you obviously dont understand piston engines, exhaust has to go arround a 1/4 inch opening in a valve and they have no problem spooling up a turbo. rotary engines put out way more exhaust per revolution than an equal displacement piston engine, thats why we run larger exhauset housings than most 4 or 6 cyl piston engines, but a piston engine puts out less exhaust than a rotary, the smaller exhaust housing dosent hurt teh engine like the same size housing would on a rotary.. thats why we need bigger turbos to make the same amount of power as a piston engine. a 90 degree turn is nothing for exhaust to make, what about the turbo manifold, the stock one is a log style, the exhaust bounces arround till it finds an opening, or an aftermarket manifold, , they make a coupple 90 degree turns before it gets compressed into a small opening and then hits a turbine wheel. a rennisis engine might even be better than a third gen motor, because the intake an exhaust have less overlap, so the exhaust ports and intake ports arent open at the same time for as long, so you dont have exhaust leaking into the intake charge and heating it up.

 

I belive that Mazda dicided to go with side exhaust ports on the renesis because of emmissions. Based on the disign sketches I saw in the Hiper-rev magazine, part of the exhaust gasses are pushed into the compression chamber to reduce temps. and increase emmissions...kinda like the EGR valve... I don't see how this can be efective for performance but...please correct me if I'm wrong

 

Less overlap people, think about what less overlap means. Overlap is the main difference between n/a cams and turbo cams in piston engines. The turbo engine wants as little overlap as possible, because that leads to blowby, which not only causes poor mileage and dirty emissions, but it causes the engine to make less power, boosted air is passing straight from intake>>exhaust, without making power. Iit's like having an extra wastegate that is always bleeding pressure.

The reason a rotary needs a larger turbo than a piston engine is because it has more taking place at once. There is virtually always an intake stroke taking place, always an exhaust stroke taking place, both at the same time. Compare this to the piston engine, where the intake and exhaust stroke are only taking place 1/2 of the time, the rest of the time is spent on compression and power.

How can some of you people own this car and not be aware of these sort of things?

-s-

 

Not only the renesis has less overlap than any previous rotary but it doesn't have any overlap at all! It was found that it in fact has 6 degrees of dwell, where both intake and exhaust ports are closed at the same time.

 

Basically, a 13BREW ingests as much air as a 2.6 L piston engine.

 

Hey...I don't think we should discount a Renesis swap entirely. There could come a time when Renesis engines are commonly available at a good price, and it will be these "pioneers" in figuring out the swap that we will owe some gratitude to.
A 20B is a VERY expensive swap. As is every domestic V8 or V6. The 13B is not nearly as powerful as the Renesis. So let's consider a future where maybe the ONLY option for some IS to put in a Renesis.
I can't help but think that the performance potential of the Renesis hasn't even been scratched yet. IF in the not so distant future you could pick up a Renesis engine and mod it up to around 275 - 300 crankshaft hp for a few grand, and have a 'kit' available with all the adapters and what not to ease the installation, I know I would consider it.
The RX8 is not that bad of a performer. It is heavier than the FD, so one could theorize that a stock Renesis in a FD would yield a car that could have mid-5 second 0 - 60 times with a low to mid 13 second 1/4 mile time. Nothing to sneeze at!

 

The LS2 will eventually be available at a good price, and if you've got a dire urge to go naturally aspirated, an aluminum 6.0 liter 400 horsepower/400 lb-ft. torque small block would be a far better platform to build on than the Renesis, if all you desire is a different engine between the fenders. I won't even bother listing the reasons why it makes a lot more sense than swapping for any other rotary configuration.

True.

Untrue. No more than swapping in a Renesis, at any rate.

One could also theorize that an LS2 or LS6 in an FD would run low 12s on street tires, have 0-60 times under 4.0 seconds, get better gas mileage, and pass emissions.

 

dont tell me i dont understand piston engines, I understand perfectly and if you knew anything you would know that a 2.6 liter piston engine (which is the same displacement per revolution as the rotary) has no chance of spooling something like a t78 with a 1.0+ exhaust housing... which our little rotarys can with ease because of the speed of the exhaust gasses leaving our engines.

the exhaust gas going around a valve and making all sorts of weird turns make the speed of the gas less.

 

If you want a slow reliable FD - just remove the turbo's and go N/A.

I'm being serious - much easier/cheaper with probably the same result.

