Another Porting Question....this one is not related to the other
04-24-05, 09:55 AM
#1
Another Porting Question....this one is not related to the other
i was wondering, when you port the motor doesn't that shift the powerband more to the right? if thats so what can my friend who has a turbo 2 do to keep a good low to mid power. or should he not port it. he is currently buying parts to rebuild his motor.
04-24-05, 06:50 PM
#2
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Go read: http://www.rotaryengineillustrated.c...-ports101.html
Open the exhaust only 1mm up and 2mm down, only match up the sides.
Don't change the primary intake ports.
Slightly extend the closing (top) edge of ther secondarey intake ports, and maybe lower the bottom edge about 2mm.
Open the exhaust only 1mm up and 2mm down, only match up the sides.
Don't change the primary intake ports.
Slightly extend the closing (top) edge of ther secondarey intake ports, and maybe lower the bottom edge about 2mm.
04-24-05, 07:14 PM
#3
Lives on the Forum
You need to understand intake and exhaust port (or valve timing for piston engines) to understand what affects what.
Once you get the relationship, then it all makes sense - you just have to apply it to the rotary engine ports.
Intake timing - open earlier increases overlap.
Increasing overlap kills low end power due to exhaust gases mixing with fresh intake charge.
Intake timing - closes later increases intake timing duration.
This doesn't really have any downsides except for allowing more intake charge to be ingested on each intake stroke.
Exhaust timing - opening earlier allows exhaust gases to exit the engine earlier.
This KILLS low end power / torque, as the combustion isn't allowed to exert it's expanding forces on the eccentric shaft / crankshaft with more conservative exhaust porting / timing.
Exhaust timing - closing later increases overlap.
It's almost the same as intake timing opening earlier, but on this end it does allow you to remove more exhaust gases from the engine...except for some of the gases wanting to go into the intake charge.
Now, that's a very GENERAL description of the dynamics of the whole thing.
With turbos, things change a little (especially with overlap) depending on the boost pressure to exhaust pressure ratio.
You can shove enough boost into the engine to prevent the exhaust gases from coming back into the fresh intake charge if it can overcome the exhaust pressure - I think this ratio is 1:2?
Trying to get into all the itty bitty details can take VOLUMES of books...
-Ted
Once you get the relationship, then it all makes sense - you just have to apply it to the rotary engine ports.
Intake timing - open earlier increases overlap.
Increasing overlap kills low end power due to exhaust gases mixing with fresh intake charge.
Intake timing - closes later increases intake timing duration.
This doesn't really have any downsides except for allowing more intake charge to be ingested on each intake stroke.
Exhaust timing - opening earlier allows exhaust gases to exit the engine earlier.
This KILLS low end power / torque, as the combustion isn't allowed to exert it's expanding forces on the eccentric shaft / crankshaft with more conservative exhaust porting / timing.
Exhaust timing - closing later increases overlap.
It's almost the same as intake timing opening earlier, but on this end it does allow you to remove more exhaust gases from the engine...except for some of the gases wanting to go into the intake charge.
Now, that's a very GENERAL description of the dynamics of the whole thing.
With turbos, things change a little (especially with overlap) depending on the boost pressure to exhaust pressure ratio.
You can shove enough boost into the engine to prevent the exhaust gases from coming back into the fresh intake charge if it can overcome the exhaust pressure - I think this ratio is 1:2?
Trying to get into all the itty bitty details can take VOLUMES of books...
-Ted
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