Port Timing Questions
03-25-2005, 09:52 PM
#1
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Thread Starter
Join Date: Sep 2004
Location: Alaska
Posts: 35
Hey,
This may be aimed more at the advanced but here we go.I've got two motors
disassembled.An 84 13b and an S5 4 port with n/a rotors.The 6 port is stock and the 4 port has a street port.
First question,when the rotor has pushed out as much exhaust possible the intake port is just starting to open,(this looks like the one drawback to a bridge port).On a modified exhaust port the port is still open for a few degrees of crank rotation looking like it would allow exhaust gasses to be recirculated.Either
A:the gas is being recirculated,B:the intake charge starting to come into the chamber creates a wall to stop this,orC:it doesnt really make that big of a difference.Anyway,at what point do you start causing problems caused from the exhaust port being too high....I understand why you would not want the bottom of the port to open too soon,but the top of the port is my hurdle.
second question:similar to the first but on the intake ports.The ports on a six port are open a long time(as far as crank duration).When the rotor has passed the point of maximum static volume the ports are still open,I have heard terms like internal supercharging but have not heard a good explanation of this.At what point of having the intake ports open too long do you start compromising velocity or just plain not being affective?the reason I ask this is that the 6 port motor can have the primary ports opened up for a very long time(through porting of course) and at least visually seem to be able to flow more than street ported 4 port...But I could very well be wrong.
Thanks for any input,I am trying to learn from other people's(is that even a word?)experience because I just do not have the parts availability to do the trial and error thing.I am going to build a few motors,one for the first gen to sell,and another for the third gen to play,thanks again
nick
This may be aimed more at the advanced but here we go.I've got two motors
disassembled.An 84 13b and an S5 4 port with n/a rotors.The 6 port is stock and the 4 port has a street port.
First question,when the rotor has pushed out as much exhaust possible the intake port is just starting to open,(this looks like the one drawback to a bridge port).On a modified exhaust port the port is still open for a few degrees of crank rotation looking like it would allow exhaust gasses to be recirculated.Either
A:the gas is being recirculated,B:the intake charge starting to come into the chamber creates a wall to stop this,orC:it doesnt really make that big of a difference.Anyway,at what point do you start causing problems caused from the exhaust port being too high....I understand why you would not want the bottom of the port to open too soon,but the top of the port is my hurdle.
second question:similar to the first but on the intake ports.The ports on a six port are open a long time(as far as crank duration).When the rotor has passed the point of maximum static volume the ports are still open,I have heard terms like internal supercharging but have not heard a good explanation of this.At what point of having the intake ports open too long do you start compromising velocity or just plain not being affective?the reason I ask this is that the 6 port motor can have the primary ports opened up for a very long time(through porting of course) and at least visually seem to be able to flow more than street ported 4 port...But I could very well be wrong.
Thanks for any input,I am trying to learn from other people's(is that even a word?)experience because I just do not have the parts availability to do the trial and error thing.I am going to build a few motors,one for the first gen to sell,and another for the third gen to play,thanks again
nick
03-26-2005, 10:59 AM
#2
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Thread Starter
Join Date: Sep 2004
Location: Alaska
Posts: 35
Maybe that was way to confusing,
I would like to hear your opinions on porting with the pro's vs. the cons of different port timing and design/style of ports.
Like I said before I don't have much experience with porting but I have allot of ideas,I don't want to go overboard....
Nick
I would like to hear your opinions on porting with the pro's vs. the cons of different port timing and design/style of ports.
Like I said before I don't have much experience with porting but I have allot of ideas,I don't want to go overboard....
Nick
03-26-2005, 11:54 AM
#4
Senior Member
Join Date: May 2002
Location: Richardson Texas
Posts: 4,326
[quote name='phinsup' date='Mar 26 2005, 11:05 AM']I am sure ito will reply however his online time is ilmted right now, I would give him a couple days 
[/quote]
i heard jerry went and killed ito but his car still doesnt run bc now theres no one to fix it?
[snapback]691151[/snapback]
[/quote]
i heard jerry went and killed ito but his car still doesnt run bc now theres no one to fix it?
03-27-2005, 12:44 AM
#5
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Join Date: Jul 2004
Location: Vero Beach, Florida
Posts: 674
[quote name='Shane.Trammell' date='Mar 26 2005, 01:54 PM']i heard jerry went and killed ito but his car still doesnt run bc now theres no one to fix it?
[/quote]
Ahhhhhhhhhhhhhhh, I concur!
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[/quote]
Ahhhhhhhhhhhhhhh, I concur!
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