The 450whp Renesis engine - why it will never happen - theory
#27
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iTrader: (2)
Going to go out on a limb and say probably not...or at least not enough to justify development of the castings.
These might also be interesting as they can likely just machine a set. Billet Inc. ? Home of the Worlds Fastest Rotary Engines Though the Billet housings with the Racing Beat wear coating (instead of the replaceable wear surface) sounds intriguing.
#28
3/From this point on wards ,while the exhaust port is closing , the rotor face closing the port is moving at near it's fastest possible rate . What this means is that the port closes VERY quickly.
4/KEY POINT :The area of the exhaust port reduces so rapidly that it's ability to expel the remaining gas can , in a boosted engine, reach a point where it just can't finish the job . This leads to an extremely high pressure remaining within the chamber through to the next phase .
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4/KEY POINT :The area of the exhaust port reduces so rapidly that it's ability to expel the remaining gas can , in a boosted engine, reach a point where it just can't finish the job . This leads to an extremely high pressure remaining within the chamber through to the next phase .
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#29
From the comparison of port area to crank angle the speed that the port is closing doesn't appear to be that fast. the peripheral port opens and closes faster. So there is defiantly a limitation of volumetric efficiency of side ports but is it due to the speed at which it is closing?
The key difference between the PP and the Renesis isn't so much the speed of closing ...it's the timing of the closing .
But ........... if the Renesis was able to remain fully open for longer but retained the same fully closed timing ...somehow ..... we would have a much higher power ceiling.
Last edited by Brettus; 11-24-2018 at 06:23 PM.
#30
That's not a very good representation of reality IMO. Renesis has a long period where it's area is constant (which should be represented by a flat line ) just like the PP does. Plus the actual crank angle closing degrees is around about the same.
The key difference between the PP and the Renesis isn't so much the speed of closing ...it's the timing of the closing .
But ........... if the Renesis didn't close as fast as it does yet retained the same timing ..... we would have a much higher power ceiling.
The key difference between the PP and the Renesis isn't so much the speed of closing ...it's the timing of the closing .
But ........... if the Renesis didn't close as fast as it does yet retained the same timing ..... we would have a much higher power ceiling.
#31
Here is the chart in the Renesis PDF . It's more accurate than the one you posted but I still feel it doesn't properly represent that last few degrees of closing .
Anyway ...it does still illustrate my point . Look at the cross hatched area ... works ok for an NA engine , but double the amount of air to expel and that x-hatched area makes all the difference in getting rid of the last of it.
Anyway ...it does still illustrate my point . Look at the cross hatched area ... works ok for an NA engine , but double the amount of air to expel and that x-hatched area makes all the difference in getting rid of the last of it.
#33
The extra port area earlier will do a good job of dumping the initial charge for lower flow situations but as pointed out earlier, even though port area is greater ......it's still got a really poor exit from the chamber . Also remember that 1/2 of that port area exits through the siamese sleeve . Hold up a siamese sleeve next to a peripheral port and you realise what a joke it is.
Even with extra port area ....my guess is that it doesn't get the gas out as fast as a PP does ....even when fully open .
Even with extra port area ....my guess is that it doesn't get the gas out as fast as a PP does ....even when fully open .
#34
This is awesome Brettus. Thank you. So what could be done?
One obvious/naive solution would seem to be to rev lower so the pressures in the chamber and beyond the exhaust port has more time to equalize, then run more boost. You'll have to redo the intake design but if you're running boost, who cares?
Hence the 4-port question, I imagine...
One obvious/naive solution would seem to be to rev lower so the pressures in the chamber and beyond the exhaust port has more time to equalize, then run more boost. You'll have to redo the intake design but if you're running boost, who cares?
Hence the 4-port question, I imagine...
One thing I am pretty sure about is that ...once the power curve on a Renesis starts heading down , the reason is failure to extract exhaust gas. So perhaps the answer is never let a high hp engine go past it's peak power...............
Last edited by Brettus; 11-27-2018 at 01:18 PM.
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Loki (11-27-2018)
#37
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Here is the chart in the Renesis PDF . It's more accurate than the one you posted but I still feel it doesn't properly represent that last few degrees of closing .
Anyway ...it does still illustrate my point . Look at the cross hatched area ... works ok for an NA engine , but double the amount of air to expel and that x-hatched area makes all the difference in getting rid of the last of it.
Anyway ...it does still illustrate my point . Look at the cross hatched area ... works ok for an NA engine , but double the amount of air to expel and that x-hatched area makes all the difference in getting rid of the last of it.
#39
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It would be interesting to see what peak numbers a MSP could produce with a large top-mounted turbo and E-85/race gas. While it would be a lag monster, maybe the lower boost and back pressure would help keep the motor together? Would the exhaust ports just choke it up? Anyone tried this?
#40
That is essentially what Turblown did with the lucky7 car.
9174 running E85 made 422 on a dynojet . I believe they are now trying a 9180 .
So yeah ...very laggy and no more top end than I made ... BUT........... promising signs in the 6-7000rpm rev range which supports what Loki and I were just discussing.
