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Hello all! Finally picked up my own rx8 a few days back and have been wondering this for a while now. Has anyone ran a turbo semi pp with the 8's 10:1 rotors? The plan in place currently is to go in with the semi pp housings, jaypro turbo intake, turbo (haven't shopped for specifics yet w that), lightened and balanced e shaft and rotors, then scalloping the rotors when going for my rebuild next summer. Ultimate goal is to push around 500/550rwhp. I know this is all costly, and have been researching all things related. I was just wondering if anyone has tried this and what the results were. Tyia
By semi pp do you mean the intake as well or just the exhaust? ( EDIT: looked that the jaypro includes the intake semiPP intake >> but I believe the other intake ports wont match up to the rx8 center iron and definitely wont pair with the rx8 6 port side irons at all. Not to mention there's little point in the semiPP+rx8 6 port side Irons.)
There has been plenty of hybrid theory tossed around and attempted, but in the end there is no point since just going for a REW setup will perform better. Many have tried the 5 exhaust port setup, but for a turbo build the side exhausts rob you of energy while adding weight and complexity while reducing cooling. As for intake ports the stock rx8 ports are insanely high flowing and variable, but this ends up hurting you in two ways. First off the primary and secondary ports will have overlap nearly equivalent to a 13b-REW bridgeported, likely poor idle and low end will show itself Brap Brap Brap. Second, the intake manifold for the rx8 is massive which is great for naturally aspirated tuning for different rpm bands. However this variable tuning isn't as important on a turbo build which should be worried more about reducing the volumes you need to pressurize between the turbo and engine for response. ( I assume/hope others will add or correct me if anything is wrong)
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My previous concept that I wondered was pairing an NA 87-88 rx7 center iron with REW PP exhaust housings with Rx8 side Irons. Which would be 4 exhaust ports, eliminating the Siamese Exhaust port while allowing the use of the rx8 intake and the rx7 center primary port would have much less overlap with a proper twinscroll setup. My hope was that the rx8 intake could help low end torque like how the REW intake was variable for the same reason. Again, it falls on its face when you look at how modern turbos can spool relatively quickly in the rpm band where the 4 stage variable intake doesn't add much of anything since you care more about the pressure instead of air velocities.
Here's a throw together timing chart I did comparing the intakes/exhausts of various Irons and Housings. (not to scale, to fit in one readable pic)
semi pp will fail on a Renesis; big time, because it adds overlap and there’s no way to avoid that with a peripheral port whether intake or exhaust
it all has to do with how the intake ports were relocated specifically for the zero overlap operation of the Renesis engine that makes it entirely different than all the previous rotary engines
but I’m sure you won’t take any heed to this just like all the other people who failed at it over the years ...
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By semi pp do you mean the intake as well or just the exhaust? ( EDIT: looked that the jaypro includes the intake semiPP intake >> but I believe the other intake ports wont match up to the rx8 center iron and definitely wont pair with the rx8 6 port side irons at all. Not to mention there's little point in the semiPP+rx8 6 port side Irons.)
There has been plenty of hybrid theory tossed around and attempted, but in the end there is no point since just going for a REW setup will perform better. Many have tried the 5 exhaust port setup, but for a turbo build the side exhausts rob you of energy while adding weight and complexity while reducing cooling. As for intake ports the stock rx8 ports are insanely high flowing and variable, but this ends up hurting you in two ways. First off the primary and secondary ports will have overlap nearly equivalent to a 13b-REW bridgeported, likely poor idle and low end will show itself Brap Brap Brap. Second, the intake manifold for the rx8 is massive which is great for naturally aspirated tuning for different rpm bands. However this variable tuning isn't as important on a turbo build which should be worried more about reducing the volumes you need to pressurize between the turbo and engine for response. ( I assume/hope others will add or correct me if anything is wrong)
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My previous concept that I wondered was pairing an NA 87-88 rx7 center iron with REW PP exhaust housings with Rx8 side Irons. Which would be 4 exhaust ports, eliminating the Siamese Exhaust port while allowing the use of the rx8 intake and the rx7 center primary port would have much less overlap with a proper twinscroll setup. My hope was that the rx8 intake could help low end torque like how the REW intake was variable for the same reason. Again, it falls on its face when you look at how modern turbos can spool relatively quickly in the rpm band where the 4 stage variable intake doesn't add much of anything since you care more about the pressure instead of air velocities.
Here's a throw together timing chart I did comparing the intakes/exhausts of various Irons and Housings. (not to scale, to fit in one readable pic)
with all that being said, what'd be your best opinion on going about getting the irons in order? Ordering a core from billet, scrounging the scrap yards, or trying to find a secondhand in decent shape? I've got an 04 6 port and love driving it, but it's going to be a drift car, hence trying for the semiPP.
And as for homeboy that said I'll probably just go for it anyway, I'm here to learn man! I wouldn't be asking random strangers on the internet if I didn't value their insight
So that guy went through the trouble of not only adding a semi pp, but matching an rx7 non variable intake while also removing the rx8 cold/ram intakebox design. The build is literally all of the negative things you can do.
