MoeMonney

I have my M96 engine apart and was considering porting the heads. Would this be beneficial or really not worth it?

Thoughts?

m3driver

Short answer is better airflow. The engine is an air pump, the more air the more power. However only porting the heads usually won't net power gains and can often times hurt performance. Porting should only be done with someone who knows what they are doing, on a flow bench, and matched to the intake and exhaust. Cams play a big roll as well, as if you don't have a cam that can take advantage of your porting you've done nothing except burn a hole in your pocket.

Mike Murphy

Not sure what effect porting would have on this specific engine. I'd certainly be very careful and get expert weigh-in before doing it.

Macster

As m3driver said better (intake) air flow and better exhaust flow.

Trouble is the intake and exhaust ports represent just a portion of the path intake air follows on its way into the chamber and then the exhaust on its way out.

You are probably better off just making sure where the intake air enters the intake port from the intake manifold runner there is no step or ridge and likewise on the other side that there is no step or ridge from where the exhaust gas leaves the port and enters the exhaust manifold.

'course, you can do a general smoothing of the intake and exhaust ports not really changing the shape or enlarging the port.

But this is a lot of work -- speaking as someone who did this for single and multi-cylinder motorcycle engine heads -- for not much real gain.

I mean generally the intake and exhaust port surfaces ain't that rough to begin with.

But ridges/steps at the transition from the intake runner of the intake manifold to the intake port in the head and ridges/steps at the transition from the exhaust port to the exhaust manifold, these can be very real and sometimes quite pronounced.

LC MotorSports

m3driver

I went from 32hp to 65hp on my Honda 450x with a port job, a different yr factory Honda cam and an aftermarket exhaust....there may or may not be potential left in the head.

Ahsai

Must read. Chat with Len at Hoffman Automotive. He did some port work for my m96 3.8 LN build.

https://newsite.hamheads.com/2016/11...age-m96m979a1/

MoeMonney

Interesting read. Basically sums up that it was little to no benefit porting the M96 heads.

Copilot

Yup - Len rebuilt my heads as well and did his Stage 1 job, which I believe was just cleaning up the bowls and polishing. Not too expensive, and he recommended not doing any more than that.

Ahsai

Exactly.

Mike Murphy

That pretty much goes with this engine in general. Most agree, "buy a Turbo" if you want more power.

Hardback

Good thing they updated the article regarding the valve seat issue as that's what happened to my engine after tracking it for a year or so.

5CHN3LL

Anyone want to see my bifurcated runners?

extanker

porting gets air in and out faster,it is a serious mod that works with other serious mods. unless you can see/feel casting ,misalignment issues with the ports/runners fuggetaboutit on a light modded street motor

Sneaky Pete

And if you add some ridges / scalps it will create more air velocity