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Mazda had to do something with the ports i suppose to make more power from NA. The most they made previously was 160hp in an FC RX7
Renesis is pretty good in its stock form, honestly.
I mean, you can make a 13B from an RX-7 make more power, but at that point, you also lose the ability to drive it daily. Idling at 2000 RPM isn't exactly a good quality for a daily driver.
Renesis is pretty good in its stock form, honestly.
I mean, you can make a 13B from an RX-7 make more power, but at that point, you also lose the ability to drive it daily. Idling at 2000 RPM isn't exactly a good quality for a daily driver.
Holy Crap ! I think Mazda just figured out how to resolve the issue highlighted on page 1 ... Have a look at the new patent. Looks like a small periport that doubles as an EGR source and a wastegate !
I get the first one, where it makes a hybrid porting configuration some people thought about here. You have a small peripheral port to force most of the exhaust gas out so it doesn't build up in the rotor. Seeing how this engine is turbocharged, this is necessary. It looks like the unburnt gas swept out of the peripheral has a way to be recirculated, so emissions should be ok(hopefully).
I didn't get the second one. Does it just move the one side exhaust port into the opposite side housing to reduce leakage? That's the only part I understood.
Not sure how close this is to production. Probably not very.
The second one is showing how they arrange the inlet and exhaust ports so that the two side exhaust ports end up in the middle and rear . This will enable effective use of a twin scroll turbo on a side port.
The second one is showing how they arrange the inlet and exhaust ports so that the two side exhaust ports end up in the middle and rear . This will enable effective use of a twin scroll turbo on a side port.
So there is only one exhaust port ( plus the recirc one) per rotor in the design?
I personally think Renesis has too much exhaust port area for lower RPM. It certainly doesn't help the low-end torque. Big intake/exhaust port area = bad for lower RPM in general.
I am not an expert, but I was just saying that 1 side port exhaust is gonna be great for low-end turbo response in this case.
The peripheral can open up at higher RPM for the variable overlap as mentioned, and also just allow more exhaust flow to get out. Then again, I am not really looking at the overlap, just the exhaust port area.
Honda moved VTEC to the exhaust side for their turbocharged engines, so they can have a lower lift for better turbo spool at lower RPM and higher lift for high RPM operation. There are some similarities here.
I was just saying that in general, smaller port area and thus, higher velocity flow will be helpful for lower RPM. I just kinda wished that Renesis had some kinda variable exhaust port mechanism that can help with the low-end torque. That's all I am saying.
Maybe I didn't phrase it clearly and I apologize for that.
Unknown .....The best comparison is the 4 port engine . That has smaller intake and exhaust ports. The torque difference is mid range and not exactly impressive , nothing much low down.
Edit: the slightly different closing timing suggests slightly smaller I suppose, never thought about it that way before:
Without timing overlap the exhaust port velocity isn’t relative. It’s all intake, which velocity/resonance there is everything as the Renesis proves with all the intake trickery. This is why a max flow exhaust provides the best NA Renesis power. Without overlap all that usual exhaust theory is meaningless/out the window on a Renesis.
However, all we’re talking about is a patent, so theoretical discussion on a theoretical idea which we lack detailed information about.
Old times sake bump, the one thing you left out of this is compression ratio. The Renesis being 10:1 is contributing to the situation a lot when you’re talking about high backpressure and exhaust gas carryover. I’d like to think that the Pettit modded 8.5:1 RX7 rotors along with full E85 would help relieve the situation some with lower dynamic pressure and lower exhaust temps. I also don’t see much talk about timing and such in here either.
Not saying you’re wrong within the context of your own experience, just that it may be more nuanced than proposed. Afterall there were a few engines that had RX7 housings with peripheral exhaust ports added on a Renesis engine that didn’t exactly set the dyno on fire with all those horzepowerz. Of course the gases spewing out of five ports of total excessive area and being brought back together again likely didn’t help the situation. I just think there’s more to it is all.
01-15-2019, 11:46 PM
