LT1 vs. Vortec vs. LSx

[kevinr1970]

So in my '82 K5 2wd I am planning a slightly more modern drivetrain.

I am not sure I want to go the LSx route as I want to keep costs low(er) and already have sbc headers, engine mounts, etc.

My orginal thought was to get a Vortec 5.7/4l60e out of a '96-00 truck ('03 for vans?). I have seen a few 2wd trucks with hi-miles come up in the $1000 range, figuring I would rebuild the engine/tranny.
But I have seen a few '93-96 Caprice/Roadmaster/Impalas come up in the same price range, same condition. Even saw a Trans-Am needing an engine rebuild for under $1000.

I am going to keep it FI, not interested in going back to carb.
Not going radical on it, just a good stock FI sbc.
Not interested in a 6.0 due to fuel mileage.

What are the pluses and minuses of either engine combo?

[Jonboy]

I had an LT1 in my '79 C10, and I liked it. I bought it as a project that needed a lot of little stuff, and worked my way through it. My truck had Alan Groves accessory brackets and a Sanden A/C compressor (highly recommended, to keep from having to notch the frane and do a bunch of other goofy stuff). Your SBC headers will fit, and the engine mounts will bolt right up if you use the high mount A/C cmopressor. Otherwise you will have to move the right side engine mount back. My truck had pretty good performance (much better than the TBI I put in my '74), got really good mileage, and looked pretty cool to boot. I would have cleaned up a lot of it if I had put the engine in myself, but it still looked pretty decent. I would recommend doing an aftermarket harness also for the LT1 swap. All in all, it was a good swap, and was quite a bit cheaper than an LS swap.

However, a pull out (with all accessories) 5.3 is going for around $1500 around here, with decent miles. I would guess by the time everything was said and done, there would probably be $1000-1500 difference in going LT1 vs LS 5.3. The 5.3 can produce a lot more power with some tuning, but the initial buy in is a lot more.

[travis401]

LSx is way better fuel ecomony ans street manners. and they tend to make some damn good power with simple bolt ons. lt1s have the dreaded optispark ignition thats prone to failure due to water getting in, but aside from that they too can make some good power with simple bolt ons and tuning. the vortecs (or atleast what are commonly refered to as vortecs) are just your stadards gen1 SBC with some of the best flowing heads GM has produced. they were offered in a TBI version in 96-99 trucks. they do well with some upgraded parts, but the tbi isnt the best FI around, although it is pretty good.
the other "vortec" engines are the later model 4.8, 5.3 and 6.0 LSx based engines. then theres those "vortec" v6s that are out there. the term "vortec" was used a lot by GM, for various different things.

[Maxzillian]

The 96-99 Vortec wasn't a TBI, but a multi port system. However, it was a bit of an oddball in that there was a central unit that served as the distribution manifold and contained all the valves. From there a set of lines fed poppet injectors located at the port. This system required 60 psi and can be pretty hard on fuel pumps. The poppet injectors are also known for plugging easily. GM offers a kit for $300-$400 that replaces the poppet injectors with more conventional unit injectors, but the kit is a bit special in that the injectors are made to work with a gutted distribution manifold and includes a wiring harness to adapt the system.

The 96-99 Vortec head is a small evolution over the LT1 and as stated above, it arguably one of the best factory heads ever offered on the small block. The LT1 engine, however, may make slightly more power thanks to the aluminum heads and reverse flow cooling system allowing the engine to be a bit more aggressive on compression and ignition timing.

My truck has the GM Performance 350HO which is a Vortec engine that included a more aggressive cam and carburetor intake. I've been pretty impressed with the engine and have netted as high as 18 mpg, but power didn't come on until it reached about 3000 RPM and the secondaries opened up. With 2.73 gears, that took forever! I'm converting the engine to fuel injection using a TPI upper manifold and Scoggin Dickey lower manifold. Hopefully the long tube intake will give the engine a bit more grunt and I won't have to wait on secondaries any longer!

[el_guapo]

Plus one on a 5.3, the lt1 optinightmare plus age make me pass.
Ls1 initial investment is too much. 5.3 is just right, that's my path.
Good luck and keep us updated.
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[Jonboy]

The opti-spark is pretty easy to access either by replacing it when you are putting the engine in, or with all of the additional room a truck provides over the original applications. This being said, I have never replaced one in any of the LT1 cars I have had yet (5 so far). I have replaced more EGR valves.

