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I know this subject has been beaten like a dead horse but I have a more technical question in regards to my FD racecar. I am building for a power to weight ratio class and my max wheel horsepower is ~200whp. I currently run non-sequential stock turbos on a stock engine and have them out while I am installing a new engine. My question is, is it smarter to go with something like a 7670 single turbo kit or keep the non-sequential set up for my power goals? I currently have a powerFC but moving to haltech and want to be able to tune the car to that horsepower goal without having issues (I've read non-sequential can have bad boost spiking). I also have a Greddy profec boost controller if that matters.
RE Amemiya raced JGTC in the 300rwhp class with an NA 3 rotor Peripheral port (450rwhp) restricted down to 300hp for power under the curve and maximum reliability.
You could build a peripheral port 2 rotor and do the same (300rwhp restricted to 200hp for power under the curve).
But maybe you dont want to build a race engine just yet.
You can make ~200rwhp on stock FD ports/engine with intake manifold swap and good headers/exhaust and have a really light simple, reliable, LIGHT engine.
Speedmaster 4150 intake manifold ($250), speedmaster 4150 throttlebody ($150), boost hat($150), lightweight full function fuel rail w/ just 2x 1700-2600cc ID primary injectors, winchester oil pan. Run or delete omp, ps, etc as wanted.
This will be ~250lb engine vs stock 420lb engine or my simplified sequential 360lb engine.
Get the rx8 4.78:1 rear end ratio if running naturally aspirated.
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Or you could keep it with a turbo if you want a bolt on solution with the most power under the curve and reliability isnt paramount.
Non sequential twins are just dogs. Go single turbo if keeping it turbo and yes, 7670 or even smaller for ~200rwhp.
Going to be weird powerband w/ efr 7670.
Will hit 350ftlb torque and 200hp at ~3000rpm and then have to drop boost/torque super fast to keep max hp at 200hp.
Wouldnt need to swap rear end gears from stock 4.1:1.
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RE Amemiya raced JGTC in the 300rwhp class with an NA 3 rotor Peripheral port (450rwhp) restricted down to 300hp for power under the curve and maximum reliability.
You could build a peripheral port 2 rotor and do the same (300rwhp restricted to 200hp for power under the curve).
But maybe you dont want to build a race engine just yet.
You can make ~200rwhp on stock FD ports/engine with intake manifold swap and good headers/exhaust and have a really light simple, reliable, LIGHT engine.
Speedmaster 4150 intake manifold ($250), speedmaster 4150 throttlebody ($150), boost hat($150), lightweight full function fuel rail w/ just 2x 1700-2600cc ID primary injectors, winchester oil pan. Run or delete omp, ps, etc as wanted.
This will be ~250lb engine vs stock 420lb engine or my simplified sequential 360lb engine.
Get the rx8 4.78:1 rear end ratio if running naturally aspirated.
__________
Or you could keep it with a turbo if you want a bolt on solution with the most power under the curve and reliability isnt paramount.
Non sequential twins are just dogs. Go single turbo if keeping it turbo and yes, 7670 or even smaller for ~200rwhp.
Going to be weird powerband w/ efr 7670.
Will hit 350ftlb torque and 200hp at ~3000rpm and then have to drop boost/torque super fast to keep max hp at 200hp.
Wouldnt need to swap rear end gears from stock 4.1:1.
.
Awesome information. I was debating going N/A but seeing how I have a brand new engine I didn't really want to open it up and swap to N/A rotors/rx8 eccentric shaft/peripheral port ect. I wanted to run this engine and then build a second race engine. My only concern is if I convert this stock engine to N/A I know my compression will suffer right? Because they aren't high compression rotors? I have a solid exhaust and don't mind getting a custom header made for N/A application. I'll look into what you listed, should I still convert to haltech if I'm N/A then? Or would the PowerFC work just fine? Might as well save where I can. I don't mind doing it right the first time so maybe I'll try your light engine N/A build.
No, Mazda factory race naturally aspirated engines used special non production rotors that were low compression (9.4:1?).
In a rotary high comression rotors do add throttle response and low rpm torque, but lower high rpm horsepower because the engine has to pump the air/fuel charge through the slot in the rotor.
I have found the various Mazda papers on this before, but I dont want to bother again.
The later Lemans engines were a outlier to this as the engine, aerodynamics and driving strategy was all based on fuel economy and reliablity to win (low revs, lots of coasting at the end of the straights).
brand new unopened 13B-REW is a good base for Naturally Aspirated power!
The part # is a supersession part to the 1999+ high power spec and they have machined rotor flanks for high rpm reliability.
I confirmed this with my new crate Mazda 13B-REW. I set 9,000rpm redline and used it often to make flames in neutral bouncing off rev- limiter and racing. No wear on rotor flanks and you can see the machining up to the oil seal lands.
In Japan Aniversary Racing Factory specializes in Naturally Aspirated rotaries if you would like some inspiration.
Cat paw pointing at ridge present on all rotor flanks from side cutting for high rpm clearance on 1999+ high power spec engines (all new Mazda crate 13B-REWs).
Here is some data.
mean brake effective pressure (torque) is shown as fairly flat here from 9.5:1 to 11:1 compression ratios.
