i would taper the ports till the got to size of the exctrator, or the sudden change or size would slow down the flow, if its slowly tapering out then the hot gasses should still be expanding

 

just make sure you still have enough area for the gasket to seal on :lolcry:

yes ^^^^ thats what i thought

Edited October 23, 200916 yr by KE55PIG

i would taper the ports till the got to size of the exctrator, or the sudden change or size would slow down the flow, if its slowly tapering out then the hot gasses should still be expanding

 

just make sure you still have enough area for the gasket to seal on :lolcry:

 

I remember reading a post by Blown to do this, just taper the corners of the ex ports.

Port matching the exhaust = intake charge contamination.

 

Get some books by David Vizard and read up. :lolcry:

well what the best thing for me to get done then ? just have the pissy tinny litle exaust ports ?

Have a read up about anti-reversion vs port matching. :lolcry:

 

Google link

 

Port matching is a waste of time.

I'm now rather interested. I'm rebuilding a 2.2lt 4y engine (think larger upright 5k) with a 260 degree camshaft, and may be fitting extractors, and I'm thinking about matching the ports to the manifolds.

 

definitely a good thing to match inlet manifolds to ports? its just the exhaust that we are a little iffy about?

 

Found my nights worth of reading on google now :lolcry: thankyou Felix!

 

Robert.

I wouldn't even bother port matching on the inlets.

 

So long as the manifold port is smaller than the inlet port you are not going to gain a huge amount. In fact the mismatch encourages re-atomisation of any fuel that falls out of suspension, and helps prevent any exhaust reversion pressure waves travelling back and interfering with the carb signal.

 

Fluid dynamics are just part of the equation with motors and engine tuning.

 

I guess the whole point is to make the ports flow in the correct direction, and reduce the effects of any flow reversals.

 

Port matching doesn't reduce the effects of any flow reversals.

It might be worth making sure my inlet ports in the head are larger than the manifold and the extractors are larger than the exhaust ports. From what I gather (reading on the world wide web of bullshit) you can open up the roof and sides to match them but leave a lip on the floor of the port/header to prevent reversion.

 

I've had a few people tell me port matching is a good thing... but they were talking about race engines, and my 4y is far from that!!

 

Robert.

rob from wha ive read u seem to be on the track that clean the edges up and top up as that flows the most match it for that then polish it but leave the step on the bottom.

Has anyone mucked around with the bowl ? any large gains to be had or a bit of waist of time ?