The Stovebolt Site Forums The Shop Area Engine Shop Vortec 5.3l in '46 panel?

I am trying to decide on a suitable engine/transmission for a project that consists of a 1946 Chevy panel body mounted on a 1945 pickup frame with a '74 Monte Carlo front end and a '89 Firebird rear end. The frame setup came from a friend's rod project that he lost interest in and the panel body came from a farm without an engine or transmission. I intend this to be a daily driver with considerable long distance driving. I want maximum engine reliability and fuel economy with reasonable power. I have a '74 small block 400 that I believe is rebuildable but I don't think I could get much more than about 12-13 mpg. Another friend has suggested installing a late model Vortec 5.3 to get the benefits of computer control. Has anyone done such a swap or does anyone have any opinions about it?

That 5.3 won.t get you much gas mileage either. I would go with a Toyota 22RE. This way you'll get the mileage you need at today's fuel prices... My $.02

I have no experience, but I have heard of people putting the new I5 from the canyon/colorado. I have no idea how hard it would be, but the gas mileage is good, and wreckers are starting to have a few... Just a thought.

I don't have any advice on how to do it, but it sounds like an excellent idea to me. I think the 5.3 engine is WAY better than the old smallblock, from fuel economy to performance. I have a 2000 Chevy 4wd pickup extended cab and I can get 19 mpg on a long drive, 15-16 on short trips. It also has far more power than any pickup I have had, although it is my understanding that the new Dodge and Ford has more power but at a sacrifice of fuel economy. It has more than enough power for any normal person.

You should try and figure out your rear end gear ratio in order to find the correct tranny combo. You can talk all the gas mileage you want but unless you know what you have the prediction will turn out w/ a better guess. Long hiway mileage needs a higher (2.70-3.20??) rear end. You will lose some gearing for power & towing but where you live it's pretty flat.

See::
http://www.smokemup.com/auto_math/index.php#3
and do the calculations


my $.02

Don Lewis: you are on the right track. The computer controlled engines and trans combo of today are considerably better than the old method of trying to do the gear thing. Take advantage of the modern technology and get that 5.3. I too can get 19 MPG with my GMC pickup. It has 186,000 miles and still runs as good as ever even though it has NEVER had a tune up. In fact other than a fuel pump I have never touched it.

Don, I think you are on the right track to go to a fuel injected LS based engine. You might ask this question on www.LS1tech.com. They have a section devoted to conversions from a non-LS based engine to the LS based engine.

On a side note, the next time I drive through your area, I would enjoy seeing your project. I live in Amarillo and am from Midland, so I make that trip regularly.

Phil

Thanks to all for the pointers and suggestions. I like the idea of using the 400 since I already have it and have been told that I can probably get it built for about $1,000. A LM7 from Scoggin Dickey costs about $3,000. But, when I compare specs on both engines (stock) I get
LM7: horsepower is 285-295 hp and torque is 325-330 ft.lbs,
sbc 400: horsepower is 180 hp and torque is ?.
The 400 seems amemic.

If I run the 400 with a 700R4 though a 3.55 rear end (what I've got) to a 29" tire, I get a little over 2000rpm in overdrive. That seem pretty good but I don't know where that fits on the torque curve for the 400. Does anyone know where I can get torque specs for the 400? I realize they will change after the engine is warmed over. I got a suggestion to use an aftermarket EFI such as the Holley Pro-Jection. Any other suggestions in addition to the Holley Pro-Jection?

Hi Don,
I think it boils down to your comfort level with the different choices. If the carby 400 can be done much more easily in terms of time & expense, that is probably the way to go. I'm very familiar with the new vortechs and aftermarket computers, and they won't make the botton end torque of your 400 without some mods. EFI (with the right tune) will get you better milage, but a 400 with really shallow gearing will get decent milage too. Do the math and gear for a cruise rpm of 1700-1900 @ 60mph. The low RPM torque of this engine is substantial. If you have used the 400 in anything you'll know what I mean. The newer chev engines include a 4.8 with only 10 or 15 HP less than the 5.3 if MPG is an important goal. They are cheaper too. Bothe 4.8 & 5.3 are iron block, AL head variants in the LS1 engine family. If you go this route, get the computer and as mich of the harness as possible from the donor vehicle. Then you will need to employ one of the tuners to disable some of the features in the PCM that look for hardware in the original vehicle which is absent from your truck (antilock brakes, etc). There are a nunmber of good tuners in TX. There is nothing wrong with persuing new horizons. I personally leave that for work, and use the familiar mechanical work to unwind and enjoy, but everyone is different. My personal choice would be for comfort and enjoyment while persuing my hobby. Where that lies is unique to you. Enjoy the journey and the end result will stand on its own. I hope that isn't too corny. Enjoying the ride is important. Life is tooo short to have your hobby irritate you too! <grin>
Mike V

Okay, too much time on my hands today <smile>.
Sort of in this same vein; Edelbrock sells a $799 carb manifold setup bundled with a MSD ignition controller, which plugs directly into the GM coilpaks. You just bolt on a carb, program the ignition with a laptop, and go. The even give you a suggested spark table that is good for 95% of their customers. They aim it at street rodders who still want a carb. The application says "LS1" but it bolts to the little sister engines too. Simple and clean! Be aware that the 5.3 owes much of it's power & milage numbers to incredible ports and flow numbers never seen by the classic small block in factory trim. The EFI is only one *part* of the milage advantage equation. GM also sells a carb manifold, but it does not perform as well as the Edelbrock unit. MSD sells the ingnition control module separately too. I think it is just over $200 (or 300?) from Jegs. Now, if you go to a complete aftermarket Port EFI with that engine, bring your checkbook. I think there are FAST systems starting at $2400 USD (before injectors). You could save some $$ if you are willing to go with a less expensive system, and adapt here and there. If you buy and ATI Ls1 harmonic balancer ($200-ish), it has provisions for the popular 3-bolt crank trigger wheels used by Electromotive and others. IIRC, the Pro-jection will not work because it depends on a distributor reference pulse signal. The LS1 family engines a have no distibutor and their factory crank trigger signal from the rear of the crank, is pretty sophisticated (read unhacked). The most economical approach to a 5.3 install would be to scavenge a low milage donor vehicle for not only the engine, but the harness & PCM. I have a new 4.8 (same bore-less stroke)GM crate engine on the stand, but I'm going with an older EFI 4.3 in my 46 panel for reasons of personal preference, simplicity and familiarity. The 4.3 was factory turbocharged in 1991 by GMC with port EFI. I want that turbo and factory EFI and I know the computer side of that particular application extremely well. Everyone has their personal preferences and hot-buttons. Sorry if we are muddying the water, but you need to weigh the items are most important to you. Some may not be obvious at first. I hpe it's helpful. You know we will help, regardless of the route you choose. You know you gotta send pictures though!
Cheers,
Mike V