8.1 vortec into 1979 k30

Vbb199 · Jun 30, 2022

Yea, me and friend already had looked into this, as he LOVED riding in my 79' c10 with a 502ci bbc,

but as appetizing as 496 ci of coil on plug motor with modern fuel injection and engine management sounds, it's about as much of a hassle as a LS is to drop into your squarebody, and additionally, as @Bextreme04 already said, you have like a whole whopping 2 vendors for gen 7 bbc parts, and it's gonna cost more than your run of the mill LS swap.

You'll reach about a max of 550hp with tune or cam until it's time to step up and get bigger heads and crank setups.

I have some friends that did a cam swap on his 8.1 avalanche, it started breaking the stock t case and 4L80e

You can also make STUPID POWER on just 15 psi of boost on that 8.1 that'll downright shame every little 5.3, 4.8, 6.0, and 6.2 out there, but it's more money than most are willing to pay.

God awful amounts of money. It's not a run of the mill generation 1-6 truck motor.
Really any large motor, unless you just pull it our with 300,000 miles and put it in your squarebody, is gonna be expensive AF

Anything large displacement is gonna be more than most are comfortable paying, bc everyone wants cheap and easy.
The 8.1 is not cheap and easy.

Vbb199 · Jun 30, 2022

I'm not trying be all negative or anything, as I LOVE big blocks, but I hate paying for them lol

I wish you would swap the 496 in , OP.

My plan one day is to do a make shift type LS conversion to my 502ci with CNP, reluctors on the crank and cam, holley dominator ECU, a custom intake with fuel rails for ported injection.... but sheit THATS even more expensive

Vbb199 · Jun 30, 2022

Side note, and I hate to say this, I don't think that 4 speed is gonna survive long behind a 8.1 vortec , unless you just play nice with it and don't abuse it too hard.

I'm sure for example, @Shorty81 doesn't wind his 496 up to 5,000 and dump the clutch.

I'm confident I could split a 4 speed in half with my 502ci in pretty short order if I hooked my drag slicks and dumped it enough tines or if anything shred a gear ot two

Put a built 4L80e behind the 8.1

Shorty81 · Jun 30, 2022

Vbb199 said:
Side note, and I hate to say this, I don't think that 4 speed is gonna survive long behind a 8.1 vortec , unless you just play nice with it and don't abuse it too hard.

I'm sure for example, @Shorty81 doesn't wind his 496 up to 5,000 and dump the clutch.

I'm confident I could split a 4 speed in half with my 502ci in pretty short order if I hooked my drag slicks and dumped it enough tines or if anything shred a gear ot two

Put a built 4L80e behind the 8.1

Well Vince...you know me well. Me and the dogs drive around the back roads sipping beer and rarely getting out of 2nd-3rd gear. Might hit 1000 rpms occasionally...LOL!!!

Craig 85 · Jun 30, 2022

This guy put an 8.1L in a Suburban.
https://www.youtube.com/c/PetesPlaceGarage

PSI bought the rights to the 8.1 from GM. They are now an 8.8L. They have a couple of belt set ups for Industrial version and transportation version.

https://psiengines.com/products/8-8-liter-transportation/

Transportation version

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Industrial version

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Lu Blunt · Jun 30, 2022

@Dooley You are correct about needing a big block power steering pump bracket. I have the psc pump and external reservoir now, not sure which bracket will work.

@Bextreme04 You are correct, the 8.1 uses a tall deck block unique to itself. I was misinformed about it sharing the 502 block. I’m familiar with raylar engineering and have been reading thru the writes ups. Plan is to stay stock and run cheap gas. I appreciate the info and link to engine mount adapters. Everything I read says the original style mounts can be used. I will see how the ORD mounts fit then go from there.

This is the most accurate info I’ve found

8.1's are based on traditional big block chevy, but share electronics with LSx family. 24x crank trigger, 1x cam trigger, coil per cylinder, drive by wire. All the bolt holes are in the same place as traditional BBC, except all holes are METRIC thread. The 8.1 is a tall deck engine, 10.2 vs 9.8 " deck height, so heads sit higher, and outward toward fenders a little more then regular big block. Exhaust manifold/header pattern IS THE SAME, but with metric holes.
Oil pan is unique. Mark 5 and Mark 6 oil pans don’t fit. The valve cover patter is similar to traditional BBC, except for one hole on each side. The heads use two additional head bolts, and a different bolt pattern. So 8100 heads WILL NOT go on traditional BBC, or vice verse.

The 8100 is net lash, no adjutment to valve train. However, you can get a stud from ARP with metric threads on bottom, standard on top, and run regular big block chevy adjustable valve train stuff.

Camshaft is roller, you CAN install older Mark V, Mark VI roller cam's. This will change firing order back to 1-8-4-3-6-5-7-2. In stock form, the 8100 shares SAME firing order as LSx family. Programming would need done to change injector bank assignment.

@Vbb199 How will it cost more than an LS swap? The 8.1 is like swapping in most other big blocks expect you’ll need a wiring harness, ecm and upgraded fuel system. LS swap will need all that plus a conversion kit to run the sm465. I agree if crazy high hp numbers are the goal than a regular 454 will be a better choice to build with a larger variety of aftermarket parts. I want the 8.1 for modern fuel injection and low rpm torque. Not cheap to add aftermarket efi to an older motor. I would have used a 7.4l vortec but found a good deal on the 8.1l. No need to spend god awful amounts of money when the stock 8.1 makes plenty of power for a work truck. I’m not worried about the sm465.

