The seals were moved outward to allow a larger intake port. They could push the opening timing even earlier this way without killing the side seals on the closing edge and strangely enough we did seen evidence of contact from this 2 years ago at RB.

 

well double duty then.

but fred remember why that engine was apart also- because it had blown on the dyno.

 

Pictures ! We want Pictures !

 

To the guys that had a chat with speedsource, do you know at what RPM does the Renesis RX-8 shift at? power starts falling at 8500 in the stock engine, is speedsource able to tune it so that it falls off later? I'd be curious to know if they develop 265 hp with the stock power cuve (elevated by quite a lot to give that much more hp) or power keeps building after 9000rpm. Maybe a combination of both. Also any info on the torque number?
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Speedsource is shifting the 3 rotor at 8500 rpm. It's pretty close to that in the 2 rotor as well. Probably somewhere between 8500-9000. As far as I know they didn't raise the powerband on the 2 rotor as they are still using the stock intake manifold and stock porting.

 

Does anybody know how i shall raise the 8700 rpm limit (according to my RotoTest hub bench) the tach shows 9500 rpm then fuel cut starts? This is very annoying when i dyno my car. Must i buy a Piggyback or is there some quick inexpensive way to do it? If there is not a quick fix what Piggy back shall i buy? Thanks in advice!

/Lasse

 

You can use an aftermarket ecu such as the Interceptor to change fuel cut. Racing Beat's reflash also raises it. The factory actually has it set at 9000. Your tach is just off. RB raises it to 9300 and the Interceptor raises it as high as you want. The real question is why do you want to do this? Retuning will get your useable rpm limit up a few hundre rpms but for the most part you won't get any more power unless you completely change the intake manifold.

 

LOL, my OE tach shows almost 10k on the limiter with the RB flash

 

mine too

 

Charlie, just so you know, I had a hell of a time with security with that engine stand adapter. They made me check it claiming it was heavy and I could really smack someone hard with it. Your airport is where all of the terrorists are getting on!

 

haha in cali? there's your problem- you didnt have a sign on it

 

Here you can see the side seal groove thickness differences as well as the side seal location difference. The Renesis side seals are definitely farther out. You can also see the apex seal depth differences.

 

Very interesting pics...
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About the rotors pics,

One interesting point here is that the side seals are already max further out (or at least almost max out) in the current rotors so no much future improvement in that area.

In my opinion rotor improvements will have to come from the use of lighter materials. Iron is not exactly a light one and again there is not much room for improvement weight wise. The renesis rotors are said to be 17% lighter than the latest inside the 13b-REW.

Thinking about alternative materials aluminium comes quickly to our mind. However I foresee possible problems with clearances due to a much higher expansion coefficient. Titanium? yes that solves both problems (weight and expansion coeff.) but casting and machining titanium is a nightmare and absolutely expensive.

So who knows what the next generation of rotors will be made of?

Cheers

jird20

 

What I find interesting is how much of the Renesis' development parallels that of piston engines. For example, moving the side seals closer to the edge of the rotor follows the trend to move the top ring closer to the top of the piston. I guess Mother Nature behaves the same no matter which engine she is in. Could the next gen. rotors be hybrid parts that have lighweight inserts in certain areas?

 

As far as the metallergy discussion, how about the same technology used in the F20C/F22C engines. The engine is carbon reinforced aluminum. From what I read it decreases the amount of thermal expansion in comparison to many other aluminum alloys, marginally stronger and more durable, light weight, and most important cost effective.

I am just not sure how much of that is good marketing and how much is true. Maybe that technology could be used in the Renesis in the future without increasing costs too much.

 

Anything lighter is better, I am sure Mazda has experimented with lighter metals/materials for the rotary engine. Hope they'll put it into production when its cost effective.
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RG, as you wrote: " A lighter apex seal can seal better with less spring pressure at higher rpms..."
I thought that a heavier seal needs less spring pressure, because of the bigger forces on it than on a lighter seal.

 

It depends what the seal is made of. Carbon apex seals are lighter but are softer. They can't use as much spring pressure but seal better above 8000 rpm. Ceramics on the other hand are the lightest out there. They are quite strong though and as such can use a very strong spring. The most important aspect of this is with the natural lubricating ability of ceramics. They are very slippery. Strength and their low coefficient of friction allows them to use high spring pressures. Carbon are soft, weak, and not as slippery. They can't have as much pressure.

 

I think ceramic rotors would be a better route than Titanium. You don't have to worry about them catching fire, there would be very little thermal growth, and they would be lighter. I'm not an expert, I don't even know what kind of ceramic or where to start but I think the concept could have promise. The problems I see are how to reduce their volunerability to shock and impact such as detonation or the gears on the e-shaft. If you put a metal gear ring inside the rotor then you'll have to deal with the hoop stress caused by the thermal growth of the metal gear ring inside the ceramic rotor.

 

You could do an aluminum rotor but the casting would have to be much thicker than the current one. You'd also have to modify oil flow through them and oil cooling as aluminum will pick up much more heat. It could be done. I wouldn't go the ceramic route. I don't see how it could survive the stresses.

 

I have thought about it.. but I dont think its a good idea to have the rotors made of brittle material. Therefore I think light metals/alloys would be the way to go.
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Are we back to steel then? Are the rotors currently cast? If so you could make forged rotors and go lighter. You could probably get fancy with the web of the rotor and make some kind of thin wall type cross section with a good FEA model. That's basically what we did when designing tubine rotors. They would have a thick center and then thin down in the web as you moved towards the rim and then add your combustion and sealing surface.

 

Heres the answer, RG answered a couple pages ago. I think they key is alloys, mixing different types of pure metals will give you benefits you cant find in any pure element.
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Yeah I agree that's the ceramic problem. Maybe some kind of metal fiber reinforcement. There are ceramic cutting tools for machining metal where they use a "whisker" reinforcement in the ceramic to help keep it from cracking.