porting the intakes on the HO 2.8

[Arns85GT]

Here is the deal.

My Edelbrock intake runners have a minimum cross section of 2.5 cm wide X 4 cm high. (10 sq cm) The HO 2.8 heads have a minimum intake runner cross section of 2.5 cm wide X 3 cm high (7.5 sq cm).

This means my heads can take in less than 3/4 of what the intake can deliver.

How much is safe to hog out from the head intake runners? I know not to mess with the ridge and the walls appear to have enough meat to grind out about 1/8" all the way around. Does anybody know about the flow and how the air speed/mixture will be affected? Has anybody done this porting and has some experience to share?

[geoffinbc]

Talk to Coiln (V6H.O.) Im sure he will chime in soon

[1QUICKHATCH]

as long as its comming off the roof of the port it should be ok. just make sure you have enough meat left to provide proper gasket sealing!

[Guest]

try www.fiero.nl THose guys over there know everything about performance. THey live it breath it talk it.

[Arns85GT]

as long as its comming off the roof of the port it should be ok. just make sure you have enough meat left to provide proper gasket sealing!

The roof has about 1/4" of meat. The sides have more. No problem going 1/8" all the way round, but not 1/4" on top. However, the flow could be compromised if I do it wrong. That is the reason I am tempted to do 1/8" on 3 sides leaving the floor shape the same.

Here is the dimension comparison of the height difference. 4 - 3.

Manifold roof__________
Head roof_______


Floor_____________

Arn

[1QUICKHATCH]

get and extra set of intake gaskets then trim them to line up with the ports on the intake manifold. Then line the gasket up on the head and see how much you have to remove. I can't see their being any problems with gasket matching the heads to the intake, but then again its hard to say with out seeing any pic's or seeing them in person.

[Arns85GT]

Thanks, but the question really isn't gasket matching.

I am already gasket matching, however the point is whether hogging out the intake runners on the head is worthwhile or advisable.

Nobody, including Edelbrock, seems to have flow numbers for matching the right head intakes runners to the right bank Edelbrock intake runners.

I don't see any research, any results, or any dyno info where I've been looking. It seems if there is some out there, nobody is sharing.

It seems somebody should have tried by now given the age of the engine design and all the racing it has done.

I'll keep looking before I put the grinder down.

Arn

[1QUICKHATCH]

RE: Thanks, but the question really isn

yes it is a good idea match the heads to the intake it will cut down on possible turbulance caused by port missalingment/uneven transition from intake to the head. if you have the stuff off the engine do it!

you don't usally find too many people that spend the time to flow the heads with the intake bolted to them, takes more time to set up but it would help if you are trying to get the most you can out of that intake/head combo.

do your heads have the vane in the floor of the intake? if they do leave it their and sharpen it abit if you want.

[Arns85GT]

Thanks Quickhatch

Here is the question.

The runner is 4 cm high, but the meat on the head won't allow me to go 4 cm. high. This means I have to change the shape of the chamber some to get the same volume.

There is a nice transition from the port in toward the bowl on the walls now, so if I just grind that transition area down a bit I may be ok. It will end up with a cross section of 3 cm wide to 3 cm high or thereabouts.

The question is potentially slowing the air speed down at entry to the valve throat. That would be bad. The question is how much is safe to take out before you affect air speed.

Arn