great for big boost drift cars but perhaps too low in the runner veloci= ty=20 area. The stronger engines need high runner velocity to provide a wide=20 power band to cover the RPM drop on gear changes. Using the 12A center iron=20= is=20 good as it has the biggest runners. So if you want big, 12A center irons wit= h=20 Cosmo ends would be good. I am not famillier with anything but 12As so you h= ave=20 to stay with all of the "O" rings in the rotor housings. You will not be lim= ited=20 by choke size as we are. So the power should be a no brainer for aircraft us= e.=20

Cooling will be a bigger problem than power.

Lynn E. Hanover

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