However the small power gain from compression increase is in the midrange rpms where an NA race engine wont spend much time.
So, I say the increase in Compression Ratio from 9:1 to 9.7:1 is not going to be worth all the expense.
The older 9.7:1 rotors will have to be sidecut for higher rpm operation anyways like new 13B-REW rotors are from factory and the power gains from increase Compression Ratio will be gone by the 6,000-9,000rpm Naturally Aspirated powerband anyways.
200whp limit you want a tiny turbo, the efr7670 can do twice that. I wouldn't go half the size but a step down would probably give the widest power band. Unopened motor with the haltech driving the warm up throttles to stage the secondary runners and a primary bridge port if you are openning the motor. You can probably have two boost vs rpm maps if it's a mixed use car and run a 7670 and make an easy ~350 the rest of the time.
Probably want to think carefully about diff and wheel alignment at such low power.
No, Mazda factory race naturally aspirated engines used special non production rotors that were low compression (9.4:1?).
In a rotary high comression rotors do add throttle response and low rpm torque, but lower high rpm horsepower because the engine has to pump the air/fuel charge through the slot in the rotor.
I have found the various Mazda papers on this before, but I dont want to bother again.
The later Lemans engines were a outlier to this as the engine, aerodynamics and driving strategy was all based on fuel economy and reliablity to win (low revs, lots of coasting at the end of the straights).
brand new unopened 13B-REW is a good base for Naturally Aspirated power!
The part # is a supersession part to the 1999+ high power spec and they have machined rotor flanks for high rpm reliability.
I confirmed this with my new crate Mazda 13B-REW. I set 9,000rpm redline and used it often to make flames in neutral bouncing off rev- limiter and racing. No wear on rotor flanks and you can see the machining up to the oil seal lands.
In Japan Aniversary Racing Factory specializes in Naturally Aspirated rotaries if you would like some inspiration.
Their site includes dyno sheets for the builds.
Thanks for all the info. Do you think doing an ITB setup would be more beneficial? Obviously it costs more but im not worried about that. Was looking into EFIs ITB setups. I'm attempting to research Japan's Aniversary pages but Google translate is rough haha. Just trying to find my best horsepower gains seeing how I'd like to have the option of having more horsepower to detune rather than chase my peek WHP.
200whp limit you want a tiny turbo, the efr7670 can do twice that. I wouldn't go half the size but a step down would probably give the widest power band. Unopened motor with the haltech driving the warm up throttles to stage the secondary runners and a primary bridge port if you are openning the motor. You can probably have two boost vs rpm maps if it's a mixed use car and run a 7670 and make an easy ~350 the rest of the time.
Probably want to think carefully about diff and wheel alignment at such low power.
Honestly was trying to find a smaller turbo for this application. With such a low power range it's hard to find something efficient enough. Should probably make a new thread heading into N/A territory. I've contemplated both but thought N/A would mean I'd HAVE to open the motor.
Thanks for all the info. Do you think doing an ITB setup would be more beneficial? Obviously it costs more but im not worried about that. Was looking into EFIs ITB setups. I'm attempting to research Japan's Aniversary pages but Google translate is rough haha. Just trying to find my best horsepower gains seeing how I'd like to have the option of having more horsepower to detune rather than chase my peek WHP.
200hp is kind of a tough spot, with an NA, you have a more peaky power band. if you just took the turbo off the FD, it should do like 170rwhp
with the stock turbos, a stock FD will do ~210-215rwhp, so you're looking at detuning the thing, which might be as simple as removing the boost pills
i know the other way is ~350hp and a heavy car, which isn't really ideal either
4150 4 barrel throttlebodies are true itb. One runner/throttle plate per port.
Or do you mean would ida/dcoe manifold be benificial where you combime each rotors ports for only 2 throttle plates. Yes, a bump in midrange depending on port style at big cost.
Running just the stock twins primary turbo alone is 250rwhp and pretty snappy. I will see if I can find a dyno of broken sequential twins for you.
You could do what Mazda intended with the stock twins. Run high boost on primary turbo for torque and then bring on tje 2ndary turbo and run very low boost to extend the 200hp as far through the rpm range as possible.
Problems, you still need stock twins which cost near as much as new engine, you still need to understand and implement sequential control, you still have complexity/reliability of sequential twins, you still have weight on front axle.
You could do what Mazda intended with the stock twins. Run high boost on primary turbo for torque and then bring on tje 2ndary turbo and run very low boost to extend the 200hp as far through the rpm range as possible.
Problems, you still need stock twins which cost near as much as new engine, you still need to understand and implement sequential control, you still have complexity/reliability of sequential twins, you still have weight on front axle.
you could use a small single and let it run tons of boost and then fall off, or make it fall off... 200hp with a turbo is like a Stock S4 with an exhaust....
