Supercharger

If you are planning to swap the Renesis with a 3-rotor engine in a RX-8, contact these specialists:

http://www.pettitracing.com

http://www.pfsupercars.com

danger

bah i dunno if i'd want to put a 20b into an rx8....

maybe a renesis 20b, but not the ones that are out right now....


plus putting a 20b into an rx7 or any other car right now is going to cost an arm and a leg, i'd hate to think how much it might cost for a new rx8.

Supercharger

If Mazda builds 3-rotor RX-8 in mass production, it would cost a lot less than a tuner-built car.

Ideally, the engine should be all-aluminum with side intake/exhaust ports and no turbo.
Estimated power is 360 hp.
The base price should be around US$40,000.

This car can beat the BMW M3. Mazda will find many buyers for such a car.
:D

fritts

Pure speculation. I don't expect Mazda will make a 3 rotor. They have allready said the 7 will have thicker rotors and that the MPS 8 will be tuned to produce 300. So no 3 rotor. It will have to be something a tuner creates. Which could be possible but I seriously doubt.

Supercharger

If Mazda wants to compete in the Speedvision or Grand-Am GT series, this is the way to go.

A 3-Rotor RX-8 can race against Porsche 911, Corvette, NSX...etc.

Hercules

The beautiful thing about rotary is that it doesn't fall into the "there is no replacement for displacement" category. The advantages of keeping the housings for two rotors may not be in power but in weight. And juice the Renesis to 300-330 horses with 220(ish) torque, add a lightweight sports car and you'll have a car that will destroy Corvettes and M3s.

Buger

Tommy Matano said the following about 3-rotors:

"Well, you know, you can pass one or two cars through emissions, or safety, but when you are going it with a mass produced car, it is a completely different story! When you are talking about thousands of cars, you run into problems of consistency, and it is very hard to get the 3 rotor tuned right, for mass production. And how much would they pay for a 3 rotor? And how many would we really sell. I do hear talk about the 3 rotor a lot, but they don't realize how expensive it really is".

The good thing about 2-rotors is that it is very easy for Mazda to use the dynamic charging effect in the intake to increase volumetric efficiency of the other rotor. 3-rotors make this much more difficult to increase volumetric efficiency evenly on 3 rotors. A 3-rotor will also require an additional iron intermediate housing that will comparitively more weight. A 10mm increase in rotor width will easily add more displacement while adding a total of 20 mm to the aluminum peripheral housings (very little weight).

Horsepower figures without weight figures are meaningless but the general public is not aware of this. Mazda does not need to get caught up in a horsepower race when they have the perfect engine to turn things into a weight race.

No other manufacturer has the capability to produce an engine as small, as light and as powerful as the rotary. Honda tuned the hell out of the s2000 engine but it is still bigger, heavier, produces less hp and less torque than the renesis. Early estimates even have the rx-8 beating the lighter s2000 in fuel economy!?!?!

Mazda needs to emphasize their individuality by creating a next rx-7 as light as they can. They are afforded the opportunity to do this because a small impractical RX-7 will attract a different market than the practical RX-8 even if they are priced similarly. Nissan has great V6s that produce a lot of power and torque but they can't put it in a car under 3000 lbs. Why should Mazda participate in a horsepower war when they have the ability to produce a small lightweight car with unmatched acceleration, handling and braking for the price? How many people would buy a small 2600 lb rx-7 with 285 hp/180 torque that could go 0-60 in 4.5 seconds and cost $32,000 US?

Brian

wakeech

thank you, thank you, a million times thank you...

your clarity of thought is a godsend to this forum. not to mention, you're one crazy ****... what's up with that speed thing around the circuit?? holy jesus christ man... :D y'know we love it :D

danger

define small, and you've got yourself a deal!

as long as its somehwere along the same lines as the FD im sold on it. Honestly like put me on the waiting list i want one.:D


thanks for the info buger... go tri-lams!

m477

Also, you forgot to mention that the renesis will rev to 9,000rpm smoother and without much, if any, extra stress to the motor. No reciprocating engine, no matter how well designed or built, will handle revving so high as well, period.

Strider

It would be very interesting to see if the power and weight of the RX cars will finally make people reallize that it's not just how much hp a car has but rather that the weight too has a major factor in the car's performance. But then again, we'll always have the muscle car people and the Fast and the Furious crowd that probably will never understand any of that....

Strider-

Supercharger

Thanks for the info, Buger.

