I agree for longevity, an engine should be balanced, but I have yet to run into balancing issues with any rotary engine. Even my s4 4-port with 300 grams removed from either rotor (and no other balancing performed) pulls smooth to 9,000 rpm. (In fact, that was how I talked the dyno guys into letting me run to 8,000 rpm was by laying my hand on the engine as I revved it to 9,000 rpm to show how smooth it was.)
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The ITS car makes about 138 lb/ft peak at around 6200 rpm. Peak power is around 7700. It has 120+ lb/ft from 4000 - 7700. Not sure what you consider "low end" but you're not going to find a rotary that makes power below 4000 and has any kind of high end power.
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This is interesting as my 4-port made 160 Wlb-ft at 6100 RPM and 216 WHp at 7500 rpm. (I still contend that this is limited by ignition and compression ratio). The curves are similar, only the 6-port is 15% lower. This 138 WLb-ft is the problem. If I could get 160 Wlb-ft out of that like I can out of my 4-port, I would have no trouble with the 200 WHp goal. That late intake port close is KILLING me. Even 120 Wlb-ft past 4,000 is not that good, as my 4-port makes that at 2500.
Reading this has almost convinced me to port the primaries and the lower port of the 6PI and fill the top port with iron-ceramic. I think I could make as much power at considerably lower revs (I'm talking 7,000 rpm territory) if I could get rid of the late port close caused by the 6PI.
I don't intend to rev this engine to 10,000 rpm, as it will have stock s4 internals (I will stop at 9,000). I do intend to make 200 WHp, but to do that - I need more torque. To get more torque, I need to have better VE. To do that, I can't force 28% of my intake charge back out into the intake manifold.
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The 182 was an SCCA ITS car, so by the rule book everything must be stock from the entrance of the airflow meter to the exit of the exhaust port, with the exception of having the 6 port sleeves and their actuators removed, which is allowed. The Dyno Dynamics dynos typically read around 15% lower than Dynojets. I'm skeptical of that number at the lower end of the scale though. Typically a good ITS car will put down 175-180 on a Dynojet. This particular car has been proven on track to be a bit of freak and is certainly at the pointy end of the class. I wouldn't be surprised to see 190 on a Dynojet but 200+ on stock ports is just hard to believe.
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I completely agree. I made 155 WHp with my stock s4 6-port and I was happy with that. Thankfully, I am not limiting myself to SCCA rules, or I would be in trouble. The big issue is that I am not running against Dynojet numbers, I must make 200 WHp on a Mustang Dyno. (Which is somewhere near 210 WHp on a dynojet).
Right now I think I will try:
Porting:
Porting the Primary port to max-effort (without changing timing, gaining port area by crowding the Oil control rings).
Porting the secondary port (the lower one) to max-effort (modifying port to max out against bottom of 6PI port and crowding the oil control rings).
Removing 6PI port from the equation altogether.
Manifold:
Matching port cross-section in LIM
Filling portion of manifold that fed 6PI with aluminum-ceramic.
Manufacturing custom UIM
I will post some porting ideas/sketches up tomorrow for discussion.