When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Ehh, I haven't read the entire thread, but wouldn't the large renesis intake ports, expose the leading sideseal end and potentially let it drop into the port ?
Just to add from what i've read and know. The purpose of the side exhaust ports had nothing to do with creating more flow, but was an effort to clean up the emmissions of the engine via no overlap where fresh air and fuel would go unburned out the exhaust.
the other thing i read in this thread which concerns me greatly in building this motor is the seal that supposedly protects the oil control rings.
The conventional periferal exhaust port means exhaust gasses are never exposed past the side seals, but only in the combustion chamber bound by the apex, side and corner seals. With the side exhaust ports, the side seal sweeps past the port, and exposes the side of the rotor to the exhaust system. This includes the back side of the side seal (probobly not a problem), but also directly exposes the oil control rings to the exhaust system.
This is probobly a problem, otherwize there wouldn't be these extra seals on the renesis rotors. I would caution a 12a renesis without provisions for a high temperature seal ahead of the oil control rings. I would expect pre-mature failure of the oil control rings, which is not a good thing at all.
Also, it would probobly be advantageous to plug the 12 exhaust port for power. Although the flow path is more indirect, the gain is from the lack of overlap, where you will not lose any intake charge to the exhaust, and will incur less exhaust gas dillution of the fresh air/fuel. This contributes to your max torque, improving your maximum volume and reducing exhaust dillution of the intake charge.
Sure you would not have the compression or light weight of a renesis, but the purpose of this is to improve the power and exoticness of a 12a no?
Secondly, the 6 port configuration designed for a 13B would provide well more than enough air flow to satisfy the 12a's needs. The ports (and a properly designed intake similar to the renesis's) which support 13B power up to 9K RPM would support a 12a to that engine speed and slightly higher, because at a given engine speed, the 12a is drawing in a bit less air than the renesis. Idle may suffer, thought I doubt it really will, because of larger ports.
I can not speak from experience, but I bet if you compare a 12a 6 port of the old days to a 13b 6 port of the renesis 6 port, you will find the culprit for poor performance of the 12a, small port size.
Anybody with any thoughts or experience concerning the seal protecting the oil conrol rings, speak up. This is a wayy cool probject!
sure, if you want to completely ignore; which most people making this mistake do, that Mazda seriously advanced the Renesis primary and secondary ports to open closely around BDC as part of the zero-overlap side exhaust port design configuration. Combining a peripheral exhaust port housing to them is the equivalent of installing a severe dragstrip camshaft into your economy emissions street legal engine. Which most people can readily see what the net result of that would be.
The Renesis primary port opens at 3* ABDC and the Renesis secondary port opens closely thereafter at 13* ABDC. The Renesis also has a intake valve that doesn’t open the secondary ports until around 4000 rpm. What this all means is the net affect is adding a ton of overlap with gasses rushing directly into both ports when the exhaust gas pressure is high with low chamber volume. It’s not at all equivalent to BPing or PPing. It will brap at idle like one, but I’ve yet to see a single 1.3L get close to what a good Renesis will do. And this being a 12A is essentially equivalent to installing an even larger camshaft in a smaller piston engine.
The only engine you can call even close to successful is what Kyle Mohan/Mazdatrix did with a turbo setup, but I personally don’t consider it successful at all because of everything else that was required. IMO it still wasn’t better than what can be accomplished on an REW without all the hoop jumping. That was adding GSL-SE housings in a Renesis, which allowed using the Renesis intake manifold with all of the intake valves.
Post the dyno results when you can, pretty confident all the wind will be gone from your sails once you see them.
thanks for the comments, i intend to run it, only with the peripheral exhaust ports on a relatively large supercharger gt35. I have installed solid corner and goopy apex.
I have done a lot of porting on the exhaust.
I have also made a handmade brace oil pan to prevent the possibility of torsion.
I believe if I can sequentially control the opening of the aux ports, I will achieve the maximum power, with stock intake manifold renesis.
I quote some photos for more comments.
yeah, that’s been done before too, without proven success to date.
what’s your plan for dealing with the Renesis exhaust ports then? You do understand that that they can’t just be blocked off at the port face, right?
Local improvement engine on rotary engines, argues that it can operate under conditions.
They can simply be blocked in the face of the port. but tell me, why do you think the opposite??, I am interested...
I would rather suggest that you put your brain to it and think about what is actually going on in the combustion and intake process. Perhaps you should find and thoroughly read a copy of the SAE paper on the Renesis that goes into depth about the changes Mazda made specific to it and reasons behind those changes. It’s not my intention to suggest anything other than it’s important to understand all those things within your own mind to fully comprehend the causes and effects that take place when this engine is in operation.
It appears that I overlooked your intention to turbocharge it, which will yield a better outcome than NA, but it will have nothing below 5000 rpm and only be so-so on the top end just like the Mohan engine. If those are 12A housings and rotors then there’s 10mm of port alignment discrepancy on each side to deal with on the manifold. Even if you successfully cut and rejoin the intake manifold to fit, imo the end result is still likely to be worse than the similar 13B variants of same that have attempted this due to the smaller displacement. Which it all comes back around to the work and effort that goes into trying to pull this off rather than using standard 13B parts and practices instead.
That said, I wish you well and welcome you to prove otherwise. The idea has been in play and done many times over the last 10+ years. Often it just disappears never to be heard from again, which we all know is rarely the outcome if there’s something to brag about. People have claimed otherwise, but never back up talk with actual results. I would contend they all know the results and are hiding them for the obvious reason that the few verifiable results have shown; total flop worst case to mediocre best case to date.
.
Why not machine down 13b renesis housings to 70milimeters and use the 12a e-shaft and rotors? Then all the complexity people are talking about would go away. Yes, you get less power but a slightly smaller engine and a light one. could call it breathing life into an old engine once again because chipping on the edges is what housings are prone to hardly any waste would be generated.
04-24-08, 12:05 PM
