When replacing the intake plenum with the Crawford unit, I noticed that the inside of the upper plenum was rough, except for the part that was modded by Doug. The part modded by Doug is very smooth. I was thinking that if you could make it smooth then you would gain some better airflow.

The same applies to the lower plenum. It is rough, there is even a stamp with numbers and letters that would disrupt airflow.

This might not gain much, but I think you would gain something, I don't think it would be a hard job either. If you have the proper tools, it could be easily done.

What do you guys/gals think?

Victor

 

When I did my plenum I polished the neck area and the back area off the plenum up to the replaced area that you are talking about. I had the same thoughts about that transition. As for the lower plenum....I think it is really important to have some turbulance as the air moves down the velocity stack to the intake valves for better fuel /air mixing. The factory sand casting texture is actually very beneficial to a better mixture mix/burn in cylinder.

 

We were discussing this today at the shops... several opinions are being looked at.

Even if it was polished... a gain of 1 - 2 hp MIGHT be had.

Big deal.

 

yeah that's that i thought, not much to be gained. but looking at it got me picky.