I have a set of LE2 heads, 2.0/1.56 valves, fully ported/polished and flow 274/191 . The cam is a GTP 236/242 with .597/.583 lift on a 114 LSA.
The guy I bought the heads/cam from had a 383 with a port matched trimmed LT4 intake. Made 446rwhp NA.

I will have a stock 350. Should I have the LT1 intake port matched and ported out as much as possible or is it not worth the time on a stock displacement 350?
I also have a LT4 intake that is already port matched for LT4 heads but hate to modify it to fit the LT1 heads.

Any input is much appreciated, thanks

 

I think a ported LT1 intake is the way to go on a 350.
I don't see that setup needing anything bigger.

 

It is definitely worth the time and effort to use a ported manifold. You can also sell the LT4 manifold for money for more mods. GM doesn't make the LT4 intake anymore so you can sell that sucker for a pretty penny. I've seen them sell in the $500+ range depending on the condition.

 

Thanks for the input. Would I be leaving much on the table by using a ported LT1 manifold over the ported LT4? (either by having the one I have machined to fit or possibly buying the one from the guy I bought the heads from)

I believe the LT1 can be ported out for about $100...I think thats what I spent on the LT4 to be port matched and fully ported out and accept a 58mm TB.

 

Most of the reputable guys that specialize in LT1 and LT4 stuff.....who also port out the LT1 and LT4 intakes will rightfully charge much more than 100 bucks for a TRUE full out port job(many out there do WAY less than what could or should be done to them and their calling it a full port)...there's about 3 LB's of aluminum that needs to come out on the small tapered port LT1 intakes, and about 2 LB's that need to come out on the larger (better in stock form) rectangle port LT1 intakes ...taking this material from the right areas of the intake is key......Lloyd Elliott has about the most fair price (and is one of the best) his go for $225 total......there are a couple others that are also good, but the cost is over double that, and up........ the LT4 intake has the smaller tapered ports like the crummy port version LT1 intake manifold has, but it does give a slightly better finished port when ported out all the way due to having some extra material..........point being: a done right full out ported intake is well worth it even on a stock bottom end 350CI motor.....by the way, port matching has been shown to do almost nothing.......................Joe

 

sorry dont mean to hijack the thread but would you say its worth it for me to get my intake ported or theres no need?

 

Thanks for the info Joe. LLoyd did the port work on the LT4 but was not a complete full port I don't believe, mostly just polishing all the runners out and the port match and opening up the TB. If I don't just end up getting the LT4 intake that Denny had, which is full port job by Lloyd also, then I'll send my LT1 to him and either sell the never used LT4 intake as mentioned above or keep it for a future project on my truck.

 

The drawback to the LT1 intake is port length. Ya can still make 450+RWHP with the proper welding and porting with one.
Ya need about 2-1/2" more runner to make any more torque or HP and that is what ya see with a carb style intake is more length-- possibly not the correct length for all apps but more length.

 

You should port match the intake. You'll be leaving good HP on the table by not doing so.

 

Port matching (making the ports on the manifold match the ones on the heads) = Good Idea
Specifically, those ports should match a cross section on the head at the pushrod pinch .

Gasket matching (making both ports match the gasket) hurts airflow.
Flowbench 101

 

There's no question that if I use the LT1, I will have it ported.
The original question is will I leave any hp on the table with the setup I have by using a ported LT1 vs a ported LT4?

I have one vote from James that the ported LT1 would be enough.
Any others?

 

When they get through porting the LT1 it will flow what/about what a ported LT4 will.
The runners are higher in an LT4 and will need a lot of work to line the mismatch up.

 

Thanks, that is the confirmation I was looking for, I figured since the deminsions are the same that the LT1 could be opened up enough to just about match the flow of the LT4 intake, and with a 350 would I even hit that limit with this set up. I'll hang on to the LT4 intake for a stroker project in the distant future

 

Guys are running in the 9's with that intake.

 

Could you get some kind of 2.5in. spacers custom made... or would this be more trouble than it's worth?
-b