[andrewmp6]

I wouldn't do a lt1 when the water pump leaks it kills the opti spark but i have seen a kit to run ls1 coil packs on a lt1 is the only way id own one again.If your looking for mpg a diesel is nice but will be pricey to do.A 4bt cummins is a 4 cylinder 3.9 just like the 12 valve 5.9 found in dodges.A 4bt in my friends 95 f250 4x4 gets around 26mpg highway on 35s.Same truck with a 351w got around 8mpg hes happy with it now.

[gGMC DOG]

an lsx swap will be more costly up front and a lot more work, but a lot more potential (especially if you go with a 6.0). the vortec route will be easier, but power will be limited

[my4by2]

Go with the LS motor - any size - GM didn't do all the development to make a better engine than the original small block & LT1's for nothing - it is VASTLY superior in about every way it can be. Yes it's going to cost you a little more up front, but the trade-off is well worth it.

As for fuel mileage, if you were run a stock TBI, LT1 & LS motor against each other the LS would win hands down. The EFI system it uses it far more advanced & accurate than either of those systems.

Full "pull-out" LS motors can be had for relatively cheap if you shop around - just be sure to get everything you need - i.e. pedal assembly, ECM, harness, etc.

[BigBlocksRule]

I'd go with the 6.0L LS. Damned tough iron block that can handle everything you can throw at it...15* valve angles, crossbolted mains, yada yada...should make a great daily driver engine with good fuel economy, if you can keep your foot out of it!

[KMK454]

Tpi l98?

[Mr. 250r]

Overall the ls may be more expensive but worth every penny the 6.0 can be bought cheap with low miles and everything on it if you look around, the vortecs, lt1/4, tpi were decent to good motors in their day but the ls blows them away in all catergories
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[SBTork]

I recently did a cost compairson between upgrading my first gen. 350 small block to TBI vs. going the LS route, and was surprised at the end result. It was a little less to go the route of TBI, I mean in the hundreds less, like one or two hundred less than the LS swap. All things invloved to upgrade the fuel system are apples to apples, you need the same parts either way so that was a wash. The harness for the fuel injection, same story. The only thing the LS will FOR SURE cost you more in, is time. We all have that.

I would recommend you do the best you can once you figure in everything invloved in every swap. You, like me, will find out that the LS is the only realistic way to go.

The only way you could come out spending less on a swap not involving an LS engine was if you had the whole vehicle, but you're talking about rebuilding the engine and trans out of a vortec/LT1 vehicle. That tilts the cost factor towards the LS being cheaper. Any basic/mild small block rebuild is going to cost more than a "lift-out" engine/trans out of an LS vehicle.

Check our LSx swap section here and go to LS1tech.com and check out their conversion/hybrid swaps section. There are TONS of people putting junkyard LS engines into any and everything for minimal dollars.

[clinebarger]

A LT1 would fit the bill really well, I got a 20,000 mile Iron head LT1 out of a 95 Cadillac Fleetwood for $500 with everything but a trans......I have about $1500 in my Cutlass including $200 for the car.

There are more optispark problems on the internet than actual optispark problem

[BigBlocksRule]

You won't gain a nickel's worth of performance with an LT1 over a 350 Vortec engine with a similar cam. After all, the Vortec head was designed off of the LT1. You WILL learn about opti-junk ignition and how little aftermarket stuff is available for 'em.
They have a cool looking intake though.

[clinebarger]

Originally Posted by BigBlocksRule

You won't gain a nickel's worth of performance with an LT1 over a 350 Vortec engine with a similar cam. After all, the Vortec head was designed off of the LT1. You WILL learn about opti-junk ignition and how little aftermarket stuff is available for 'em.
They have a cool looking intake though.

The Vortec 350 has its own set of problems, Injectors, Intake gaskets, cracked heads.....And my all time favorite.....Leaking FP regulators catching the inside of the intake on fire

[travis401]

and with alittle work and welding you can have the lt1 intake on a vortec 350....

[travis401]

i wouldnt suggest using the vortec 350's FI system anyway. either carb it, or fit whatever FI system you already have on it. those vortec FI systems were terrible to say the least.

[kevinr1970]

Thanks for all the input!

I said I wasn' going to consider the 6.0 due to mileage, but mileage is not my "main" concern; meaning I am not considering a deisel swap.
Although a Duramax in my K5 would be an interesting truck to drive!