9174 running E85 made 422 on a dynojet . I believe they are now trying a 9180 .
So yeah ...very laggy and no more top end than I made ... BUT........... promising signs in the 6-7000rpm rev range which supports what Loki and I were just discussing.
Last edited by Brettus; 11-28-2018 at 01:38 PM.
#42
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I notice that nobody ever takes a turbo MSP engine out to 9,000 RPMs, which seems to be that the smaller low-mount turbos are moving way outside of their efficiency. In the dyno chart above horsepower was pretty flat as you mentioned, and the power appeared to fall with the boost pressure. It would be nice to see what would happen from 8,200-9,000. Even a laggy turbo with a 3,500 RPM (5500-9000) powerband would be a monster in a straightaway.
#43
I notice that nobody ever takes a turbo MSP engine out to 9,000 RPMs, which seems to be that the smaller low-mount turbos are moving way outside of their efficiency. In the dyno chart above horsepower was pretty flat as you mentioned, and the power appeared to fall with the boost pressure. It would be nice to see what would happen from 8,200-9,000. Even a laggy turbo with a 3,500 RPM (5500-9000) powerband would be a monster in a straightaway.
Power just drops sharply away after 8000 ....... that's if you haven't blown the engine.
Last edited by Brettus; 11-28-2018 at 02:59 PM.
#44
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...
Additional to the above "port closing early" theory, the momentum of the gas as it flows in and out of the engine also impacts efficiency. When you compare the gas flow out of a side port vs a peripheral port, the peripheral port doesn't require the exhaust gas to change direction as it exits the chamber into the port - the opening is right in front of the rotating rotor face, so it's a natural path for the exhaust gas to take. Compare this with the side port, where the exhaust gas needs to take a sharp right angle turn to leave the chamber. I would expect this also has a significant effect on the engine's ability to breath, particularly at higher rpm.
Additional to the above "port closing early" theory, the momentum of the gas as it flows in and out of the engine also impacts efficiency. When you compare the gas flow out of a side port vs a peripheral port, the peripheral port doesn't require the exhaust gas to change direction as it exits the chamber into the port - the opening is right in front of the rotating rotor face, so it's a natural path for the exhaust gas to take. Compare this with the side port, where the exhaust gas needs to take a sharp right angle turn to leave the chamber. I would expect this also has a significant effect on the engine's ability to breath, particularly at higher rpm.
The extra port area earlier will do a good job of dumping the initial charge for lower flow situations but as pointed out earlier, even though port area is greater ......it's still got a really poor exit from the chamber . Also remember that 1/2 of that port area exits through the siamese sleeve . Hold up a siamese sleeve next to a peripheral port and you realise what a joke it is.
Even with extra port area ....my guess is that it doesn't get the gas out as fast as a PP does ....even when fully open .
Even with extra port area ....my guess is that it doesn't get the gas out as fast as a PP does ....even when fully open .
Bottom line... the PP is simply the more elegant, and efficient design for power.
Last edited by jcbrx8; 01-03-2019 at 04:52 PM.
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EZAS (02-20-2020)
#46
Smoking turbo yay
- RX-8 is a lot cheaper than FD(FD was almost as expensive as a Corvette from the same time period), and in general targets a lower market
- RX-8 has to face stricter emission standards
- FD was designed during Japan's bubble economy. That was a time where some of the best Japanese sports cars were made, because the Japanese manufacturers weren't concerned about what they should make, but rather what they can make.
IMO comparing the RX-8 and FD is about as reasonable as comparing a Corvette and a V6 Camaro. Made by the same company, a similar engine, so fair comparison, right?
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New Yorker (01-15-2019)
#47
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I agree with unknown jinX. Comparing the RX-8 to an FD is idiotic. One came with turbo(s) from factory, the other was designed to be N/A.
There have been several recent YouTube channels that published this type of RX-8 / Rotary bashing, saying the engine is a POS, slow, etc etc.
ok, why are you comparing a Rotary to a V8? It ain’t an apples to apples comparison, you imbeciles.
There have been several recent YouTube channels that published this type of RX-8 / Rotary bashing, saying the engine is a POS, slow, etc etc.
ok, why are you comparing a Rotary to a V8? It ain’t an apples to apples comparison, you imbeciles.
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New Yorker (01-15-2019)
#48
Smoking turbo yay
I agree with unknown jinX. Comparing the RX-8 to an FD is idiotic. One came with turbo(s) from factory, the other was designed to be N/A.
There have been several recent YouTube channels that published this type of RX-8 / Rotary bashing, saying the engine is a POS, slow, etc etc.
ok, why are you comparing a Rotary to a V8? It ain’t an apples to apples comparison, you imbeciles.
There have been several recent YouTube channels that published this type of RX-8 / Rotary bashing, saying the engine is a POS, slow, etc etc.
ok, why are you comparing a Rotary to a V8? It ain’t an apples to apples comparison, you imbeciles.
And TBH I am used to this at this point. We are all more or less keyboard warriors and guilty of bashing a car at one point or another.
Some of these articles and journalism can be summarized as "It's like people only do things because they get paid. And that's just sad."