Anybody have some hard numbers on what the runners on a LT1 intake manifold flow?

Also what do most is a ported intake most of the shops sell? Is it just opened to 58mm an the throttle body, and the runners opened up to a gasket some? Or are they actually performing some work up the runners?

What kind of restriction would the manifold be on a set of 300cfm heads?

Is there any real benefit to Extrude Honing the manifold?

Sorry for all the questions, but my heads are about done and I am exploring my options for the manifold, want to retain the factory manifold as long as possible on my 396 I am building...willing to give up 10-30hp at this point.

Thanks for the help.

Dave.

 

Haven't seen any unfortunately, I wouldn't consider it a restriction though.

Ask them! You can do the work yourself as far as opening it up for a larger TB, although it will take time, and require a good cleaning out. I like to block the front with some rags so getting metal shavings out is easier. You can raise the runner if your heads require it, if they do not then you do not want to raise the intake runner, otherwise you will block flow into the head from the intake, I didn't bother opening up the runners on my intake, just opened up the front a bit.

If your willing to give up 10-30 HP then I wouldn't worry about fancy extrude honing, however not opening it up for a 58mm TB (remember you can do this yourself quite easily) would probably cost you more than that with such a large amount of air required, dont have evidence or math to back it up for you though. I ran a 58mm on my 350 FWIW.

 

My AFR 190cc heads are in cylinder head purgatory right now...ie the head porter's shop. I also took him a manifold, to open up to 58mm (I had already done it like you suggest to the manifold on the car currently). He is supposed to flow the finished cylinder heads with the manifold to see if it is a restriction. But in the meantime I was just looking for a comparison, to see if anybody had actually flowed the factory manifold. Looking for ideas, not real thrilled at the prospect of putting 310cfm heads under a 260cfm intake manifold runner, etc (if that was the case). I checked into extrude honing, but at nearly $600 I can buy a lot of porting, etc.

Thanks, Dave.


[This message has been edited by Dave69Z (edited July 06, 2002).]

 

For $600.00 you could also step up to a real manifold converted to EFI, i.e. Victor Jr., Super Victor, or Brodix piece.
That's really the only way you'll get the best manifold for your set-up.
Unless you want to spend $2000.00 for a sheetmetal intake.

Good luck,
Dave Brown

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If a little's good,
More is better,
And too much is just right!!!

 

Not that its very practicle to spend $2K on a sheetmetal intake.... but for arguments sake does anyone have a clue on what benefits you could expect by using one on a healthy heads/cam car?

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Ken Mook - 97' SS #2544
Advanced Tech Posting Guidelines

• Almost Alive: ?rwhp & ?rwtq Naturally Aspirated on the Stock Bottom End.
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[This message has been edited by kmook (edited July 06, 2002).]

 

See Ken, thats where I get confused.. When you look at how well the LT-1 intake is engineered, I don't see how it could improve much.
Only thing I could see making a difference would the the intake runner length.

-Shannon

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"Yep, getting drunk at the ol' flower shop"~ Homer Simpson
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If a super stock NHRA racer can run mid 10's on a LT1 with stock heads, intake and throttlebody, I don't really see where it is a bottleneck. If you look closely at a LT1 intake from the inside out, it looks like a short runner sheetmetal intake in basic construction. Ever wonder why no aftermarket comapany has tried to better it? I know of none who have.

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[This message has been edited by FASTFATBOY (edited July 07, 2002).]

 

FASTFATBOY,
Have you seen one of those engines up close, the intakes?
There's a lot more done to them than you think.
The TPIS Miniram, I believe was a copied/better version of the LT1 intake.
Sure you can get some power out of it, But we're talking about the MOST power and you won't get that with the LT1 intake.

Dave

------------------
If a little's good,
More is better,
And too much is just right!!!

 

FASTFATBOY, Edelbrock produced a prototype LT1 intake that never saw the light of day because the performance gains were negligible at best and couldn't justify the price tag. That's what I was told when I contacted Edelbrock about it. Oddly enough, it's still listed on the Doug Rippie site...

http://www.dougrippie.com/drm/induction_components.htm

The caption states "Edelbrock’s testing showed that this manifold made 35 ft-lbs. more torque and 25 more horsepower than the stock intake. Its improved runner design not only delivered more power but increased throttle response as well." Interesting. Wonder why a manifold that effective was discontinued?

strokedTA, when I contacted TPIS about their Mini-ram, I was also told that it had been discontinued for the LT1, as performance improvement did not justify the (relatively) high price tag. It's a vast improvement on a TPI motor, but apparently the LT1 intake is just fine the way it is.

So why did I end up with a Hogan's Racing sheet metal intake on my 396? Well, the only other option was converting a Victor Jr. to EFI, and I didn't have the hood clearance for a manifold with a traditional carb pad mounting scheme for a throttle body or elbow. My raised runner heads required a change of manifold, and we (Mark Montalvo and I) decided to go with the Hogan's to get the hood clearance I needed (it's 1/2" shorter than a standard LT1 intake) and match the heads. The results (which can be mainly attributed to the heads, though) have been excellent.

http://www.c-zone.net/markm/JimLaBre...d/P1190044.JPG
http://www.c-zone.net/markm/JimLaBre...d/P1190094.JPG
http://www.c-zone.net/markm/JimLaBre...d/P1190098.JPG
http://www.c-zone.net/markm/JimLaBre...d/P1190110.JPG
http://www.c-zone.net/markm/JimLaBre...o/P1010114.JPG

 

Brings a tear to my eye. Hey Jim ever gonna come visit me? I want a ride in it when its done

 

Hey Jim,
Looking at that manifold, maybe I'll just make me one. It doesn't look too difficult if you're handy with a welder. It does look nice, I wonder how much better it really is?

By the way, are those the new Jessel shaft mounted rockers?

That's a WAY COOL motor you got there



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SSMOKEM

1995 Impala SS "Cherry Bomb"
Best ETs: faster than my '65 pickup
Mods: 93% stock

My Super Impala SS Website

 

Unfortunately, I don't have the flow numbers for the intake or the heads. Mark's still holding on to those.

Those are Crower stainless shaft rockers with a 0.180" offset to clear the intake ports.

http://www.c-zone.net/markm/JimLaBre...d/P1190101.JPG

And thanks.

 

I have seen a few diff changes done to the LT1 intake. having the bottom cut off and then weld onto the bottom of the ports so you can enlarge the runners. I have heard (not seen the numbers) that it gains you some power.
I personally went with the hogan as well. (for a few diff personal reasons)

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