Best Normally Aspirated Engine for the RX8

[RxRebels]

Hi all!
 
Excuse my ignorance as I\'m new to the world of Rotary but I like what I see.:Thumbs-up  I am looking at using an RX-8 for Motorsport use.  The RX-8 is homologated and class rules mean I can use any normally aspirated (N/A)Mazda engine up to 2000cc/1.3 wankel.
 
I am about to buy an RX-8, is the engine in the RX-8 the best solution for getting about 300 bhp or should I be looking at buying a 13B engine from the RX-7.  Does anyone know which engines you can get the most power from reliably and finally who are the best engine builders in Europe?
 
I am aware that a lot of MK2 Escorts run N/A 13B engines.  Are these 13B engines form the RX-8\'s of RX-7\'s.  Will I have to buy both an RX-8 and then the best engine seperately?
 
I would be very greatful for any comments.
 
Thanks a mill,
 
RxRebel.

[Will66]

The first thing I would say is that if you\'re looking to swap engines I wouldn\'t go anywhere but another rotary.  A piston engine would not be worth the effort.
 
As for engine tuning, it\'s not been easy particularly in terms of naturally aspirated tuning.  Without serious changes it\'s difficult to get more power out of the stock setup.
 
The UK model is rated as having 228 bhp and the japanese model was rated as having 237bhp.  The R3 is rated as having 235 bhp and those that have driven it say the R3 motor feels noticeably stronger than the 228bhp in the Original RX8.  Now according to some tests in America where they tested the 6 port Renesis (228bhp in the UK) against the N/A Six Port from the FC RX7 the Renesis is making better power throughout the rev range indicating the progress between the two.
 
The problem with getting more power out of the RX8 is the PCM (Powertrain Control Module) it\'s difficult to remap successfully and piggybacking it can cause it to go into limp home mode.  Solutions are coming but it\'s taking time and it\'s not going to liberate lots of power on its own.  I don\'t know of many RX8s racing other than those which got used in the Formula Women series and I think those were stock motors.
 
There are several RX8s running around with 300bhp or so but they are using forced induction and so far only one is using a remapped stock ECU (Pettit Racing).  My guess is that you\'d need to change the induction tract a fair bit to liberate the extra power.  The fuel system should cope with it (Greddy, Blitz and Pettit all use stock fuel systems on their FI tuning packages for the RX8) even the brakes and suspension seem well able to cope with the extra power.
 
There was a chap in Belgium who built an Renesis Engined Sports Prototype who may have some ideas about power and how it should be done.
 
This is his website:  http://www.rotarydevelopment.net/

[BlitzBoy]

yep it is going to be hard to get the RX8 engine up to 300bhp and keep it NA,easiest way is to turbo/supercharge, you may get it up to 250bhp with a remap,decent exhaust and keep it NA. Any more then you are looking at major mods and money to keep it NA and 300bhp eg taking the engine apart making it a Proper Peripheral Ported engine after market ECU, fabrication for Throttle boddies etc.
The Americans whack in the 20B Tripple Rotor from the Cosmo and make it NA and this is the most reliable way of getting 300bhp but this would be a 1.9 litre wankel engine so breaking your class rules.
WGT in Cheshire have good experiance in building race engines for circuits give them a call

[AshRX]

HKS do do a F Con V Pro Gold loom now to link to the HKS ecu, maybe able to get a bit more out but as said above only forced induction and supercharge will get anywhere near 300bhp.

[Will66]

Hayward Rotary made a Three Rotor Renesis (Side Port) rotary for a drift RX7 that was making well over 300bhp.  It\'s big advantage was it was quiet.  That said putting a 3 rotor where a 2 rotor was can give issues with weight distribution.

[shaunwil]

Would have thought as long as noise isn\'t an issue then a PP 13b would by far be the best option. It would need to be of an older engine because the RX8 has the ports in the wrong place for mad tunning !

Although didn\'t re-ameria do a kit for the rx8 that was na that made silly power ??

Shaun

[Will66]

Re-amemiya did get 300bhp out of an N/A RX8.  I think it used N/A 13B-RE housings with RX8 rotors, however it was a bit of a pig because it ran a lot of overlap and wasn\'t tractable at low revs, good for racing but not for road, pretty expensive too.  Because the RX8 runs side ports it\'s difficult to get the overlap necessary for big power at high rpm without forced induction.  It\'s a shame really but as I am finding getting more power out of an RX8 is an expensive business.

[california styl]

an NA 8 wont see much power increase without major investment of time and money. But a smallish increase is possible by letting it breath easier and tweaking the tune.

Do your class rules mean it must stay NA?

[HaywardRotary]

A custom built 13b engine using a combination of RX8 rotors,and Peripheral Port rotor housings with a custom throttle body and ecu would be what you want. That should make around 300hp,and if noise is not to much of an issue then it will make more hp.
Regards
Carl

[antnicuk]

carl, what did the 3 rotor in the same spec make?,  that would give an indication of what to expect from a 2 rotor

[RxRebels]

A custom built 13b engine using a combination of RX8 rotors,and Peripheral Port rotor housings with a custom throttle body and ecu would be what you want. That should make around 300hp,and if noise is not to much of an issue then it will make more hp.
Regards
Carl

Thanks for all your comments, it seems it\'s not easy to get power out of the RX-8 engine.  But, sometimes he who dares wins...
 
