The 450whp Renesis engine - why it will never happen - theory
#1
The 450whp Renesis engine - why it will never happen - theory
As many of you know , I've been pursuing the goal of creating the highest whp Renesis ever recorded . I believe I have succeeded in doing that (arguably) but along the way have encountered many engine failures. Each failure, while devastating for me, has made me think about "why is this so hard?" . I have had a few theories along the way and attempted to solve the issues I saw . One being the reversion created within the siamese exhaust port area . While I still believe this happens and is a negative ...... I now think I have worked out what the real issue is. Up till now most engine tuners/builders have gone with the 'exhaust port size is too small' theory. I say ...port size is perfectly adequate . The issue is actually exhaust port closure timing. I will attempt to explain :
Here we have the exhaust port about to begin closing .
Note a few things here
1/There is still a ton of exhaust gas left in the chamber. In a boosted engine the pressure will be more than double what it would be in an N/A engine.
2/The tip of the rotor (where the arrow is ) is the furthest part of the rotor from where the teeth are engaging with the stationary gear. This means that tip is at a point where it is moving faster than any other point on the rotor.
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 .
Now take a look at the rotor position just as the exhaust port fully closes.
Note:
1/The rotor has now reached top dead center for the exhaust phase of the cycle. Up until this point the rotor face has constantly been compressing the exhaust gas to expel it from the chamber .
2/Any remaining exhaust gas is automatically carried over to the next cycle.
Now have a look at a peripheral exhaust port engine as used in earlier rotaries . Exhaust port about to begin closing.
Note
1/Compare the amount of exhaust gas left in the chamber with the first pic. above .
2/The rotor has already gone PAST exhaust top dead center and is only now about to close . Meaning the exhaust port is FULLY open during the entire period that a Renesis exhaust port is rapidly closing and is fully open for the entire period before it reaches top dead center.
3/By allowing the exhaust port to be fully open for so long , the power potential for this engine is massive, as has been proven over the years.
Edit 29/082020 : I only recently came to the realisation that there may also be a major issue with the Siamese port . That being that around the 400 mark , I believe this port becomes totally flow choked. As in , it will just not carry any more flow whatsoever. What this does is direct any extra flow to the outer ports, exacerbating the issues already mentioned above.
Summary:
EDITED
My previous statement was that there was a horsepower ceiling of 450ish WHP. It has been proven that with a turbo big enough /low compression rotors and some internal trickery higher whp is indeed possible. But requires making some extreme choices that make the engine impractical for most situations.
Here we have the exhaust port about to begin closing .
Note a few things here
1/There is still a ton of exhaust gas left in the chamber. In a boosted engine the pressure will be more than double what it would be in an N/A engine.
2/The tip of the rotor (where the arrow is ) is the furthest part of the rotor from where the teeth are engaging with the stationary gear. This means that tip is at a point where it is moving faster than any other point on the rotor.
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 .
Now take a look at the rotor position just as the exhaust port fully closes.
Note:
1/The rotor has now reached top dead center for the exhaust phase of the cycle. Up until this point the rotor face has constantly been compressing the exhaust gas to expel it from the chamber .
2/Any remaining exhaust gas is automatically carried over to the next cycle.
Now have a look at a peripheral exhaust port engine as used in earlier rotaries . Exhaust port about to begin closing.
Note
1/Compare the amount of exhaust gas left in the chamber with the first pic. above .
2/The rotor has already gone PAST exhaust top dead center and is only now about to close . Meaning the exhaust port is FULLY open during the entire period that a Renesis exhaust port is rapidly closing and is fully open for the entire period before it reaches top dead center.
3/By allowing the exhaust port to be fully open for so long , the power potential for this engine is massive, as has been proven over the years.
Edit 29/082020 : I only recently came to the realisation that there may also be a major issue with the Siamese port . That being that around the 400 mark , I believe this port becomes totally flow choked. As in , it will just not carry any more flow whatsoever. What this does is direct any extra flow to the outer ports, exacerbating the issues already mentioned above.