-no laminar flow into the maf
-no variable intake for naturally aspirated rpm band tuning (equivalent to going from a piston engine with variable cams to nonvariable oversized cams)
-dirt poor low end power+idle due to low velocity air caused by having 8 intake ports open all the time.
-lots of $$$ in custom fabrication
that’s your proof; a lot of blah-blah-blah while cruising around with zero confirmation on anything?
the engines have been built and run, that isn’t the issue. The issue is the actual power and torque output results. It won’t make as much as a proper Renesis 6-port for either low or high rpm use in NA form is the usual proven result.
Again, Mazda completely reconfigured the Renesis for zero overlap and this is not well understood by most people. Once overlap is added *everything* changes. Which if you really understand the dynamics of what he has combined there; technically assessed and not virtual fantasy bs thinking that seems to prevail today, it doesn’t bode well imo.
but show me some actual results that can be assessed and lets see
with all that being said, what'd be your best opinion on going about getting the irons in order? Ordering a core from billet, scrounging the scrap yards, or trying to find a secondhand in decent shape? I've got an 04 6 port and love driving it, but it's going to be a drift car, hence trying for the semiPP.
And as for homeboy that said I'll probably just go for it anyway, I'm here to learn man! I wouldn't be asking random strangers on the internet if I didn't value their insight
well first thing you have to understand is that larger more intake ports does not equal more power and more faster. Its a trade off. It is kind of annoying when you see youtubers giving people this notion that its free power.
Stock ports will be well rounded
Streetport will suffer fuel economy with a bump across the board usually, might see a loss low rpm
Bridgeport will greatly suffer fuel economy, raised idle, with a decent loss in the low end and a decent bump up high rpm
PPort wont have fuel economy, raised idle, big loss low with a gain up top
Keep in mind that if your exhaust is restricted there's no point in going for larger intake. This is why reputable shops will ask you twice if you really want to port the renesis intake ports, due to how restrictive the exhaust ports are.
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For a drift car in particular you will probably want a wide power band, and choosing anything that acts like a bridge or PPort will just bog down. Unless you have $15,000 to toss at a Rew build just do a plain renesis rebuild or some junkyard v8 swap. I wouldn't search for more power personally if I was sticking with the renesis, I'd focus on finding tires with no grip that you can slide around on and gutting as much weight as possible.
well first thing you have to understand is that larger more intake ports does not equal more power and more faster. Its a trade off. It is kind of annoying when you see youtubers giving people this notion that its free power.
Stock ports will be well rounded
Streetport will suffer fuel economy with a bump across the board usually, might see a loss low rpm
Bridgeport will greatly suffer fuel economy, raised idle, with a decent loss in the low end and a decent bump up high rpm
PPort wont have fuel economy, raised idle, big loss low with a gain up top
Keep in mind that if your exhaust is restricted there's no point in going for larger intake. This is why reputable shops will ask you twice if you really want to port the renesis intake ports, due to how restrictive the exhaust ports are.
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For a drift car in particular you will probably want a wide power band, and choosing anything that acts like a bridge or PPort will just bog down. Unless you have $15,000 to toss at a Rew build just do a plain renesis rebuild or some junkyard v8 swap. I wouldn't search for more power personally if I was sticking with the renesis, I'd focus on finding tires with no grip that you can slide around on and gutting as much weight as possible.
I have been following Aaron Parker's build for a while and was honestly hoping I might be able to do something similar with the renesis. Seeing as how it's impossible bc of above reasons, what would be the best route of finding an rew that just needs a rebuild? Ik that's like finding a needle in a haystack, but I love the rotary too much to give it up for anything else. I'll definitely find some shitty tires in the mean time though lol
I have been following Aaron Parker's build for a while and was honestly hoping I might be able to do something similar with the renesis. Seeing as how it's impossible bc of above reasons, what would be the best route of finding an rew that just needs a rebuild? Ik that's like finding a needle in a haystack, but I love the rotary too much to give it up for anything else. I'll definitely find some shitty tires in the mean time though lol
People sell Rew blocks+trans+intakes all over the internet, but tbh those are gonna be shot in the dark. Personally I don't like to trust random people online.....and it comes to the simple fact of why isn't that engine still in an rx7?
The other option is to find a reputable builder that will do the build. Spend a week and read the various rx8 rew threads and you will see that a lot of custom fab work and choices has to go into the build. Expect it to take 2+ years and $10-15k in the long run.
I have been following Aaron Parker's build for a while and was honestly hoping I might be able to do something similar with the renesis. Seeing as how it's impossible bc of above reasons, what would be the best route of finding an rew that just needs a rebuild? Ik that's like finding a needle in a haystack, but I love the rotary too much to give it up for anything else. I'll definitely find some shitty tires in the mean time though lol
The stock intake ports are actually really good for this engine. They only require port polishing and not any type of fabrication. If you want the engine to make better power, you can bore out the exhaust ports only. The exhaust ports are what limit the potential power of this engine design and not the intake ports. hope this helps.
03-16-2021, 06:24 PM