My FI truck experience has been with a '98 crew 4x4 (5.7), an '00 crew 4x4 (7.4) and my '87 crew.
The TBI in my '87 crew seems to have quite a bit more power than the crate 350 in my K5 now, but I wonder how much of that is due to the 3.73 vs. 2.73or 3.08(?) ratio?
Both the "vortec" trucks seemed to have ample power and in stock trim seem like they would perform very well in my application.

My goal is to have a good driving truck, with minimum of reliability problems, with maximum of performance without doing anything drastic; headers, intake, tune (ECM, PCM, ABC, PDQ, ETC).
I want to be able to put my key in the ignition and drive acros the country at any time, and be able to pass people at will.

After putting 4k miles on my '00 crew in three years I sold that truck to fund my K5 and am itching to start getting some progress done there.


PS; I recently found a 5.7 vortec, "new in crate" for " '96-01 application" for a good price.
My girlfriends dad has an aftermarket TBI kit (after market TBI manifold, stock TBI body, custom injectors, harness, ECM) he had on a street rod for very few miles that he kept when he sold that car. He would practicly give that to me.
Is a newer "vortec" engine compatible with a TBI system?

[SBTork]

Originally Posted by kevinr1970

Thanks for all the input!

I said I wasn' going to consider the 6.0 due to mileage, but mileage is not my "main" concern; meaning I am not considering a deisel swap.
Although a Duramax in my K5 would be an interesting truck to drive!

My FI truck experience has been with a '98 crew 4x4 (5.7), an '00 crew 4x4 (7.4) and my '87 crew.
The TBI in my '87 crew seems to have quite a bit more power than the crate 350 in my K5 now, but I wonder how much of that is due to the 3.73 vs. 2.73or 3.08(?) ratio?
Both the "vortec" trucks seemed to have ample power and in stock trim seem like they would perform very well in my application.

My goal is to have a good driving truck, with minimum of reliability problems, with maximum of performance without doing anything drastic; headers, intake, tune (ECM, PCM, ABC, PDQ, ETC).
I want to be able to put my key in the ignition and drive acros the country at any time, and be able to pass people at will.

After putting 4k miles on my '00 crew in three years I sold that truck to fund my K5 and am itching to start getting some progress done there.


PS; I recently found a 5.7 vortec, "new in crate" for " '96-01 application" for a good price.
My girlfriends dad has an aftermarket TBI kit (after market TBI manifold, stock TBI body, custom injectors, harness, ECM) he had on a street rod for very few miles that he kept when he sold that car. He would practicly give that to me.
Is a newer "vortec" engine compatible with a TBI system?

I would think so. The main difference would be the intake. GMPP sells a TBI intake to work w/vortec heads but it's not cheap.

[travis401]

the 96-01 vortec is just a gen 1 SBC with vortec heads. they require a vortec specific intake since the bolt pattern and intake ports are different from standard gen1 SBC. like SBTork said, GM sells a TBI vortec specific intake, but its not cheap. you can however get a generic carbed vortec intake (theres plenty of them and they run about the same as a standard carbed intake) and run a TBI adapter plate to mount the TB.

[kevinr1970]

When you say "vortec", are any '87+ heads with the center-bolt style valve covers considered "vortec", I have always been a little confused about this?

The intake he has was for center-bolt style heads, but was machined for the older perimeter-bolt style heads.
Not sure if that means that manifold is now no good for the center-bolt heads, or it could be used for either?

[travis401]

no, not all centerbolt heads are vortecs, but all vortecs have the center bolt pattern. the vortec head was only made from 96-99. it has a different bolt pattern and intake design compared to 87-95 heads.

vortec head

standard head


you can see the bolt pattern differences there. vortec heads also have a taller intake port, so thats why it needs the vortec specific intake.

[travis401]

theres basically 3 different intake types for gen 1 SBC, pre 87, 87-95, and then vortec specific. the only difference between the pre 86 and 86-95 is the angle of the 4 center bolts. you can grind those holes out and use a washer to make them interchangeable. the vortec intake cant be used on non vortec heads and vise vera.

[travis401]

this is a vortec head with a standard intake cutaway to show the port differences.

if you notice the vortec head is an aftermarket one, that offers both the vortec bolt pattern and the standard bolt pattern. they usually supply a special gasket to use when using a non vortec intake that covers the gap at the top. but you stilll have the mismatch on the bottom that interupts air flow.