Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Port matching...yes or no??

My first post

OK, I have gotten some input on this at NECO but now that your back..Here is the Q.

SVT lower (secondary) ports & head ports are about 34-35mm
SVT upper (secondary) runners are smaller, about 32mm

Would it be worthwhile to enlarge the final portion of the UIM runners to 34mm or so to basically match the LIM size. Or, from a flow velocity standpoint..should I leave it alone.
I vaguely recall someone once (Terry?) IIRC said something about tumbling effect of the mismatch being a good thing???

OK gas flow experts..whatcha got...thanks as always & good to have CEG back!

Well, opening the entire length of the UIM runners with a little extrude honing would certainly show some gains...just ask Demon.

I'm not sure that just port matching the joint between the two would be worthwhile. My guess would be too much effort too little gain. Also the difference in size is not as bad as you have stated...for the '98, like me, I think its a 32/34 split, or in that range, but that was improved on the later models.

If you go ahead and do it be sure to let me know

I believe in port matching. It has made a noticable difference in any engine I've done it on. I have not had anything apart to do it on my SVT, but if I ever do, I will match the ports. In the past I have done it along with other head and intake manifold work.

On a much earlier engine, a Ford 460 that I built for my 72 Ranchero, the Super Cobra Jet intake manifold was the hot set up since no one made an aluminum high rise manifold for that engine. The Super Cobra Jet had ports that you could nearly stick your closed fist into. The heads I had were not nearly as big. Without port matching, the manifold was worth 20 HP. I ran it that way for a while, then I pulled the heads to port the heads to match the Manifold. The result was very impressive. I did not have the low end power drop that I expected and the engine really pulled much stronger above 3500 RPM.

Chevy small block engines I have built also responded to port matching as have 302 Fords.

If you are doing manifold or head work anyway, I would take the time to match the ports.

A friend of mine had it done to his 2.4L neon that he is building and I noticed a difference in the performance. I plan on having this done to my when I have the extra cash to do it. From what I have seen I believe that it is well worth it.

Port matching is worth while. The tumbling effects occur farther down in the ports near the intake valve. When the air swirls or tumbles it needs to do it into the combustion chamber. So I don't see port matching hurting the tumbling at all. When you have ridges like the ones in the secondary ports on the Duratec the buffeting effects hurt airflow quite a bit. They are to far up in the head to aid in anything in the combustion chamber. You're just going to get backpressure in the runner. The reason Ford didn't open it up is probrably cost. I'm sure they reached their power goals with the SVT. It would have cost alot of money to re-tool and make new lower manifolds just for a low run of 10,000 or so cars. If you think of it there is very little that is extremely different on the SVT. I think there are some power gains to be had.

Roger

If it is within your cost limits....BY all means do it...there is power to be had there...ARE YOU A MACHINEST.?