bucky katt

i just got a 78 L-48/Auto trans car this past week. it's complete except for the motor and i'm looking at crate motors and putting in a 200R4 lower cruise rpm's. because this is going to be my daily driver, i'm looking to improve mileage as much as possible, i know i'm not going to get mileage like my saturn wagon will BUT i do want better than the 14-16 the stock L-48 TH350 cars do. anything will be an improvement in power over the stock 185 of the stocker. i'm looking at running a self-tune 4 barrel throttle body injection.

Shark Racer

A modern, modest cam grind with better heads and a proper tune should do easily over 20mpg with an overdrive and well tuned EFI. The ZZ4 seems like a very simple, reliable solution. It's not a big power motor, but it's healthy and well-known.

tekvette

I just bought a crate 406 from NYES Auto. They build street, race engines. I did ALOT of research and chose them over other builders like Shafiroff for eg. because they build a very reliable product.
Not sure what kind of power you're lookin for but here's their base pump gas 383 longblock that puts out 400hp for $3,000.
http://www.nyesautomotive.net/383SBC_400HP.html

Ralphbf

I've had great results with the Edelbrock Cam and Manifolds as far as better performance AND better gas mileage coupled with Doug Thourly Headers it's hard to go wrong.
A 454 in my 27' motor home went from 7mpg to 14mpg using these parts.

Ralph

jackson

Best Crate Motor Value
Year One CT350PC1
http://www.yearone.com/serverfiles/f...archid=6191850

MN80Vette

I have a GM Performance 350 HO crate in my '80 with a carb and true dual exhaust. I got tuned pretty well over time. I got 16-18 mpg with the original Super T10 4-speed and it produces at least the advertised 330 hp. I am just finishing my Kiesler 5-speed overdrive installation with a new mandrel bent 2 1/2" exhaust system. I am looking forward to the mileage improvement.

The ZZ4 was mentioned already, but if hp isn't a high priority, then GM also has an economical 290 hp crate that a few C3 Forum members have. Maybe they will join in this thread.

GM Performance Small Block Crate Engines

U17

I went with the ZZ383... and 700R4... 20mpg, 425hp... 450#torque....

Shark Racer

If $$ is an issue, go cheaper, sure, but the ZZ4 has alum heads and a roller valvetrain, which will both help to squeeze more economy out of the motor. When the engine in my 78 comes out, I'm definitely never installing a flat lifter setup again.

billla

These discussions best start with price

Many choices out there; are you looking for a complete turn-key or willing to do a bit of final assembly? Often the best buy is one of the crate short or long blocks.

The GMPP engine line up is problematic to me, as I feel there are some odd compromises in some of the engines. ZZ4 is a case in point; relatively "eh" heads, forged crank but with PM rods and hypereutectic pistons! The 350 HO is a better overall value from my perspective, especially if bought as longblock.

Ralphbf

What horse power and RPM range are the ZZ4 heads suitable for?

I'm guessing below 365 horse and below 6000rpm.
I'm also guessing they would be better on a 325hp 350 below 5500 than most aluminum heads, but I, just guessing.

Ralph

billla

For reference, the P/N for the heads is 12556463.

Well, the ports are 163cc, which is relatively small. Not a bad thing for port velocity, but certainly a limiting factor. They top out around 200 CFM @ .500...which is ~40 CFM below an iron Vortec head! The roller cam certainly helps the power - but I wonder if the engine actually makes rated power installed...

Ralphbf

So what would be the horsepower and RPM limits of these heads?

Ralph

Shark Racer

I'd imagine they'd be good for at best 6k RPM, maybe 6500 with a lot of port/polishing work.

I find crate motors to always be some kind of compromise. I don't think I'll ever put a crate motor in my 'vette, part of the fun in it (for me) is designing a motor.

mfpvette80

I'm one of the guys that have gone with the 290HP crate motor. It's been outfitted with an "RV" cam, shorty headers and a true dual 2.5" exhaust. Coupled to a Tremec TKO-500 gearbox (American Power Train kit) I get 25-27 MPG on the highway. Around 20 in local use. The motor sounds awesome (Summit turbo mufflers) and has loads of torque for easy driving. The horsepower is sufficient, and I don't have to worry about busting the Dana 44 rear end so much.

scottyp99

You probably aren't gonna want to hear this, but GM Performance 10067353 (260 hp) is the exact same engine with an rv cam already in it, for $500.00 less than the 290 hp engine. Sorry........


Scott

69vettester

ZZ three-eighty-three

SmokedTires

Just averaged my MPG on a trip I took with my custom built SBC, while I thought I've been getting good milage on the highway with the overdrive, I just realized I'm getting about 10 mpg's

Richard Cooper

I just put a new crate motor in my 1981, It was from Pace Performance and is a 350/300HP. I've only got about 50 miles on the new motor but so far I am very happy with it. The price was great too.

billla

I don't really think about heads in terms of RPM limits...

As for power capabilities, there's a formula that estimates (<--see the underline? ) power from flow...it's a little conservative, but it's a pretty good rule of thumb.

257 x (intake CFM x intake manifold induction loss) x cylinders.

An Edlebrock Performer is going to create an induction loss of about 25%, so...

257 x (200 * .75) x 8 = 308 HP.

Now...the engine is advertised at 355HP, but I kinda question that as noted previously.

I did a little search to see if there were dyno numbers out there, and found a Hot Rod mag article, which these days does some really outstanding work, and a 314 HP run...and this was likely with dyno headers.

http://www.hotrod.com/techarticles/e...s/viewall.html

A better intake would likely get the numbers up a bit...but I can't see making more than about 340HP max.

scottyp99

Yeah, I think that's the official rating for it, but it's usually referred to as the 260 hp engine. Regardless, it's the same engine. You don't have to take my word for it, just look at the specs.

I would like to say, also, that I agree with billa, GM's choices are a little odd when it comes to the crate engine lineup. For instance, the 12499529 (290 HP) is the 10067353 with a different cam. So you are paying 500 bucks for a cam. Also, how sweet would it be if they offered the 10067353 with vortec heads? They could sell it at roughly the same price and still have the same profit margin per unit, but they would sell a gazillion of 'em!!!! And, you can make a pretty close copy of the 19210007 (350 HO 330 HP) by taking the 10067353, installing vortec heads, and installing a Summit racing cam (SUM-1103). Total price about 2250 bucks.


Scott