na race engine
06-06-2011, 03:43 PM
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na race engine
hi all. looking to build an NA race engine to put in our mx5/miata race car for next years season. the car is currently a turbocharged 1.6 pushing 250bhp but is running so much boost it is a real handful to drive on the limit. the idea of fitting a renesis is really appealing as the power delivery would be so much smoother.
my question is what are the options and limitations of an NA renesis engine? turbo is out of the question really due to space limitations in the mx5 and series penalties. i was going to go full standalone management for starters and have been thinking about lightweight rotors and increasing the rev limit. i read somewhere that the higher you rev these engines the more power you get???
any help with this would be much appreciated. i am pretty new to the rotary thing having recently bought an rx8 but have been a mechanic for years and i have my own garage specializing in mazda mx5's.
thanks in advance.
my question is what are the options and limitations of an NA renesis engine? turbo is out of the question really due to space limitations in the mx5 and series penalties. i was going to go full standalone management for starters and have been thinking about lightweight rotors and increasing the rev limit. i read somewhere that the higher you rev these engines the more power you get???
any help with this would be much appreciated. i am pretty new to the rotary thing having recently bought an rx8 but have been a mechanic for years and i have my own garage specializing in mazda mx5's.
thanks in advance.
Last edited by sideways-dan; 06-06-2011 at 03:46 PM.
06-06-2011, 04:42 PM
#2
People on here have pushed upwards of 235bhp in a NA renesis. Lots of work to be done, and there is definitely a big law of diminishing returns pushing above ~210bhp. Search for threads from EricMeyer and TeamRX8 among many others. good luck! We want videos when its done!
06-06-2011, 05:07 PM
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so what work is there to be done and what parts would be needed? is it done with stock internals? if we could get somewhere close to the power we have now but with more drivability that would be great but surely there is more to be had. would i be better off with an rx7 engine or is the renesis the 1 to have? i have heard of some pretty high powered na rotaries.
06-06-2011, 05:25 PM
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so what work is there to be done and what parts would be needed? is it done with stock internals? if we could get somewhere close to the power we have now but with more drivability that would be great but surely there is more to be had. would i be better off with an rx7 engine or is the renesis the 1 to have? i have heard of some pretty high powered na rotaries.
I have not heard of anything over 230 at the wheels but I will subscribe to this thread to see what pops up from the more experienced members here. I do know the intake will get you a little bit, also some to be had from the exhaust, I have heard of some mild porting that can be done but I have not actually scene it done, you can run speedsource pullys to reduce some rotating mass, as well as a light flywheel. other than that as you already said a stand alone ECU is the only other thing that I can think of that will get you any real gains.
Good luck,
Stephen
06-06-2011, 05:42 PM
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^what he said and I also heard of someone that just did some intake porting I believe it was. I think you have to send your engine to him and pay him to have it done. If you were to do it yourself without a proper diy the trial and error wouldn't be worth it. I'll see if I can find that thread. I believe he got good gains from it.
06-06-2011, 05:56 PM
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hmmm maybe the costs will outweigh the gains. may be better off with a good standard engine with basic power mods and good management. the car only weighs 900kg in its current form and the renesis would be a lot lighter. the car has to be competitive otherwise its just not worth doing.
06-06-2011, 06:01 PM
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https://www.rx8club.com/showthread.p...intake+porting
Without going FI you prob need to port. Here is the intake port thread. Sorry it took awhile. I always get sidetracked by other threads that catch my eye while searching
Without going FI you prob need to port. Here is the intake port thread. Sorry it took awhile. I always get sidetracked by other threads that catch my eye while searching
06-06-2011, 06:01 PM
#9
^what he said and I also heard of someone that just did some intake porting I believe it was. I think you have to send your engine to him and pay him to have it done. If you were to do it yourself without a proper diy the trial and error wouldn't be worth it. I'll see if I can find that thread. I believe he got good gains from it.
Sidenote that ported engine by BDC made 223+ whp. I've never heard the 235 whp numbers in my life.
you will find power in:
Tighter side seal clearances
Extensive porting work
Tuning
Everything else is for noise, or bragging rights.
06-06-2011, 06:17 PM
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06-06-2011, 06:23 PM
#12
The X is silent
DAN- look into a 20B 3 rotor engine from a Mazda Cosmo. It's not terribly difficult to make big numbers with this motor, even in NA trim. The sky is the limit with this motor, and if you're willing to do the fabrication (as you would for a Renesis) this is the way to go. It's a good deal torquier, as well. It isn't something you can just walk into, but neither is a Renesis, if the car isnt set up for it.
06-06-2011, 06:26 PM
#13
All ported renesis engines make consistent power through however high you go, if they do drop off its very little.
if and when he hits 230+ I'll consider it an accomplishment, not saying he doesn't have a good foundation to work off of but 223 is still not that amazing after a years worth of research.