Why does Mazda use cast iron intermediate housing instead of aluminum?

MWG

Making a 3 rotor is the only way to go. You wont be able to make enough torque with just making the rotor housing wider. you might get just 30ft-lb of torque or about 50 horsepower. Torque is what makes cars go. not horsepower. I love the rotary but there is only so much that can be made by N/A engine. I know because I own 2 RX-7. If you made it a 3 rotor you could use alot of parts allready made. which is cheaper than making every thing over for a wider Rotor engine.

MWG

Another thing I just though about is that when you slow the speed of the rotors down by having a 3 rotor you get better emssions and making more power. If you made a 3 rotor you would need a 2 center housing that would hold a stationary gear and allow for the E. shaft to be added on like on a 20B. Plus intake and exhaust. That's pretty much it. You can use part from the other cars. they are strong enough. The weight would not be that much more. I could be used in the next Rx-7 and a truck or in place of a V6 or V8. That would help keep the cost down.

MWG

I don't think you can get over 200 ft-lb of torque with just wider rotor engine. I do think you can get it with a 3 rotor engine. Much more.

Buger

I believe that cast iron is mainly used because of it's lower thermal expansion, lower thermal conductivity and lower price.

Moller uses all aluminum housings for his flying car but I don't know the cost or complications involved with it.

Buger

Hi MWG,

Although you may think that a 3-rotor will be cheaper than a 2-rotor, you might not have read my post above:

http://www.rx8forum.com/showthread.p...4588#post24588

from Tommy Matano: "I do hear talk about the 3 rotor a lot, but they don't realize how expensive it really is"

Torque is what makes cars go but rpms get added to the equation for hp and weight is what affects everything.

Given the following info:

Car A:
engine: ... 150 hp, 250 ft-lbs torque

Car B:
engine: ... 250 hp, 150 ft-lbs torque

The 2 cars have the same weight, same size wheels/tires, are both geared to have shift points at the same speeds, and have the same shape for their torque curves (scaled of course).

Which car do you think would accelerate faster?

Brian

Buger

I'm not sure that the 3-rotor will have better emissions and I'm not sure that you really care about emissions. You just want more power right? :D

Seriously, Mazda has been quoted several times as saying that they now realize that the rotary should be kept in sports cars and not in things like trucks. Anybody can make an engine with lots of hp and torque, why should Mazda go down that road? Weight affects all aspects of performance. Acceleration, braking and handling. This is where Mazda's advantage lies.

Brian

MWG

I know he said it was expensive but you cant tell me having to make new rotor, E. Shaft, Rotor housing, intake, cost to get ready for mass proudtion is not More than using parts allready built and Making a few extra part to make it work. I know that they both are expensive but there is lots of money in the RD need to make all those parts. because larger rotors act different than smaller rotors because of the size, weight, Etc.... I think Tommy just doesn't want to do it. Kind of. I also agree that gearing makes a difference but its not like we are getting a Stock motor that rev's at 12,000 or 15,000 rpm. Also The more torque you have you can make the gear longer therefore staying in gear longer and having more time to speed up. Now if we got something like a 6 or 7 speed transmission that is like they have in Ferrari's that shifts alot faster than you or me. Even though we are really fast shifters! That would be different. When they gear it they make it shift pretty much in the same places.

MWG

Now a car like a lamborghini is still in 2nd gear when going 100 mph. Now I know it make alot more horsepower but they rev to maybe 8000 which is alot more than most piston cars. You and I know than a RX-7 handles alot better than a lamborghini in feel of road and agility. It is a lot faster than a stock RX-7 but I has like a 6 liter engine or something like that. We all love the rotary because of it avantages like weight, smoothness, it loves to rev, size, Etc.... Anyone could make the power a lamborghini makes with a engine that size. but a 3 rotor would have more torque, still be much smaller, etc... If it was put in something like the 3rd gen Rx-7 with a lower gear ratio and that would put it out of many cars league. I mean a McLauren would of course be faster but that car cost 1,000,000 plus new. A lamborghini cost 275,000. A Rx7 with a 3 rotor and lower gear ratio would be 50,000 or maybe on the far end 60,000. most likely cheaper.

