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  #121  
Old 05-03-2006, 05:35 PM
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I have heard, and am hoping, that the Renesis is a little bit quieter with the three port exhaust as apposed to the two port 13B. I am also wondering if the egt's might be a little lower also because of the three ports?? I do plan to use a small muffler as far away from the collector as possible to tame the ear splitting sound of exhaust.
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  #122  
Old 05-04-2006, 12:32 AM
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Quote:
Originally Posted by David Clifford
I have heard, and am hoping, that the Renesis is a little bit quieter with the three port exhaust as apposed to the two port 13B. I am also wondering if the egt's might be a little lower also because of the three ports?? I do plan to use a small muffler as far away from the collector as possible to tame the ear splitting sound of exhaust.
The EGT on a given engine design is mainly related to compression ratio, ignition timing and AFR. I don't expect this is significantly different on the new Renesis.

I've never noticed much difference in sound levels between PP and conventional port Wankels. In unmuffled race mode, both are well over 120 decibels. I did some sound measurements on a street ported 13B for a rally car with various mufflers on my dyno, years back. The factory Mazda race muffler brought the sound from 124 to 109 with a loss of only 6 hp. Still pretty painful. This was a BIG muffler carefully designed by Mazda.

The SuperTrapps often used did little with a lot of plates and lost major power when only a few plates were installed. I was never fond of these. The sound pressure level of the Wankel is brutal on mufflers. This combined with the high EGTs makes muffler life short.

I remember watching a night endurance race in BC about 20 years ago. When the RX3s rounded the corner we were at and wailed up the straight, you could look right up that 4 inch pipe and see the fires of hell inside glowing red hot at the back of the car. We're talking maybe 1500F 10 feet back from the engine! Between this and the red hot brake rotors, I was awed. Cool S**T.
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  #123  
Old 05-04-2006, 10:37 AM
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Quote:
Originally Posted by rv6ejguy
Cool S**T.
Sounds like HOT S**T. to me
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  #124  
Old 05-04-2006, 11:02 AM
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I'm just guessin and a ponderin so don't take offense, just give me how i am wrong.

the pipes on the rotary are HOT, we are guessin that it is currently 1950 +, that may be reduced with a timing change

But my tinkin is, and it is just tinkin, because the rotary has no valve to wear out (see the compliment) the inside of the engine is exposed to the IR heat through the open port, and that may cause a long term internal heat problem.

could the heat travel that way to the rotor and combustion chamber?

it seems to on the turbo side of things, as the turbo creates more heat than it should and that has been attributed to IR heat transfer.

Just a tinkin
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  #125  
Old 05-04-2006, 01:11 PM
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I don't doubt that the EGT on a Wankel can easily reach 1800F but this is normal. In endurance racing, naturally aspirated, these engines have demonstrated excellent long term reliability. The problem comes when turbocharged where at higher hp levels, the RATE of heat production seems to exceed the engines ability to keep certain internal components below critical temperatures and life is considerably shortened. This combined with the high EGTs in the exhaust and turbocharger have made high output turbocharged Wankels very rare in road racing for instance where fairly continuous, high power is needed.

I'm not saying it can't be done in aircraft where the specific output is much lower than in racing just that there are problems to be solved in doing so.
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  #126  
Old 08-14-2009, 03:38 PM
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Default Re: Turbo experiments continue

Quote:
Originally Posted by John Slade View Post
Well I just got my answer from Tracy Crook:

Quote:
Hells' bells John, 1650 on takeoff is stone cold. I normally saw 1760 - 1800 on a NA 13B. Turbos normally run higher (pre- turbo) than NA. A turbo with LESS restriction will give higher EGT readings down-stream of the turbine so this could be normal.
I will try adjusting the timing a little in flight to see if that makes any difference.
Steve, this is the post i was quoting
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