Well here goes. I plan to build up my RX8 as many of us do. I also have done some math. Keep in mind this is a major guess at what the engine can handle, and we may all be pleasantly suprised or let down when it finally comes but based on some of the FD knowlege this is what I have in mind.

I will be waiting for lower compression rotors, hopefully down to about 8.2:1 or 8:1 so that way i can run 15 psi, and on this motor your looking at roughly a 150 hp gain, keep in mind though you will be losing fifty HP (approx) with low compression rotors, so thats 350 HP. Do some porting and based on what some FD's did I assume about a 35% power increasement (thats hard for me to swallow but that is what has been said) and that takes you to a wopping 470 hp (rounded DOWN). Add a good exhaust and you can benefit to about an additianal 10-20 hp, I say 15 for arguments sake. Thats 485, add an intercooler and get another 15 and you now have 500 crank hp. and 400 RWHP. Am I adding in the wrong order, are any of my numbers off, please discuss this in here.

I'm not sure if (street/mild) porting will do much for this engine since its ports are going to be very tall in stock trim from the factory. Unless, however, you were thinking of bridge porting :D Then maybe your numbers will actually be very close.

Yes it was bridge porting that was brought to my attention.

Keep in mind velo that there's all kinds of street and bridge ports. I'll list them for you:

1) Street port-
The side port is extended slightly. A mild increase of 20 to 30 HP can be expected.

2) Bridgeport-
An extra port is added to a street port right up against the edge where the peripheral housing meets the side housing. If performance carbs and exhaust systems are installed you could get a 70 to 90 HP increase.

3) J-Port-
A bridge port is extended past the edge of the peripheral housing, but not far enough to break into the water seal.

4) D-Port-
Very big port, the water seal is violated and so is the water jacket, so there must be restoration to maintain cooling. Don't expect the engine to last very long.

5) Peripheral port-
The rotor housing is ported. This port is often eliminated by racing rules. The motor will not run below 2000 rpm.

This is what you would expect on a normal and current rotary engine (10A 12A 13B 20B) and not a renesis rotary. But we won't know the pros and cons of the engine until it arrives in the u.s.

If your only looking at running 15psi then going to decompressed rotors is not needed.

Keeping the compression std aids off boost performance, and as long as it intercooled properly and the management system is tuned correctly you will have no worries.

9.5:1 is a wee high for turbos I think. It may work, but engine life will be extremely lower. I just have to wait and see.

Why will engine life be lower?

Engine life is related as much to tuning as anything else.

We built an RX-4 about 7 years ago for a mates girlfriend, which had a mildly ported std compression RX-4 engine, 2-speed powerglide transmission and the std 3.9:1 RX-4 diff. The car weighed 2680lbs, ran premium unleaded fuel (95 octane) and had a set of 26x8" M&H street tyres.

The car run 10.91@124.8mph in full street trim, as driven too and from the track. The engine in the car has been totally reliable with no so called compression related dramas.

The car is running a MoTeC M4 Pro and has been tuned correctly, and this I feel is where reliability is gained or lost.

std, 9.4:1

Okay, dumb question, what is porting? Must be a rotary thing.

Porting is simply changing the shape and size of the inlet and exhaust ports to increase the amount of air they will flow.

I'm betting Mazda has evolved the NA 1.3L Wankel about as far as you can go. More power probably means boost or N2O.

Originally posted by Dazz
Why will engine life be lower?

Engine life is related as much to tuning as anything else.

We built an RX-4 about 7 years ago for a mates girlfriend, which had a mildly ported std compression RX-4 engine, 2-speed powerglide transmission and the std 3.9:1 RX-4 diff. The car weighed 2680lbs, ran premium unleaded fuel (95 octane) and had a set of 26x8" M&H street tyres.

The car run 10.91@124.8mph in full street trim, as driven too and from the track. The engine in the car has been totally reliable with no so called compression related dramas.

The car is running a MoTeC M4 Pro and has been tuned correctly, and this I feel is where reliability is gained or lost.

hate to tell you this but in the states we need lower compression rotors cause the Highest octane gas anymore is 92 or 91. 93 is like non exsitent and we will have to add octane booter every time we gas up. and I don't know bout you but I am very forgettful and If that motor gos cause I didn't put the oct booster I will be pissed off.

I don't see how you can think the rotary has evolved about as far as it can go. The piston engine has been around far longer and had many, many times more research dollars put into it and advances are still being made. If the rotary had anywhere close to the research put into it that the piston engine had, it would be much farther along than it is.

Of course, the rotary has benefited a tremendous amount for the work that's been done on piston engines. I still think the point is valid. If piston engines aren't maxed out, neither are rotaries.