A few points:
1. The engine cannot be either Super or Turbocharged under any circumstances and must not have a greater capacity than 1300cc wankel/2000cc normal.
2. I will be definitely sticking with the Rotary.
3. I intend on using Motec Engine Management and doing whatever it takes to get 300BHP.  Ideally I would settle for 285BHP and heaps more torque but it seems torque is really out of the question with these engines. So, without much torque I will need a minimum of 300BHP to be competitive.
4. The 231 BHP UK model will be my starting point but I will buy a car from continental Europe as I am used to left hand drive and for Motorsport there is a much better market for LHD cars.
5. Noise is one of biggest concerns, the noise from about 1 foot from the tip of the exhaust must not exceed 100 db\'s at 4500rpm.  The FIA are very strict with their noise tests.
6. Essentailly the engine would be built to Group A spec which is the
equivalent to the kind of power found in BTCC & WTCC touring car engines.
7. The car will run with a sequntial flat shift gearbox.
 
Carl, I am glad to see there is light at the end of the tunnel!  So, if I buy an RX-8, the engine will not be a complete waste?
 
RxRebel

[Will66]

100db at 4500 rpm shouldn\'t be a problem.  It\'ll be at 9500 rpm that will create issues.

[HaywardRotary]

Thanks for all your comments, it seems it\'s not easy to get power out of the RX-8 engine.  But, sometimes he who dares wins...
 
A few points:
1. The engine cannot be either Super or Turbocharged under any circumstances and must not have a greater capacity than 1300cc wankel/2000cc normal.
2. I will be definitely sticking with the Rotary.
3. I intend on using Motec Engine Management and doing whatever it takes to get 300BHP.  Ideally I would settle for 285BHP and heaps more torque but it seems torque is really out of the question with these engines. So, without much torque I will need a minimum of 300BHP to be competitive.
4. The 231 BHP UK model will be my starting point but I will buy a car from continental Europe as I am used to left hand drive and for Motorsport there is a much better market for LHD cars.
5. Noise is one of biggest concerns, the noise from about 1 foot from the tip of the exhaust must not exceed 100 db\'s at 4500rpm.  The FIA are very strict with their noise tests.
6. Essentailly the engine would be built to Group A spec which is the
equivalent to the kind of power found in BTCC & WTCC touring car engines.
7. The car will run with a sequntial flat shift gearbox.
 
Carl, I am glad to see there is light at the end of the tunnel!  So, if I buy an RX-8, the engine will not be a complete waste?
 
RxRebel

Noise on the static test is worse than when the car is running around the track,but since the car is pretty big there should be no reason that with a comprehensive exhaust system the noise can\'t get to that figure,also with fuel injection it will improve the midrange as well as top end.
Some parts from the RX8 engine can still be used yes.
Regards
Carl

[clive]

Hello and first of all welcome to Mazdarotaryclub,

Unless your going to up against BRG Cosworth engines and the like you should find the Rotary should offer a good way of being very very competitive, plus cheap because you wont need the expense of steel cranks, fancy cams or big valve heads etc etc,

As said above one of the first things your going to need to do is get rid of the stock management system preferably for a Motec system or as said above the HKS V Con pro as this way you can not only gain power but have the car tuned for race without the constraints of it needing to be driven on the road and get the power properly focused where your going to need it in the rev range,

The Rotary will bring more gain than a piston engine with intake and exhaust mods,  hopefully you can get rid of the cast exhaust manifold as I think you will find that a custom manifold with long primary\'s should give good power gains and whilst it may be obvious, you will really need the most free flowing exhaust system you can get away with noise wise as this will help the Rotary, once again more than a piston engine.  

You may already know that the RX-8 was raced in Britcar over here to very good effect with the real speed of these cars coming through dumping weight and the suspension system which is a very good system as stock and will really only need springs shocks and bars to get it going quick, if your up against "conventional" saloons I would say this is where your going to really score by using an RX-8,

There are already good roll cages on the market for the RX-8 as obviously a good cage will let the already good suspension work properly when the platform its attached to is nice and rigid.

The Britcar team actually took the route of leaving the engines alone and just kitting them out with a Motec ECU as by their own admission they didn\'t know enough about the Rotary to mess around with it, however they did very well with the cars.

Also last but not least you will find there are two reputable four pot upgrade kits out there on the market to take care of braking for you as once again the Britcar RX-8\'s had these fitted.

Hope the above helps,

Whilst at this stage we are not sure what type of cars etc your up against, I wish you well and success on you new "adventure" and please keep us informed of your progress as we have people from all over the world who will follow your new project,

[Will66]

AS regards exhaust manifolds, Racing Beat do one for the RX8 that will only fit LHD.  If you\'re getting a continental one then why not go for this!