Vortec 8.1?

[dirtyhick42]

No reason to change the whole drivetrain just because you swap transmission. My buddy put a 4l80 in his truck and didn't change anything besides the trans.

 

[Klumpper]

1st, from the factory they were only drive by wire engines. a) install a dbw pedal from a 6.5 diesel truck, b) make a gmt800 pedal for dbw fit, or c) run a custom OS through EFI live to make it cable driven.

The factory also put them in 2001 3500HD trucks on a gmt400 platform with an i-beam front axle. I have heard, but not confirmed, kodiak / topkick accessory mounts allow you to relocate the AC compressor so you don't have to modify the frame. I'm not sure if we're going to run into oil pan clearance issues with this engine in a gmt400.

Basically a taller deck metric version of the 454, but heads are not interchangable, trans bolt pattern is the same as the small block/big block. 4l60 will probably last until you want to really work the motor. I believe you can reuse GMT400 big block motor mounts, as previously mentioned.

I'm actually staging up to do this swap in my 2000 k3500. I still need a DBW pedal and harness, motor mounts, and the accessory bracket if I can confirm it works. Although, my biggest holdup is workshop space, I may end up confiscating a friend's polebarn to do the swap in, as I WILL NOT do it in the driveway! I'm also planning a baby cam from Comp Cams, earlier engines had issues with camshaft longevity, namely lobes 14,15, and 16 in stationary applications, but i'm still torn if I send the heads out for porting or leave them be.

My first step was getting the 411 controller running the 350, still need to fix the gas gauge issue. I also want to track down a radiator for a 6.5 truck.

 

[Chris]

Can't see why you'd want to. All those engines are good for is burning prodigious amounts of oil and making a great anchor for my schooner. There is also very little aftermarket available for them. They're a ******* child to begin with, since they're DBW, DIS and have an odd-ass firing order. For all the work involved in swapping it in, you would come out ahead with a 6L LS swap that would run circles around a stock, tuned 8.1L. (400rwhp is attainable from an LQ9 6L with just a cam, tune and headers) They're good for lugging around a ton of weight at low speed, but that's about it.

If you're stuck on a BBC, why not just find a (cheaper) 7.4L, refresh it, throw in a small cam and get it tuned? It would probably give you less headache than the 8.1L. (I had a buddy with one in a NBS2500, it was a PAIN IN THE ASS to do anything with, trust me) Not to mention it's a direct swap.

 

[Southern Pride]

You should get an AllData account! I just tried doing a quick search "8.1l swap into a k1500" and there was one thread the first link

I've got to agree with everyone else. 8.1 must be combo'd with a 80E or your really wasting alot of time, effort, and $$

 

[Klumpper]

Simple, dare to be different. Also, I've heard reports of oil consumption being pulled way back when running a lower temp thermostat (180 degree). and the old boy saying, 'A little smoke means it has good lubrication!' Hell, even the oil consumption of it will be significantly less than the oil my 350 leaks right now!

but realistically,
1) displacement. It's basically a stroked 454.
2) coil on plug ignition. plus, changing a distributor cap on a 454 GMT400 makes me itch for the sawzall to fire up on the cowl.
3) it's going into a work truck, it won't be a racer, and 20k lbs isn't out of the question.
4) price, when i was looking, price was no different between a 454 and a 8.1 for the hard parts. Plus it came with a 4l85 trans, while the lockup function of my current 4L80 is acting up... need to get it looked at
5) it was MUCH cheaper than my next alternative, a duramax.



I may have to get an alldata account...

 

[Chris]

Keep in mind, just because you have a "heavy duty" engine does not mean you've increased the towing capacity of a vehicle. Never, under ANY circumstance should you think about exceeding the OEM's tow rating by a significant amount. Going over it to haul something from one end of the farm to another is one thing, but getting out on the road with an unstable, grossly overloaded vehicle is dangerous not only to yourself but to everyone on the highway. Not to mention a legal disaster if you rearend someone even accidently, and the state patrol weighs you and you come in overloaded. Just because a vehicle isn't commercial doesn't mean they don't do it. Tow ratings are there for a reason, sure it COULD pull more but there are reasons it isn't safe to do so. You don't have a heavy duty frame, heavy duty brakes, etc.

 

[Klumpper]

oh believe you me, i realize this.... and no, my swap will not involve a half or 3/4 ton truck.

 

[zraffz]

It isn't for towing but realistically you will NEVER get that cammed 6.0 to come near the bottom end torque of the 8.1.
I want it to lug around a lifted truck, not interested in a large cam, aftermarket converter and having to turn 6,800 RPM to get it to move.

 

[Chris]

It isn't for towing but realistically you will NEVER get that cammed 6.0 to come near the bottom end torque of the 8.1.
I want it to lug around a lifted truck, not interested in a large cam, aftermarket converter and having to turn 6,800 RPM to get it to move.

Lol, you won't have to. Even a mild cam with a 3200-ish converter will make you grin. Just because an engine doesn't make peak torque at 1800rpm doesn't mean it's less desirable. Hell, the owner of this site has a lifted LSx truck, ask him how that's working out. There one replacement for displacement will always be technology. 400hp/450tq will get you moving equally as well whether it's made at 2000rpm or 4000rpm.

 

[92Raiderburban]

Lol, you won't have to. Even a mild cam with a 3200-ish converter will make you grin. Just because an engine doesn't make peak torque at 1800rpm doesn't mean it's less desirable. Hell, the owner of this site has a lifted LSx truck, ask him how that's working out. There one replacement for displacement will always be technology. 400hp/450tq will get you moving equally as well whether it's made at 2000rpm or 4000rpm.

It's fun to live fantasies, isn't it. 11 yearz after this post and once again to be schooled for what it is. There is NO replacement for displacement . No 4.8, 5.wee or 6.slow will ever duplicate wat an 8.1 or a 472 can dish out. These are the facts. Whether the trend crowd continues choose screamers over torquers is their problem. Speak facts, not opinions. The only fast LS engines are the ones with power adders. Stock for stock, without it, they are just another small block that loses all it's steam after it's wound up.