Renesis Hybrid Engine
03-20-2021, 08:05 PM
#1
Renesis Hybrid Engine
Hey everyone I am new to this forum and I am looking for a challenge. I have a background in engineering and love doing what people say is impossible.
I want to experiment with the Renesis Hybrid engine design and have my own personal attempt at creating a reliable boosted platform using as many parts from a Renesis engine as I can.
After all, the way I look at this is this engine is just a pump like any other pump. However over the years I have been reading and watching many conflicting story's regarding this heavily criticized engine. But no one has any solid proof of any side of the argument, no one has documented this in detail and tried to design or solve the issues that cause failure's under heavy boost. I am looking for anyone would like to to help me with this next challenge of mine. I am not interested in hearing about how I am wasting money or my time as I said from the start I am doing this to document and show in great detail. All my experiments will be filmed and posted to my YouTube channel Mechanical Warrior. if my goal can be achieved and if the Renesis can be used in high power applications I would then like to see if there is a way we can manufacture parts in order to help others who want to go down this same path. Also I will also point out I am horrible at spelling an grammar so let get that one out of the way as well
I would love to hear what others have to say regarding this topic and I hope we can keep it constructive and on point.
Tell me the problems you have heard of or problems you have encountered building these engines and lets see if there is a way we can solve them. Also I would love to know what setups others have tried before. I have heard of many designs but which ones have you heard of being the most successful.
Thanks everyone
I want to experiment with the Renesis Hybrid engine design and have my own personal attempt at creating a reliable boosted platform using as many parts from a Renesis engine as I can.
After all, the way I look at this is this engine is just a pump like any other pump. However over the years I have been reading and watching many conflicting story's regarding this heavily criticized engine. But no one has any solid proof of any side of the argument, no one has documented this in detail and tried to design or solve the issues that cause failure's under heavy boost. I am looking for anyone would like to to help me with this next challenge of mine. I am not interested in hearing about how I am wasting money or my time as I said from the start I am doing this to document and show in great detail. All my experiments will be filmed and posted to my YouTube channel Mechanical Warrior. if my goal can be achieved and if the Renesis can be used in high power applications I would then like to see if there is a way we can manufacture parts in order to help others who want to go down this same path. Also I will also point out I am horrible at spelling an grammar so let get that one out of the way as well
I would love to hear what others have to say regarding this topic and I hope we can keep it constructive and on point.
Tell me the problems you have heard of or problems you have encountered building these engines and lets see if there is a way we can solve them. Also I would love to know what setups others have tried before. I have heard of many designs but which ones have you heard of being the most successful.
Thanks everyone
03-20-2021, 10:18 PM
#3
Registered
If you want to get up to speed on why the hybrid concept doesn't work I explained it a few days ago in this thread. I did a lot of research comparing parts and different ports. I also talked to quite a few people about the topic.
https://www.rx8club.com/new-member-f...emi-pp-272595/
To make it simple, I'd say read up on how to turbo a normal renesis up to 350-400hp. Most simple MSP REN upgrades you will need is a fresh build with rx7 apex seals and I'd probably streetport the end plate exhaust ports. Read up on Brettus's thread about the Siamese center exhaust port.
After that look for a rew to go anywhere above that range. From what I have found it is hard to be emissions legal without finding one of the old style piggy-back intercept Adaptronic ECU's. I might try to see if I can make the stock computer happy without anything other than the OBD2 plugged in with MazdaEdited DTC codes and run one of the current gen Adaptronics.
https://www.rx8club.com/new-member-f...emi-pp-272595/
To make it simple, I'd say read up on how to turbo a normal renesis up to 350-400hp. Most simple MSP REN upgrades you will need is a fresh build with rx7 apex seals and I'd probably streetport the end plate exhaust ports. Read up on Brettus's thread about the Siamese center exhaust port.
After that look for a rew to go anywhere above that range. From what I have found it is hard to be emissions legal without finding one of the old style piggy-back intercept Adaptronic ECU's. I might try to see if I can make the stock computer happy without anything other than the OBD2 plugged in with MazdaEdited DTC codes and run one of the current gen Adaptronics.