Summary:
EDITED
My previous statement was that there was a horsepower ceiling of 450ish WHP. It has been proven that with a turbo big enough /low compression rotors and some internal trickery higher whp is indeed possible. But requires making some extreme choices that make the engine impractical for most situations.
Last edited by Brettus; 09-18-2024 at 05:39 PM. Reason: Updated
#2
Project Seca
iTrader: (10)
Now while your extensive work put into the Renesis arguably supports this claim, I would like if possible if you could clarify something for readers who are aiming at increasing power output of the Renesis.
Overall would you say to someone looking to increase power to do so with the Renesis, or to swap the motor out for an engine such as 13b-re or 13b-rew?
And does your response also apply for those whom are aiming for a much lower and more modest, factory like power output of around 260-300 whp? What would you say for those individuals?
I believe if anyone is qualified to answer those questions, it would be you.
Overall would you say to someone looking to increase power to do so with the Renesis, or to swap the motor out for an engine such as 13b-re or 13b-rew?
And does your response also apply for those whom are aiming for a much lower and more modest, factory like power output of around 260-300 whp? What would you say for those individuals?
I believe if anyone is qualified to answer those questions, it would be you.
#6
Smoking turbo yay
You did a good job explaining it.
Combined with the fact Renesis was made with emissions(where more recycled unburnt gas and no intake/exhaust port overlap are good) in mind, this doesn't really surprise me.
Combined with the fact Renesis was made with emissions(where more recycled unburnt gas and no intake/exhaust port overlap are good) in mind, this doesn't really surprise me.
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Brettus (11-21-2018)
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EZAS (02-20-2020)
#10
Registered
iTrader: (1)
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...
Last edited by Loki; 11-21-2018 at 09:17 AM.
#11
Registered
Brettus, have you measured exhaust pressures and EGTs? Might give some insights depending how the numbers trend as boost is added.
It'd be destructive to the housing, but a pressure transducer clocked to the exhaust port centerline of the housing would also give insights into what exactly is happening. If the pressure wave is still strong when the port closes, we'd see a spike in the housing as the volume is briefly compressed before the intake port opening is exposed.
Tuning equipment, dyno time, and turbo fabrication aside, has the actual engine cost been extensive for you? You noted several failures -- were they housing-damaging failures, or were they such that you were able to get back to action with just new seals?
It'd be destructive to the housing, but a pressure transducer clocked to the exhaust port centerline of the housing would also give insights into what exactly is happening. If the pressure wave is still strong when the port closes, we'd see a spike in the housing as the volume is briefly compressed before the intake port opening is exposed.
Tuning equipment, dyno time, and turbo fabrication aside, has the actual engine cost been extensive for you? You noted several failures -- were they housing-damaging failures, or were they such that you were able to get back to action with just new seals?
Last edited by furansu; 11-21-2018 at 11:35 AM.
#13
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...
#14
Yes , have been watching both of those all along . I spent a lot of effort in reducing turbine pressure but it never did much for peak power as you would expect. I believe due to the port timing issue as explained above.
Well ................. It's been an interesting hobby for me. I would say it's been expensive but I could have picked other hobbies that cost me a ton more too . Failures generally result in a stuffed housing and possibly an iron or a rotor. Each failure has cost me between $2500 and $5000. I've learnt that a bad detonation will do damage to something no matter how you build the engine. If you go with bendy apex seals and they don't break ....you end up distorting the rotor and breaking a corner seal which can do just as much damage .
Well ................. It's been an interesting hobby for me. I would say it's been expensive but I could have picked other hobbies that cost me a ton more too . Failures generally result in a stuffed housing and possibly an iron or a rotor. Each failure has cost me between $2500 and $5000. I've learnt that a bad detonation will do damage to something no matter how you build the engine. If you go with bendy apex seals and they don't break ....you end up distorting the rotor and breaking a corner seal which can do just as much damage .
