6.2L or 8.1L
 

My 86 Crew Cab C30 has a tired old 454 and im going to be replacing it in the next couple months. Ive really been looking into using an 8.1 cause it bolts in place of the 454 thats in it and saves me from having to buy a new transmission as well as several other things that have to be modded for the LS platform. But at the same time if I can snag a 4l80/5 I can put my gear vendors overdrive unit on it and have underdrive as well. However the 6.2L has its perks as about the same HP not as much torque but easily upgraded and lots of aftermarket parts for support. So I guess while im pondering Ill put it out to you guys to see what you think. I will be pulling a 30+ foot camper and maybe at times a GN or 5th wheel car trailer. Just a little more info.

Pic of the dually for reference.

Re: 6.2L or 8.1L
 

Had an 02 with a 8.1 loved power but was hard on gas. Had a new 02 work truck same time it had 6.0 . It had decent power and better mileage not sure what 6.2 is old diesel? Oh ya nice truck.

Re: 6.2L or 8.1L
 

6.2 is the latest LS engine came in the escalades and the denali's. I had an escalade with one and it did good for towing my 18ft trailer with a truck on it. This truck is a bit heavier and ill be pulling bigger loads. I guess the question is how good of gas mileage do i really expect out of either setup pulling a huge 30ft camper?

Re: 6.2L or 8.1L
 

Wow punch 6.2 in lot talk. Looked at a crate Eng. 8 grand have to run premium gas I would probably just rebuild the 454. have 5 grand left over for gas.

Re: 6.2L or 8.1L
 

True but some of that would be eaten up by the fact im ditching the carb and going fuel infected. Tired of dinking with carb setups.

Re: 6.2L or 8.1L
 

My 2012 is peppy with or without a load in the back. Hook a trailer to it, and it has me wanting a little more grunt. I typically tow 6000-7000 lbs a few times per year, for a few hundred miles at a time. Total combined weight about 15K. Kind of wish I got the Duramax. but I don't tow that often, and it is perfectly adequate when I do.

This is assuming the 6.0 and the 6.2L engines perform similarly.

If I were building a truck to tow, I'd go 8.1L or Cummins. I'd want the Allison to go with it though. The 4L80E didn't come with the 8.1, unless it was in the van I think.

One word of warning, and this is second hand info at best; but the 8.1L motors seemed to have some oil burning issues. Seems like some guys on other message boards had to rebuild their engines because of excessive oil consumption and piston slap/scuffing. I have not hand any first hand experience with these motors so that could just be rumor or bashing.

What about rebuilding the 454 and adding aftermarket (like Holley) FI? Not really original, but it will give you a strong truck with dependable power for a reasonable-ish price.

Re: 6.2L or 8.1L
 

The 6.0 and 6.2 are very similiar the 6.2 just has a little more power and torque than the 6.0 and its all aluminum if memory serves. Could be mistaken on that one though. 6.2 has about 430 hp from the factory. I have no desire to go cummins or any diesel for that matter. Not that i dont like them its just if i were to go to a diesel id just rebuild the 454 to play with and go buy a new duramax 3500 4x4.

That being said the 8.1 with just a tune on the computer and some added fuel pressure are putting out 450hp and 630ish torque at like 3500 rpm's which ought to pull a darn tank.

I will be pulling the camper 100 miles or so every couple a weekends during the summer and taking the truck to shows as well. So gas mileage is not something i really expect. I just want to make sure the power is there when i need it.

Re: 6.2L or 8.1L
 

Yeah - I think my 6.0 has 360 Hp in stock form. Can't remember torque. So the 6.2L would have the power advantage.

I get about 14 mpgs when the stars are aligned, empty truck, easy & flat highway driving and no faster than 65 mph. Towing is as low as 8 mpgs.

My truck weighs in at a portly 7500 lbs empty. I have 265/70 R18 tires and 3.73 gears (thought that would help with mileage!!) with the 6L90E auto transmission.

My guess is that either engine will be hovering around the 10 mpg range no matter what. Might as well go for all the grunt you can get.

Re: 6.2L or 8.1L
 

My 02 Gmc 2500 had the 8.1 and the Alison went through Alison to get a over drive cutout switch.

Re: 6.2L or 8.1L
 

Dunno why anybody would want an 8.1L :lol:

Re: 6.2L or 8.1L
 

I am jealous, that is a nice looking truck. Cant find one for my self to save my ___.

Re: 6.2L or 8.1L
 

It's your fault I'm even considering this larry!! Lol. I am pretty much convinced to go 8.1 but figured I would consider the 6.2 since they are more plentiful and have a better aftermarket following. But their torque just isn't as much as the 8.1.

Re: 6.2L or 8.1L
 

:lol: You know, everybody keeps talking about the lack of aftermarket support for the 8.1L but in all reality, what does a person need from the aftermarket?? The engine management system is no different from a Gen III LS and a bone stock 8.1L running a decent tune will easily turn 400 HP and close to, if not more, than 500 lb. ft. of torque. I don’t think a lot of people realize a 400 HP big block “feels” more powerful than a windup 450 HP small block any day just because of the low RPM range where things happen. I personally don’t care for the small block Gen III LS engines that must whipped on all the way to 6000 RPM to get peak power of them. Spinning the hell out of an engine is not achieving useful power in a heavy truck in my opinion. A bone stock 8.1L is making over 355 lb. ft. of torque at 800 RPM straight from GM Powertrain’s product detail. Go look where a 6.2L is making that kind of torque. It will be at least 3,500 RPMs or higher....and if someone really wants to throw away money on aftermarket doodads, any older BBC header will fit the 8.1L and RayLar, CompCams and may many others offer an array of cams for them. I am partial to RayLar and run a RayLar 202 in my Burb. It honks well! It has a date for a Dyno Tune in late May to get the tune dialed in to compensate for the RayLary cam. Anxious to see how it turns out.

The best ,and worst thing, about the 8.1L is nobody knows a damn thing about them.

Re: 6.2L or 8.1L
 

My vote would be for the 8.1L.

Re: 6.2L or 8.1L
 

For a crew dually I would go 8.1 as well. Nothing like 400 foot pounds barely off idle for towing.

Re: 6.2L or 8.1L
 

There's no replacement for displacement.
I've seen a handful of 472 & 500 CID caddy engines in these trucks for that same reason.
496CID with modern fuel injection... If I had the 76 to do over I'd go with an 8.1

Re: 6.2L or 8.1L
 

I have pretty much talked myself into the 8.1 but I did that along time ago. lol I was considering the 6.2 as another option if I cant find a suitable 8.1. I think I have found one though that's still on a burb 2500 chassis. motor trans and everything with very low mileage. now I just have to get my cash together. its got the 4l80 behind it I think that's whats in a burb and if that's the case im gonna add my GV overdrive onto it from my 400 I have now. Probably wont be good for towing other than the underdrive but on just a flat run ought to help with gas mileage a bit.