greghennings

Hey guys, been thinking about doing some upgrades to my 76 L48. The first up is doing a Holley EFI (or Edelbrock), has anyone used/using one of these things? Are they a good way of adding hp and reliability? I have a Holley 650 dp and its ok, but its fussy. i can get the engine to start, but either the wife or anyone else for that matter it would take a while to figure it out. Thought a Holley EFI would be a good way to get a better starting engine. And i could go from 650 cfm to 950 cfm should add a little more hp.

One thing i have been wanting to do for a long time is get a set of Edelbrock aluminum heads. So if i do change my carb, i'm going to get these, and then also change my intake manifold. Right now i have an Edelbrock Performer dual plain aluminum manifold and i don't like it. Came with the car. The dual plain intake makes fitting my Holley 4150 carb a little iffy. It fits, but its not right. I want just a standard aluminum square flange 4150 intake, but from what i've read edelbrock says theirs don't fit under a stock corvette hood. Well, i have a performer intake with a 1/2 extension between it and the carb, and it fits fine. Has Edelbrock changed their performer intakes so they won't fit now?

427Hotrod

I've had great results out of Holley EFI. It's on my car and I've installed several others. Starts perfectly even when dead cold and driveability will "self tune" to whatever you've got under the hood and whereever you live (heat/altitude). Or you can manually hack anything you want to supertune it.

The EFI in and of itself won't necessarily add any power by itself. If a carb is really well tuned, EFI will be similar under WOT. BUT...if someone isn't good at carb tuning or it's out of whack for the combination...the Holley EFI will definitely add power just by reason of it being "tuned". Street driveability is great with throttle response at all times and on "hot and nasty" hot rod engines, it does a great job with driveability and keeping plugs clean etc.

Most throttle bodies are a hair shorter than a carb..so hood clearance improves. I don't think Edelbrock has changed the intakes....that "not fitting under a Corvette hood" statement is listed on tons of intakes that have proven to actually fit with a little work as you described. The right air filter can make things fine. The Performer is a decent intake for a mild engine...not sure I'd change except for something better. As HP climbs, typically a little work on the plenum divider helps things overall.

If changing heads...I'd certainly look into doing something with that L-48 cam. You're not working with much there and the heads won't deliver what they can/should after spending all that money.

Here's a couple of articles I've done on Holley EFI stuff:

http://www.carsandparts.com/en/exper...-simple-1.html

http://www.carsandparts.com/en/tech/...xperience.html


JIM

greghennings

Great info 427Hotrod, just to add to it, i do have a CompCam installed. But that's all i know about it cause it was in there when i bought it. When buying new cylinder heads, do i need to figure out if i need to get different pushrods? I have Arrow iron heads right now (again previously installed), so they're not stock. Maybe what a guy needs to do is strip it all out and start over with new parts that are all the same manufacturer. I really don't want to mess with the camshaft though, but if it would take some guess work out of it...

427Hotrod

Yes....you'll need to determine pushrods to make it all correct. Can't do that until you have the heads on the motor to do it right.

You'll want to make sure the springs match the cam and that the lift can be handled by heads/cam. Probably not an issue...but you'll want to ck. I would spend some time determing what cam I have with a degree wheel and dial indicator. Heads and cam need to match to work their best. I'm talking proper duration for head flow.

The Edelbocks are "middle of the road" street heads as far as performance. Maybe tell us more about what your plans are, gears, trans etc to help pick best ones. Definitely need to know what pistons are in it to pick correct chamber size on heads.

You don't have to use same Mfg....no guarantees there...just need to make sure stuff fits together well. No telling what was done in the past...so no telling what it needs now for sure until you get in there.


JIM

greghennings

Ok, my plan is to get this all planned out before i purchase anything so that way it'll all go smoothly at the time of installation. I kind of like the price of Edelbrock stuff because of the "middle of the road" idea. I don't want cheap junk, but i also don't want high end professional grade drag strip stuff. I can say with almost 100% confidence the pistons are factory, not bored out. So whatever chamber size that is right off hand i don't know. My corvette has a 200r4 tranny with 3.90 rear-end gears and they are staying in.

