I've been following the latest efforts, and have a few questions. Companies like Holley and Edelbrock have had systems for a few years now, that use single plane intakes and four barrel throttle bodies that bolt on in place of a carb. They are port systems, with fuel rails and individual injectors.

The home made systems I've seen lately have a plenum built on top of the intake, I suppose so you can bolt up your stock throttle body. Is there any benefit to a plenum versus the throttle body that bolts directly to the intake? I know part of this is so the home made system is basically a bolt on, but would one of the aftermarket systems be that hard to adapt? You'd obviously have to go speed density, if yours was a MAF car, but the fuel system and the elctronics are already there.

 

1 the plenum adds volume to the intake like the supper ram does which i think is a plus
2 the 4 bbl throtle body can only be used with a speed density car or aftermarket computer system like acell or fast no maf sensor
3 the manifolds the manifold co use are garbage they do not use a good intake where the aftermarket you can make virtually any single plane work :cheers:

 

I am considering just such a set up for my '84. The problem with the '84 is getting air to the inlet with a horizontal TB. The Crossfire is a "top feeder" rather than a "front feeder".

Corky,
Have you looked at the Edelbrock 29785? No, it's not a "Super Victor" and Jeb doesn't like the way they've installed the bungs, but it looks like the manifold mfgs are catching on. Good luck, and...

RACE ON!!!

 

Is this one any better?
http://www.holley.com/HiOctn/ProdLin...901-101-1.html

Chevrolet SB Intake Manifold
1957-86 262, 283, 305, 327, 350, 400 V-8;
1987-Later w/Aluminum Heads
Part #: 9901-101-1

Features
2000-6000 RPM power band.
Designed for port fuel injection systems.
Accepts 1000 CFM Holley 4-bbl throttle body.
Single plane manifold design

 

I think another reason for using the plenum is hood clearance on the C4s. We are limited to what we can use because of the low hood clearance.

 

:iagree: I have one already to go, but the 4V throttle body will clear the hood on my C4 but not with a air filter, so I'm gonna fabricate a plenum or sell it and convert a tunnel ram I have laying around. This is a pic of My converted Holley Strip Dominator, it migt be for sale soon!

 

Some one on the forum has done the same already , but when they installed a fabricated air cleaner (like a NASCAR intake) that would fit under the vette bonnet ,it was so restrictive it killed any gains that were had running without it.

 

I just ran some tests with a single plane converted over to EFI. It turned out VERY good, check out the links I made on this. Search for my username, and they are all listed under single plane...

It was as good as the SR, even though the gearing was not properly matched for the single plane intake. :cheers:

Here is the link: http://forums.corvetteforum.com/zerothread?id=691202


[Modified by ski_dwn_it, 10:25 AM 12/4/2003]

 

I was typing a responce, last night when my ISP decided I'd been on line long enough. I have looked at that manifold, too. It has the same port size as the Edelbrock, FelPro #1205 gasket. I don't know the height. I am told it has the same bung installation problem the Edelbrock has. Either is likely to work well, it it isn't a max effort engine. Then, a custom bung installation would probably be worth while. For no, good, explainable, reason, *I* lean towards the Edelbrock. Good luck, and...

RACE ON!!!

 

OK guys here goes my treatise on the single planes out there right now offered in EFI configuration. Some facts first...
Height from bottom of cowl to front block rail- 9.150"
Edelbrock Super Victor Height- 5.52"
Edelbrock Victor Jr. Height- 4.58"*
4v throttle body (Edelbrock, MSD, Holley) Height- 2.185" (they are all within .100" of each other)
*- The Victor Jr. is actually a "tapered" flange manifold, they do this in order to keep carb bowls level upon acceleration; but on EFI it requires the carb pad to be machined flat.

The problem with the 4v throttle body is EXACTLY as Juan said above...You cannot get a reasonable air filter to fit with one under the stock hood. Someone else mentioned seeing a Forum member with a fabricated NASCAR style air box; well that was me... It was really neat looking (bead rolled and TIGed aluminum) but it cost me roughly 40-60 hp because there was not enough height and width to give adequate airflow. Unless you have a cowl induction hood of 2" or more you might as well forget about running a 4v t.b. What Cork said about the MAF cars also applies in this situation; there is no way to run the MAF with the 4v unless you want to do some REALLY restrictive plumbing.

The problems with the current EFI single planes on the market is that they are designed to easily convert (usually with the mfg's own computer system) carbed vehicles to EFI. The majority of the customers they expect to buy these systems are people with tow vehicles they want to get better gas mileage and for street rodders who wanted EFI... Most of these people really could care less about optimum power combinations (you know, like we do); the results are poorly located injector bungs. The location of the bungs isn't really as big of a deal as the simple fact that they cast them down into the runner! Holley's are SO bad that they kill about 40 cfm off of their standard X-Cellerator single plane! When I was first building the my single plane system about 5 years ago Holley hadn't yet released their EFI X-Cellerator but had built some for stand-alone ECM mfg Electromotive. I talked with Fred at Electromotive at length about the EFI single plane and he sent me one of the ones Holley built for them...The first thing he asked me was what kind of power I was planning on making; I said between 550 and 600...He told me to build my own because there's no way the Holley would support it...He was right; when I got the manifold I noticed the injector castings down in the roof of the port. Ick...Oh well, I can grind them out and port match to a 1206...WRONG!! If you grind them out the o-rings no longer seal! The Holley is designed where the injector is actually DOWN IN THE MANIFOLD!!! I recently looked at one of Edelbrock's pre-production Victor EFI manifolds and damned if it didn't have the same problem! It wasn't as bad and can largely be removed, but if you've got heads that are on the large side of a 1205 or bigger at a 1206, forget it... It's simpler to jig a carb single plane in my Bridgeport and TIG in the bungs where I WANT THEM as opposed to buying one already done. That way if I get froggy and want a 1206 or a 1207 matched intake it's not a problem; I have plenty of room for porting, no airflow restrictions, and I can tailor the manifold to its application.

The plenum adapter is another story...Once Jesse gets the prototype back to me I'm going to make a few changes and it will be ready for anyone who wants one. I actually picked up 6 cfm with the addition of the adapter on a stock single plane. I attribute this to a combination of two things:
1) The adapter lessened the air shear and the manifold's intake flange and actually smoothed it out somewhat.
2) The additional volume added to the plenum allowed a positive pressure to be achieved by reserving or "stacking" air.

The best thing about this setup is that it will BOLT ON YOUR CAR WITH NO FURTHER MODS! I can't tell you how much it pisses me off to have to change all sorts of crap around to fit a "bolt-on" part...So, I did it first and know exactly what it needs to simplify installation (ask Jesse how easy it is). You retain your large cap distributor (unlike the HSR), your OEM air ducting and filter assembly, your stock wiring harness... The ONLY things that need to be changed is adapting the factory fuel feed and return lines for the AN stuff and that will be part of the deal (or I'll tell you what you need).

Jesse has pics of the prototype as well as my old 4v setup with the NASCAR style ducting that he can post if someone needs a refresher...
-Jeb

 

Thanks JB, you're the first to give me some feedback on the positive aspects of a plenum (other than "I think it does some good"). I'm going to build a 406 for my '85, I'll be really interested in one of your systems when they are ready.

 

Jeb:
Any thoughts on the Edelbrock Torker II? It is actually lower than the Weiand #7547 X-cellerator. Same type of runner arrangement too. I know it may not support a 600hp setup but it may be just fine for 400hp. I'm running one on my '86 383 with an Edelbrock carb and a drop base aircleaner. I'd like to run a single plane EFI setup with a hood scoop but it will have to wait until next year ($$ issues).