belair

Doing a LQ4 build up with L92 heads and looking over the Car Craft build up along with listed crate motor HPs, it seems a 750 Holley and GM or Vic Jr intake will produce more than a EFI setup. I am swapping into a 928 Porsche and it seems to get harness,computer, and a connecting harness to the Porsche VDO($800 with programming) I am cheaper and more power with carb. Thoughts?

KCS

iTrader: (20)

There are several guys here claiming pretty big gains with the carb manifold and a 4150/4500 style EFI throttle body, even over a 90* elbow. It's not just the carburetor itself, but it seems it's the pathway that makes the difference.

TooLateVTEC

iTrader: (2)

The intake itself is just a better design than having the T/B mounted on the front like a regular LS1/2/3/6/7 etc.

If motors made more power with them on the front, the Pro Stock guys would be doing it.

Old SStroker

Thoughts:

Unfortunately any single/carbed is going to stick a bunch above your hoodline. I can't imagine a 928 as a pure drag car...but maybe yours is.

If your desired power peak rpm is above 7000, a single plane/carb may help. The Vic Jr. is not the first choice, and 750 cfm is a bunch small if you are looking for big power. The single plane manifold that works is from Performance Induction. The good manifold and porting required to make lots of power will be way over $800.

The stock LS3 intake should fit under the hood and make ~550 rwhp if things are done right. Are you looking for more than that?

I wouldn't base my engine build choices on articles in Car Craft.


Jon

NemeSS

iTrader: (127)

efi will net better mpg but costs more. if not really intrested in peak mpg a carb is a good way to go with, depends on what parts used will determine the price range.
i for one had no prob with with a vic. jr on the street with a 750hp carb.
car ran mid 10's n/a. drove evrywhere, hiway, gtg. was cheeper for me since i have some exp. with carbs. i could tune at the track or on hotter or colder days. or if was taking long trips, would adjust for that also. throttle response is immediate and crisp, pulled to shifted at 7000 rpm. without a glitch.
fun street car. i am going with super victor and same size carb. on new project.

belair

To clarify further it is to be a street car but why not be a fast one. 550 rwhp is plenty adequate. From my best guess a single plane and carb will only be about 2-3inches through the hood and I don't think a say Mustang scoop would be too bad. I don't want to base my choices on Car Craft either that's why I'm here!!!
Thanks

Old SStroker

Every once in a while Car Craft has a fairly good tech article, but there is a lot of mis-information also. There is a lot of similarity with CC & LS1Tech in that respect.

IMO, a 750 on a Vic Jr. won't make 550 rwhp (630+ fwhp)...at least not for an easy driver.

Look at the height of the P.I. single plane, carb and 3 inch aircleaner vs the Vic Jr. The height of that manifold helps in the power making.

Here's a link to a pic of one on a cathedral port head. The L92 is similar. It's on the BES engine.

http://www.popularhotrodding.com/eng...rp/index1.html




Jon

belair

Yeah the more I think about it the hokier the hole in the hood sounds. What combination on the LQ9 build are you speaking of to make 600+ at the crank. Keep in mind budget and not a cam that will cause me to run over someone at the grocery store.
I have a complete oil pan to intake new LQ9. I was thinking fairly stock L92s maybe a 228/228 581 or so cam, LS6 springs, some decent but cheap intake and call it a day around 500-525 crank. Thoughts?
Going for EFI I have to score harness, computer, adaptor to the VDO stuff, not sure what I can use off the truck intake. Open to suggestions on the top.

Old SStroker

For your power and drivability goals the complete truck intake is good to go, but 1) it's REALLY ugly and 2) hood clearance might be a problem. If you can work that out, it would be the cheapest way to go as you already have it. You'd need a mechanical (non-drive by wire) throttle body, or adapt the complete PCM and thottle pedal, etc from the truck the engine came from.

I don't think "decent" and "cheap" are mutually exclusive, but the whole system needs to be designed to work together, especially if you go carb.

You really need professional help with the valvetrain. What you have suggested is not where I would go, especially the springs. Well, not the cam either. The intake and exhaust systems and your goals will determine cam timing. Not everyone does L92 cams correctly. The L92 heads want different things from what the cathedral port LS heads like.

Jon