na race engine
06-08-2011, 02:03 AM
#52
It is possible to build a competitive 13b-msp, trading a bit of power for a broader powerband, the downside is the cost.
06-08-2011, 04:32 AM
#53
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cost is not really that much of an issue. i dont have an unlimited budget but the business is paying. my business but it feels less like my money...
how much do you think a build like this would cost? just the motor side of things.
how much do you think a build like this would cost? just the motor side of things.
06-08-2011, 05:24 AM
#54
It's hard to state a price for "just the engine" as the engine itself is just a part of a successful build in this case.
The amount of labor you're going to do yourself also changes it by a fair amount.
When I say that the engine is just part of the build i mean that, to achieve that power level, we're not talking about internal modifications only. The lower intake manifold needs some work, so does the upper plastic one (shortening it yields some upper-rpm gains). The whole exhaust system has to be non-stock and the clutch and flywheel combo comes into play as well. A 5.5" or 4.5" clutch and matching flywheel is rather expensive thing.
After that comes all the previously ignored engine work and it really ranges from stock plates porting to side ports blocking and older, peripheral port, housings adoption (thus killing the "msp" side of the 13b-msp we drive lol).
Balancing the rotating assemblies (rotors and e-shaft), e-shaft lubrication nozzles re-jetting etc are added costs and fairly unusual works here in Europe.
The pcm of choice also has is share in such builds.
Your goal, given the platform and race series you're going to race in, should be to define the power band you want and work from there. PhillipM lives with his tyres in the mud so the broader the power curve the better, in your case you should make some gearing charts and see where you will spend most of your time rpm wise.
Reputable sources like Mark (TeamRX8) will probably disagree with what i wrote so you will need to weight my opinions and their expertise yourself.
G
The amount of labor you're going to do yourself also changes it by a fair amount.
When I say that the engine is just part of the build i mean that, to achieve that power level, we're not talking about internal modifications only. The lower intake manifold needs some work, so does the upper plastic one (shortening it yields some upper-rpm gains). The whole exhaust system has to be non-stock and the clutch and flywheel combo comes into play as well. A 5.5" or 4.5" clutch and matching flywheel is rather expensive thing.
After that comes all the previously ignored engine work and it really ranges from stock plates porting to side ports blocking and older, peripheral port, housings adoption (thus killing the "msp" side of the 13b-msp we drive lol).
Balancing the rotating assemblies (rotors and e-shaft), e-shaft lubrication nozzles re-jetting etc are added costs and fairly unusual works here in Europe.
The pcm of choice also has is share in such builds.
Your goal, given the platform and race series you're going to race in, should be to define the power band you want and work from there. PhillipM lives with his tyres in the mud so the broader the power curve the better, in your case you should make some gearing charts and see where you will spend most of your time rpm wise.
Reputable sources like Mark (TeamRX8) will probably disagree with what i wrote so you will need to weight my opinions and their expertise yourself.
G
06-08-2011, 06:54 AM
#55
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sideways, my street-legal swap plans has an estimated cost of $10,000 to $15,000 US, but that cost includes the cost of buying a donor RX-8 to pull most of what I need from it, AND cost reduction from the cash back from selling off basically a complete car from all of the un-needed parts between the donor RX-8 (interior, suspension, impossible accessories such as cooling components, body panels or the entire shell as a whole, etc...) and the Miata parts from the chassis (engine, drivetrain, wiring, ecu, accessories)
It might be unrealistic, but I suspect not. A lightly wrecked or roller RX-8 can be had for ~$5,000 US that would give me everything I need. The only additional costs that I can determine would be the custom driveshaft (if the NC driveshaft wouldn't fit), and exhaust work, possibly the fabrication of the motor mounts and PPF if I outsourced them.
It might be unrealistic, but I suspect not. A lightly wrecked or roller RX-8 can be had for ~$5,000 US that would give me everything I need. The only additional costs that I can determine would be the custom driveshaft (if the NC driveshaft wouldn't fit), and exhaust work, possibly the fabrication of the motor mounts and PPF if I outsourced them.
