If I were to gasket match, port and polish the ports of the keg and did not port and polish the heads of the engine would I be wasting my time?

 

yes..

gotta open up both the head ports and the intake ports- and gasket match.. if you were to just do the intake manifold and gasket match, you could possibly be introducing restriction instead of eliminating it..

if you do the head intake, you may as well do the exhaust too..

it's said for every additional cfm of flow, add a pony.. if you can add 5 through the whole shabang for every cylinder, you'd be looking at 40hp and a good bit of torque simply by grinding it down.. if you have your engine taken down, you'd be crazy for not spending the extra three or four hours to do that gasket match port job.. just my thoughts on the matter.

 

dumb question...whats a gasket match? that 40+hp and added torque sounds appealing

 

the basic concept to gasket matching is having the gasket and manifold ports the same exact size, and then matching the ports on the heads too.. so you have a continuous matching flow through all three..

you also grind out any sharp shoulders or abrupt bends in the throat of the ports both on the intake manifold as well as the heads intake..

to do it right, the exhaust ports should be ground out too, to eliminate or lessen abrupt bends or shoulders.. then matched to gasket, then to exhaust manifold/header ports..

just doing the intake manifold and the gasket will leave a 'shelf' on the head side, and that will create an area of resistance which kicks the air right back into itself, which limits the velocity and volume of the flow.. not good... this is the reason you do all three, or you don't bother with any..

if air goes in, it's gotta come out.. that is why you do exhaust too..

5cfm per cylinder is easily done.. you could maybe squeeze as much as 10.. we're talking 10cfm ALL THE WAY through the engine to get it- but 10cfm additional would be somewhere around 80hp.. and done with a simple grinder.. if you do it right, you should easily be able to get the 40 more.. for 80, you're looking at a lot of material ground out and having the surface finely polished.

 

ah, thanks....good info.

 

80hp? You would never see those gains even with optimal cam-intake combo. The basic formula for head CFM vs HP is CFM X .257 X 8 cylinders = .....you may see 20hp with 10 more cfm. Stock mag heads can support 420hp as is.

 

Head porting is largely overrated on basically stock engines, there are many other mods that would serve you better before the need to port and polish is reached.

 

I'm only repeating what I'm reading- and obviously, the places I read it are written by people who've done it, which means they are likely going to be really optimistic about the work they just did..

the formula i read about 1cfm adding up to 1pony is based on air through the engine- as in through from the air hat to out the exhaust tip.. to get that you gotta have a lot of items to do it, right? cam most notably imHo.. the porting is a good compliment, though I've never done it- the guys who have swear by it.

 

Squeezing performance out of your engine is all about air flow. Getting it in, and out, of the engine, makes it more efficient. Thus, more power. So, my philosophy on that is, if you are there anyway.... why not? Simply gasket matching the intake/heads will give you a bit of a bump, and if you do it yourself, its basically free power. Question there becomes: Why WOULDN'T you want to?

One of the problems with cast parts, is core shift. Things are not always exactly where they should be. These little misalignments leave obstacles to airflow, and reduce efficiency. Little cavities between head, and intake, create turbulence, which also impedes air flow. Put your gasket up to you intake, where you see metal INSIDE the gasket port, is going to leave a void in the head/manifold interface. Same goes for the head. Having a smooth transition there is easy horsepower.

Folks spend a couple hundred bucks on headers, and then hook those up to the stock exhaust, net gain: Nothing. The manifolds aren't the biggest restriction.... Granted, you don't have to pull the heads to install headers....

So, if the heads are off, something as simple as gasket matching IS a worthwhile endeavor. Yanking the heads just to do it though? Well, that would be a debatable issue.