Raising compression ratios?
11-26-09, 12:32 AM
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Raising compression ratios?
When I was searching around about compression ratios (yes folks, searching does do wonders!) I came across this thread https://www.rx7club.com/showthread.p...pression+ratio in which someone later in the thread says
Now I have no idea about the credibility of the poster, but it raises the question to me-Is this possible?
While the OP says that there is something to the material that needs to be used, and I expect there would be considering you most certainly wouldn't want the metal coming off the rotor while its running, how hard could it be? Has anyone done this? While this guy shrugs the power gains off as being insignificant, 10hp on an N/A 12a would be quite fantastic.
Guys their is a way to create higher compresion rotors.
You Take light weight S5 and you add material to the divits than you use water displacement to measure. This is a messed up way of doing it but it works.
A side note rotor must be rebalanced after this procedure sense you alter the mass of the rotor. I will not tell you what material is used in this process or the technique used to fuse it to the rotor. Im sorry but I went through alot to figure it out. Anyway power gians are not that signifigant at 10.0 you gian around 10hp after about 4k in the power band untill redline.
You Take light weight S5 and you add material to the divits than you use water displacement to measure. This is a messed up way of doing it but it works.
A side note rotor must be rebalanced after this procedure sense you alter the mass of the rotor. I will not tell you what material is used in this process or the technique used to fuse it to the rotor. Im sorry but I went through alot to figure it out. Anyway power gians are not that signifigant at 10.0 you gian around 10hp after about 4k in the power band untill redline.
While the OP says that there is something to the material that needs to be used, and I expect there would be considering you most certainly wouldn't want the metal coming off the rotor while its running, how hard could it be? Has anyone done this? While this guy shrugs the power gains off as being insignificant, 10hp on an N/A 12a would be quite fantastic.
11-26-09, 01:03 AM
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I would say yes its possible, but its not plausible.
Automakers don't design things to be half ***. When you think about how far Mazda brought the rotary engine from its original form to being reliable and usable, there's probably a reason for the way they shaped the rotors. Considering the cost this would have among other things like time, I'd say leave this alone. There's better ways to gain 10hp than messing with such a critical component.
Automakers don't design things to be half ***. When you think about how far Mazda brought the rotary engine from its original form to being reliable and usable, there's probably a reason for the way they shaped the rotors. Considering the cost this would have among other things like time, I'd say leave this alone. There's better ways to gain 10hp than messing with such a critical component.
11-26-09, 01:07 AM
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I'd just use Rx-8 rotors and counterwight. They're 10:1 rotors over stock 13B's 9.4:1(and lighter too). for 12A I don't know what you'd do.
Also, I'd say the guy was lying. I see no reason to keep something like that a secret from the fellow community. Just because it took a long time to figure out, you want to hide helpful information? Why even be on a forum? I'd say he's lying. Although it is true that making the divet smaller would raise compression, the theory is where it stops. I doubt he would have the funding to try several different compounds and fusing techniques, put it on a rotating assembly, balance it, and build the motor and dyno test it. The only reason he's keeping it a secret is because it's not true. If it was liability he was scared of, he could type out not being responsible if you tried it, hell this way he typed is even worse, he wants people to trash motor after motor trying different material adding techniques?
Also, I'd say the guy was lying. I see no reason to keep something like that a secret from the fellow community. Just because it took a long time to figure out, you want to hide helpful information? Why even be on a forum? I'd say he's lying. Although it is true that making the divet smaller would raise compression, the theory is where it stops. I doubt he would have the funding to try several different compounds and fusing techniques, put it on a rotating assembly, balance it, and build the motor and dyno test it. The only reason he's keeping it a secret is because it's not true. If it was liability he was scared of, he could type out not being responsible if you tried it, hell this way he typed is even worse, he wants people to trash motor after motor trying different material adding techniques?
11-26-09, 01:22 AM
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While I don't know of the specifics of getting RX-8 rotor into the 13b, I do know its not a drop in setup and does need some fairly substanial mods.
