Using turbo rotors on an NA PP build
12-01-17, 10:45 AM
#27
Intake pressure is lowest when the exhaust port pressure is highest... on the primary length that loses by 15% volumetric efficiency at 5k RPM.
You have confused yourself looking at data.
The data shows intake and exhaust pressure- yes. But it is measured in the intake and exhaust manifold.
The fact that pressure traces in the exhaust manifold vary with exhaust length shows the effect of measuring in the manifold versus what is happening at the port.
You KNOW the exhaust velocity and pressure is highest in the exhaust port as soon as the exhaust port opens and then it quickly blows down.
Now, mock up a side housing, rotor housing, e-shaft and rotor and turn it to where the exhaust port is just opening.
Put plexi over the top with a hole to blow compressed air into the exhaust chamber and put a magnehelic gauge in the intake port (or confetti).
Now imagine the order more powerful the dynamic is with actual exhaust port velocity and flow with 300hp of air and fuel being exhausted.
12-01-17, 12:05 PM
#28
spoon!
You're proposing over and over that the main scavenging effects are due to the initial blowdown. Not the acoustic tuning of the exhaust primary, where the negative pressure wave is seen at the exhaust port at a time after blowdown determined by (simplifying a little) primary length and the speed of sound in hot exhaust.
If the primary scavenging effect were due to initial blowdown, exhaust runner length would not matter. The mechanism of action you're talking about would all happen in at most about 20 degrees, on the outgoing pulse, too fast for any acoustic effects.
I say that there is more than adequate experimental and real world evidence that changing exhaust primary affects volumetric efficiency at various RPMs, exactly in the manner that acoustically tuning exhaust runner lengths affect volumetric efficiency at various RPMs on piston engines.
Tell you what, I'll delve into this again if I determine on the engine dyno that changing exhaust length doesn't affect anything.
12-01-17, 12:54 PM
#29
No, I agree that the traditional scavenging through pressure wave/pulse tuning of the exhaust has a great positive affect on the rotary power as all the evidence and years of experience show.
I agree that what Mazda has done and what can be further done on the 13B-MSP to make power is a testament to this.
That is what you CAN change on the rotary engine, so of course we focus on that when trying to make more power.
I am simply saying the main overlap scavenging affect of peripheral port exhaust rotary from exhaust blow down is built right in with the peripheral exhaust port and cannot be changed (but can be amplified by increasing the amount of intake port open to communicate with the intake manifold while the exhaust blow down scavenging is in affect).
The 13B-MSP is also a testament to this.
With exhaust, intake and other tuning on the 13B-MSP you still fall short of what can be done with similar intake port on the old peripheral exhaust port 13B. I'm talking big money race team making 225rwhp on the 13B-MSP (amazing) in Grand Am racing and club racers making 240rwhp on 13B with a streetport and a carb (while being limited on intake opening line) in SCCA E-prod racing.
Put a bridge or peripheral port intake on the 13B-MSP and what we have seen so far (not as many as I would like) the difference to a bridge or peripheral port 13B with peripheral exhaust and the difference becomes further magnified on the order of over 100hp difference.
Not much development yet on the bridge and peripheral port 13B-MSP yet though- they will improve if there is any reason to run that set-up (racing rules).
I agree that what Mazda has done and what can be further done on the 13B-MSP to make power is a testament to this.
That is what you CAN change on the rotary engine, so of course we focus on that when trying to make more power.
I am simply saying the main overlap scavenging affect of peripheral port exhaust rotary from exhaust blow down is built right in with the peripheral exhaust port and cannot be changed (but can be amplified by increasing the amount of intake port open to communicate with the intake manifold while the exhaust blow down scavenging is in affect).
The 13B-MSP is also a testament to this.
With exhaust, intake and other tuning on the 13B-MSP you still fall short of what can be done with similar intake port on the old peripheral exhaust port 13B. I'm talking big money race team making 225rwhp on the 13B-MSP (amazing) in Grand Am racing and club racers making 240rwhp on 13B with a streetport and a carb (while being limited on intake opening line) in SCCA E-prod racing.
Put a bridge or peripheral port intake on the 13B-MSP and what we have seen so far (not as many as I would like) the difference to a bridge or peripheral port 13B with peripheral exhaust and the difference becomes further magnified on the order of over 100hp difference.
Not much development yet on the bridge and peripheral port 13B-MSP yet though- they will improve if there is any reason to run that set-up (racing rules).
12-02-17, 07:27 AM
#30
BLUETII,
If I may interject with a question, so if my understanding is correct, you're predicting that a 13B-MSP with a peripheral or BP intake side port will produce an larger, albeit undisclosed/undiscovered, power gain over the older sideport intake/peripheral exhaust?
-Tim
If I may interject with a question, so if my understanding is correct, you're predicting that a 13B-MSP with a peripheral or BP intake side port will produce an larger, albeit undisclosed/undiscovered, power gain over the older sideport intake/peripheral exhaust?
-Tim
12-04-17, 12:37 PM
#31
I think peripheral port intake side port exhaust 13B-MSP 13B could improve over its current state of ~264hp engine dyno #s.
But I also feel like side intake peripheral exhaust port 13B #s could improve over the current 280hp engine dyno #s as well (because that E-prod engine had conservative intake port opening timing.)
If one used 13B-MSP engine with side exhausts blocked off and ported 13B GSL-SE rotor housings or just 13B-MSP rotating assembly with 13B-REW side ports ported to 13B-MSP opening specs I would expect one could get over 290hp engine dyno (250rwhp Dynojet) with a lot of careful work.
But I am not going to spend $$$$ on dyno hours, ECU tuning and exhaust/intake length tuning to support either of my predictions. It is just an opinion.
But I also feel like side intake peripheral exhaust port 13B #s could improve over the current 280hp engine dyno #s as well (because that E-prod engine had conservative intake port opening timing.)
If one used 13B-MSP engine with side exhausts blocked off and ported 13B GSL-SE rotor housings or just 13B-MSP rotating assembly with 13B-REW side ports ported to 13B-MSP opening specs I would expect one could get over 290hp engine dyno (250rwhp Dynojet) with a lot of careful work.
But I am not going to spend $$$$ on dyno hours, ECU tuning and exhaust/intake length tuning to support either of my predictions. It is just an opinion.