Engine Choice: Inline 6 or LS?

[short&wide65]

I'm looking for some advice and opinions on what engine I shoud install in my 65 GMC.

The truck will be a mild pro touring build using the original chassis with upgrades. I'd like to do some autocrosses with it but just for fun. I have a serious autocross car that will always be faster no matter how much money I spend. Seriously, it has taken down full chassis, six figure, pro touring musclecars with ease.

My choices are:

Build the original 230 inline 6. Full block/headwork, forged rods/pistons, lump ports, maybe EFI? Maybe even turbocharge it?

Find a 6.0 iron block LQ4/9 and build a 408 stroker. I have no interest in turbocharging the LS and it will be fuel injected not carb'd.

A manual transmission will back either engine. Probably a 5-speed for the 6 and a 6-speed for the LS.

I keep flipping back and forth. It is going to be one of these two engines. No interest in anything else. I know the 292 is the better inline 6 but I don't have one.

My concern is that LS swaps are too common. Of course there is a good reason for that. The inline 6 is cool but I think it's going to cost a lot more and make less power. I do want the truck to be reliable enough to drive across the country and back. Even fuel economy is a conern as I want it be decent on the highway.

Thoughts?

[AcampoDave]

Of the two choices you have given and the goals you've stated, I'd choose the LS

[Warrens69GMC]

Build your ls like this-
5.3L from 2005/2007 era non-dod, swap the 5.3 piston for 4.8l pistons, add a 224/230 cam, 110 lsa and your choice of transmission - this works best with 3.42-3.73 rear gear ratio and overdrive

[mongocanfly]

I'd agree with the LS based on what your wanting to do...
After seeing what dayj1 did with his inline has me saying the cool choice would go to the 6...

[short&wide65]

Originally Posted by Warrens69GMC

Build your ls like this-
5.3L from 2005/2007 era non-dod, swap the 5.3 piston for 4.8l pistons, add a 224/230 cam, 110 lsa and your choice of transmission - this works best with 3.42-3.73 rear gear ratio and overdrive

I don't see a lot of reason to go with a 5.3 over a 6.0 since they aren't that much cheaper. 6.0 stroker kits are reasonably priced too.

Originally Posted by mongocanfly

I'd agree with the LS based on what your wanting to do...
After seeing what dayj1 did with his inline has me saying the cool choice would go to the 6...

Yup. This is the dilemma

['68OrangeSunshine]

I would put in a 292 L6.

[LS short box]

I would go LS. Build the L6 NA and maybe get 200-220 flywheel hp? Even with a turbo maybe 325 hp?
Build a 6.0 with a small cam and L92 heads and get an easy 400 rear wheel hp. I know what I would rather drive.

[AussieinNC]

$6500 buys you this....

Pretty but still only around 300 HP.

Nostalgia winner of course...

This is why a lot of folk go the LS route....

Its your truck...you do what you want...

[short&wide65]

Originally Posted by AussieinNC

Its your truck...you do what you want...

Absolutely and I will. But it's always interesting to hear other's opinions and thoughts.

[Tom]

LS without question.

More power. Better sound. Parts availability.

Do something cool like a 4.125" bore with a little 3.267 crank from the 4.8L if you want different.

[Ziegelsteinfaust]

What about the atlas inline 6 from the trailblazer?

A couple of bolt-ons, and a aggressive tune they supposedly can be good for 325hp. Top her off with a turbo, and 500hp is easy enough.

Still has the inline 6 vibe, and its not exactly a LS.

I helped a friend set a 5 cylinder in his 65, and he wired it up. It was a very adequate driver, and good on gas. He had to do it for insurance/wife issues.

[short&wide65]

Originally Posted by Ziegelsteinfaust

What about the atlas inline 6 from the trailblazer?

A couple of bolt-ons, and a aggressive tune they supposedly can be good for 325hp. Top her off with a turbo, and 500hp is easy enough.

Still has the inline 6 vibe, and its not exactly a LS.