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MechanicalWarrior (03-21-2021)
03-21-2021, 03:39 AM
#4
Do you know there channel names ?? I would love to see what they are up to! Maybe I can help
03-21-2021, 03:44 AM
#5
What about blocking the side exhaust ports off with devcon and opening the exhaust PP on the older rx7 housings ??
also I still don't understand why cant you run rx7 rotors in the renny if you was to block the side ports up ?
Another thing to has anyone experimented with making a bigger corner seals to counter the heat ??
also I still don't understand why cant you run rx7 rotors in the renny if you was to block the side ports up ?
Another thing to has anyone experimented with making a bigger corner seals to counter the heat ??
03-21-2021, 02:24 PM
#7
The problem with running rx7 rotors is that the side seals hit the intake ports end on. They say you can bevel the ports to prevent an issue there .... I would be very interested to hear if this works on a long term basis because I would like to try this myself. Petit have been doing it for years but you just don't hear about how well they last for some reason.
Last edited by Brettus; 03-21-2021 at 02:30 PM.
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sharingan 19 (05-21-2021)
03-21-2021, 05:06 PM
#8
there are numerous threads on here about it
hard to take you serious if you can’t even bother to research the subject yourself, but have to ask everyone to come hand it to you for documenting on youtube. Why does anyone here need it documented on youtube? That sounds more like a plan to serve your own interests and purposes rather than the way it’s presented.
by all appearances you don’t even seem to understand the basics which would have eliminated using devcon immediately for anyone with basic common knowledge of this particular “air pump”
so many things wrong here, but doing my best not to go Johnny 5 Full Flame On.
Just how much were you planning to invest in this; $20k, $30k, more??? Because the only way to take you seriously is if you have cash to burn when most people won’t even spend what it takes to rebuild a standard Renesis properly. let alone act like they’re going to take it to a new level on a half-hearted budget build.
hard to take you serious if you can’t even bother to research the subject yourself, but have to ask everyone to come hand it to you for documenting on youtube. Why does anyone here need it documented on youtube? That sounds more like a plan to serve your own interests and purposes rather than the way it’s presented.
by all appearances you don’t even seem to understand the basics which would have eliminated using devcon immediately for anyone with basic common knowledge of this particular “air pump”
so many things wrong here, but doing my best not to go Johnny 5 Full Flame On.
Just how much were you planning to invest in this; $20k, $30k, more??? Because the only way to take you seriously is if you have cash to burn when most people won’t even spend what it takes to rebuild a standard Renesis properly. let alone act like they’re going to take it to a new level on a half-hearted budget build.
03-21-2021, 07:58 PM
#9
there are numerous threads on here about it
hard to take you serious if you can’t even bother to research the subject yourself, but have to ask everyone to come hand it to you for documenting on youtube. Why does anyone here need it documented on youtube? That sounds more like a plan to serve your own interests and purposes rather than the way it’s presented.
by all appearances you don’t even seem to understand the basics which would have eliminated using devcon immediately for anyone with basic common knowledge of this particular “air pump”
so many things wrong here, but doing my best not to go Johnny 5 Full Flame On.
Just how much were you planning to invest in this; $20k, $30k, more??? Because the only way to take you seriously is if you have cash to burn when most people won’t even spend what it takes to rebuild a standard Renesis properly. let alone act like they’re going to take it to a new level on a half-hearted budget build.
hard to take you serious if you can’t even bother to research the subject yourself, but have to ask everyone to come hand it to you for documenting on youtube. Why does anyone here need it documented on youtube? That sounds more like a plan to serve your own interests and purposes rather than the way it’s presented.
by all appearances you don’t even seem to understand the basics which would have eliminated using devcon immediately for anyone with basic common knowledge of this particular “air pump”
so many things wrong here, but doing my best not to go Johnny 5 Full Flame On.
Just how much were you planning to invest in this; $20k, $30k, more??? Because the only way to take you seriously is if you have cash to burn when most people won’t even spend what it takes to rebuild a standard Renesis properly. let alone act like they’re going to take it to a new level on a half-hearted budget build.
Obviously I am not on here to **** in the wind and talk about documenting a project on YouTube without the intent to spend money to get the job done!! Im here to look for answers and help, not be judged on what I may or may not know. Or how much money I have in my pocket.
Its the age old saying "If you dont have anything positive or nice to say, Then dont say anything at all."
