6.5 td instead of 454tbi

[BurbanAZ]

Ive noticed on our latest trips our biggest issue is the range we get before having to stop for gas, and if were way out its just annoying always having to keep that in mind. I have a 92 k2500 suburban with a 454tbi and a 4l80e, i was thinking of swapping a 6.5 td in place of the 454. Ive heard its not super involved as far as engine swaps go. I was thinking of looking at the government auctions and trying to find one with low miles pretty cheap. Any idea of what id be able to squeeze out of a 6.5 for mpg? Im getting like 7-8 now with my 454 and that's being light on throttle and braking, its just killing me on long trips. Also would a 6.5 td be a better choice than a 6.5 naturally aspirated or a 6.2? i still want the same towing ability that i have now, but if i could squeeze out close to 20 mpg that would make a huge difference.

 

[shortbus4x4]

I have owned both the 6.5 turbo and 7.4 tbi and vortecs. With the current cost of diesel versus gas, the cost of a conversion, and more power from a 454 than a 6.5 I would say get a bigger tank for your suburban. The 6.5 is ok but I don't think you will get 20 mpg with it in a sub loaded down. My 92 K2500 PU that had a 6.5 with a 4l80e used to get about 13-14 empty driving it as a commuter. My 96 K3500 crewcab dually with a 5 speed is worse, of course it is always dragging around a 22' gooseneck. My 96 K2500 sub with a 7.4 vortec and a 4l80e used to get 11 on long trips and it had lots of power. If you do the swap make sure you change the transmission too, don't use the gas one behind the diesel or the diesel one behind the gas trans. They have some differences in torque converter stall speeds and valve bodies from what my tranny builder tells me.

 

[arveetek]

I've done several GM gas to 6.2L diesel conversions. After it's all said and done, I would recommend selling your current vehicle and buying a factory diesel vehicle if you're set on diesel power. (I love diesel power myself!)

My '95 Tahoe with 6.5L turbo, 4L80E, 3.42 gears, and 31" tires pulls down a consistent 18 mpg highway, and drops to around 13 mpg when towing. I used to own an '81 2500 pickup that I converted to a 6.2L turbo, 700R4 tranny, 4.10 gears, and 31" tires, and it used to pull down close to 20 mpg, but it was 2WD.

As was said, with the price spread being so large between gasoline and diesel, it's hard to justify the expense of an engine swap. You'd have to drive a ton of miles to even break even. However, if you can sell your current vehicle and purchase another without having to spend a lot of extra money, that would make sense.

Casey

 

[1leglance]

I would agree with the others that selling & buying is the best way to go...
That said I am currently dropping a 6.2 w/ aftermarket turbo/700r/208 into my 1970 Suburban.

Now I love the 70 burb and I got the entire donor vehicle for $700.
My wife works at a diesel engine machine shop so I won't be paying for much of anything from machine work to gaskets to any parts I need.
Even the turbo recondition & IP/injectors should either be free to super cheap as those shop love my wife

Of course I still expect to pay for the trans recondition, building up the transfer case, new cross member, fuel filters and all those little bits that add up to another $1000 plus.

So unless you are like me and have a rig you must keep, enjoy working on vehicles, and have some serious inside connections it is way better to sell & buy.

 

[Buliwyf]

It's your lucky day. I'd imagine a diesel swap is at least 7$.

Sell. Get one of these instead:
http://www.autotrader.com/fyc/vdp.j...s=25&seller_type=b&cardist=358&standard=false

Tuscon Arizona has tons of clean Excursion Diesels. Avoid the 6.0's. Look towards the 7.3's. Transmission rebuilds/swaps are $2200-3000.

You're not going to get 20mpg from that swap, or from this Ford. But it will be a bit better. I drove a gas Excursion from Ohio to the upper penninsula of Michigan. I don't recall needing to stop often for fuel during that week of vacation. And that was only a V10 gasser. I don't think the Ex had a big fuel tank either. But there are aftermarket tanks.

You could allways swap in a modern Gas 6.0 into your Burban. Source the engine from a used 1 ton Van. I'd bet that that would be cheaper and a better combo with a larger fuel tank.

 

[haven]

The EPA does have fuel economy ratings for the 1990 Suburban 1500 4x4 model with gas and diesel engines. The EPA Combined mpg figure is 16 mpg for diesel, 12 mpg for the 350 gas motor.

Diesel costs more than regular gas. Using the figures provided by the US Energy Information Administration (http://www.eia.gov/petroleum/gasdiesel/), the average cost of a gallon of regular gas in USA is $3.39. Diesel cost is $3.85.

Using these numbers, the cost of fuel to drive 10,000 miles using the gas engine is
(10,000 miles / 12 mpg) * $3.39 per gallon = $2,825

10,000 miles in a diesel truck would be
(10,000 miles / 16 mpg) * $3.85 = $2,406

That means a diesel engine would save $419 in fuel costs in 10,000 miles of driving, using the numbers provided by the government.