 

I am reminded of all my years spent in driving/maintaining English cars. There were several companies in the mid to late '80s - early '90s that had complete kits available to retrofit domestic engines into English cars. One of my cars of that era was a 1978 Triumph TR-7, it was notorious for its poor engine. There was a kit to put an aluminum Buick V6 into them turn-key for about $1200. That little Triumph with 160 hp or so under the hood was a ROCKET with that conversion!

 

Back to the original question. To do the swap you would have to solve several problems, including:
1. Motor mounts in completely different locations and no holes in original locations (as mentioned above).
2. You can put in a Motec or some other ECU to run the engine, but you have to control the staged intake valves. If that can be done, then you may be ok. I doubt you could use the RX-8 ECU as it also controls the ABS, DSC, intrument cluster, etc. etc. and would be very upset if they weren't present. It goes into a "protect the customer" mode.
3. I understand the transmission bolt layout is also different.
4. You will have to have a driveshaft shortened or lengthened (and not the RX-8 one - it's carbon fibre), or a new custom one.
5. You need to get the diff. ratio down to compensate for the low torque output of the engine (as mentioned above). Swapping the RX-8 diff. in would be almost as much work as the engine.

It's a lot of work! An alternative -might- be to build/have built an RX-7 engine using some of the renesis parts. The object would be to increase the RPM ceiling. Whether that would include side exhaust ports or not is a question -I- couldn't even guess at. You'd need to find a rotary -EXPERT-.

I've driven an RX-8, and that rev. band is amazing. The downside is the torque feels like my RX-7 when I'm waiting for it to come on boost (below 2500 RPM). While waiting you suddenly notice you're 20 MPH over the limit!

 

I'm pretty sure an RB26DETT could spool it...

 

Renesis engines are putting down 300 to the wheels with a turbo at 6 psi. That's pretty good if you ask me.

 

David, on the rx8club, the greddy turbo kit was making about 240 to the wheels at 7 psi. Are you talking about another turbo setup? 2 people just dynoed and both were in the 240 range.

Tim

 

nuff said.

 

Tim, the Speed Force one is putting out some good power. It's got a larger turbo, it is a little more expensive though.

 

From what I've seen/read there isn't much room to squeeze extra HP outa the Renesis. It's been out now for almost 2 years now, and how many 300+ rwhp Rx-8's are there?

It's been proven time and time again, its pretty easy to get 350-400 rwhp outa the 13BREW with the right mods and modest dollars.

I agree with the others...it would be a futile effort with little to no benefit.

But hey, whatever floats your boat.

 

Thanks for the info David, but damn that is an ugly hp/tq curve

Tim

 

I think the Renesis is fine for lightly modding - modest HP gains and can be tuined to provide a very smooth curve
But I think there is a c. 300 hp limit
I think the best convesrion for an FD if you want to change the engine is an S15 engine
Lighter than a 13B-REW and easily modifiable to do low 11s

 

it is an ok idea.. but not worth the time/money IMO. why not just purchase an rx8..?

 

I say go for it. You may have to get around the intake manifold or you can use MSD RPM activated switch to open the valves in the runners. I never heard of a Renesis been ported, but I don't know if it even can be done. If it can be done that would help the hi end but it will really kill your low end. Don't let this people cut you down. Like it was said before, in the future it might be our only replacement if we want to stick to a rotary motor. You are going to spend a lot of money but I don't think it will reach the levels of a 20B swap.

 

http://www.rx7.com/techarticles_rx8power.html

-Alex

 

That's NA vs NA. I would hope that in 13 years Mazda could come up with a way to increase the power by a significant amount. No one is saying that the Renesis is a bad motor. We're just saying that in a FD, it's a waste.

 

If I do well in college, my old man his hooking me up with a new 7 when it comes out in afew years. Drool..

Is there any more information on whats going on in regards to the 7? It was supposed to debut in 07.

 

why would someone wanting to do this?? there is no point in it..

to put in one, you might need to modify subframe, drive train and drive shaft..
which will most likely cause steering issue.. or get the engine rebuilt with endplate to accept fd tranny and don't have to mod the subframe.. which I'm not sure if its possible..

I don't care how cheap rx8 engine gets, I really don't ever seeing it go below 13b rew engine. Completely pointless. If you are going to spend money and time... and modifying subframes and such.. go LS1 or 20b.... better yet, just get the engine rebuilt and upgrade your turbo.. It will still drive like an FD and will have more power..