03-21-2021, 08:05 PM
#10
A guy on u-tube filled the rene ex. ports up with ........Tin . His first engine threw a side seal and his second seemed to run ok but again ................. no results after a decent period of time. But I would a agree with the theory that ...if any hybrid is going to work well ... it will be one with the side exhaust ports blocked.
The problem with running rx7 rotors is that the side seals hit the intake ports end on. They say you can bevel the ports to prevent an issue there .... I would be very interested to hear if this works on a long term basis because I would like to try this myself. Petit have been doing it for years but you just don't hear about how well they last for some reason.
The problem with running rx7 rotors is that the side seals hit the intake ports end on. They say you can bevel the ports to prevent an issue there .... I would be very interested to hear if this works on a long term basis because I would like to try this myself. Petit have been doing it for years but you just don't hear about how well they last for some reason.
03-24-2021, 12:09 AM
#12
So, I didn’t immediately put myself to good use lifting you up higher than you had already lifted yourself up to. Then in your brief excursion of the forum you determined yourself fully informed and justified to tear me down followed by an emotional array of excuses and sidestepping diversions rather than just addressing my post in a clear, concise, logical manner. Ok, got it.
What response would you expect popping up suddenly on the Elon Musk forum and stating, “I have an engineering background and don’t see what the big deal is about establishing a commercial flight service to Mars. After all, a rocket is just a rocket. Just send me everything you have on it and I’ll go graciously document it over on youboob for you”? Which btw, what exactly is having an engineering background suppose to mean rather than just stating you’re an engineer, possibly listing your credentials if you consider it necessary to establish yourself as having expertise, and possibly also listing some of your past accomplishments demonstrating how you overcame some other unique challenges?
You want to be lifted up? How about not just popping up and addressing a group of people you never met before like they’re helpless and without understanding, but you’re now here to be served and save them over on youtube? Because there’s no “lifting you up” to be done here, but rather only letting you down to the realities of a subject you are without understanding of. Further of which, over in the other thread you posted in I did kindly lift you up to the thread links that provide the basis of understanding on this subject and your response was to immediately dismiss the information. Which only confirms a lack of understanding of the most general basics involved. That precludes you having already demonstrated your engineering background suggesting devcon to seal off a port that will be directly exposed to 1600*F+ exhaust gases with a guillotine swinging past it every cycle revolution and just daring the rabbit that has no other exit path to try and stick it’s head out of the hole.
So let me try again to lift you up out of the beginner basement of air pump fundamentals 101 and point out that adding those housings to a Renesis is no different than putting a Super Stock dragstrip camshaft in your otherwise factory stock emissions legal 4-banger economy car engine thinking you’re going to “really make teh powrz now”. Furthermore, assuming you can effectively close off the side ports, it only serves to seal off an alternate exhaust flow path and otherwise has no impact at all on the exhaust port timing that is now entirely dominated by the peripheral exhaust port that was added. This in turn being done on an engine that Mazda reconfigured around a zero-overlap intake-exhaust timing principle that is unique among all combustion engines, that modification now adding an oil tanker load of intake/exhaust timing overlap that entirely changes the dynamic it was originally intended for. in your defense, you’re not alone in that lack of understanding.
It can just be documented here if you were to so will it, but then that precludes being the center of attention to receive glory and praise by a bunch of people who understand as little or less than yourself about it over on youtube. I’m still waiting to see from that other guy over there if the snap, crackle issue was instead a snap, crackle, popped the engine issue from revving it mercilessly without being under load just because it sounded neat and would make more “look at my cool video” bait. Which btw, if anyone has any desire for their Renesis engine to have a long life, don’t do that; modified or not.
It’s not honest to claim that you came here and meekly asked to be directed to any information on this subject to help educate yourself and further gain a better understanding about it, and then had a piano dropped on your head for asking. That’s just not true, but at the urging of someone else I gave you the benefit of doubt in that other thread and then also reworking my original post here too. All you’re upset about is being challenged rather than praised and lifted up. I worship neither the world nor the men of it, without apology.
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What response would you expect popping up suddenly on the Elon Musk forum and stating, “I have an engineering background and don’t see what the big deal is about establishing a commercial flight service to Mars. After all, a rocket is just a rocket. Just send me everything you have on it and I’ll go graciously document it over on youboob for you”? Which btw, what exactly is having an engineering background suppose to mean rather than just stating you’re an engineer, possibly listing your credentials if you consider it necessary to establish yourself as having expertise, and possibly also listing some of your past accomplishments demonstrating how you overcame some other unique challenges?
