Overall, which would be the best choice for a street BBC with rect heads: the LS-6 intake (3933163) or the Air-Gap? Looking for pros and cons (if any) for both of these. Thoughts on this are appreciated.

6 of one 1/2 doz of the other imho.

I'm with Gene. I have a C427X that I will be using. It is a copy of the GM alum with the plenum divider removed. I would bet if you removed the plenum divider an equal amount as the RPM intakes, you would gain the 25 - 30 HP that Edel claims and has been shown on dyno tests.

A friend has a pretty good flow bench. The Air Gap had quite a variation in flow numbers from port to port. Edelbrock couldn't explain it in a phone call other than to beat around the bush. The C427X was virtually the same in flow numbers to the Chevy hirise intake. Take manufacturer's claims with a grain of salt.

C427X - $40.00 at swap meet

1/2 hour to clean it up

$200.00 saved over getting new Air Gap - priceless

Keith, thank you for confirming what a few pros have shared with me as regards the dyno. No measurable, repeatable difference between a Winters or EDEL casting.

Use a C427X along with a few Motion Performance decals and keep people guessing.

graemlins/thumbsup.gif

You just gave away my secret plan!

i would have to see it to believe it. every chevy motor that i've seen anyone dyno here recently, has picked up power with an air gap over just about any intake period, let alone a 30 plus year old designed intake.

When I talked with Tony at AFR, He said the Weiand Stealth made more power on their heads then the Air-Gap. He said the internal passages are larger.

Originally posted by SMS:
The Weiand Stealth made more power on their heads then the Air-Gap. I've read that same thing on other boards.

Thanks for all the responses. So what you guys are saying is the C427X is basically the same as the stock intake? Can I assume the performance will be similar to the C427X (with plenum divider removed?) I guess I have time to make the decision, but overall, you guys would recommend the stock intake with plenum dividers removed-considering I already have it?

On a different note I wonder how the Weiand works with GM heads.

Thanks again for all the input.

From the side x side comparison I was able to do, an old C427X has the plenum divider removed and may have slightly larger ports. Dual planes like the C427X were basically dropped when the single plane craze took over, but of course, dula planes are back as mainstream now. I assume advertising and an effort to make the old dual planes obsolete are what created the Performer and RPM names. That and the fact that the modern engine crowd does not associate with a 427 motor anyway. But I see these manifolds all the time for 50.00 - 70.00.

I have not heard one bad thing about the air gap. It does well for hood clearences and like m71 stated, it has always beat the other manifolds during dyno tests. If anyone has something to say bad about one speak up. Information about this stuff is hard to find when the magizines wont say anything bad about a advertiser.

Jim
http://img.photobucket.com/albums/v508/JLerum/f5dcd614.jpg http://http://img.photobucket.com/albums/v508/JLerum/f5dcd614.jpg

The original LS6 intake was a flat panlake looking sucker.
I don't think you can go wrong with either the Performer RPM or the old GM factory hihrise(eg 427/425 or 396/375 of 1969 or earlier)but not the flat 70 LS6.
The air gap looks certainly more "trick".But Chrysler(please forgive me for using this blasphemy) has had this("air gap idea")for years, even on their factory stuff.

The original LS6 intake was a flat panlake looking sucker.
I don't think you can go wrong with either the Performer RPM or the old GM factory hihrise(eg 427/425 or 396/375 of 1969 or earlier)but not the flat 70 LS6.
The air gap looks certainly more "trick".But Chrysler(please forgive me for using this blasphemy) has had this("air gap idea")for years, even on their factory stuff.

The guys running in the certified/pure stock muscle car classes will argue that point.
Stock LS6 cars run at these events usually are at 108-112 MPH,so the intake can't be that bad IMHO...
I swapped from a Performer to an RPM on my 454 and gained no ET or MPH..

I will guarantee you will notice a difference (eg slower) if you changed your configuration to the pancake 70-72 design.

Originally posted by BORDERT:
I will guarantee you will notice a difference (eg slower) if you changed your configuration to the pancake 70-72 design. ..I agree..that low rise cast iron qjet intake isn't one of my favorite intakes.

Heck, the air-gap is only $230 or so. Considering what this whole project is going to cost, drop in the bucket. Besides, if I ever wanted to, the orig is there to put on. Thanks again guys.

Actually their have been some guys whom have gone 114+ with that pancake manifold. Reguardless, if your not rule restricted or have the hots for the restortion look do the Air Gap.

Jim

I looked at the Air Gap but decided to go with the Brodix HV2016. It's good from 3500 - 6800 rpm. The height is 5.175" and the divider is already cut out. But if you run a nitrous plate system you will want to grind out the rest of the divider.

Originally posted by davegumm:
I looked at the Air Gap but decided to go with the Brodix HV2016. I orderd a HV1016 and received the HV2016.
That thing was awsome looking.Maybe cause it was for rectangle ports.

Not a Big Block guy, but DAAAMMMMMMMMMMM!

I sent it back and received my 1016.
I felt cheated :(

I agree!

The old Weiand 8004 SB dual plane over a SB Performer AND a good old 8005 up to an RPM, the look at the Stealth..

AND I wish HOLLEY would upgrade the great old 300-36 SB as well as the BB equivalent to it b/c I think E-brock is spending too much on advertisement and passing that cost onto us!!

pdq67

PS., Holley probably needs to do NO MORE then just open up the 300-36 ports about 10 to 15 CC's is all b/c it is a winner on everything below a STRONG 388 in my book!! In other words, LEAVE the design alone except to up the inside's of the ports like 10 to 15 cc's is ALL...