any gains from polishing ports b18


driftervin

driftervin

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Feb 21, 2011
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479
as they are done from standard is there any gains to be had from it to do it again?? ill prob have the head off this week and ive a friend that can do it for me..
 
Im no expert but from what I have read, polishing your inlet and outlet ports, maybe along with your valves may free up 1-2bhp which has been lost through crap build up and will possibly sharpen throttle response... I think reccommended is about 80grit for the inlet as you don't want it too smooth and you can go to town on your outlet...

But if you are going to port, thats slightly more advanced, you could port match/gasket match both manifolds to both ports, just to give it that bit extra, for that you would want one of those carbide, diamond cut heads for your dremmel/drill. I was gonna have a crack at it myself but for what gains I will get, I dont want to chance it lol.

bit wordy but theres a reply :)
 
polishing the exhaust ports makes sense as you want to get the gasses out of there pronto, although polishing the inlet ports is a no go

leaving some surface texture allows the fuel and air to mix better

by the way, the ports are not polished as standard, the only work that is done to the head is the ports are opened up slightly next to the valve seats, this allows a greater flow through the ports

the inlet ports are PLENTY big as standard, the exhaust ports can do with opening up a bit though, will dig out photos of the head on my car before i fitted. it was ported and gas flowed by race developments (PROPER race company that generally builds motorbike race engines). you can see from the photos that the inlets have been cleaned up by the exhaust ports have some substantial work
 
ye friend that can do it for me is a motorbike engine tuner..hes the best around for engine work..pics would be great if u have any..
 
I'd recommended leaving it. Unless you have experience or practice theres a good chance you'll mess it up. Porting a head without experience is just a bad as doing it blind folded with experience.
 
I wont be doing it..the person doing has about 30 years experiance in tunning engines..
 
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