You want to be lifted up? How about not just popping up and addressing a group of people you never met before like they’re helpless and without understanding, but you’re now here to be served and save them over on youtube? Because there’s no “lifting you up” to be done here, but rather only letting you down to the realities of a subject you are without understanding of. Further of which, over in the other thread you posted in I did kindly lift you up to the thread links that provide the basis of understanding on this subject and your response was to immediately dismiss the information. Which only confirms a lack of understanding of the most general basics involved. That precludes you having already demonstrated your engineering background suggesting devcon to seal off a port that will be directly exposed to 1600*F+ exhaust gases with a guillotine swinging past it every cycle revolution and just daring the rabbit that has no other exit path to try and stick it’s head out of the hole.
So let me try again to lift you up out of the beginner basement of air pump fundamentals 101 and point out that adding those housings to a Renesis is no different than putting a Super Stock dragstrip camshaft in your otherwise factory stock emissions legal 4-banger economy car engine thinking you’re going to “really make teh powrz now”. Furthermore, assuming you can effectively close off the side ports, it only serves to seal off an alternate exhaust flow path and otherwise has no impact at all on the exhaust port timing that is now entirely dominated by the peripheral exhaust port that was added. This in turn being done on an engine that Mazda reconfigured around a zero-overlap intake-exhaust timing principle that is unique among all combustion engines, that modification now adding an oil tanker load of intake/exhaust timing overlap that entirely changes the dynamic it was originally intended for. in your defense, you’re not alone in that lack of understanding.
It can just be documented here if you were to so will it, but then that precludes being the center of attention to receive glory and praise by a bunch of people who understand as little or less than yourself about it over on youtube. I’m still waiting to see from that other guy over there if the snap, crackle issue was instead a snap, crackle, popped the engine issue from revving it mercilessly without being under load just because it sounded neat and would make more “look at my cool video” bait. Which btw, if anyone has any desire for their Renesis engine to have a long life, don’t do that; modified or not.
It’s not honest to claim that you came here and meekly asked to be directed to any information on this subject to help educate yourself and further gain a better understanding about it, and then had a piano dropped on your head for asking. That’s just not true, but at the urging of someone else I gave you the benefit of doubt in that other thread and then also reworking my original post here too. All you’re upset about is being challenged rather than praised and lifted up. I worship neither the world nor the men of it, without apology.
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Last edited by TeamRX8; 03-24-2021 at 12:40 AM.
03-25-2021, 09:19 PM
#13
Registered
There is a builder in Australia who has built many of them,
but they all seem to never make it to dynos, ****-themselves or disappear.
there is a a facebook group dedicated to them
but they all seem to never make it to dynos, ****-themselves or disappear.
there is a a facebook group dedicated to them
03-27-2021, 07:48 PM
#14
The problem with running rx7 rotors is that the side seals hit the intake ports end on. They say you can bevel the ports to prevent an issue there .... I would be very interested to hear if this works on a long term basis because I would like to try this myself. Petit have been doing it for years but you just don't hear about how well they last for some reason.
He recommended a dry sump oiling system to deal with aeration, but conceded that wasn’t probably necessary for general street or autocross (short duration WOT use) applications. That’s with the REW rotors that they modify with custom cutoff seals to help limit blowby between chambers. As per the SAE paper, it only does so much without also moving the side seals further out to the edge of the rotor like was done on the Renesis rotors. He focused solely on that particular point without mentioning anything else other than it allowed using the deeper RX7 seals that he recommends modifying Renesis rotors for as well. Which is well known about since around 2005 or so any way.
Using unmodified 13B rotors is sailing in uncharted waters. Landspeed/Jetset has them unmodified in his engine, but that doesn’t really correlate to pretty much any other engine being considered by most people. The more I think about it the more I grow resistant to the idea of doing it. I believe all we’re talking about is 7.26cc (0.44 in^3) being the difference between 10:1 and 9:1. Despite the Renesis rotors being notoriously thinner than the earlier rotors kind of thinking trying to find that amount by further planing the scallops, face clearancing the rotors, and generally spreading it out over as much area as possible on a CNC mill might be worth considering.
some of the relevant differences
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Last edited by TeamRX8; 03-27-2021 at 08:23 PM.
