Whiplash! (RX8 style rotor beveling)
#27
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Awesome, its always nice to see people trying something different to make some power. I saw the post about the CLR rotors in the Rotary Performance section a few months back, that rotor is amazing! I'm sure theirs are crazy expensive though.
Keep us updated on any abnormal wear/vibrations in the rotating assembly.
Keep us updated on any abnormal wear/vibrations in the rotating assembly.
#28
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Well, since I have two engines to play with, I know what I'll be looking into when I decide which one to play with.![bgth](https://www.rx7club.com/images/smilies/biggthumpup.gif)
I just wonder how much it'll hurt smogability. I guess I could just swap out the engine/exhaust every two years!
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I just wonder how much it'll hurt smogability. I guess I could just swap out the engine/exhaust every two years!
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So upon doing this, did you lose any low end torque? And as for the rotating assembly comment, Are you talking aout the housing or what? Curious....
#31
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Anytime you increase the port timing past a certain amount, you should lose low end torque (below 3k rpm). Although, stock ports are so bad, you can port quite a bit more timing into them and keep all the low end your stock motor has so long as you keep the exhaust port small. The exhaust port really sets the power potential and low end torque of the rotary in my opinion.
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Those rotors are crazy, wish I had some extra dough! Might be worth trying to bevel like the renesis rotors, since I have an extra pair sitting around... lol
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#33
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Originally Posted by Icemark
The rotor champhering is the same as porting for timing (rather than volumn). You effectivly delay the close of the intake slightly longer.
Last edited by scathcart; 06-30-05 at 01:09 AM.
#34
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Heck, I put the bevels on the entire rotor, not just one side so I've got more opening and closing timing than before, and the powerband sure feels like it. The reduction in the sharp corner as the rotor obscures the opening or closing port is the main reason I did it, but the added few degrees of opening and closing timing didn't seem to hurt.
#35
Originally Posted by 88IntegraLS
Anytime you increase the port timing past a certain amount, you should lose low end torque (below 3k rpm). Although, stock ports are so bad, you can port quite a bit more timing into them and keep all the low end your stock motor has so long as you keep the exhaust port small. The exhaust port really sets the power potential and low end torque of the rotary in my opinion.
this is interesting.
care to offer any more input on this? i'm currently porting my exhaust and intake ports...
#36
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You can port the intakes with a lot of timing without a lot of port volume if you do it a certain way. I've always tried to keep my port runners and bowls small while getting a lot of timing, and I think that's why I've gotten away with such large ports after all these revisions and still have stock low end torque from 1.5k-3k rpm. Below 1.5k my engine doesn't make much power but it idles smooth at 800 rpm with .4 atu vacuum, but above 3k it's like a very mild bridgeport in that it wakes up and starts hitting its power band. The torque peaks at about 5.5k and doesn't really fall until 7k, probably due to my stock main cat and cat back. I sold my SAFC so it's maxing out the airflow meter again at 6.5k like it used to.
But yeah, keep the runners and bowls small, keep the exhaust sleeves, keep everything smooth smooth smooth, exhaust port bevels can actually be radiuses from the housing to the port runner. Small corners cause turbulence which = aerodynamic drag for the fluid flowing through the engine. I didn't take pix of my latest ports because I'm at my wits end with side seal issues, but I've thoroughly abused this engine for the past two tanks of gas and it just begs for more. It's running better than ever, so maybe my side seal problems are over, who knows.
I wrote up a porting thread on nopistions covering all this, and 90% of the members ate it up and wanted more, but their wannabe rotary dieties called BS and didn't want to provide proof of the flaws they supposedly saw in my ideas. Water under the bridge.......
But yeah, keep the runners and bowls small, keep the exhaust sleeves, keep everything smooth smooth smooth, exhaust port bevels can actually be radiuses from the housing to the port runner. Small corners cause turbulence which = aerodynamic drag for the fluid flowing through the engine. I didn't take pix of my latest ports because I'm at my wits end with side seal issues, but I've thoroughly abused this engine for the past two tanks of gas and it just begs for more. It's running better than ever, so maybe my side seal problems are over, who knows.
I wrote up a porting thread on nopistions covering all this, and 90% of the members ate it up and wanted more, but their wannabe rotary dieties called BS and didn't want to provide proof of the flaws they supposedly saw in my ideas. Water under the bridge.......
#37
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Originally Posted by 88IntegraLS
On the RX8 renesis rotors, there is a ~3mm bevel on their sides, for good reason: half the time in a running engine, the ports are obstructed by part of the rotor as it sweeps past. In our FC engines, this edge is a sharp corner but in the renesis it is a more aerodynamic bevel shape. Looking for any last tweak I could do to make my s4 NA engine totally rock, I tried beveling the rotor sides like this the last time I had the motor apart.
Fast forward to right now. The motor fu$king rips harder than ever before! I didn't do anything to my ports other than minor little tweaks, and the engine definately has more port timing as well as a flatter power band up high. It could seriously not fall off above 7.5k rpm like it usually does, if only the rev limiter was gone (megasquirt 'n spark to the rescue). This is like having a bridgeport without the bad emissions and gas mileage, rough idle, etc. Oh yeah, the car is like a harder hit of cocaine now than it once was before, I just want to floor it up to 130 and back over and over again! The power band is unbelievable, it just wants more and more, the more you rev it the more it puts out.
