Seems edelbrock is putting out a stealth ram like intake manifold for a BBC with rectangular port heads but it adapts to an LS style throttle body and it even looks decent too. Calling it a pro flow XT.
http://www.chevelles.com/forums/attachment.php?attachmentid=33348&d=1281630800

I think it can fit under my 71's domed SS hood. Next question is throttle body. I think a 90mm is better for my street driving I plan to do and I have narrowed it down to three candidates.

E-brock, for simplicity and cheapness has a 90mm. low $300 with sensors

Holley has a fancy billet 90mm that looks really good, but costs a bit more and no sensors.

I also found Texas Motor Sports has a 92mm that looks pretty interesting:
http://www.texas-speed.com/shop/item.asp?itemid=1093&catid=73

anybody here have a good hook-up on GM IAC and TPS sensors?

What do I do for a throttle cable with the TB so far up and the lever is on the passenger side? Will I have a problem with full range of motion using my stock chevelle gas pedal?

Is 90mm even big enough?

Anybody know of an online calculator for CFM ? I'm not sure how boost plays into cfm.

90mm is suposed to be 1150cfm. Which is like a really huge carb', am I right?

a 105mm is like 1500 cfm. Just seems crazy huge. I wonder if the LS guys are buying into the "bigger is always better" hype like the carb' guys did back in the days by going to the biggest demon they could find on a little 454 N/A motor.

Just thought I would post back that I decided to go with a 102mm
http://texas-speed.com/shop/item.asp?itemid=891&catid=73

Is 90mm even big enough?

Anybody know of an online calculator for CFM ? I'm not sure how boost plays into cfm.

90mm is suposed to be 1150cfm. Which is like a really huge carb', am I right?

a 105mm is like 1500 cfm. Just seems crazy huge. I wonder if the LS guys are buying into the "bigger is always better" hype like the carb' guys did back in the days by going to the biggest demon they could find on a little 454 N/A motor.

While you can go too big on throttle body here as well you will most likely hurt throttle response but not necessarily top end power. The difference is with a carb you are flowing air and fuel through it and the fuel limits the airflow more than many would think. Not to mention how a carb like a Dominator has alot of trouble metering part throttle fuel/air. Whereas with fuel injection you have a dry flow through the throttle body and the injectors take car of the fuel metering. So the short answer is yes you can still go too big but its not as critical as a carb.

I run twin 90's on my 491. Although that is way more than it needs, it picked up 60' and MPH increasing it over what it had. Point being it wasn't too big on my BB.

Years ago I worked with a VERY small engine that had EFI put on it and it (70 HP or so) and a twin 58mm unit was installed. That did very bad things to the WOT power and we ended up putting a throttle stop on it.

So you a lot of room before you over throttle body an EFI engine. What you care about is the off idle driveablity based on the air flow curve it has.

"What you care about is the off idle driveablity based on the air flow curve it has"

When I was talking to fast they told me how they payed special attention to the shape or contour of the throttle BODY on the lower portion where the throttle blad opend in ward. There is a slight hump in that area to slow down the off idle air so it does not surge and cause a difficult-to-tune lean condition.

Thanks for the input though. Seems every decision I am making has some risk associated with it, and the more thumbs up I get, the better I sleep. :D

Now send me some of that new fancy Holley hotness you got going on so I can "evaluate" it. :cool:

All the FAST TB's I've seen have a straight bore. The Holley LS throttle bodies have the humps as you call them like OE. MUCH harder to machine. Maybe FAST copied that now. Don't know, have to look so I know.

FAST told me that they made a revision to their big mouth TBs and now they too have the hump.

So that's part of why the holley costs a bit more. I thought it was just the shiny factor, but a complicated bore process better explains it.