bse50

Except that in our case you'd have to drill through the cooling jackets!
I never had the opportunity to test fit an older housing to our side plates, even in that case i'm curious to see if the cooling holes\jackets correspond.

r0tor

iTrader: (1)

then drill it out and sleeve the hole with a heay guage pipe

alnielsen

iTrader: (4)

The p-port in the housing should suffice, you still have a problem with the siamese center port and the exhaust header design would be a bitch.

Mazdatrix has already done that as an experiment. I don't know that they had the same result.

r0tor

iTrader: (1)

I just always thought the renesis rotor housing looked made for additional p-port exhaust ports... -shrug-

Zelse

iTrader: (12)

So I wonder if they even make NA RX7 after market manifolds so if someone were to do this, they wouldn't have to custom fab a exhaust manifold as well. That would kind of suck :/

r0tor

iTrader: (1)

you'd want a custom manifold anyway so you would have to redo the entire exhaust. I'm pretty sure the bigger problem for this application for a street engine is a p-port with renesis intake side ports would yield large amounts of overlap and a questionable idle quality (or a need for a pretty high idle)

rotarygod

They used peripheral intake ports with the stock side exhaust ports and got 260 horsepower on an engine dyno which is what Speedsource Racing gets at the flywheel with stock ports all around.

r0tor

iTrader: (1)

btw... i was thinking something like this but smaller and on the exhaust side
http://www.youtube.com/watch?v=LkKw72dZ2yc


i have always believed clearly the exhaust restricts engine output much more so then the intake side

rotarygod

The Panspeed engine is definitely the good old peripheral port 13B. It just uses Renesis rotors.

I don't think anyone here should get all that excited over this. It's not something that anyone should be doing to a street car and nothing that would pass inspection anyways. If you think your gas mileage is bad now, drive a peripheral port around!

Zelse

iTrader: (12)

But then what about using a older 13B with Renesis rotors, but NOT P porting it? What kind of out put would we see you think? Or some other similar combination?

rotarygod

The power differences between a 9.7:1 compression RX-7 rotor and a 10:1 compression RX-8 rotor are practically immeasurable. The apex seals aren't as tall on the Renesis though and may see potential issues over time from crossing peripheral exhaust ports.

Here's the sad truth for RX-8 owners whether they want to admit it or not. You guys have some pretty damned good engines and you really aren't going to get much more out of them no matter what you do short of forced induction. All you can do is reduce rotating mass such as a lighter flywheel to aid in acceleration, free up the exhaust, strengthen the ignition system and retune it. Your engines with side ports, regardless of any porting done to them such as a bridge, are limited to about 260 fwhp using a high octane fuel with some serious tuning. You can get that on stock ports IF you are VERY good. That's somewhere around 230 at the wheels. Realistically on standard gas available at the pumps, you'll be limited below this. Probably somewhere around 220 or so at the wheels max and that is doing everything perfectly. The average person should be happy with 200 or so and get over the fantasy of having more naturally aspirated while maintaining streetability.

Yes there are ways to get more power than this. Is it something that most people are going to be willing to do? Doubtful.

bse50

Well, a maxed out renny tops exactly at the power you said but what other the other ways to get more NA power you're referring to?
Streetability is not something my lonely neuron thinks about

rotarygod

Remove the stock ecu from the car and throw it away. Replace it with something like a Motec. Install a peripheral port 13B engine and be done with it. Don't ever pass inspection ever again. At least not in the U.S. Simple. Less than 10 mpg, loud as hell, poor low load performance, but you can get 300 hp.

You guys have small engines. Get over it! You have 2 options. 1 is to install a larger engine such as a piston engine or a 3 rotor. The other is forced induction. This will allow the least number of compromises.

Zelse

iTrader: (12)

Gotcha, well I guess thats that then. Thanks for all the input Rotary God. I mean like he said, I've only seen this in Race cars and it's basically a race car setup (adding the ports that is) but yeah..Hmm... Well RG, you said lightning up rotational mass such as flywheel and all that..what about RacingBeat's lightweight rotor setup they offer? Any advantage to that you think?

rotarygod

That rotor isn't much lighter and the weight that is removed is done so relatively near the center of the rotating mass. This may be beneficial on a race engine where every last little bit helps but it's not anything you will see on a street engine. That combined with it's $2000+ price tag really makes it out of place.

IF you really wanted to go all out on a non peripheral port engine and get more power, there is really only 1 way and that is more rpm. However your engine has to breathe accordingly which means your intake manifold will definitely have to change. A downside to this is that your low end and mid range power and in turn fuel economy will also suffer. It would be ALL top end. In order to take it up here you will need to build the engine for higher rpm use. If you top 10K rpm, you really need a scatter shield on the transmission. In the event that your clutch and/or flywheel blow apart, you don't want your feet to be severed by flying shards of steel. Needless to say high rpm use is inherently dangerous! This is why everything has to be very light and balanced up high.