200hp is kind of a tough spot, with an NA, you have a more peaky power band. if you just took the turbo off the FD, it should do like 170rwhp
with the stock turbos, a stock FD will do ~210-215rwhp, so you're looking at detuning the thing, which might be as simple as removing the boost pills
i know the other way is ~350hp and a heavy car, which isn't really ideal either
I was looking hard into non-sequential racing. Pettit Racing used to run non-seq and it worked well for them. I would have to rebuild my twins (quoted roughly $1000) and then full non-sequential them because at the moment they are poor manned non-seq. I don't mind adding some weight for the right set-up, at the moment some more weight would be better so I can run a little more power.
Give us an engine/drivetrain development budget to dream with.
If its a 200hp class you want 200hp for as many rpm as possible.
Option 1- modified sequential twins 13B-REW
200hp from 3,500rpm to 9,000rpm. Weighs 360Lbs
Option 2- single turbo 13B-REW
200hp from 3,000rpm to 9,000rpm. Weighs 330Lbs
Option 3- NA 13BREW stock block w/ bolt-ons.
200hp from 7,500rpm to 9,000rpm. Weighs 250Lbs
Option 4- NA 13B-REW peripheral port race engine restricted.
200hp from 5,500rpm to 9,000rpm. Weighs 250Lbs
Option 5- NA 20B peripheral ported race engine restricted.
200hp from 4,500rpm to 9,000rpm. Weighs 330Lbs
*longer too*
$$$ options-
Aluminum side housings take ~20-70Lbs off all engine weights ($3,000 to $10,000 option, start front to back).
Improved chassis dynamics.
Drysump, subframe mod and engine lowering and set- back.
Improved chassis dynamics. Reliability.
6 speed sequential dog engaged transmission ($10,000).
Keep engine at 200hp for the lighter, peakier engine options.
Ill say this first, I do NOT want to run sequential at all haha. I understand the system well, and with racing you already get enough problems. I'd rather not have to track down boost leaks or vacuum leaks for a well operating seq set-up. I don't have the time or patience to be worrying about the rats nest. Second, my budget and weight requirements are a bit odd. I don't mind adding weight for the right set-up, in this class its about finding the right weight/power to go the fastest, so I am fine testing some different tunes and weights. As far as budget I would either like to do a single turbo set-up (spend roughly ~5k for it) I have all supporting mods (V-mount, boost controller, fuel pump ect.). Or, go N/A and spend roughly the same to make a good set up. My problem is I do not want to open the engine only because its my only one and would like to do testing before the year ends. I don't want to be waiting on it to be ported and more because I would rather get some track time in. When my second engine gets here I will most likely go PP N/A. So I am moving towards the N/A set-up. I'd rather not spend money on dogboxs or drysumps until I can dial the car in a bit. And a 20B is out of the question only because of the initial expense, installation and the upkeep. I'd rather keep a simple and clean racecar thats easy to work on and correct.
I'd rather keep a simple and clean racecar thats easy to work on and correct.
you might try a low boost non sequential, basically run what you have this year. it gets you out and doing testing and you can worry about all the other stuff
Im with you on wanting a simple, easy to work on set-up for racing.
If someone gave me the budget I would use this formula.
Stock block engine.
Speedmaster 4150 throttlebody and 4150 intake manifold and a boost hat.
Just 2x 2600cc ID injectors for fuel in aftermarket primary fuel rail.
Cast long runner dual WG EFR manifold.
EFR 7670.
2x electronic WG (because of your 200hp requirement).
Haltech 1500.
I would try Blitz FMIC (stacks IC and radiator) as it leaves lots of room in engine bay for turbo intake, waste heat management and working on stuff
If radiator ended up runnimg too hot I would go V-mount.
Intank surgetank for fuel (coachman, radium, etc).
Winchester trap door oil pan OR Mazda in front cover drysump ($3,000)
Would be a simple, easy to work on set-up with low weight. Can have back-up engines and parts ready to go. Dont have to wait on machine shop or modify stock parts before use.
Im with you on wanting a simple, easy to work on set-up for racing.
If someone gave me the budget I would use this formula.
Stock block engine.
Speedmaster 4150 throttlebody and 4150 intake manifold and a boost hat.
Just 2x 2600cc ID injectors for fuel in aftermarket primary fuel rail.
Cast long runner dual WG EFR manifold.
EFR 7670.
2x electronic WG (because of your 200hp requirement).
Haltech 1500.
I would try Blitz FMIC (stacks IC and radiator) as it leaves lots of room in engine bay for turbo intake, waste heat management and working on stuff
If radiator ended up runnimg too hot I would go V-mount.
Intank surgetank for fuel (coachman, radium, etc).
Winchester trap door oil pan OR Mazda in front cover drysump ($3,000)
Would be a simple, easy to work on set-up with low weight. Can have back-up engines and parts ready to go. Dont have to wait on machine shop or modify stock parts before use.
It's a hard decision for me. Might make a post in the naturally aspirated section for some insight and advice. How important do you think the drysump is for my short sprint racing if I go N/A?
As long as you can maintain oil pressure on long sweepers and dont have a problem with oil climbing out of the engine into the catch can your fine.
The trapdoor, vertical sided Winchester 7qt oil pan was enough on my FD running 18x11 and 295 race tires and likewise the MazdaComp 7qt oil pan with home made baffle plate welded in was enough for my FC (no trapdoors) with 255 race tires.
08-23-22, 12:28 PM
