97 6SPEED Z

I thought you guys would appreciate this "heads up".

According to the May 2006 issue of "Corvette Fever" magazine, (please see the article starting on Page 58 called "Building the LT1 to 500 Hot Horsepower"), the LT1 and LT4 intake manifolds are identical except for the red powder coating! On Page 63 of this article, (see photo 30), they measured both the LT4 and LT1 intakes, and declared them identical except for color. Let the debate begin!

Chopstix

the intake ports are located higher to match up to the raised runners of the LT4 heads...1/10th of an inch I believe

97 6SPEED Z

Chopstix, yep, that's always been the report, you needed the LT4 intake to match up with the LT4 heads, because of the raised runners.

Now I'm quoting directly from the article I mentioned above:

"Dimensionally, the LT1 and LT4 manifolds are identical. If you're looking to save a few bucks, stick with the LT1 manifold".

aggiez28

not the first time a magizine has printed bad info

Z28SORR

No debate, they're simply wrong!!
GM part numbers: LT1 12552137, LT4 12550630. LT4 intake has 0.10" (2.5mm) higher ports then the LT1 intake. GM does not use different part number for identical parts.

P.S. They also have different intake gaskets for the two. LT1 12524653, LT4 12528884. If you need more proof.

97 6SPEED Z

Z28SORR, nope, don't need more proof just want to know who feels like penning the "Letter to the Editor" on this one.

thesoundandthefury

This is a totally wild guess, but I would say that because aftermarket vendor support makes up alot of these magazines' budget, I wouldn't be surprised to find out that Edelbrock was somehow involved in "influencing" the data in this report to give their still yet to be released LT4 replacement intake manifold an edge in filling the missing stock LT4 gap in the marketplace. If they can convince enough people that their intake ports are bigger and flow more than the stock LT4's, and are offered at a huge discount compared to what LT4 intakes are going for now, they stand to set themselves up to make a killing in sales. Just a guess though.

Injuneer

Before you start writing your "letter to the editor"......

The port dimensions on the LT1 and LT4 intake manifolds are virtually identical. The ports on the LT4 head are 0.100" taller than the ports on the LT1 heads. The LT4 intake does not correctly match the LT4 heads. It needs port work to improve the flow.

The LT4 intake has more metal at the top of each runner, so that the ports can be enlarged to match the heads, but "as-cast", the LT4 intake does not have the 0.100" taller ports. It is the extra metal at the top of the LT4 intake runners that interferes with the valve cover rail on the LT1 heads, and it is that interference which prevents you from bolting an LT4 intake on an LT1 head, without machining one of them.

96capricemgr

This needs to be repeated OFTEN.

Injuneer

I bet I've typed that info 50 times, and numerous others have also.

sprayedtransam

as always, good info Fred

sad that you will probably be re-writing it again tomorrow to explain it to someone else...

1racerdude

The archives are a good thing for people that DO use them. Can ya imagine the repeat questions that would be asked if they weren't there. As of know ya can say to a question to do a search for so in so and the question asker will get more than he/she wants to read on most subjects.

96capricemgr

Sometimes a question does need to get asked again because say 5 years ago someone asked what was the best heads and cam package, I am betting the answer is different than the AI and LE answers you would get today.

This one though seems to go around all the LT1 forums like wildfire every time any magazine does an intake review on ANY motor.

TransAm2k4

Wait i do like the archives and read them a lot. Dont go erasing them. Maybe the more important stuff should be placed in a distint folder or something like that.

TransAm396

I have 3 of them..anyone need one?