MWG

The cars could be faster if they made like I saw is some other car that I cant think of right now. What they did was if you made the rear end ratio higher and made it so that the first 3 gears would be higher so you would get better acceleration in 0 to 60 and 0 to 100 then gears 4 though 6 would be set so that they were lower for highway speed and maybe 6th gear would be a cruise gear. They did this by making 1 through 3rd gears run on one shaft and then the 4 through 6 would run on another shaft in side the transmission that would make the high rear gear ratio not be so high. so you would get they best of two world you could get really good acceleration and good gas mileage and higher top speed. You would be able to use the gearing to make say 5th gear be at the torque peak so you could use gearing to make the Rx-7 or Rx-8 go 180 mph or faster, Etc.....

MWG

I think the reason I belive that it would get better emssion is because if you give the gas and air longer to burn it will be better for the cats to take out of the air as aposted to just more fuel and air, when you add a 3 rotor the acually speed that the rotor rotate at slows down becaus there is another rotor firing. Also if it is slower than you will get better thermal Effecitty. which help emssion. I do want more power and lower emssions. The reason I think mazda should go down that road is because if you make enough torque you can use gearing to make it pull alot of weight just like a truck would do. I think mazda should use the rotary engine in more cars because of it avantages. I think it would help in all cars. Plus with a rotary engine in, weight would still be down. because it is lighter than the average pistion engine. Plus if they used it in a truck or what ever they did they could turbocharge, supercharge, it for even more power in a truck. Plus no one really get perforance from a truck. Its a truck. Lighter weight means better braking, etc..... you are right that is were Mazda has a advantage, it lies in the rotary engine. Sorry for my spelling. I cant spell very well.

MWG

I also think mazda is making a mistake in not using there rotay engine in more of there cars. They just cant expect a 2 rotor engine like the 13B to make as much torque as a 5.7 liter engine without adding rotors or somekind of FI. I mean lets be real it is the best engine in the world but it has limits just like the old piston engine. I Like the rotary for being different and the way it works. I mean having a piston go up and down what is so exciting. Unless it is has some kind of trick intake system to make alot of power, and then being in the right car or truck. I think that is where mazda messed up expecting to much. They should be making the RX-8, a new RX-7, and other cars using the rotary engine and making crate motor for guys like me and you who want to put a renesis in our RX-7 or rotary power cars and going wild. they should making more parts so it is easy to get a renesis crate motor. So we can put them in our cars. I mean less get real I dont want people to think of my rotary engine as a little gimick. And have them look at me say. It's he got a little cool car. I want them to say. I want what he has. A rotary engine in my car.

MWG

One more thing I've got to say today is look at all the cars out there all the cars with more torque allways have better peformance in 0 to 60, etc..... we know that our RX-7's handle better why should we be shafted on the 0 to 60 numbers. I mean Porsches have good handling and good 0 to 60 and go 1/4 mile,etc.... why should we have it. Just my two cents. I feel better now. So what do you think about what I've said.

Buger

6 posts in a row?!?! You're more of a freak than I am! :D That was a lot to skim over but I still don't think you answered whether you thought car A or car B would be faster though. Do you believe the higher peak engine torque/lower horsepower car will accelerate quicker? You are correct that torque is what moves you. Why wouldn't the higher peak engine torque car accelerate faster?

If the 3-rotor really was less expensive, produced greater power/torque, and generated less emissions than a wider 2-rotor why would Mazda not want to use it? Mazda has repeatedly stated how they felt about the 3-rotor. They considered it for the fd3s and turned it down because they didn't want the fd3s to succumb to "zevolution". More weight here means more weight has to be added there which leads to worse handling and braking unless more weight is added to improve that which means...

Mazda has a large loyal customer base of people who appreciate smaller, lighter, better handling cars for a great price. I think one of the biggest reasons why the RX-8 will be successful is because there is a VERY LARGE customer base of Miata owners that will appreciate a car with the same qualities that the Miata has but has more practicality. Whatever Mazda decides to do, it should target their loyal customer base to be as successful as it can be.

If Ford let Mazda produce a version of it's F150, how so you think it would do? If somebody wanted a big truck, wouldn't they just buy a big Ford or GM truck? I'm sure some people would still buy a "Mazda150" but how much of a chance do you think it would have of making a lot of profit for Mazda?

The Whopper has been good for Burger King. What if McDonald's wanted to create their own "whopper"? Would McDonalds take away a significant amount Burger King's customer base by making their own lettuce/tomato sandwich? Hot side hot, cold side cold? Wha???

Every question that you come accross in life is a learning opportunity. It doesn't matter whether you think of the question yourself or whether it comes to you from somebody else. Answering the questions will not always make you wiser but the person who always strives to do so is headed in the right direction.

I will quit babbling now. :D