6.5 or 454?

[BurbanAZ]

I have a 3/4 ton 92 suburban with the 454tbi and a 4l80e tranny with a 14boltff rear end and 3.73 gears. The engine is great and i love it towing and just in general the only thing that bothers me is the mpg which honestly im not really that concerned with but id like to do some further trips and stuff and id like the range without adding a second tank. I love the simplicity of the tbi set up the engine is super simple to fix on a trail if u have to. I know these years also came with a 6.5 diesel do u guys think it would be worth switching? i dont know much about these diesel engines so its hard to say.

 

[Rot Box]

If it came down to me choosing between a 6.5 or 454 suburban with the same options I'd pick the 6.5 for several reasons but I wouldn't swap out a 454 for a 6.5. From my experience I feel my last 6.5 with a few modifications would out tow the 454 TBI's and provide MUCH better fuel mileage. Overall they can be a very reliable motor (my brother had one with 550k on the stock engine :Wow1 but time is money and the cost/headaches that come along with it I don't think it would be worth it--not to me anyway.

 

[BurbanAZ]

thanks for the input, i was thinking the same thing i was thinking i would just keep the 454 for as long as i can then if it ever dies or just gets too tired i may swap the 6.5 in there. I do love the 454 and if the mpg was a little better id happily keep it forever especially with how cheap parts are for it

 

[random]

I used several of those trucks as work trucks. I liked the 454 allot better. It was allot more reliable, had plenty of power. The couple of 6.5 trucks we had were constantly in the shop. They still have the 454 truck, and it's running well after 300,000 hard miles.

However, your mileage may vary.

 

[DoMiNiC1]

If I was going to swap I would find a 12 valve Cummins. My .02. That's a swap that would be worth the trouble. IMO

 

[greengreer]

I really like the 6.5 in my pickup however I would think you could buy a whole lot of fuel for the cost that would be involved in the swap. Even if the 454 is getting tired, freshening it up will still end up cheaper in the long run.
That being said, the 6.5 also has more options when it comes to fuel. Biodiesel or WVO and the dramatic increase in mpg could negate the cost of a swap over a much shorter time period.

Another thing to consider would be a 6.0 lsx motor. good mpg's and lots of power, that is if you aren't intimidated by the electronics like I would be.

 

[Buliwyf]

I'll 2nd the 6.0L LSX gas nomination.

 

[xpndbl3]

do a 5.3L or 6.0L swap, either motor makes more power/torque than the old 454 and mileage is much much better. So is turning the key and it starts in half a second too.

 

[Larry]

Meh, go big or go home. Diesels are a has been, most peeps here just haven’t coped with the loss yet. Just like the old days there is no replacement for displacement. Do an 8.1L big block gas. They are an easier swap than a 5.3 or 6.0L gas and the 8.1L delivers more HP and diesel like torque with the proper ECM calibrations with the same fuel economy of a small block 5.3 or 6.0L. A stock 8.1L with a hot tune will deliver a minimum of 425HP with 550+ lb ft of torque with the right ECM tuning. The only problem with that is getting your hands on an 8.1L as they can be a rare find. I claimed my steak and scored a load of them a few years ago….

Just kidding…not all of these are mine. Wish they where!

I did score a few of these for my own consumption though

 

[496Burb]

Will agree whole heartedly with Larry. Ran several Suburbans with either 350 or 454 and they were fine; but my world changed when I got into my current suburban. It's an 02 3/4 ton with the 8.1 and allison 5 speed tranny. Not really sure which I like better; but won't live without both. The engine just has tons of torque like a diesel; but runs 87 pump gas. Because of the single coil and all of the electronics its so much more efficient. With the torque and low revs with the allison; i rarely get up above 2500 rpm unless I am passing someone; and then they wonder what passed them. With my set up and 3:73 gears in the rear end; I manage 12-14 city/highway and 14-15 on the highway on cruise at 70. I have a fair amount of equipment in the back and so I'm not empty. So with that and the autoride system on it - best truck I've ever had.

Would suggest you proceed on the 8.1 swap - the motor mounts on the engine will line right up; and then you'll just have to figure out the tranny part. Good luck!

 

[496Burb]

By the way; I chose the 8.1 as I had a buddy who bought a 3/4 pickup with the 6.0. He tows a heavy trailer frequently and his big complaint is not enough power when doing so. I've NEVER had that problem!

Cheers!

 

[Larry]

Will agree whole heartedly with Larry. Ran several Suburbans with either 350 or 454 and they were fine; but my world changed when I got into my current suburban. It's an 02 3/4 ton with the 8.1 and allison 5 speed tranny. Not really sure which I like better; but won't live without both. The engine just has tons of torque like a diesel; but runs 87 pump gas. Because of the single coil and all of the electronics its so much more efficient. With the torque and low revs with the allison; i rarely get up above 2500 rpm unless I am passing someone; and then they wonder what passed them. With my set up and 3:73 gears in the rear end; I manage 12-14 city/highway and 14-15 on the highway on cruise at 70. I have a fair amount of equipment in the back and so I'm not empty. So with that and the autoride system on it - best truck I've ever had.

Would suggest you proceed on the 8.1 swap - the motor mounts on the engine will line right up; and then you'll just have to figure out the tranny part. Good luck!

Cool story…. but, your Sub doesn’t have an Allison transmission. 2000-2006 Suburban’s and Avalanches’ with L18 8.1L engines only came with 4L80E transmissions so no Allison’s for them. Allison transmissions were only behind 8.1L engines in the Silverado/Sierra HD and Workhorse commercial and RV chassis during those years. SUV’s and G-Vans with the 8.1L got saddled with the 4L80E hydramistake.

 

[rxm6]

I don't know what the laws in Arizona are regarding engine changes, but I would see if it's legal to swap a diesel into a gas truck. I know in California, it is illegal to swap a diesel into a regulated gas truck. But, then again, California is on the forefront of motorist torture.

As far as your situation goes, would you be doing this work yourself? There is quite a bit of work involved in any swap and unless you have a garage, a low frustration threshold, and/or a friend, I'd say to stay away from a swap.

As for the engines, the 454 really is a great engine. In fact, it's hard to go wrong with any big block from GM. Additionally, if you did decide to swap in a different gas motor, you would have a lot of the wiring already intact from your original engine.

The 6.5 is a pretty good engine, but it has its issues. Personally, if I were going to swap in a 6.5, I would go with either an Optimizer 6500 or a P400. Both of which are 6.5s with upgraded castings and engine components built new by AM General that eliminate a lot of the issues with the original 6.5s. Although, keep in mind, with a diesel swap you're going to be paying for little parts that are going to add up very quickly and be very expensive unless you found a donor vehicle.

In my opinion, if it was my truck, I would look into a newer big block and a roof rack or custom bumper to hold extra gas cans. It will most likely be cheaper and quicker then the 6.5 swap.

 

[Mark Harley]

Find a wrecked bread van with a Cummins B4 and transmission.
That would be a good swap. good mileage and plenty of torque.

 

[jluck]

cummins 12v swap all the way! super easy swap and end up with some mileage after the investment.