06-08-2011, 07:24 AM
#56
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Fwiw, I reckon it cost roughly 2.5K outright to convert the car from it's original engine to a Renesis for us.
Then modifications to the springs/dampers/geometery/cooling etc, after that to complement the change on top...
Then modifications to the springs/dampers/geometery/cooling etc, after that to complement the change on top...
06-08-2011, 08:04 AM
#57
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You will see 215 on an honest dynojet and 145'ish foot lbs. These are peak number but more importantly you'll have the most area under your curve. You can make a few more peak ponies but you'll have OVERALL less power. Measuring peak numbers is for rookies. I would revisit your turbo charged application as several friends have gone done this road and make waaaay more power than an NA Renesis. You can make these easier to drive as well. I own and drive a modified Mercedes E55 that makes over 600 at the wheels and these guys wax me out of the hole up to about 100 and then my torque/thier lack of torque comes into play. You could NEVER EVER do this will a stock Renesis. I don't know your driving and chassis setup background but there are several non-engine options to make your race car work. If you have these rt now (or lack thereof) a lower hp and torque is going to hurt you more than help.
Tell me more about your race car please. I've owned 1/2 dozen spec miatas and even more Renesis race cars with NA or as you offer it "race" motors.
Tell me more about your race car please. I've owned 1/2 dozen spec miatas and even more Renesis race cars with NA or as you offer it "race" motors.
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.
06-08-2011, 08:20 AM
#58
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Hah hah. Way off bro. Waaay off. Those numbers are marketing jibberish meant to sell cars. US flywheel hp in race trim runs 270 with headers and a race tune. These are the same engines used in the Star Mazda race cars and run the dry sump that Team touched on. They run a lower resistance transaxle and make a bit North of 230 and 160 ft lbs. There is really not much in these engines. Your better bet is to go w a street ported 13b as they will make about 25 more ponies than a very well prepped Renesis. There is a ton of info on how to make this happen in addition to supplier base, parts, tuning info. That motor has been around forever and a day and has a better power curve than the Renesis.
06-08-2011, 12:58 PM
#60
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currently the race car is a 1.6 mk1 (na) mx5 (miata). seam welded chassis, custom cage, gaz gold pro suspension, polly bushed etc... the engine is a rebuilt 1.6 with m-tuned rods, ACL bearings, flyin miata manifold, gt28 bb turbo 25psi, large intercooler, fm-link ecu, custom exhaust 2.75" etc..
both cars are ours but race in different series. its the white 1 for the engine swap.
both cars are ours but race in different series. its the white 1 for the engine swap.
06-09-2011, 06:36 AM
#61
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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???
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???
On the WGT dyno, stock RX8's get up to 170rwhp, mine is now over 190 and is going back later in the year for final tuning since the tuner expects it to get to 200. It's been really difficult to squeeze out the last few hp without sacrificing midrange torque.
Power delivery is smooth and linear, much easier to drive than the twin-turbo rotary I have. Torque is about the same as a supercharged miata so the rear diff and half-shafts don't need to be changed.
Basic spec is :
- Adaptronic e1280s standalone (need lots of outputs for intake manifold control and 3 injectors per rotor, integrated traction control to link up to the stock miata ABS sensors)
- Skyline throttle
- Custom intake (length and straightness was critical, big swings in torque curve if wrong, required rad to be tilted down)
- Custom exhaust (<1.5psi backpressure).
- Miata alternator
- P/S and A/C removed
- Not ported, simply cleaned up
- Evans waterless coolant
- Bosch coils
- Stock injectors
- EOMP controller for oil injection (separate tank for premix injection)
- Twin oil coolers
Have a read of "Street Rotary" if you want to consider a rotary in the miata.
06-09-2011, 06:57 AM
#62
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For the NA series Miata, the 2 biggest issues that have come into play are:
- Driveshaft tunnel having to be physically higher than it exists for the 1.6/1.8L. This means re-fabbing the tunnel to be higher (the e-shaft exists from the center of the rotary 'block', contrast to the 1.6L exiting from the bottom. The engine is lower, but the output shaft is higher)
- Stick shift placement. Between the above issue, and having to modify the firewall to get it to sit in the right spot, there has been notable difficulty in getting the stick shift in a reasonable spot. Some say it's nearly impossible to get it in the exact same location.