Vbb199 · Jun 30, 2022

Lu Blunt said:
@Dooley You are correct about needing a big block power steering pump bracket. I have the psc pump and external reservoir now, not sure which bracket will work.

@Bextreme04 You are correct, the 8.1 uses a tall deck block unique to itself. I was misinformed about it sharing the 502 block. I’m familiar with raylar engineering and have been reading thru the writes ups. Plan is to stay stock and run cheap gas. I appreciate the info and link to engine mount adapters. Everything I read says the original style mounts can be used. I will see how the ORD mounts fit then go from there.

This is the most accurate info I’ve found

8.1's are based on traditional big block chevy, but share electronics with LSx family. 24x crank trigger, 1x cam trigger, coil per cylinder, drive by wire. All the bolt holes are in the same place as traditional BBC, except all holes are METRIC thread. The 8.1 is a tall deck engine, 10.2 vs 9.8 " deck height, so heads sit higher, and outward toward fenders a little more then regular big block. Exhaust manifold/header pattern IS THE SAME, but with metric holes.
Oil pan is unique. Mark 5 and Mark 6 oil pans don’t fit. The valve cover patter is similar to traditional BBC, except for one hole on each side. The heads use two additional head bolts, and a different bolt pattern. So 8100 heads WILL NOT go on traditional BBC, or vice verse.

The 8100 is net lash, no adjutment to valve train. However, you can get a stud from ARP with metric threads on bottom, standard on top, and run regular big block chevy adjustable valve train stuff.

Camshaft is roller, you CAN install older Mark V, Mark VI roller cam's. This will change firing order back to 1-8-4-3-6-5-7-2. In stock form, the 8100 shares SAME firing order as LSx family. Programming would need done to change injector bank assignment.

@Vbb199 How will it cost more than an LS swap? The 8.1 is like swapping in most other big blocks expect you’ll need a wiring harness, ecm and upgraded fuel system. LS swap will need all that plus a conversion kit to run the sm465. I agree if crazy high hp numbers are the goal than a regular 454 will be a better choice to build with a larger variety of aftermarket parts. I want the 8.1 for modern fuel injection and low rpm torque. Not cheap to add aftermarket efi to an older motor. I would have used a 7.4l vortec but found a good deal on the 8.1l. No need to spend god awful amounts of money when the stock 8.1 makes plenty of power for a work truck. I’m not worried about the sm465.

I figured you'd likely just be using it as a utilitarian type setup.

There ain't but one reason (i) personally would own a large displacement motor, and that's to curl the hair of a moostang owners coyote lol

For what I suspected you're using it for, it'll work great! Sm465 and all!

I didn't necessarily mean dropping it in the hole is more expensive than a LS swap

But going from a small block build to a stock LS doesn't require much change....
Exhaust sizing doesn't change, the trans doesn't have to be built.... it's all pretty simple.

Going from a sbc setup to a BBC setup with bigger exhaust, bigger radiators, a better/bigger trans, IS more expensive than a standard LS.

Please create a build thread on this, I'm anxious to see it.

CheemsK1500 · Jun 30, 2022

The 8.1 is still a powerhouse, even if it doesn't share much of anything with the smaller LS based stuff. The swap shouldn't be too hard though, since you have compatibility with most GM transmission and other drivetrain components.

fast 99 · Jun 30, 2022

Well that explains it, thanks

Bextreme04 · Jun 30, 2022

My best friend growing up had one in his 73 Nova with twin chinese 80mm turbo's on it and a blow through carb. He ended up upgrading to Sniper EFI and then pulled the whole thing for an LT4/8L80e combo from Chevrolet performance because it wasn't reliable or daily drivable. He gets double the fuel mileage and much more usable power from the supercharged 6.2L. The 8.1L was a monster and super fun to drive, but he broke it a lot and it was hard to get parts and they were pricy.

Bextreme04 · Jun 30, 2022

Here’s the nova with the twin turbos and 8.1l

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And then here it is with the LT4

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Vbb199 · Jun 30, 2022

That's what I'm talking about !

Bextreme04 said:
Here’s the nova with the twin turbos and 8.1l

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And then here it is with the LT4

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It's one of them things. It's a dedicated punisher that you constantly dump money in lol

Such a waste, but so much fun, which is why I said, it's for gaptizing coyotes in a truck. lol

Within a respectable power level.

Dooley · Jul 1, 2022

Here's a square body with twin turbos.
Only a 6.2 diesel.

SquareRoot · Jul 1, 2022

Search "Dirty Larry" on the other square body site. He's done exactly what your thinking. His thread will answer any question you can ponder.

TPISly-C10 · Jul 4, 2022

CheemsK1500 said:
The 8.1 is still a powerhouse, even if it doesn't share much of anything with the smaller LS based stuff. The swap shouldn't be too hard though, since you have compatibility with most GM transmission and other drivetrain components.

Agree!

8.1 vortec into 1979 k30

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