I don't really have a good reason to want aluminum heads, just for the idea of it i guess, take some weight off the engine. And its winter and i'm bored .

427Hotrod

Hey...a good enough reason is MORE POWER!!

Go for the smallest chambers you can find...64cc at least.

JIM

bluedawg

If your set on edelbrock heads, check out the etec CNC heads or look at afr 180cc eliminators, match the intake to the heads. Cam shaft for injected I believe runs a wider lobe seperation.

toobroketoretire

If you're young I recommend taking the money you have set aside for upgrades and stick it into investment accounts so you'll have money in your retirement years (something I didn't do). My sister stuffed her money into investments her whole life and at 74 years she has more money than she could ever spend.

greghennings

Hey guys i'm back, still been just doing some thinking about what i want to do this winter. I think i'm tossing out the idea of new cylinder heads, i don't think i'd be gaining enough to justify the time and expense. But i do want to do a Holley EFI, it looks like a good project. I want to try the Avenger EFI, but i noticed it looks a little tall. Does anyone know if its taller than a standard holley double pumper? I can't find any physical specs on the thing. If i have to, i'll go with the terminator efi, it looks more like a standard carburetor.

Also, i noticed that the Avenger injectors are above the throttle plates, but the Terminator EFi injectors are below the throttle plates. I've been reading many threads and as far as i can tell its the difference in how the gas gets atomized before getting to the cylinders but no one has really said which is better. Right now all i see is a $200 price difference. My engine is probably in the 260-280 hp range at best guess so i don't really need a big CFM throttle body with 85 lb/hr injectors.

Shark Racer

MSD Atomic Efi is a little shorter than a carburetor, not much. I doubt it's any taller than a double pumper.

As for atomization, it's a really good question. I've heard some of the ones w/ below throttle blade injectors have such a steep angle that the fuel will pretty much slam into the plenum of a dual plane intake, if that's what you're running with.

At WOT, atomization is *less* important as the mixture is moving so fast it's more likely to stay in suspension.

I'm pondering going with a single plane intake on my TB EFI setup due to the very question of atomization. Less corners to turn means less chance of fuel puddling.

gdh

Holley's new Sniper EFI @ $999 or the new FiTech unit to be released this spring @ $799 might be a good fit for your L48 as well.

greghennings

holy crap gdh i didn't even look at the sniper unit. its going to be a thousand dollars less, its all integrated into one unit, and it even looks good. and still gives you a nice lcd touch screen, ignition controlled timing (that i hope to use some day), but holley doesn't specify the need for an O2 sensor for this unit, do you think that will still be in the package? I kind of hope so personally. I might just have to wait till March 31st for this thing, might be worth it.

Shark Racer

I'm very confident the Sniper system will require an O2 unit. It's definitely a good looking unit, especially for guys who love the look of a double pumper.

gdh

Maybe they just are not including the O2 sensor to keep their price under $1k and selling it as an addition. Reading on another forum that compared the specs of the Sniper to the FiTech unit they said based on what info is available on the Sniper that the FiTech unit has more features. They also think that come spring that FiTech will drop their price to try to keep ahead of Holley. Will wait and see. From what I was told all the throttle body units for the different mfgs are manufactured at the same co. in China with software designed by each company in house. I wouldn't be surprised to see Edelbrock and MSD come out with similar low priced units.

greghennings

it would be sure great to see these things drop in price, $2500 bucks for the terminator master kit really? worth it probably yeah but ges. but yeah guess we shall see at the end of march..

flyeri

Ive been looking at both of these. There is a review post on here for the FITech. I'm not crazy about their command center header tank under the hood but you can run it with an in-tank or in-line pump.

Also according to the FITech website wide band o2 sensor is included along with bung. It does not include pump and fuel lines for $995.

donnie1956

https://www.holley.com/products/fuel...4bbl_tbi_kits/

81corvettevortec

I'll be doing a throttle body EFI swap on my '81 this spring and will likely go with the Fitech. But I'll be honest, i really wish it came with a handheld similar to the Holley. Would look so much nicer mounting it somewhere permanently. The Fitech handheld looks circa 1995ish. Trivial since it doesn't affect performance but still.