Quote:
Originally Posted by TitaniumTT
HA! That's ballsy for an engine that's so pristine  I would have to build an entirely new exhaust system and I seem to be getting overloaded with projects this winter. Altough, I think the RE mani would be the best suited for an N/A - least amount of bends. |
If you polished the outside radius of each bend and equalized your cross-sectional area throughout the runner and matched that to the port. You should see significant improvements on my 216 WHp. I would expect your engine to make about 240 WHp as it sits, (given the previous assumptions based on piston engine knowledge) With the following additional assumptions:
Intake port timing has been changed to close a little later than stock.
Intake manifold has been port matched, but not blueprinted.
Non-polished rotors do not significantly impede flow past TDC cusp in the rotor housing.
If your manifold were Blueprinted (constant cross-sectional area through entire intake runner) I think you could look 260 WHp in the face.
If you didn't change stock port timing, I think you could get 285 WHp.
Believe it or not, (it seems impossible to convince turbo guys of this) 0.91L will not hurt your engine NA. 1.1L will not hurt your engine NA. You will not burn a hole in a rotor (your rotors are oil-cooled) and detonation is not a problem when you are naturally aspirated. Ignition timing is not a problem either, run whatever give peak power (34 BTDC may be better for you with 9.0:1 CR and un-polished rotors). If it makes you feel better, run 0.86L (this will give almost identical power to 0.91, these are the edges of the peak power range).
Quote:
Originally Posted by TitaniumTT
The FD will recieve a 13B-RE engine. Whether it is the engine that is in the FC, that will be determinted based on timing. Ideally I'd build an RE with twin GT28's or 32's sporting thier own wastegate and runner. They'd be parellel which is why I'm leaning towards the GT28's. I'd like to see 450 RWHP and slightly quicker spool than I'm getting with the twin's running non-sequential.
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Why RE and not REW? I think that the RE has bigger intake ports (could be good, if runners will match) and earlier exhaust port opening (not necessarily good for EGT). What other advantages does it have?
Quote:
Originally Posted by TitaniumTT
What are you running for coils now?
I would REALLY like to see some back to back comparisions between whatever coils you're using now and the Yukon truck coils. I'm actually planning on upgrading to them over the winter. Either those or some Bosch coils that have been dyno proven to give an increase over the renni coils which the guys at MoTeC loved for a long time.
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Bone Stock 200,000+ miles coils that came on the car.
Quote:
Originally Posted by TitaniumTT
If you're going for some 9.5:1's.... isn't it 9.7:1?.... why not just go for broke and rock some FE 10:1's?
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The rotors are 9.5:1 because they have been polished to 2000 grit and lightened to < 4kg. (CR empirically determined with sealed ports).
I have a very limited budget for this car, most of my parts were either obtained out of the scrap hopper at work, given to me by friends or custom fabricated by your's truly. I try not to spend much money on this hobby.
Quote:
Originally Posted by TitaniumTT
Why would you expect a street port to exceed the P-Port? The P-Port will be peakier no doubt, but it can swallow a ton more air. I would think that the P-Port would overtake the street port after a certain RPM.
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I don't intend for the P-port to be a crazy runner, I am not building it for such. It will have 9.4:1 normal rotors, minimal overlap (for a PP) and tame port sizing. My goal is not to rev it to 12,000 rpm and make power all the way, but rather to see if I can get it to be mild-mannered and street-drivable while still making 250 WHp. I see it as the poor man's PP.
The only way to make a P-Port swallow more air than a streetport is to make the intake port larger than the combined total of both intake ports on the street port and to make the exhaust backpressure absolutely minimal, while maximizing the intake pressure. High-overlap engines tend to be more finicky and make less average power than equivalently built lower-overlap engines. Building them is not really that easy. (For example, I have a combined cross-sectional area of intake ports/runners of 3.2 in2, this would be a very large P-port, slightly over 2-inch diameter). I am intending more like a 1.7-2.0 in2 port cross-section for the p-port. I want to try for max power on a later p-port, but this one will have stock internals and I will not rev it past 9,000 rpm (eliminating the need for big ports).
Piston engine guys need large overlap times to scavenge the chambers and to get air through their restrictive intake valves and runners. Rotaries don't have any of those problems with > 270 degrees of eccentric shaft rotation per intake stroke from a street port or 320 from a p-port (duration is not that much better on the P-Port)
The VE (empirical, based on fuel and AFR, probably reads 3-5% high due to injector energization delay) on my 4-port breaks 100% @ 4800 rpm, peaks at 108% @ 7700 rpm and drops to 102% @ 9,000 rpm. At tuned resonance, a P-port could achieve ~125% VE (due to overlap), but could not hold that for a broad torque curve. Peaky power bands do no good for performance, area under the Horsepower curve is your friend.
I really should be posting this in the general Rotary tech section, but most of it is already there.