Originally posted by rototlewski
[B I don't know bout you but I am very forgettful and If that motor gos cause I didn't put the oct booster I will be pissed off. [/B]

He's talking about needing 95 octane in a hugely modified old rotary. An unmodified rotary in the RX-8 should be reliable. There is no reason to suspect it won't go 200k+ miles if properly maintained. Of course, it's possible that there will be problems, but that likelyhood exists in all engines.

In std trim an aspirated rotary does not need high octane fuel due to a lowish compression ratio compared to most late model high performance engines like the Honda V-Tecs and such.

Even with the 3rg Gen RX-7, most of the problems were not engine related. Problems with turbo's, manifolds etc have nothing to do with the reliability of the engine itself.

doctorr said:
However, the new engine has little, if any, room to port the exhaust- it is a large polished runner already, but the real kicker is a new heat guard treatment they apply- the runner is ceramic lined.

How about replacing the runner entirely with a new one using the same or similiar ceramic/heat coating process? How expensive would this be (guesstimate)? I'm guessing then it would have to be port matched if this was possible at all. Am I way off, or is this a possibility with the right R and D?

I'm also interested in knowing how many other mods are needed in a street port to gain 20-30HP. To me that's a pretty good gain from only one mod. Also, does porting(street or bridge) effect low end torque like it does sometimes with modified cams in piston engines? Sorry for all the questions, I'm still new to rotaries and interested in learning.

i don't think your asking too many questions. the only thing i know about rotories is they go round and round instead of up and down! i'm just glad someone knows something to ask. i was lost at "porting" until some asked and answered that one:D

...now if only one of the resident RX-8 forum experts would be so kind as to respond with some answers or educated guesses :) .

I'm not new to the concept, my dad had a second gen convertable, but that was before I could drive. I've had several friends with RX-7's but they were happy with them in stock form.

I don't know much about what mods will eventually be available for them. I'm too chicken and cheap for big time projects, but I was hoping that with upgraded intake, exhaust, and electronics we'll be able to get the RX-8 up around 300 HP.

Or am I wrong; will Mazda have the Regenisis close to it's maximum potential when released?

...until they tuned it back for whatever reasons (maybe reliability). I seriously doubt the Renesis is maxed out in factory trim. Mazdaspeed and other tuners will no doubt jump on this car from the get-go and make some good aftermarket parts with good power/handling gains. If I modded my RX-8, I would keep it NA. I would hope to gain 30HP with no loss in driveability, but until the car is actually here we can only speculate on its potential.

I'm also interested in keeping the engine in NA form so as to keep it more reliable and simpler. However, I intend to eventually procure just the Renesis motor, possibly with a Rx-8 trans, and install it in a Rx-3. The Rx-3 from 1972 was rated at 2060 pounds and would really haul ass with 280 to 300hp and some 4.5 gears in the diff. It'll take a while to get all the necessary pieces together but I deffinitely think the finished product would be well worth it.

i'm not going to allowed to do any big time mods by my wife. but hope there will at least be a chip swap available i could slip that by her. and maybe my exhasut will develop some hole by "accident" so that i can maybe replace it with something thay will loosen up a little hp. :D

I figure with standard bolt ons (intake, exhaust, ignition) a lightened flywheel, and maybe some deeper gears the rx-8 will got mid 13s. Thats enough for a daily driver.

legend has it that california is one the most largely-targeted markets for the rx-8. thus, as california has some of the tightest anti-smog laws in the states, then im guessing the power difference between the rx evolve and the rx-8 is largely due to emissions control. thus, in order to get a significant power increase out of the rx-8, one may have to not give a hoot and pollute. (go woodsy owl!) IMHO, cars that are 73 and older are the ones people should buy, tinker with and trick out. i mean, if youre spending $30k on a car only to void the warrenty and risk ruining the engine (not to mention potentially having to smog check your car illegally), and ending up with a 2700lb car and 300HP, then why not just spend the same $30k+ on an old beater car and make it haul butt? even though i love to fix things that arent broken, i think the rx-8 (as with buying any new car) may be best left stock. or at least modify in moderation like Rumblee - chips and exhaust are one thing, but porting and adding turbos are another.

i think Mr. Wankel has the right idea with taking a smog-exempt car and putting some new technology in it. its not going to cost him as much, he can even strip off all the smog gear from the renisis if he wants and he'll still have a killer yet legal car.

I will be happy to tune the vehicle, hopefully to get around 300 hp without turbocharging. Any suggestions??

I would say that the Renesis design allready allows the maximum porting for a street engine that is fully 'smogged'.

As was mentioned, highest gains for power would be

1. de-smog

2. free flow exhaust

3. adjustable fuel delivery


I suspect this would bring your Renesis to 300 hp with ease.

The way things go I would even bet on a bolt on supercharger that may take you to 350 hp or more.