That's for the light duty 1500. If we assume the diesel 2500 Suburban gets 10 mpg when driving with a load, and the 2500 Suburban with big block gas engine gets 6 mpg loaded, the result is quite different.

Gas: (10,000 miles / 6 mpg) * $3.39 = $5,650

Diesel: (10,000 miles / 10 mpg) * $3.85 = $3,850

That's an $1,800 difference in fuel costs in just 10,000 miles.

 

[haven]

Here's another example of a 2000-2002 Ford Excursion with 7.3L diesel
http://www.autotrader.com/fyc/vdp.jsp?ct=u&car_id=311740403

 

[rblackwell]

It's your lucky day. I'd imagine a diesel swap is at least 7$.

Sell. Get one of these instead:
http://www.autotrader.com/fyc/vdp.j...s=25&seller_type=b&cardist=358&standard=false

Tuscon Arizona has tons of clean Excursion Diesels. Avoid the 6.0's. Look towards the 7.3's. Transmission rebuilds/swaps are $2200-3000.

You're not going to get 20mpg from that swap, or from this Ford. But it will be a bit better. I drove a gas Excursion from Ohio to the upper penninsula of Michigan. I don't recall needing to stop often for fuel during that week of vacation. And that was only a V10 gasser. I don't think the Ex had a big fuel tank either. But there are aftermarket tanks.

You could allways swap in a modern Gas 6.0 into your Burban. Source the engine from a used 1 ton Van. I'd bet that that would be cheaper and a better combo with a larger fuel tank.

I owned a 1997 suburban with the 6.5TD for a number of years and covered over 100,000 miles in it. It had 4.1 axles. It regularly gave 15mpg. The final drive was a bit
high for my purposes (previous owner towed) and 3.73 would have given (slightly?) better mileage (lower rpm at highway speed).
If you go for a 6.5TD be careful of the big transistor throttle-position sensor that sits in the well of the v8. This can overheat and cause the engine to simply stop.
The solution to this problem is to move the transistor to one of the fender skirts. If you look on the net you will find a source for the wiring harness to make this mod (it is so long since I did this I have lost the link).This mod saved my vehicle.

When we traveled through central america we were accompanied by a guy in a 4x2 7.3 Excursion. We where getting 13-15 mpg in our Duramax Tiger, he was doing much better than us. I did not do the numbers on his consumption but I would guess at least 15-18. He claimed 20mpg, maybe thats right - but was certainly better than us.

Rob Blackwell
whiteacorn.com

 

[Rot Box]

I agree it is a better idea to sell your current rig and buy one already equipped with the diesel. There's a lot more to it than swapping engines. Things like fitting the huge radiator, making the trans work, fuel tanks-lines-pump-pickup, exhaust, AC, etc can nickel and dime you to death and take up a lot of time.

Having owned a 6.5TD and driven many TBI 454s: Would I do it? Yes... but only because I'm bias towards the old breed of diesel engines and I think they're best lol! There are years to steer towards and years to avoid when it comes to the 6.5TD and a few reliability mods that are mandatory as well so do your homework. Also VERY few people are content with the power output of a N/A 6.2/6.5 in a Suburban. I would shoot for the 6.5TD and open up the very restricted exhaust a bit so it can breath. They can provide good power with little effort--good as in comparable with the TBI454 not comparable with a chipped Duramax.

 

[Revco]

I'd skip the 6.5 and do a Cummins 6BT swap. I've comtemplated the same thing with my 454 Suburban...should I swap in an Small Block? LS? Cummins? Sell it?

Then a guy I know back home did a 12-Valve 6BT swap into his 454 powered mid 90's Suburban 4x4 and reports getting 22mpg on 35" tires on the highway. He did the swap for the cost of a wrecked donor truck and fabricated his own mounts.

 

[BurbanAZ]

ill probably just keep working with my truck the way it is, and just try to get my mpg up with the 454, if i could just get to 12 or 14 id be very happy. Then do all the other stuff i want to do with the truck then down the road maybe swap in a cummins or something.

 

[Revco]

I'm getting right at 14mpg on the highway in my '93 K2500 454tbi/4L80E. It's all stock though. The mileage was 12.6 on the last tank which was a mix of city/highway.

 

[BurbanAZ]

I'm getting right at 14mpg on the highway in my '93 K2500 454tbi/4L80E. It's all stock though. The mileage was 12.6 on the last tank which was a mix of city/highway.

i would be happy with 14mpg on the highway, is ur k2500 a pickup or a suburban?

 

[Revco]

Suburban

 

[FellowTraveler]

6.5 td hands down unless a cummins can be had cheap

An enhanced block 6.5 turbo diesel built from May 1999 forward is the ticket, it does not suffer from any of the earlier 6.5 issues. This diesel can be found in pickups and vans up to 2002.

Run a mechanical pump DS-2 or a DS-4 if you can keep everything cool.

Trans control can be through a $500. controller which you would have all the control too. A triple Kevlar clutch billet converter would be nice if budget allows.

I average mid 20's mpg with an occasional 27 mpg on highway using highway tires and lower 20's when aggressive tires are used.