LT1 POWR

Do you want the edges of the runners in the intake rounded off like how the intake comes from Edelbrock or somewhat sharp when porting a single plane?

Does anyone have any pictures of their ported single plane intakes that they would like to share?

Also on World's Motown single intakes, does that turtle at the base of the intake ,to help distribute the air, actually help low end torque at all, cause I can add one to my Vic Jr pretty easily if it will show any gains?

mdacton

they need to be rounded like an airplane winge...sharp makes it turbulent...


world product thing is crap...never see anyone running that stuff anyway

LT1 POWR

World isn't the only company that has an air divider at the bottom of the intake. I've seen a custom pyramid shaped epoxy "turtle" with a kind of golf ball textured skin (with dimples) that is supposed to help with low end torque. I think I have it in one of my magazines. I'll see if I can scan it and post up a picture.

LT1 POWR

Found the magazine. It was in a 2007 issue of Popular Hot Rodding. After I read through the article, I realize that this was on a carbonated motor, so the pyramid probable has to do with fuel puddling more than anything. Here is the picture.

rskrause

You are right, the "turtle" is there to direct liquid fuel.

Rich

Stroked96Bowtie

I was told that since the intake is just moving air (EFI)...not fuel...porting is not as essential as on a setup that passes fuel and air through it. Can anyone comment on that thinking?.

Ive got an unported single plane for my LTx setup.

mdacton

the porting is the same, but the finish can be smotther, after you port it you can get it nice and smooth but a carb you want a little rough to mix the fuel/air

LT1 POWR

Will smoothing it out promote better/faster air flow, maybe helping throttle response a little?

mdacton

probly not

WS6T3RROR

No, due to boundary layer effects you wont see any real gain from polishing the surface. That is why many times the cnc cutter marks are left in cnc ported heads. The air (which is a fluid) forms kind of a skin on the surface and as you get very close to the surface the velocity of the air will be the same as the port (zero). The longer the surface the thicker the boundary layer gets, although with air we are talking VERY small layers even at the speeds seen ports.

The rounded edges in the plenum dividers is to create a very normal (laminar) flow. Sharp edges and other such geometry will tend to cause a disruption in flow and create turbulence. All sorts of bad things happen when you trip to turbulent flow, the airflow goes down because it cant get out of its own way, and the convective heat transfer goes up like you wouldnt believe (ie the air gets hotter).

Porting is every bit as critical with efi as it is with a carb, you're trying to make it as easy as possible for the air to get to the cylinder so you can use it to burn fuel. The name of the game when porting intake manifolds is minimizing the loss of airflow when its attached to the head. When you port an intake manifold think of it the same as an extension of the cylinder head, treat it accordingly.

Disclaimer: This is all very simplified and is only meant to give a very basic idea of the principles involved.