Fast forward to right now. The motor fu$king rips harder than ever before! I didn't do anything to my ports other than minor little tweaks, and the engine definately has more port timing as well as a flatter power band up high. It could seriously not fall off above 7.5k rpm like it usually does, if only the rev limiter was gone (megasquirt 'n spark to the rescue). This is like having a bridgeport without the bad emissions and gas mileage, rough idle, etc. Oh yeah, the car is like a harder hit of cocaine now than it once was before, I just want to floor it up to 130 and back over and over again! The power band is unbelievable, it just wants more and more, the more you rev it the more it puts out.
-Ted
#39
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Renesis rotors only fit their smaller apex seals which, according to mazdatrix.com, won't work with S3-S6 13b peripheral exhaust ports. They built a motor with renesis rotors and peripheral exhaust housings using the stock renesis seals and had problems I guess, but I can't remember where I read it. To use the S3-S6 apex seals in renesis rotors, some kind of special milling will be required because the renesis seals are not as deep.
#40
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Originally Posted by RETed
You're telling me you rebuild your motor and kept everything else stock *except* for putting chamfers on the rotors???
-Ted
#41
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Originally Posted by LiquidMetal
Wow thats cool,but If I were running an NA,would it be a better idea to go with the renesis rotors since they have a little higher comp?
#43
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Originally Posted by RETed
I don't get an answer to my question?
-Ted
-Ted
This is my understanding at least, but he can correct me if I'm wrong
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#44
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I beveled the rotors this last time, the time before I just smoothed off the sharp corner to give a .25mmish radius to them instead of a corner. This last time I added a full 2mm bevel all across the edges of each rotor corner.
The port job is now a semi-combined aux / secondary style, where the side seals see one big port like a ported FD secondary, while the runners see their bowl / aux sleeve like before until about 5mm below the side housing surface.
I can't believe how badly the power from 5k on up kicks ***! *giggle* Ddub, drive the car after I get the megasquirt on it. Zjbarra drove it, astrochild7 drove it, all before I did my latest surgery. I think they found it pretty entertaining.
The port job is now a semi-combined aux / secondary style, where the side seals see one big port like a ported FD secondary, while the runners see their bowl / aux sleeve like before until about 5mm below the side housing surface.
I can't believe how badly the power from 5k on up kicks ***! *giggle* Ddub, drive the car after I get the megasquirt on it. Zjbarra drove it, astrochild7 drove it, all before I did my latest surgery. I think they found it pretty entertaining.
#47
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Originally Posted by dDuB
He's been fine tuning his ports for a while as far as I know. With the extreme streetports he's been developing he had side seal issues, and every time he figured this out he'd tear it back down to further troubleshoot the side seal problem. The tear down before this last one is when he beveled the rotors I believe, I think I remember him telling me that or reading it in the NW section, can't remember precisely. But soon after discovered side seal problems still. So this last tear down, again I think, he finally got all the bugs worked out on his ports and might have beveled the rotors slightly more, and is now actually able to tear up the streets with his car and really feel the difference of the beveling and port design.
How do you get a good baseline if the engine had problems prior to this???
-Ted
#48
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Originally Posted by RETed
So you're saying the engine never ran well prior to his previous rebuild.
How do you get a good baseline if the engine had problems prior to this???
-Ted
How do you get a good baseline if the engine had problems prior to this???
-Ted
Originally Posted by 88IntegraLS
Looking for any last tweak I could do to make my s4 NA engine totally rock, I tried beveling the rotor sides like this the last time I had the motor apart.
I didn't do anything to my ports other than minor little tweaks, and the engine definately has more port timing as well as a flatter power band up high.
I didn't do anything to my ports other than minor little tweaks, and the engine definately has more port timing as well as a flatter power band up high.
#49
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so,
how accurate IS your butt dyno?
lol.
interesting stuff but its all butt dyno comparison so far isnt it?
that CLR rotor is beautiful, how much $$$ is that work?
how accurate IS your butt dyno?
lol.
interesting stuff but its all butt dyno comparison so far isnt it?
that CLR rotor is beautiful, how much $$$ is that work?
#50
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Originally Posted by 88IntegraLS
Friend, you are mist[aken. The engine ran extremely well for about a month to a year before a side seal would break. Regarding the baseline that I am comparing to, it is the state of my street port prior to beveling the rotors. In my first post I wrote:
If you can't surmise the point of my post without getting defiant with me, I have nothing left to say........... have a great day!
If you can't surmise the point of my post without getting defiant with me, I have nothing left to say........... have a great day!
I have a hard time just beveling the rotors will offers such a performance increase.
I think it's psychological or you never got a good baseline in the first place.
If side seal problems were the culprit early, the side seal would've been damage right after the initial start-up.
Side seal damage will affect compression negatively.
Beveling the rotors amounts to adding a few degrees of intake duration; this increase in intake duration is not supposed to make that big of a difference.
So either your claims are overstated or something else is amiss.
If you had dyno charts before and after, it would be different.
But I call the bullshit flag unless you have better evidence of such claims...
-Ted