is there really that much more of a max potential out of the LT4 over the LT1 intake being ported? is it worth keeping my lt4 and porting it or does the lt1 pretty much come close to the same? thanks

 

not sure but i know that the LT4 intake runners are a bit raised which is suppose to have a higher air flow

 

No they are not raised. The intake manifold ports are the same. The intake ports in the heads are taller, floor being in the same place as an LT1 head.

Here is a picture GIZMO posted some time ago.
http://i85.photobucket.com/albums/k5...1/DCP_1456.jpg

If you have a head(LT4 or aftermarket) with a huge port that needs a huge manifold port I suppose ported it could be worth something.

Most people get carried away though. bigger is NOT necessarily better.

 

the ports on a LT4 are supposedly raised over an LT1 port by a tenth of an inch. your not going to be able to tell the difference of a tenth of an inch with your eyes. most LT4 owners port-match their intakes with the "777" gasket to match the ports in the heads. i never checked if the ports actually matched up exactly with the heads when my intake ports were stock. what i do know is the stock LT4 intake gasket does block some of the port from the factory

doubt its worth buying an LT4 intake over a LT1 intake though. if you have an LT1 intake now, just have it ported if you need more flow. if you already have a LT4 intake, theres no point in switching to a LT1 intake

 

In the head they are taller not raised. Raised would imply the floor was moved, it was not.

The LT4 manifold is internally the same as the later LT1 intakes been covered MANY MANY times but the ignorance persists.

 

when i say "raised" i mean the roof of the intake port is raised. i dont think anyone would assume i meant the floor of the intake port was raised

like i already said, i never measured the intake manifold port, but i do know my LT4 heads had a slightly taller intake port in the cylinder head. what i had to do was switch the intake gasket to the "777" gasket and port match the LT4 intake manifold to the new gasket and cylinder head port to get everything to match up

 

well i have an lt1, but i have an lt4 intake in my garage. someone wants it on trade with my car. and if the lt1 intake is roughly the same then im not gonna sweat throwing in the lt4 intake into the deal.

 

The runners on the 1996-97 LT1 intake (12552138) are identical as-cast to the LT4 intake. It is the best one to use on an LT1 if you are NOT planning to gasket match. The LT4 intake has more material above the runner so that it will seal against the LT4 heads. The LT4 intake will not fit an LT1 unless that extra material is removed. Which would make the LT4 intake an LT1 intake!

 

i wish there was a picture of the gaskets laid on top of the unported intake, so better show this. i think it would clear it up for most people.

(i know what the difference is)

 

Honestly I think I lost more bottom end switching from the LT1 to Edelbrock LT4

 

If you come on a car forum using your own definitions in place of standard automotive terms, you're going to get little help, and a lot of abuse.

 

every publication ive ever read stated the intake ports on the LT4 were "raised 0.10 of an inch". this is true for the vortec ports as well. i wasnt aware car forums used different terms for this. why would "raised" imply that the floor was moved and not the roof?

i think most everyone on here knows the head port on a LT4 is higher at the top than a standard LT1 port. whether i said "raised" or "taller", im sure everyone knew what i was talking about. seems like nit-picking to me

 

Every indication is that the Edelbrock parts are not worthwhile. I would blame that more than the LT4 designation they put on them.

Their own flywheel dyno numbers are lower than what can be expected from a good ported gm LT1 heads setup makes at the tire.

 

Huh, so what gasket to do you recommend porting an LT1 intake to? I have a stock LT1 intake and gasket and the stock LT1 runners are taller than the gasket, but appear to be lower in the manifold (the bottom edge of the gasket covers the bottom of the runners in the manifold). I could always trim a gasket to clear and then port the rest to match it, but I'd much rather have a standard gasket that I know that I could buy off the shelf and use rather than modify one when I need one.

 

wow this is a old thread. just port match it to a stock lt1 gasket.

 

Yep, and like I said, that's not helpful, I have 2 sets of stock gaskets here and both cover some of the bottom of the port opening (and yes, the intake is still rough cast inside, it hasn't been cut)