#15
What about getting a set of plates milled to match the intake ports and block the exhaust ports? Giving you mill the iorns to accept them. Could you then open the standard side ports to the water jacket and have a external coolant manifold. That way you can utilize some cooling in the area to help prevent warping of the plates? I imagine I am over looking an obvious flaw in the idea.
The 12a housings could be used or add a exhaust p-ports to a renesis.
The 12a housings could be used or add a exhaust p-ports to a renesis.
#16
What about getting a set of plates milled to match the intake ports and block the exhaust ports? Giving you mill the iorns to accept them. Could you then open the standard side ports to the water jacket and have a external coolant manifold. That way you can utilize some cooling in the area to help prevent warping of the plates? I imagine I am over looking an obvious flaw in the idea.
The 12a housings could be used or add a exhaust p-ports to a renesis.
The 12a housings could be used or add a exhaust p-ports to a renesis.
#17
the insert done similar to the one I screen shot. To keep the stock intake ports. I am thinking you could then run p-port exhaust. In just covering up the side exhaust ports it would create a hit spot that would warp. So open the side exhaust ports into the coolant jacket so coolant could flow along the back side of the plate in that area. Leading to needing a way to contain the coolant trying to exit the iorns where the oe manifold was. If someone took a flange and built something for the coolant to flow though to close it back in to the system.
I wish I knew more on how the coolant flows through the engine without knowing that I think my idea is dead in the process.
Thanks for giving us a realistic cap on power before it starts to sound like a jar of marbles in a hyper child's hands.
#18
the insert done similar to the one I screen shot. To keep the stock intake ports. I am thinking you could then run p-port exhaust. In just covering up the side exhaust ports it would create a hit spot that would warp. So open the side exhaust ports into the coolant jacket so coolant could flow along the back side of the plate in that area. Leading to needing a way to contain the coolant trying to exit the iorns where the oe manifold was. If someone took a flange and built something for the coolant to flow though to close it back in to the system.
I wish I knew more on how the coolant flows through the engine without knowing that I think my idea is dead in the process.
Thanks for giving us a realistic cap on power before it starts to sound like a jar of marbles in a hyper child's hands.
I wish I knew more on how the coolant flows through the engine without knowing that I think my idea is dead in the process.
Thanks for giving us a realistic cap on power before it starts to sound like a jar of marbles in a hyper child's hands.
#19
Hybrid Greddy Boosted
Assuming this theory is correct, we would expect to see max power improvements from exhaust porting that extends the exhaust port opening by a few more degrees of rotation. Does anyone know if extending exhaust ports has shown to improve max power on a turbo renesis?
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.
#20
Assuming this theory is correct, we would expect to see max power improvements from exhaust porting that extends the exhaust port opening by a few more degrees of rotation. Does anyone know if extending exhaust ports has shown to improve max power on a turbo renesis?
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#21
FULLY SEMI AUTOMATIC
iTrader: (9)
ya bunch of newbs are over thinking this. a turdblown turbo kit gets ya 500whp out of the box lol
#22
Registered
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Aluminum Front Side Housing for 86-95 Engines - Racing Beat
#23
Too bad they don't offer Renesis plates with the exhaust ports deleted...
Aluminum Front Side Housing for 86-95 Engines - Racing Beat
Aluminum Front Side Housing for 86-95 Engines - Racing Beat
#24
Just to add to this ...I looked up Dynapack dynos and found they are even more optimistic than Dynojets .
Pretty sure they used a 4 port for this and yes it was probably on E85 but realistic whp will be well under 400. Note also how low the rpm was at peak power (which is what we were discussing earlier) and how poor the turbo response is ...meaning it made a lot of torque but had a very narrow power band - similar to Turblowns' effort with the EFR9174.
Pretty sure they used a 4 port for this and yes it was probably on E85 but realistic whp will be well under 400. Note also how low the rpm was at peak power (which is what we were discussing earlier) and how poor the turbo response is ...meaning it made a lot of torque but had a very narrow power band - similar to Turblowns' effort with the EFR9174.