The following 2 users liked this post by TeamRX8:
NorCalEight (03-28-2021),
sharingan 19 (05-21-2021)
03-29-2021, 01:57 PM
#16
I’m still waiting to see from that other guy over there if the snap, crackle issue was instead a snap, crackle, popped the engine issue from revving it mercilessly without being under load just because it sounded neat and would make more “look at my cool video” bait. Which btw, if anyone has any desire for their Renesis engine to have a long life, don’t do that; modified or not.
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03-30-2021, 01:19 AM
#18
no disassembly yet; claims he’ll go back to Renesis rotors, like that will matter with low temp tin in the exhaust side ports
as I stated in one of the previous posts, filling the Renesis exhaust ports does nothing wrt to port timing/overlap, which is entirely dominated by the addition of the peripheral exhaust port housings.
Hard to believe the one commenter from here still lacks a full understanding about it at this point. The virtual generation thinks they can just imagine it into being 〜〜
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as I stated in one of the previous posts, filling the Renesis exhaust ports does nothing wrt to port timing/overlap, which is entirely dominated by the addition of the peripheral exhaust port housings.
Hard to believe the one commenter from here still lacks a full understanding about it at this point. The virtual generation thinks they can just imagine it into being 〜〜
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03-30-2021, 07:03 AM
#19
Registered
It must be an alloy of some kind. I find it hard to believe he knowingly put plain tin in an exhaust port that would see temps 3 times as high as tin's melting point. I mean, you'd have to be some kind of special to have access to equipment that could accommodate that and still not know about melting points....
03-30-2021, 09:50 AM
#20
Registered
I mean there is a reason I put the disclaimer that a rew would perform better, and willing to bet the hybrid concept would still not beat out a turbo Renesis.
I'm sure there are concepts that I am missing since I don't have decades of racing/building experience, and if I'm being honest, learning based off what people bicker about on forums isn't exactly a great way to get solid information.
Even for the concept hybrid that I commented about, it still falls on its face for the fact that the overlap stifles the benefits you are attempting to gain from the Renesis. At the same time the intake and exhaust manifolds and ports you have to run to "try to get" those gains from the Renesis end up drastically hurting turbo response. Again, I'm sure there is more I am missing, but even these negatives are enough that I don't believe there are any available work arounds.
I'm sure there are concepts that I am missing since I don't have decades of racing/building experience, and if I'm being honest, learning based off what people bicker about on forums isn't exactly a great way to get solid information.
Even for the concept hybrid that I commented about, it still falls on its face for the fact that the overlap stifles the benefits you are attempting to gain from the Renesis. At the same time the intake and exhaust manifolds and ports you have to run to "try to get" those gains from the Renesis end up drastically hurting turbo response. Again, I'm sure there is more I am missing, but even these negatives are enough that I don't believe there are any available work arounds.
03-30-2021, 02:25 PM
#21
no, he straight up used the lowest temp tin possible because it was done at the farm without a forge. Which the plates also were not preheated, so the tin hardened before fully filling out the inner port face opening. You can see it in a past vid where he documented the port filling. Which he acknowledged it only having a 700 degF melting point, but convinced himself they won’t ever get that hot.
I’d surmise that one of those tin slugs coming apart is just as likely to have taken out one of the rotors. In the prior vid where it let go he was wailing on the throttle in neutral trying to show off the sounds of a crack/pop exhaust tune. Look, it’s easy to criticize, but just like the way this thread started, people who have ideas but no comprehension beyond desiring fame & fortune are only setting themselves up to fall far and hard.
Not sure why people at this point are believing in this ever being worthwhile in any form. The only person close to doing anything with it is Kyle Mohan. I won’t use the word successful because imo it’s simply not. Even he had to both bridgeport it heavily and hog out the peri exhaust port too to accomplish low 400 whp. It didn’t even make 300 whp at the beginning. It’s pretty dead below 5500 rpm regardless. It’s not my effort and resources, but still qualifies as an all-around waste of everything put into it.
The other guy on youtube with the NA version claims he got it up from the original 160whp to 175 whp by disconnecting the ABS/DSC fuse, but failed to notice that the rear bumper caught on fire and torched the rear of the car on the dyno. So he bought another RX8 and was transferring everything over to it.
