Markbo

I don't know if this is advanced tech worthy, but it's a good place to start. I am going to ARP 220's and thus have to upgrade to an LT4 intake manifold. Not being able to swing a full on custom sheetmetal intake, and realizing that a big reason for the LSx making power so easily is it's long intake runners, I had a thought.

What about just cutting and raising the top of an LT4 intake plenum? Just an inch or 2.. I know this wouldn't be actually extending the intake runners, but would the additional plenum volume accomplish a net result of that?

I am not looking at this as a big HP gain, but a (relatively) simple and inexpensive mod to take maximum advantage of the new heads and cam (a Bret Bauer custom).

Any thoughts from anyone with any experience or practical knowledge would be appreciated as like I said... this is just a thought and may not be a good idea for reasons unknown to me.

And secondly...does anyone know where I can get an LT4 intake manfiold cheap?

Kryckter

Summit Racing Has your manifold, New it is 229 or so. Heres the part number
NAL-12550630
As for the intake runners, I think they have discussed that before on this forum but Im sure some of the guys will be able to answer that.

FASTFATBOY

I have a LT4 Manifold for sale, max ported by West Coast Cylinder head, opened for a 58 MM throttle body, manifold new was $240, port work $400, take $500 for it. New never been used.


David

Injuneer

Did you see Ken Mook's post on LT1 Engine Tech about his new BRE Pro Ram intake manifold? Might want to take a look there.

http://web.camaross.com/forums/showthread.php?t=286104

Mindgame

Alot of the advantage found in the LSx is right there in the cylinder head. A little more runner length for us LTx guys wouldn't hurt things but that alone is not going to level the playing field.

If you have the fab skills, then you could always extend the runners up into the plenum. Of course that takes a little volume away so adding some up top might not be a bad idea.

Then there's the BRE Pro Ram Fred mentioned. Nice piece of work indeed.

-Mindgame

Markbo

Thanks guys - yeah I know about that BRE piece. Believe me... if I could swing the cost of it, I wouldn't be talking about this! I would love to... just can't afford it. I figure for about 1/3 the cost, I can alter one a little less radically and get about 1/2 the gain from it.

I understand a big part of the cost is in the hours for extending the runners, so that probably will not be an option for me, thus the question about the 'effective increase' or net result, i.e. will raising the plenum net me more HP/TQ in my stroker and is it worth the money?

Only I can decide the worth. I am hoping someone will pipe in on the modification and if they found an increase.

Mindgame

Bret's intake is built around a whole nother casting. Not exactly a cheap piece either... but I'll let him explain that.

On the plenum volume. Most of the guys who're using the stock casting with bigger plenum are only really seeing gains at extreme rpms. If you're not going to be reving the engine to 7k and better, you probably won't see much. Just my opinion though.

-Mindgame

FASTFATBOY

Always the option of a carb style with an elbow, Steve Quinn also has an intake option, think his site is norushracing.com. You can always do like my Dad and I did, call Mr. Wilson
BTW Markbo, that setup had damn well better make more than 420 to the tires with a six speed, I would consider a 4" mufflex exhaust system for that car, or true duals.

David

jnjspdshop

Carb style with a PTE elbow will be the biggest bang for the buck

AdioSS

2 things

1. Markbo, that has got to be the longest signature on the board!

2. I'm liking the BRE ProRam. I'm going to try to make something similar...

Turbo6

Markbo

Mindgame-Thanks for the input
Turbo-Thanks for the link
Adios-1. See why I keep deleting it! I originally just wrote it up to keep track of all the mods. I since have a lot more, but decided to just keep all that info there justto keep it handy. 2. I like that BRE unit too.. the possibilities look very good. I just can't afford it and so far, Bret has not been willing to give me one to use as a test mule.
jnjspdshop-I am not familiar with this option... do you have any link or pics I can check out?
Fatboy-Sorry, you lost me on the Mr. Wilson reference. I actually have a pretty large exhaust and frankly with no cats, it is too loud - I'm an old fart and this is a street car. The only way I would do true duals is if I could get the oval pipes (for ground clearance) and restore cats. That would quiet it down and assure me passing emissions testing. There is precious little rooom underneath with that big carbon fiber driveshaft.

But you are right on the power. It had damn well better. It is a long, long story I won't bore you with, but this car has been off the road for 3 years and I finally feel some confidence with the advice and assistance of Bret - not to mention Injuneer Fred, Ken Mook and a few other helpful souls here at CZ28.com. Once it's running I will be highly disappointed it it is not an asphalt digging, corner carving, strip clearing, child scaring, old man intimidating beasty! I am actually hoping for 420-440rwhp & tq with a very streetable cam.

Thanks again guys
Mark

sseeya

Here's what he was talking about...........http://www.wilsonmanifolds.com/

atljar

http://home.wideopenwest.com/~squinn0039/products.html
Thats steve quinns intake, 1500 plus core. HE cuts them apart, adds plenum etc. See sight for details

If you decide to go single plane with carb style throttle body (still fuel injected of course), let me know. Ive got a throttle body adapter made to fit under 4th gen hoods.

sleeperz28

Lt1 intake will work on the 220 LT4 heads. Yes the ports are longer but not by much. The LT1 ports are wider. The LT4 intakes are junk IMO. The bolts never lined up great. If you buy it I would drill the bolt holes a bit bigger.