On a new car????? no way ! hamx0r said best to play with old beaters. try this on for size... make an old 12A run backwards and turbo the intake through the exhaust ports. Looks feasable to me in order to increase the combustion time by 20 or 30 percent. might make a good boat engine, hmmmm

Originally posted by veloceracing
Well here goes. I plan to build up my RX8 as many of us do. Ya know, depending on how it drives, responds, etc. I don't plan on doing anything major to it. As much as I love the turbo in my Miata, and as a balanced of a car it is turning out to be as I'm developing it (brakes, tires, suspension, etc. in addition to the engine mods), I do miss the basic, simple feel that the car originally had. So if the car comes close to the Miata as having that balanced feeling, I'm going to be keeping it quite close to stock. Especially since it will be under warranty, and since I'll have a faster car on the side to take care of my "power-joneses".

With that being said, let's talk tuning! :D ...I will be waiting for lower compression rotors, hopefully down to about 8.2:1 or 8:1 so ...keep in mind though you will be losing fifty HP (approx) with low compression rotors... Although high compression pistons/rotors certainly do handcuff a car's ability to handle boost with pump gas, I don't know if you need to go that low for 15 psi. For a street car, I would personally rather gain a little bottom end and off-throttle/off-boost response and lose a little top end power with a little higher compression ratios, but that's me. I hate lag-monsters on the street, regardless of how much "top end" power they may have. And with those low compression ratios, it would be a lag monster IMO. ...Do some porting and based on what some FD's... Since the port relocation is the big difference in the engines, I wouldn't even start talking about port gains at this time. ...Add a good exhaust and you can benefit to about an additianal 10-20 hp, I say 15 for arguments sake... I think you're mixing basic NA benefits and turbo benefits. You would already require a properly sized exhaust setup to reach the gains you are already talking about. ...Add an intercooler and get another 15... Same as the exhaust. At 15 psi on pump gas, you'll need an intercooler to reach those initial levels you are talking about (at least on a regular basis). Remember, heat is the rotary's enemy, and stuffing a hot intake charge into one will hurt more than help. Regardless, at 15 psi on a car that runs 230 at NA levels (considering your lower compression numbers), the difference between intercooler and no intercooler is going to be a bit more than 15 hp, IMO...

As far as smog legality, more and more municipalities are requiring smog testing similar to California. California is simply the toughest standard in the states, so car companies use it as a guideline for their U.S. setup (regardless of where they might be "marketing" it), 'cause if you can make it there, you can make it anywhere.

The emissions requirements on this engine are going to be as different as the porting setups, and one thing that we do know is that it won't require as much emissions equipment as the previous rotaries to make the required smog levels. So, I don't think that we'll see as big of a gain from removing smog equipment as you once could.

It will be interesting, though, to see how you would have to adjust these new ports to change the "cam profile". Just like other NAs, once you balance the engine, remove restrictions (polishing ports, intake, exhaust, rotating weight, etc.), all you are left with is spinning the thing as fast as you can (meaning running it at higher rpms).

---jps

The RX-Evolv only had a 280 ps estimated target power output. The RX-8 is supposed to have 250 ps (247 hp).

Smog equipment? Does that refer to the catayltic converter. The RX-8 should NOT need secondary air injection because it runs lean. You can't just take off the cat. I would hope that the exhaust is very free flow from the factory (dual exhaust or just dual tips)

I would hope to get 250 hp, and if N20 is used when the top end ports open up (6500?) maybe 375 hp is possible,(if you replaced all the incoming air with NOS) and a whole lot of fuel is put inside the RENESIS

ya, i speculated before on another thread (the "turbo?" one i think) that Mazda is building this car with performance in mind, not grocery-getting, so the exhaust system ought to be pretty trick coming from the factory...

also, the 5+6 ports activation range can be seen on the torque graph someone posted earlier (where is it now?? lemme see... yep, looks like your hunch is about right MikeW) illustrates this... and you think you could jam a 125 shot in that sucker?? wow...

A 125 shot is a lot especialy for a rotary. It can be done but its a lot for a stock engine to handle.

N2O is probaly the best major power adder. Other things requred i know (more fuel, higher flow injectors, ect)

That would be alot of fun to put a renesis in a RX-3. 300Hp 2000lbs Whoa!

I don't see how you can think the rotary has evolved about as far as it can go. The piston engine has been around far longer and had many, many times more research dollars put into it and advances are still being made. If the rotary had anywhere close to the research put into it that the piston engine had, it would be much farther along than it is.

Of course, the rotary has benefited a tremendous amount for the work that's been done on piston engines. I still think the point is valid. If piston engines aren't maxed out, neither are rotaries.
He was a prophet.

:eek:

How did you find this ancient thread?

i don't think your asking too many questions. the only thing i know about rotories is they go round and round instead of up and down! i'm just glad someone knows something to ask. i was lost at "porting" until some asked and answered that one:D

This ancient post gave me a chuckle.