In any event my personal opinion would be to forget about swapping a rotary unless you have some strong financial backing, or want to learn how to rebuild engines.
if and when he hits 230+ I'll consider it an accomplishment, not saying he doesn't have a good foundation to work off of but 223 is still not that amazing after a years worth of research.
In any event my personal opinion would be to forget about swapping a rotary unless you have some strong financial backing, or want to learn how to rebuild engines.
06-06-2011, 06:30 PM
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that guys figures from porting looks really good! not had time to read it all but it has alot of good content. wonder how much he would charge to do the porting work??? perhaps he could just supply the parts and port them to save me sending them over from the uk. anyone care to estimate how much a build like this would cost considering i will be doing most of the work myself? i have never rebuilt a rotary but build all of our current race engines and customer engines. rotaries are something i have been wanting to get into for a while. whatever engine i use it has to be mazda. i get a 70% displacement increase for turbo and 40% for rotary. the rotary would drop me a class where i would be alot more competitive.
Last edited by sideways-dan; 06-06-2011 at 06:37 PM.
06-06-2011, 06:32 PM
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^If you have plenty of money then go for it. A 20b is a great engine and even na you would be able to easily make what you want plus some. However it is a very expensive build. You would have to rebuild the engine when you get it. It would be about 15 years old so 3 grand for the engine and another five grand or so rebuilding/porting etc. So you would have about 8 grand in the engine. Plus you need a transmission. So your best bet is the rx8 tranny if youre running lower hp numbers. So another 1500-2000. Just figure out your budget before you start the build so you dont get half way through and run out of money. Also formore info on the 20b you could go to the rx7 forum. They have a subsection for it or pm or look at angels thread. But warning. If you look at angels thread be prepared to change your pants afterwards
06-06-2011, 06:41 PM
#18
yeah, renesis is jsut going to be way way cheaper than a 20b.
as was said, some porting, exhaust headers, obviously no emissions devices, tighter seal clearances (ceramic seals?), and just very good tuning. I dont think there has been much success with stuff like lightened rotors.
and yes i meant 230whp
as was said, some porting, exhaust headers, obviously no emissions devices, tighter seal clearances (ceramic seals?), and just very good tuning. I dont think there has been much success with stuff like lightened rotors.
and yes i meant 230whp
06-06-2011, 06:45 PM
#19
that guys figures from porting looks really good! not had time to read it all but it has alot of good content. wonder how much he would charge to do the porting work??? perhaps he could just supply the parts and port them to save me sending them over from the uk. anyone care to estimate how much a build like this would cost considering i will be doing most of the work myself? i have never rebuilt a rotary but build all of our current race engines and customer engines. rotaries are something i have been wanting to get into for a while. whatever engine i use it has to be mazda. i get a 70% displacement increase for turbo and 40% for rotary. the rotary would drop me a class where i would be alot more competitive.
Not to talk down the guys business but I've seen a few ported renesis put down numbers that were 5 or 6 hp off of what his brand new build got. IMO it wouldn't be worth the shipping costs for someone in the UK.
^If you have plenty of money then go for it. A 20b is a great engine and even na you would be able to easily make what you want plus some. However it is a very expensive build. You would have to rebuild the engine when you get it. It would be about 15 years old so 3 grand for the engine and another five grand or so rebuilding/porting etc. So you would have about 8 grand in the engine. Plus you need a transmission. So your best bet is the rx8 tranny if youre running lower hp numbers. So another 1500-2000. Just figure out your budget before you start the build so you dont get half way through and run out of money. Also formore info on the 20b you could go to the rx7 forum. They have a subsection for it or pm or look at angels thread. But warning. If you look at angels thread be prepared to change your pants afterwardsWhere are these ideas coming from.
06-06-2011, 08:06 PM
#24
Well the MX5 chassis handles better than the SE3P chassis up to a certain power point and the lighter chassis along with the smooth rotary powerband might do OK even at the current race output level
The Renesis has durability issues for extended high RPM operation, on a 13B you can get good power and durability at high RPM but you pay a big price in killing the low and mid range powerband to achieve it.
What series/class is the OP shooting for?
The Renesis has durability issues for extended high RPM operation, on a 13B you can get good power and durability at high RPM but you pay a big price in killing the low and mid range powerband to achieve it.
What series/class is the OP shooting for?
06-06-2011, 08:45 PM
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OP. I would look towards an earlier model 13B. The numbers you are posting are achievable and the swap has been done with the earlier motors. Also it can be run off a Haltech Sprint RE. I can go more in depth on the ECU and I can answer more questions through PM's if you wish.
You will have a hard time getting the info you are looking for as most of these guys have never opened up one of these motors. Having said that there are a few w/ great information on here you have to sift through what is good and what is not.
Good luck on the build.
You will have a hard time getting the info you are looking for as most of these guys have never opened up one of these motors. Having said that there are a few w/ great information on here you have to sift through what is good and what is not.
Good luck on the build.