Of course to do this you'll need to clearance teh rotors differently and I'd suggest a 2 piece eccentric shaft from Guru Racing which allows you to install a center bearing for added support and decreased e-shaft deflection. Balancing the entire rotating assembly is a must. A new ecu system would also be beneficial. There are many other things you'd need and even then after tens of thousands of dollars you may still not have the performance of even a small turbo bolted onto a stock Renesis engine.

As I've said before. Anyone with a Renesis should get high power numbers from a naturally aspirated engine completely out of their minds. It's not a reality. It's a fantasy. Forced induction is the only way to get an appreciable amount of power out of the engine cost effectively. Everything else is just senselessly spending money on bragging rights only to still be slower than those who did it the easy way. The only way that spending this much time and effort on an n/a engine is worthwhile is when it is a 100% dedicated race car that is in a class that requires use of a naturally aspirated engine and where cost is no object. It better not be!

Zelse

iTrader: (12)

lol Well thanks for that Rotary God. Sounds good. Well I guess the topic is dead now since RG just stole the magic of those race cars but I guess it really just boils down to either turbo, supercharge, or just 3 rotor. Personally, I'd go 3 rotor NA and call it a day. But that's just me. Anyways, thanks for the insight, was good to learn more about this swap and see the benefits and all.

ChrisRX8PR

iTrader: (1)

So that being said....Lets put all our heads together and figure out how to add more "duration" to the exhaust timing. Forgetting port size (which the renesis already has a healthy amount off) total exhaust opening is hindered by the side exhaust timing configuration. Its not just about size... The renesis has what I call "Negative Overlap" on the exhaust when compared to the previous engines... By that what I mean is that the closing of the port actually happens before the opening...this sounds ridiculous....but I'll try to explain...:

RG, I am sure you understand what I am saying. If you move the rotor to where the exhaust is just opening and mark the apex seal location on the housing and then turn the motor to where the exhaust port closes and mark that apex seal location on the housing you will see that the second mark is lower on the housing than the first mark...so it "closes before it opens"(as ridiculous as that sounds)... On previous engines it doesn't close until the apex seal passes over the top edge of the exhaust port which is obviously above the bottom edge. this allows for way more duration....on the reni we end up with an engine that has X% more theoretical exhaust port area....but whose exhaust duration is greatly decreased...this taking away from the overall ability to exhaust the gasses which doesn't help the engine when trying to evacuate large amounts of gasses from FI or possibly really high rpm N/A operation.

What are your thoughts on this...I am sure you've though of this

Chris

rotarygod

A side effect of the side port location is less duration. More is not necessarily better. The only way to get it on a Renesis is to bridge it which can't be done due to water jacket location. That means the only option is a peripheral exhaust port but now we're back to the good old 13B. I don't think port location or duration is the problem. I don't think port area is the problem. I think flow through it is. This is where someone needs to figure out how to get a very smooth transition from port to runner on the exhaust side just lilke the intake side has. Once we can get flow smooth through there, then we can start playing with other things. The intake isn't restricting things at all so that isn't an area to even look at aka bridging it. I also don't think the solution is in overlap as I think the benefits of it are fundamentally misunderstood by most people. It doesn't do what everyone thinks it does to the extent they think it does it.

bse50

Right, might making bigger exhaust sleeves help a bit? It's just part of the puzzle but maybe better made sleeves might turn out to be useful!

rotarygod

The exhaust sleeves are already larger than the available port area. You can't even port out to the existing size of the sleeves because you'll hit the water jacket. Guess how I know!

bse50

We did the same mistake then
I know that they're bigger than the exhaust area but i don't like how they transition from the port itself to the header. I think that working them a bit could help up top, the problem is that removing them is a real pain in the back!
I lack the engine dyno at the moment otherwise i'd spend my days testing this kind of stuff. I love NA engines

rotarygod

It wasn't really a mistake. I knew I'd hit the water jacket. I was hoping that I could port it out as large as I wanted and then weld/fill in the water jacket in that area to create a nice shape. It didn't work out so well.

Cam

iTrader: (1)

RG,

Kinda OT,

but you stated earlier for 230 RWHP you'd have to ditch the OEM ECU for a Motek. Why?

What can the Motec do for increased horsepower that the stock ECU with the Cobb AP cant?

mac11

iTrader: (1)

Don't forget it must be within the rules. And chances are, it's not. In most cases where natural aspiration would be required of an RX8 the rules are more of a blanket statement something along the lines of "no" or ""tightly regulated" or "minimal" internal engine modifications.

Classes that would allow the types of modifications you are talking about would also allow forced induction, in about 99% of the cases.

This is why you don't see many of the big players from the rx7 community doing these types of things for the rx8/renesis platform. Let's face it, with these engines the racers drive a major portion of the demand. The racers don't need things like these so Racing Beat, Pettit, Ianetti, Engman, etc do very limited applications for these types of things because they don't pay the bills.

10:1 compression, stock redline - GT30, huge hot side, 8-10psi call it a day, save your motor.

9:1 compression, new ballgame.

PhillipM

A few times I've sat idly wondering about blocking the centre plate siamesed ports up completely and using just the ports on the side plates plus a small PP exhaust, not sure if I want to go into it yet without a few spare engines though!