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A couple of thoughts, if you're going to emulate Tracy's intake.
#1, don't do what I did. I looked at his plywood/fiberglass plenum & thought, 'hey, I can do that in aluminum.' Nope; not if it's a box. Tracy took one look at mine & pointed out that the intake pressure pulses will quickly (instantly?) destroy the flat sided aluminum box. So, either thick sides like Tracy's, or something with rounded surfaces. I've got some 6" dia aluminum irrigation pipe that may become my new plenum.
#2. Bell mouths/velocity stacks on the end of the intake tubes make a difference. Tracy may talk about it on his site.
#3, Supposedly, ideal tuned length for 6k rpm is somewhere around 19"; pretty hard to do without bent tubes (impedes flow). I originally wanted to tune for 6k rpm because that's roughly 180 hp at sea level, & I could more or less mimic a 180 Lyc's performance at altitude (2.85-1 reduction). But apparently, at less than full power we don't need to worry as much about precise tuning. So I just made my intake tubes as long as would fit inside my cowl; about 11 3/4". I think that's just a touch longer than Tracy's on his Renesis. IIRC, Tracy told me that his Renesis is just starting to come 'on the pipe' somewhere around 7-7.5K rpm, flat out, and if he can go in the neighborhood of 220 mph in a -4 with that tuning, I think I'll be happy with mine.
#4. IIRC, Steve Boese has a 6 port Renesis running on a test stand, and he found that at altitude (his field level is normal cruise altitude for most of us), it made better power with the 3rd pair of ports blocked off (better flow velocity?). So if you're running a 4 port, an old Ford 5 liter stock throttle body is just about a perfect area match for the sum of the 4 ports. It's also very easy to strip to very little weight, and last time I checked, they were really cheap on ebay. It's also relatively easy to reconfigure the return springs to act like an a/c throttle body, so it will fail to full throttle if a throttle cable breaks.
None of these ideas are mine (except the bad ones). I shamelessly copy anything I can find that works.
That's about all I can think of now; I hope Tracy & Steve will jump in if I've misstated anything.
Charlie
On 10/13/2015 8:00 PM, Mark McClure wrote:
Thanks for the info - I was actually hoping it would help me with my intake plans. And it has.
Thanks for the link Charlie there's some good pictures on the old site - including the intake modifications that Tracy use to offer.
I think realistically I just need to jump in instead of planning to perfection.
Thanks for all the help,
Mark
On Oct 13, 2015, at 9:28 AM, Tracy <flyrotary@lancaironline.net> wrote:
HI Mark,
I never did post a lot on the Renesis because for our purposes there really is not much difference between it and the earlier 13B. Here are the main ones:
1. The bare block weight is about 10 pounds lighter, mainly due to the water pump changes.
2. The exhaust ports are in the side housings instead of the rotor housings so there are three ports instead of two.
3. The 'safe' max continuous RPM is maybe 1000 rpm higher. The best BSFC rpm is still the same at 5000 - 5600 rpm.
4. EGT is about 100 F cooler.
5. The exhaust noise is considerably less making it a bit easier to muffle.
That's about it. The power and fuel consumption at any given RPM are the same as before in aircraft applications. The other minor differences are internal parts that don't matter unless you are overhauling the engine.
Tracy
Sent from my iPad
On Oct 12, 2015, at 11:51, Mark McClure <flyrotary@lancaironline.net> wrote:
Reading though the conversion book again the RENESIS info is mentioned but referenced to the website.
Tracy, any way we can get the RENESIS info posted back on the website or to the group? Or does anyone have it saved offline?
Mark
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