There’s another NA version on there from Singapore that has been awol since posting the first startup video from 3 months ago. I suspect he got it on the dyno and is scratching his head wondering why it isn’t making any of the magical big horsepowerz ...
on the other hand we have at least three successful long term Renesis turbo setups on here making low-mid 400 whp and good low end. 9k had a good mid-300 whp run with a modified Greddy before selling his RX8. Most of the failures fall on either lack of proper funding or lack of proper understanding/decision making.
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I’d surmise that one of those tin slugs coming apart is just as likely to have taken out one of the rotors. In the prior vid where it let go he was wailing on the throttle in neutral trying to show off the sounds of a crack/pop exhaust tune. Look, it’s easy to criticize, but just like the way this thread started, people who have ideas but no comprehension beyond desiring fame & fortune are only setting themselves up to fall far and hard.
Not sure why people at this point are believing in this ever being worthwhile in any form. The only person close to doing anything with it is Kyle Mohan. I won’t use the word successful because imo it’s simply not. Even he had to both bridgeport it heavily and hog out the peri exhaust port too to accomplish low 400 whp. It didn’t even make 300 whp at the beginning. It’s pretty dead below 5500 rpm regardless. It’s not my effort and resources, but still qualifies as an all-around waste of everything put into it.
The other guy on youtube with the NA version claims he got it up from the original 160whp to 175 whp by disconnecting the ABS/DSC fuse, but failed to notice that the rear bumper caught on fire and torched the rear of the car on the dyno. So he bought another RX8 and was transferring everything over to it.
There’s another NA version on there from Singapore that has been awol since posting the first startup video from 3 months ago. I suspect he got it on the dyno and is scratching his head wondering why it isn’t making any of the magical big horsepowerz ...
on the other hand we have at least three successful long term Renesis turbo setups on here making low-mid 400 whp and good low end. 9k had a good mid-300 whp run with a modified Greddy before selling his RX8. Most of the failures fall on either lack of proper funding or lack of proper understanding/decision making.
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03-30-2021, 06:27 PM
#22
I believe all we’re talking about is 7.26cc (0.44 in^3) being the difference between 10:1 and 9:1. Despite the Renesis rotors being notoriously thinner than the earlier rotors kind of thinking trying to find that amount by further planing the scallops, face clearancing the rotors, and generally spreading it out over as much area as possible on a CNC mill might be worth considering.
You def. wouldn't want to take anything off the faces close to the apex seals (that's where they dent typically) but there could be room to remove some material from the combustion chambers. Taking 1mm out of the entire combustion chamber area gives you 4.94cc which is getting close. Chamfering the intake side the same as the exhaust gives another 0.18ish .
Last edited by Brettus; 03-30-2021 at 07:56 PM.
03-30-2021, 11:15 PM
#23
well that’s the reason people do REW rotors with a Renesis imo. It does more than that though wrt to FI.
Been thinking about your theory more. if you consider piston/cammed engines, typically the more overlap, the more compression it needs to overcome “leakage”. As RPMs increase so does dynamic/effective compression due to less time for it to leak by. In theory the opposite seems just as likely. Which on a Renesis is good for NA, but possibly a hindrance for FI.
When the REW rotors and peri exhaust ports are paired on Renesis plates, that combo adds a ton of overlap due to the repositioned pri/sec ports and also reduces compression. I never thought the motor in that vid sounded good when he was driving it around and commented elsewhere that you could hear the result of those two things combined in the way it sounded flat, but then also said the largish turbo might end up being a plus to offset that at higher rpms.
The Mazdatrix/KM hybrid engines used Renesis rotors as far as I ever knew. Petitt only uses the REW rotors in the Renesis (no peri port exhaust). So both of those sort of make sense as compared to pairing REW rotors and housings together like was done on the engine we’re discussing
So you said lower CR allows less octane, but it also allows more boostz safely for the same reason. There are other factors; turbo efficiency, IC efficiency, elevation, etc.
Again in general, imo the thing for people to learn from the topic we’re discussing is that just dreaming something up that seems good on the surface is no guarantee. In this particular case, most people are doing zero technical assessment and missing how adding the 13B peri port exhaust housings on a Renesis is like adding a full-on extreme racing cam to a piston engine. Mazda shifted the intake ports around on the Renesis to specifically to take advantage of the no-overlap condition. So combining these previous 13B parts with it is not going to result in the same effect.
