Engine port explanations please

[tellor]

Hi all,

I'm thinking of a new engine and am interested in a particular one but they have 3 different off road types;


a 5 port ----appears to be high torque ( got that)
a 7 port ----appears to be high speed ( got that)
and a 5 + 2 port ????? bit of both??



Can someone explain what the differences are and am I likely to notice the difference between the cheapest and dearest one?


cheers

[leestokey]

Hi as far as im aware ports make a bit of difference on different engines but I think the os speed is only a 3port engine and revs to 40,000 rpm, but are a really powerfull engine a friend at the track has 1 and it blows all the other engines away both bottom end and top end compared to 5 ports and 7 ports, so buying an engine just for ports isnt the be all and end all theres tuning and gearing to take into account thats how I see it someone might see it completely different.

[thevmister]

i believe that a 3 port will have more bottom end while a 7 port will have more top end power as it can exhaust and feed fuel quickly in , overall the differences are not massive really

[eyeayen]

More ports usually means smoother power I think.

However I'm still a little lost when it says plus, so a seven port engine is just that but I don't understand how the 5 + 2 bit works ?

Technical explanations greatly appreciated

[thevmister]

5+2
5 for fuel in 2 for exhaust

[Neil Skull]

generally more ports means more power and smoother power band. but also less fuel efficiency.

For a beginner a 3 port engine is a good choice. like the Novarossi 21R
For Racers with some experience a 4 or 5 port like the Plus 4 is a good choice.
For the speed animals and Truggy guys a 7 port could be fun.

[Kurtje]

I've got the OS Speed XZB on my buggy and truggy...
It's 'only' a 3 port engine and I think not only for beginners
Powerband, power an fuel consumption is VERY good ...