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I just was told that the org FD rotors are week, and I hade to use the S4 rotors..
Then I could have a boost of 1.6 bars on race fuel..
Anyone heard of that?
hmmm sounds dumb to me... the rotors are perfectly stout... if anything the apex seals are the weak point...but thats on all rotors... not sure of the compression ratio on an s4 but I think the fd rotors are a lower compression ratio.... I've heard of people putting s4 NA rotors in to raise compression and run c16 to get more low end... but the purpose behind low compression is to alow more boost on pump fuel. On c16 I've heard of ungodly compression ratios used like 14~16:1 with boost in the upper 20'sto mid 30's.... failure parts would be apex seals and housings not rotors.... if an apex seal is made that can take that kind of pressure I'd like to see it though. Only heard of piston motors running that kind of pressure.
Anyhow 1.6 bar is possible with stock rotors on pump/meth injection.... thats what like 22ish psi?
The guy that told me this is a tuner in sweden, he told me that the rotor would implode..
It sounds like bullshit..
1.6 bar would be like 22 psi.
There are 2 tuners in sweden, and they don`t agre on anything.. LOL
I`m building a PP 13B and I don`t wont the motor too fail on maping..
Thats why I`m checking..
FD rotors are thinner on the face they are much easier to dent should you have any det. The older rotors are thicker, and once lightened are preferred for higher hp motors by lots people for their ability to handle abuse better.
wow didn't know that... guess you really do learn something new every day.... but if you happen to ping bad enough to dent a rotor wouldn't the apex seal fail anyways and trash the rotor regardles?
What Zero R said, the FD rotors are casted thinner under the faces of the rotor and have been known to dent from excessive combustion chamber pressures (from detonation or bad timming). If you use the s4 rotors, you must run the appropriet s4 counter weights and or lighten the rotors and have them balanced using the FD counter weights. Balancing any race engine is a good idea in my opinion anyways (I balance my street engines).
BTW, the FD/s5 static compression ratio is HIGHER then s4 (9:1 vers 8.5:1)
wow didn't know that... guess you really do learn something new every day.... but if you happen to ping bad enough to dent a rotor wouldn't the apex seal fail anyways and trash the rotor regardles?
NO, not always. I've first hand seen a dented rotor and the apex seals did survive, however the rear plate did crack near the oil pedistol. I've also seen many dented rotor pictures, a few did not have apex seal failures. one in particular didn't have anything wrong except a dented rotor. The engine was eventually pulled and rebuilt because it just finally wore out and had low compression, who knows how long the rotors were dented.
Dented rotors usually comes from extremely high combustion chamber pressure. For this it actually doesn't matter much whether you are detonating or not, but timing too advanced will raise pressure and make this damage more likely even if you avoid any sort of detonation. Apex seals aren't affected by excessive pressure much because they will leak before they will bend and this leakage does not damage them. Detonation on the other hand breaks apex seals because it is a shock wave rather than simple high pressure, and the apex seals are simply not big enough to withstand the impact.
I don't know whether the S6 or S4 rotors are stronger. It's plausible the S4 are. Either way it is not going to matter until your power is VERY high.
Dented rotors are usually caused by ignition crossfire, where you are actually trying to turn the rotors backwards. We see this all the time on FDs and the cure seems to be new trailing coils.
S4 rotors are marginally stronger than FD (S6) rotors, but the lost compression means you will need to run even higher boost to get back the lost torque. In practice, there is no good reason to run S4 rotors in place of FD rotors as long as the tuning is good/safe. If the tuning is not good/safe, stay home.
So im guessing based on the knowledge from above; SCAPLLOPED (FD) Rotors are definitely out of the question since material is taken off on all 3 of the thin faces, thus having a higher chance to EMPLODE sooner.
also what about doing a race clearance?
correct me if im wrong; because I was seriously considering on doing this for my current single turbo engine build.
Scalloped rotor is nice because you can add port timing without adding port volume which improves intake velocity for low end punch.
It is also nice in racing if the class puts limits on the port opening line, but allows such modifications to the rotor (earlier port opening like RX-8 rotor).
I think the RX-8 proves that the scalloped rotor isn't just good for race engines. RX-8 has scalloped rotors on the 6 port high power engines and the 4 port low power engines...
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As far as torque with higher compression rotors.
Show me a turbo rotary dyno sheet where you can conclusively say a motor makes more torque on higher compression ratio than another on lower compression ratio rotors. Won't happen.
High compression ratio rotors will provide better engine response and gas mileage.
Higher boost from running lower compression rotors will always provide more torque. Torque you can easily see on the dyno sheet.
I think the RX-8 proves that the scalloped rotor isn't just good for race engines. RX-8 has scalloped rotors on the 6 port high power engines and the 4 port low power engines...
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But lets not forget that the scallop exposes the side seal to more heat in the Rx8 engines. I remember reading that Mazda has moved the side seals furthure inward and eliminated the scalope on the newer engines. I would rather have long term reliability over a few ponies.
Yes, I agree the scallops contributed to the weakening of side seal springs and wear on sideseals on the side exhaust port Renesis.
On a peripheral exhaust motor the only downside I can see to the scallop is it exposes the side seal groove to more of a possibility of foreign object damage.
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Mazda definitely is moving the side seal back toward the center of the rotor a bit to help relieve the Renesis problem. On the peripheral port intake generator motor the rotor bevel was obviously eliminated.
I don't know if the Skyactiv-R 16X will be side intake port or peripheral intake port. If its side intake, I bet the bevel will be back on the rotor.
Only way I can see that they can add the overlap back in with a peripheral port intake and meet emissions is if it is direct injection timed or placed so the injection event happens after the apex seal closes the intake port.
With an PP intake, how would you stabilize the idle with the overflap? Even with direct injection, you would still have air reversion back up the intake runner from the late closing port timing. I'm hoping for the return of the PP exhaust myself.
With an PP intake, how would you stabilize the idle with the overflap? Even with direct injection, you would still have air reversion back up the intake runner from the late closing port timing. I'm hoping for the return of the PP exhaust myself.
You have choices.
1) you don't stabilize the idle you use idle engine stop technology.
2) you don't have a throttle plate so there is no exhaust drawn into the intake stroke. This is in conjunction with homogeneous charge compression ignition/direct injection which is something that has been hinted at.