When you bridgeport it’s just that small BP eye that creates the overlap and on the earlier 13B this is well into the intake sweep process when the chamber volume is increasing and exhaust gas pressure dropping, then as the rotor transitions the bridge limits flow, and finally the full port opens. However on the Renesis, due to where the ports are repositioned to open so early in the intake sweep, the full port is open to overlap extremely early with the rotor chamber also is at it’s minimum volume, and exhaust gasses under high pressure are rushing in to create extreme EGR and reversion. So the entire dynamic is completely different on a Renesis with these 13B housings than is being recognized, and the end result as well.
sorry to sound like a broken record, but some people seem to have trouble understanding and/or seeing it.
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Been thinking about your theory more. if you consider piston/cammed engines, typically the more overlap, the more compression it needs to overcome “leakage”. As RPMs increase so does dynamic/effective compression due to less time for it to leak by. In theory the opposite seems just as likely. Which on a Renesis is good for NA, but possibly a hindrance for FI.
When the REW rotors and peri exhaust ports are paired on Renesis plates, that combo adds a ton of overlap due to the repositioned pri/sec ports and also reduces compression. I never thought the motor in that vid sounded good when he was driving it around and commented elsewhere that you could hear the result of those two things combined in the way it sounded flat, but then also said the largish turbo might end up being a plus to offset that at higher rpms.
The Mazdatrix/KM hybrid engines used Renesis rotors as far as I ever knew. Petitt only uses the REW rotors in the Renesis (no peri port exhaust). So both of those sort of make sense as compared to pairing REW rotors and housings together like was done on the engine we’re discussing
So you said lower CR allows less octane, but it also allows more boostz safely for the same reason. There are other factors; turbo efficiency, IC efficiency, elevation, etc.
Again in general, imo the thing for people to learn from the topic we’re discussing is that just dreaming something up that seems good on the surface is no guarantee. In this particular case, most people are doing zero technical assessment and missing how adding the 13B peri port exhaust housings on a Renesis is like adding a full-on extreme racing cam to a piston engine. Mazda shifted the intake ports around on the Renesis to specifically to take advantage of the no-overlap condition. So combining these previous 13B parts with it is not going to result in the same effect.
When you bridgeport it’s just that small BP eye that creates the overlap and on the earlier 13B this is well into the intake sweep process when the chamber volume is increasing and exhaust gas pressure dropping, then as the rotor transitions the bridge limits flow, and finally the full port opens. However on the Renesis, due to where the ports are repositioned to open so early in the intake sweep, the full port is open to overlap extremely early with the rotor chamber also is at it’s minimum volume, and exhaust gasses under high pressure are rushing in to create extreme EGR and reversion. So the entire dynamic is completely different on a Renesis with these 13B housings than is being recognized, and the end result as well.
sorry to sound like a broken record, but some people seem to have trouble understanding and/or seeing it.
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Last edited by TeamRX8; 03-30-2021 at 11:19 PM.
03-31-2021, 04:33 PM
#24
Been thinking about your theory more. if you consider piston/cammed engines, typically the more overlap, the more compression it needs to overcome “leakage”. As RPMs increase so does dynamic/effective compression due to less time for it to leak by. In theory the opposite seems just as likely. Which on a Renesis is good for NA, but possibly a hindrance for FI.
A low compression rotor may improve this situation somewhat but wont eliminate it. This is why I was scratching my head when Jetset made so much power. Till I found out about the overlap induced by the lack of a cutoff seal.
03-31-2021, 04:51 PM
#25
not entirely convinced myself
still think there may be more to it, but maybe not; the amount of overlap required for that power level seems not to be sufficiently supported by just that alone imo.
but if true, in theory it seems like you could just leave the cutoff seals out of the Renesis rotors if that were the case; wanna’ be the canary in the coal mine?
still rummaging through it all, so not making any claims for or against anything
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still think there may be more to it, but maybe not; the amount of overlap required for that power level seems not to be sufficiently supported by just that alone imo.
but if true, in theory it seems like you could just leave the cutoff seals out of the Renesis rotors if that were the case; wanna’ be the canary in the coal mine?
still rummaging through it all, so not making any claims for or against anything
.