# of Engine ports
07-16-2010, 03:56 PM
#1
# of Engine ports
Can someone explain the effect that the number of engine ports have on an engine?
For example, does a 3 port engine have more low end grunt but less top end speed than that of a 5 port. And what about fuel mileage effect?
:t ire:
For example, does a 3 port engine have more low end grunt but less top end speed than that of a 5 port. And what about fuel mileage effect?
:t ire:
07-16-2010, 04:01 PM
#2
i believe a 3 port has a lot, more torque than a 5 port and i know too.
a 5 port is more of a top end / midrange engine, and im currently running a 5 port on my truggy.
as for fuel milage i think, a 3 port whould use more fuel up than a 5 port.
a 5 port is more of a top end / midrange engine, and im currently running a 5 port on my truggy.
as for fuel milage i think, a 3 port whould use more fuel up than a 5 port.
07-16-2010, 04:30 PM
#4
07-16-2010, 04:44 PM
#5
Tech Master
iTrader: (3)
As far as I know, 3 ports = more torque and fuel economy. 7 ports = screamer that uses a bit more fuel. This is my experience as well. I had a WS7T that was absolutely insane on the back straight and a 3pt Go that was stupid fast coming out of the corners.
Now I run the Werks B5's, they're the best of both worlds and fuel economy to boot.
Now I run the Werks B5's, they're the best of both worlds and fuel economy to boot.
07-16-2010, 05:09 PM
#6
In general 3 port motors have more tourque, 5 ports are in the middle and 7 ports have the most top end.
This is the way the motor compainies typically market them. The timing of the ports has more to do with the engines power band though. I have ran a 8 port that had a ton of tourque and there are 3 ports that have a ton of top end. Before making a motor decision you should ask around and buy from a dealer or hobby shop you can trust will get you what you need in a motor. In fact some motors don't even have the # of ports they say they have, they count the bypass ports etc.
Rex
This is the way the motor compainies typically market them. The timing of the ports has more to do with the engines power band though. I have ran a 8 port that had a ton of tourque and there are 3 ports that have a ton of top end. Before making a motor decision you should ask around and buy from a dealer or hobby shop you can trust will get you what you need in a motor. In fact some motors don't even have the # of ports they say they have, they count the bypass ports etc.
Rex
07-16-2010, 05:17 PM
#7
a 3 port usually has more bottom and a 7 port has more top end. but as far as fuel milage goes its all in your driving a 7 port can get more run time than a 3 port beeing that a 7 port takes longer to get to full rpm meaning most tracks your not pushing a 7 port as hard where a 3 port is topped out 1/4 to half way down the stretch so you got to run it richer cause you constintly topping the rpms out making it run hotter. 5 port is the way to go in my opinion its a medium motor excelent bottom with good top end. and then you got vspecs/reedy that are 4 port i believe and there making smooth bottom with good torque and also scream on the top.
07-16-2010, 05:20 PM
#8
I would not base an engine purchase on number of ports. It can be misleading. O.S. vspec and speed are 2 of the fastest most powerful stock motors and they are 3 port. They have tons of low end and a blistering top.
the pipe you choose plays a much bigger part in performance imo
the pipe you choose plays a much bigger part in performance imo
07-16-2010, 05:22 PM
#9
a 3 port usually has more bottom and a 7 port has more top end. but as far as fuel milage goes its all in your driving a 7 port can get more run time than a 3 port beeing that a 7 port takes longer to get to full rpm meaning most tracks your not pushing a 7 port as hard where a 3 port is topped out 1/4 to half way down the stretch so you got to run it richer cause you constintly topping the rpms out making it run hotter. 5 port is the way to go in my opinion its a medium motor excelent bottom with good top end. and then you got vspecs/reedy that are 4 port i believe and there making smooth bottom with good torque and also scream on the top.
07-16-2010, 05:24 PM
#10
porting is definitely not the most important part of the engine 
but the design of the ports do aid in proper fuel/air flow , 5 ports have vertical transfers that change the flow dramatically when in the mid to upper rpm range
there are cranks also
crank timing and design are a huuuuge part of the engines performance
but the design of the ports do aid in proper fuel/air flow , 5 ports have vertical transfers that change the flow dramatically when in the mid to upper rpm range there are cranks also
crank timing and design are a huuuuge part of the engines performance
07-16-2010, 05:50 PM
#11
Interesting...Houston I never even thought about the cranks ! 
So theoretically if driving style,pipes and cranks are identical the following would be true:
3 port= lots of torque, not the best top end. Best for small tracks?
5 port= good low end,good top end. Good to great on all size tracks?
7 port= poor low end, screamer on top end. Best for big tracks?
Just trying to dumb down the understanding of this.....
So theoretically if driving style,pipes and cranks are identical the following would be true:
3 port= lots of torque, not the best top end. Best for small tracks?
5 port= good low end,good top end. Good to great on all size tracks?
7 port= poor low end, screamer on top end. Best for big tracks?
Just trying to dumb down the understanding of this.....
07-16-2010, 05:56 PM
#12
Interesting...Houston I never even thought about the cranks !
So theoretically if driving style,pipes and cranks are identical the following would be true:
3 port= lots of torque, not the best top end. Best for small tracks?
5 port= good low end,good top end. Good to great on all size tracks?
7 port= poor low end, screamer on top end. Best for big tracks?
Just trying to dumb down the understanding of this.....
So theoretically if driving style,pipes and cranks are identical the following would be true:
3 port= lots of torque, not the best top end. Best for small tracks?
5 port= good low end,good top end. Good to great on all size tracks?
7 port= poor low end, screamer on top end. Best for big tracks?
Just trying to dumb down the understanding of this.....
i think a 5 port is the best for, a large outdoor offroad track just enough power without too much power.
and yes a 3 port is really good on a small tech track, but you can get it to run pretty good on, a large track you just have to gear up.
i dont know about a 4 port.
07-16-2010, 06:08 PM
#13
You can't judge engines by thier ports anymore. Some really fast engines are very similar to 3 port mills.
They just took the time to get the ports perfect, then used better crank, rod, bearings, carb etc. Even then I doubt that a NR +4, is really twice as expensie to produce compared to a cheap N21b. But if your good at something never do it for free.
I think the 7 port italian mills are easier to tune. And have seen plenty of people get competitive run times with the RB WS9 or NR FMS powerhouses.
I'd go straight to the Picco, WS9, FMS for big tracks. +4, V-spud, B5, for shorter tracks.
They just took the time to get the ports perfect, then used better crank, rod, bearings, carb etc. Even then I doubt that a NR +4, is really twice as expensie to produce compared to a cheap N21b. But if your good at something never do it for free.
I think the 7 port italian mills are easier to tune. And have seen plenty of people get competitive run times with the RB WS9 or NR FMS powerhouses.
I'd go straight to the Picco, WS9, FMS for big tracks. +4, V-spud, B5, for shorter tracks.
07-16-2010, 06:45 PM
#15
alot of people think it's a 4 port. Even i did till i got told different. I am not sure which port it is that is not counted i think it's the exhaust port. But there is definitley 4 holes but only 3 ports.