FunK73, while this is true, every auto manufacturer needs to make comprimises. They are to make money selling street cars, not to produce the perfect racing machine. Its not that higher compression rotors would completely ruin some magic aspect of the rotary, to the contrary Mazda has realized the importance of them, with the Renisis running high compression rotors and I believe the proposed 16x has pretty high compression as well.
While I'm not going to dig on the poster who claimed this, I'm thinking that fusing the two metals together couldn't be that hard, or am I overlooking at the forces the rotor faces endure? Either way, the sad part is that it would be hard to test out this theory without ruining motors.
FunK73, while this is true, every auto manufacturer needs to make comprimises. They are to make money selling street cars, not to produce the perfect racing machine. Its not that higher compression rotors would completely ruin some magic aspect of the rotary, to the contrary Mazda has realized the importance of them, with the Renisis running high compression rotors and I believe the proposed 16x has pretty high compression as well.
While I'm not going to dig on the poster who claimed this, I'm thinking that fusing the two metals together couldn't be that hard, or am I overlooking at the forces the rotor faces endure? Either way, the sad part is that it would be hard to test out this theory without ruining motors.
11-26-09, 02:14 AM
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I don't see how it wouldn't just work? It's the same dimensions. The RENESIS is a 13B. It uses 13B rotor housings, just without the peripheral port machined into it.
11-26-09, 02:28 AM
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Or maybe I'm just being retarded again. Lol.
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11-26-09, 03:08 AM
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I looked it up and it says that you can swap directly, but it's recommended that you machine to accept 2nd Gen apex seals, as the RENESIS uses thinner seals because there is less of a chance of apex seal failure without the seal passing over a peripheral exhaust port. So when you install them in an engine with the peripheral port, they are less durable. The side seals are also a little different, but will work.
11-26-09, 11:55 AM
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If you're going to go to that much effort, why not just buy and install a renesis engine?
Do any of the reputable race-prep companies ever fiddle with trying to change a rotor's compression ratio? None I'm aware of. You see a lot of extremely technical mods, but not that one. gotta be a reason.
The divot in the rotor is there to allow proper flame-front propogation; if you raise engine compression by eliminating divot volume, you do it at the cost of interfering with combustion efficiency. Kind of seems self-defeating.
Do any of the reputable race-prep companies ever fiddle with trying to change a rotor's compression ratio? None I'm aware of. You see a lot of extremely technical mods, but not that one. gotta be a reason.
The divot in the rotor is there to allow proper flame-front propogation; if you raise engine compression by eliminating divot volume, you do it at the cost of interfering with combustion efficiency. Kind of seems self-defeating.
11-26-09, 01:26 PM
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If you're going to go to that much effort, why not just buy and install a renesis engine?
Do any of the reputable race-prep companies ever fiddle with trying to change a rotor's compression ratio? None I'm aware of. You see a lot of extremely technical mods, but not that one. gotta be a reason.
The divot in the rotor is there to allow proper flame-front propogation; if you raise engine compression by eliminating divot volume, you do it at the cost of interfering with combustion efficiency. Kind of seems self-defeating.
Do any of the reputable race-prep companies ever fiddle with trying to change a rotor's compression ratio? None I'm aware of. You see a lot of extremely technical mods, but not that one. gotta be a reason.
The divot in the rotor is there to allow proper flame-front propogation; if you raise engine compression by eliminating divot volume, you do it at the cost of interfering with combustion efficiency. Kind of seems self-defeating.
There is a thread entitled "New Rotor Technology" where they're experimenting with higher compression ratios (they're shooting for 13:1) on billet rotors that will be/are for sale. The biggest issue that I can see with going that high is that you'll be required to run race fuel or meth injection to stop knock.
https://www.rx7club.com/showthread.p...tor+technology
11-26-09, 01:36 PM
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I will have to take the time to sit down and read all those pages, but skimming through it I saw that they never really addressed the concern of seal wear on the billet aluminum housings, I would also like to see how they dealt with flame propagation. If I remember correctly there was a Mazda Racing Manual that described expanding or filling in the rotors to adjust for racing applications, perhaps similar theory could be applied to increase compression without affecting flame propagation?
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