Since a rotary engine doesnt have any valves,pistons,cams,cam gears,valve springs,etc,etc,etc, wouldn't they much more cheaper to modify than a piston engine like the 2jz-gte from the supra? And if the rotary does explode then wouldn't you have money from the things you didn't have to buy like a piston engine to rebuild it possibly?

 

many things can be done to a rotary that will not break your bank and still pick up some ponies. and you share the same theory as i do... less moving parts = less complications. so is a rotary "better"? thats for you to decide.

 

Yes a rotary can give more bang for the buck than a piston engine. Especially when you look at the horsepower to weight ratio.
A good example of what could be done to make major power on a budget. With stock engine components you could make a peripheral port engine. Build or buy an aftermarket intake and a Holley carb (to avoid a high dollar ECU setup) and put a header on it.
Once you tuned that you would have too much power for your stock drivetrain as far as it would not hold up to a motor that could launch as hard as it is capable of doing very many times. But that get you to the same point that any kind of car would need drivetrain mods at that point.
A piston engine to create that dramatic change in horsepower would require forged components to hold up, a big cam to make the power and a few other items that would add up way beyond the cost of this pport engine I described.
Some stock engines do have forged components to start out with but they are an exception and generally cost a lot more for the core so if you include the initial investment the rotary still comes out ahead.

 

some of the rotary engines parts are expensive...ie new rotors and housings

 

A rotary is better to rebuild. Once torn down to just the housings, they can easily be moved around. The single heaviest part is the rear cast iron plate I think. Try picking up a piston engine block by yourself (yes I know, some people can carry a 350 smallblock blah blah).

 

is there as much potential in a rotary as there is in a piston engine to make fast? since there are less stuff to mod will a rotary have less horsepower?

 

When you compare the price of two new rotors and rotor housings to a set of forged pistons, forged rods, forged crankshaft, block, valves, cam, rockers, heads, etc. the piston setup would be much more.
But if you are talking about building a motor using new components this would not be a very budget minded project as the thread suggested.

 

If we are talking about a non-budget minded motor the answer is no. Look at a top-fuel dragster.
But if we got into something more realistic for most of us consider this: The Renesis is a new breed of rotary that we are all aching to get our hands on.
Mazda pulled 100 more horsepower out of the Renesis as compared to the 13b NA based on the same motor.
The 2nd gen NA's were around 150hp and these are 250hp. I think the math works out to an incredible 67% increase in power.
Using lower compression rotors or modding the stock rotors and playing with port mods plus turbocharging I could not begin to guess how much power this would be capable of.
My point of this is that we will be seeing an entirely different rotary than any of us have dealt with. Within the next year we will see people breaking a lot of records with these new components.

 

f_3s, it also depends on which piston engine you're wanting to build. Some engines have plenty of aftermarket support, while others are pretty slim pickins. Rotaries, for instance, do have a decent amount of aftermarket support.

 

yeah but the torque sucks.

 

We will see once we get our hands on them what they are capable of. Modifying the intake (length of runners, etc.) and building a tuned header might make a world of difference in torque. My bet is that we can do some things with this motor that is going to change a lot of peoples minds on rotaries.

 

I thought from what I have heard the middle exhaust ports share the outlet in the midplate. So, wouldn't this screw any plans of a tuned header being used to its full potential?
Nick

 

That would be true if it was not for the "wonders" of fabrication. These pictures are very promising. You can see that the exhaust insert has a seperation but it stops just short of where the manifold mounts.
Most of you can already see the workaround but bear with me. I would fab new exhaust inserts with the separation flush to the exhaust manifold surface and the shape more condusive to flow to a tube header.
I played with the bottom pic to give an example of what may be done to the new insert. I can't draw with a mouse so don't give me no **** about it!
I would use a 1/2" thick header flange and form the center tubes and the flange to flow as efficiently as possible. Any of you that are familiar with the "D ports" that Pontiac used and seen the way that 4 tube headers were fabbed have seen what I am talking about.

 

That 'digital' port mod looks good.

 

yeah but break-in priode is a bitch for rebuilts..

 

On low mile and new components breakin is not a problem. So save up for a crate motor.

 

where is this crate motor u speak of?

-mike

 

In a land far, far, away called Japan. The parts department at my local dealership is on high alert as well as a few other people on when they become available. I have heard rumors you can get them now but when pressed for details no one seems to know.

 

I have a feeling this new motor will not handle the extra power from turbocharging very well.Its allready stressed at 250HP at high RPM at that, anymore might cut into its durability sharply.Mazda might have changed it here and there but its basically still a 13B.

 

Stressed at 250 HP, and where did you get this info?
Basically a 13B? With sideports, hmmm, I don't think so.
Show me your facts man!

Frank

 

I doubt the Renesis is stressed at 250 HP. This engine is supposed to be reliable.

 

The only reason it wouldn't handle turbo charging very well is that it has a 10:1 compression ratio...but even that can be overcome in one of several ways.

I guarantee you the engine is not "stressed", as it has obviously been detuned to meet emissions requirements. The European version makes 10hp less for that very reason. It makes peak power at 8500rpm which is actually pretty conservative for a 250hp 13B. I would not call that "high rpm" by rotary standards.

 

I mentioned using lower compression rotors or modding the stock rotors for turbocharging. It will not be stressed anymore than any other high powered rotary.

 

high comp can be turbocharged people! it's all upon the tuner, my friend has 10:1 comp in his honda and it's turbocharged, and it survive 91 octain blast with 10 PSI, due to very good tunning.

-mike

 

I would rather run a lower rotor compression and higher boost. A much more lenient setup.