I helped a friend set a 5 cylinder in his 65, and he wired it up. It was a very adequate driver, and good on gas. He had to do it for insurance/wife issues.

Well, you had me intrigued. So I did a quick bit of research. These engines are easy to find and are reasonably priced. There are also turbo ones running around.

However it’s hard find one with low mileage and apparently rebuilding one isn’t a cheap option. There is also a tendency for the main and head bolts to snap off in the block upon disassembly.

There are no performance cams available. Rods and pistons have to be ordered custom. An aftermarket oil pan is available though. Don’t know about engine mounts. It would also need an adapter plate and flywheel to use a manual transmission which are available but aren’t cheap.

I think I’ve decided that an LS is the way to go. Still planning on an iron block 6.0 as I have no interest in having to eliminate the DOD or VVT. A 408 stroker kit for the bottom end and LS3 heads/intake manifold for the top end would work perfectly with an aggressive cam and a nice set of headers.

[LS short box]

Again my .02 on the cam is don't get too crazy. You will be surprised how well a "medium" size runs with your 408 planned combo. Depending on how you build the 408 I would be shocked if you didn't make at least 450 rwhp with a medium size cam that is super easy to tune. 450 hp at the wheels is over 500 at the crank. Are planning a manual or auto trans?

[short&wide65]

Originally Posted by LS short box

Again my .02 on the cam is don't get too crazy. You will be surprised how well a "medium" size runs with your 408 planned combo. Depending on how you build the 408 I would be shocked if you didn't make at least 450 rwhp with a medium size cam that is super easy to tune. 450 hp at the wheels is over 500 at the crank. Are planning a manual or auto trans?

That's probably good advice. I guess when I mean aggressive I'm probably talking the limit of a "medium" cam.

I certainly don't need a race cam. I'd be happy with 400 at the wheels so 450 would be plenty. I will be putting a 6-speed manual behind it.

[chev-obsession]

LS for sure. You'll get a more efficient and effective power plant. It's as simple as that if your wanting an auto x truck.

[b454rat]

I'm not on the LS bandwagon, but IMO, a naturally aspirated 6 is pathetic, an LS would be my choice. But then I have no experience with a 6 either. But they barely make 300 ft/lb torque, think my lawn mower makes more than that.

[blazer2007]

I like the six,everybody has a LS

[truckster]

Have you decided? I would give the LS my nod, although I chose to go with the L31. Having owned numerous L6 and V8 engines, including performance versions of both, I can say that having an engine that's different is cool, but the cool factor tarnishes quickly when the kid in the ricer next to you blows your doors off.

[gmc684x4]

V8 all the way either gen 1 350 or ls
And if you have to buy one i would go ls
I ditched my straight 6s 3 decades ago

['68OrangeSunshine]

You really can't beat it for $1900 bucks.
Just wondering why it says it's for 1996 to 2000 GM trucks. What about 67-72s?
Do those have mechanical fuel pumps?

[short&wide65]

Originally Posted by chev-obsession

LS for sure. You'll get a more efficient and effective power plant. It's as simple as that if your wanting an auto x truck.

Yup. I autocrossed this past weekend in a friend's C6 Z06 and I'm 100% sold on the LS. It was a riot.

[Tom]

Originally Posted by '68OrangeSunshine

You really can't beat it for $1900 bucks.
Just wondering why it says it's for 1996 to 2000 GM trucks. What about 67-72s?
Do those have mechanical fuel pumps?

Do you mean L31's? They said that because they are the stock replacement engines for 96-00 trucks that came with an L31. You can modify them to go in anything. No, they don't use mechanical pumps.

['68OrangeSunshine]

Originally Posted by Tom

Do you mean L31's? They said that because they are the stock replacement engines for 96-00 trucks that came with an L31. You can modify them to go in anything. No, they don't use mechanical pumps.

Yes. L31. No new production engines with a mechanical fuel pump is possibly the reason my local NAPA doesn't stock them for SBCs anymore.