Edit : Regarding the 20B, WGT got 400-500bhp out of a peripheral ported engine that recently won Banzai car of the year (in an RX7 body).
Last edited by ukmiata; 06-09-2011 at 07:36 AM.
06-09-2011, 07:43 AM
#64
Did you start off with a fresh engine? 170rwhp is a very low number for an engine in good conditions.
06-09-2011, 04:04 PM
#67
What rulebook do you follow Mark to build an engine? I'm pretty curious about that but i'm highly unfamiliar with american racing serieses.
G
06-10-2011, 02:38 AM
#68
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170rwhp was the best stock RX8 of several obtained from a local Mazda dealer for comparison. Some were much lower and subsequently fixed under warranty. Every dyno is different and it was thought best to get a reference/comparison reading rather than get hung up on absolute numbers.
My engine was rebuilt with all new seals and ports were cleaned up (rather than modified).
After thinking about this thread overnight, the cost-no-object choice would be a peripheral ported, naturally aspirated 20B at 400-500bhp. With a rotary classified at +40%, the capacity would be 2.75L.
06-10-2011, 03:44 AM
#69
New seals are only part of the game in a rebuild as sideplates and housing wear accounts for a big part of the result as well.
Our average dyno for good engines reads around 180-190rwhp with fresh\complete rebuilds giving a bit more (in the 200\204rwhp range) on the same dyno of course. Numbers are not that important here but the percentage is (5-8% range).
That's why experienced guys stress more on the engine build itself than the mods to go with it.
A properly built 20b in that power range is going to cost you around 15k$ (if not more) and will require even more fabrication to fit in the miata, as well as a new transmission if yours doesn't hold up to its torque
In the end it really comes up to the budget you have and what your needs are!
Our average dyno for good engines reads around 180-190rwhp with fresh\complete rebuilds giving a bit more (in the 200\204rwhp range) on the same dyno of course. Numbers are not that important here but the percentage is (5-8% range).
That's why experienced guys stress more on the engine build itself than the mods to go with it.
A properly built 20b in that power range is going to cost you around 15k$ (if not more) and will require even more fabrication to fit in the miata, as well as a new transmission if yours doesn't hold up to its torque
In the end it really comes up to the budget you have and what your needs are!
06-11-2011, 03:35 PM
#71
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That's something we are looking into. New suspension fitted as well as corner weighting and geo all done for the next race in a couple of weeks. Cant be any worse than it was in the last race. If it's no better we will have to look into power delivery a bit.
Anyone done a 13b twin turbo in a miata?
Anyone done a 13b twin turbo in a miata?
06-11-2011, 04:29 PM
#72
You don't need a twin turbo. A properly sized one is more than enough
However... suspension, gearing and differential account for more than a 30hp difference at the track. What did you go with?
However... suspension, gearing and differential account for more than a 30hp difference at the track. What did you go with?
06-12-2011, 05:11 AM
#74
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We are running gaz gold pro suspension, standard box (as we have them coming out if our ears), 4.1 type 2 torson diff. My mate at HWR racing is doing the geo this time allong with the corner weighting. Usually we do our own.
06-12-2011, 05:21 AM
#75
That says it all.
Keep your engine and get some high level motorsport coilovers. Moton, Jrz, Penske, Ohlins, Bilstein (their competition stuff, not the usual commercial one) are some good names.
The torsen differential is nice for the street... go with a clutch one.
There's more time to be gained there than by spending the same amount on a new engine option.
Keep your engine and get some high level motorsport coilovers. Moton, Jrz, Penske, Ohlins, Bilstein (their competition stuff, not the usual commercial one) are some good names.
The torsen differential is nice for the street... go with a clutch one.
There's more time to be gained there than by spending the same amount on a new engine option.