Chris,

Your static is very low compared to mine!  My static is in the range of 5800 to 5850 rpm IIRC.  I'll confirm  static rpm soon.  Does the engine run smoothly at max rpm?  I didn't know your engine was a 4 port Renesis - I thought it was an  earlier RX-7 unit. 

A question was asked about my exhaust system and Hp.

I do slightly better than my neighbor's 180 hp. Lyc, powered RV-7A.  He and I will try to make some more comparisons this spring.  I believe mine is in the area of ~190 Hp. but it is only a guess.  This is one reason I wanted to post performance numbers so we can compare similar and different systems.

My exhaust uses the Renesis exhaust manifold.  The exhaust is pointed forward toward the prop.  To reverse the flow, I used a 4" dia. stainless tube mounted horizontally and parallel to the prop.  The tube acts as a swirl tube - the flow enters parallel to the inboard end and exits parallel to the outboard end of the swirl tube and the exhaust is toward the rear of the aircraft.  The exhaust than enters a Hushpower II Resonator and than out and down to the rear. The resonator is shorter than the normal Hushpower II muffler.  All my exhaust system is inside the cowl.  I used some stainless and some aluminum for heat shields.  With 230 hours of total run time I have not had any problems.
See attached picture and the article in the current issue of Van's Rvaitor.

When I built the exhaust system "Swirl Mufflers" were the "in thing" on the list.  Also, I had trouble finding 180 deg. stainless tubing with a sharp enough bend radius to fit in the space available in the cowl.  If I were building it now I'd use a 180 bend stainless tube instead of the swirl tube.  Probably would make a little more noise and Hp!

Dennis Haverlah

Chris and Terria wrote:

Dennis,

 

What is the max static RPM you can get?  There are two of us with the same Renesis, RD1-C and Catto 76X88 and the best we get is 4750.  Does that match what you get?

 

Chris