HyperSpeed

I had a shop in Arizona modify my SuperRam base about a year ago to accompany the GM Fast Burn heads I got. The original TPI ports are shorter so these heads would typically not fit TPI applications unless some port matching was done. So here is the question. Taking into consideration the physics of flow/velocity/etc, would expanding the port right before the head slow down the velocity too much? I have a stock SuperRam setup (runners, plenum) going to the slightly modified ports shown below. Any adverse effect that some might see? How about supercharging, would that decrease the effect as the pressure is increased?
Thanks in advance.

Der91Z

iTrader: (1)

Holes in the intake ports????? You must be hooked on those fastburn heads to do that.

90iroc5spd

holes in the intake ports???? are you talking about the injector holes?

HyperSpeed

I don't remember saying anything about "holes". The PORTS were enlarged on the manifold to match up with the heads. The holes you see are injector holes and a small one for mounting some other components. Basically think of the stock port and raise the top of it about 1/4" - thats all that was done.

Jim85IROC

iTrader: (2)

When the SDPC manifold was still under development, I remember reading something that discussed the shortcomings of converting a conventional base to work with the vortec heads. I might be talking out my *** here because it's been so long since the discussion took place, but I thought I remembered the conversation mentioning that even if you add material to a stock base (like what was done to the one pictured above), there was still an issue of the port having a sharp enough bend that it would disrupt airflow to the point where it became a pretty substantial restriction. Anybody remember this or am I flying solo here?

SQUIRLEYMOFO

Looks great they did a nice job, Jim you are flying solo on this Scoggins said a lot of stuff so they could sell you a $400 manifold.I've modified several manifold and redrilled the heads w/good sucess.

Jim85IROC

iTrader: (2)

I never said it was Scoggin Dickey that made the comment. It was mentioned by a a few people on this message board.

Oh well... since there's somebody that's got first-hand experience that says it works, I'll be quiet now.

HyperSpeed

Where are you physics guys and engineers at? Will velocity with these heads and intake suffer? I am really considering swapping intakes to a MiniRam since thats the only one I know of compatible with these heads. I would rather keep the SuperRam though. Any more input??

dhirocz

iTrader: (2)

How big are the intake runners in the heads?

T. Spoto

From a physics and engineering standpoint, it you raise the outlet on the manifold to match the fastburn intake port then you will have some slowing of the intake charge as it moves from the smaller cross section of the intake to the larger port in the head. The other issue is the flow path since the fast burn heads have a raised port opening to allow for a more direct path to the valve. The tpi intake is really not designed to take advantage of this due to the round about way the port comes into the head. I think the original Scoggins Dickey arguement about modifying a tpi to flow into vortec/fast burn style heads was more about using a stock lower intake, which could not keep up with the flow potential of vortec heads to begin with. And of course they would argue that the intake they made was better than a modified competitors lower intake. However, I don't think there would be any significant impact on the power numbers, and since you said you are using a 383 with a manual transmission, any low end power you may have lost due to slower port velocity will be of little importance.
If you go to a mini ram specifically designed for those heads, you will probably avoid all that, but I don't know if its worth the cost considering all that you already have done. The mini ram would give you pretty much a straight shot right to the valve (like an LT1). If you are planning on spinning the motor over 6000 rpm, the the mini ram would probably match your combo better.

Just my two cents... for what its worth I am an engineer.

HyperSpeed

Off hand I don't know the exact size of the ports though I know they are just about 1/4" taller than the typical TPI ports are, whatever that would be.
Here are all the basic specs on the heads though they seem to always miss something.
Fast Burn Heads

T. Spoto;
Thanks for your engineering input. I spoke with AS&M today about it and was told I should leave it and it should work well.

Thanks for everyones help. It looks as though I'll just keep the setup the way it is...

Now the question is what cam should I look into... hmmm