• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

6.5L crate motor

red

red

Being a lake bum in Texas
Messages
2,028
Reaction score
1,761
Location
Lake Brownwood, Texas
throwing around a few ideas for my tow rig and considering swapping it over to a 6.5L turbo diesel, where can i find a good quality crate motor (or low miles) 6.5 at?


truck has a 454 in it with great power, just crunching the numbers (fuel cost) looks like it would cost me about $1500 more a year to drive the 454 at 10mpg as compared to driving a diesel at 19mpg, ouch. doubt i can improve the 454 to the kind of fuel economy i want (14mpg), and i'm familiar with the 6.5L.


another option would be to pull the 6.5L out of the yukon, go through it since its at 155k miles and hasnt lived a hard life, and relocate it to the tow rig.
 
Not going to be a popular suggestion, but have you considered a 12V cummins?

Might be worth the headache if you're building a rig specifically for towing....

Or, if you have cash to burn, perhaps a p400?
 
Crankme69 said:
I'd be looking for a diesel truck B4 I ever considered trying to convert a gasser into a diesel. IMHO way to much work & $$$ to convert...
Click to expand...

X2, specially in these economic times.

Also, it's a rare 6.5 that gets 19 mpg. 15 to 17 hwy more like it.
 
Crankme69 said:
I'd be looking for a diesel truck B4 I ever considered trying to convert a gasser into a diesel. IMHO way to much work & $$$ to convert...
Click to expand...
Not really that hard to convert that age truck.I keep looking at my 77 gmc c3500/454 and thinking about doing it. The wiring part would be real easy.The exhaust would be a challenge.
Since it is a conversion, A used engine with all the accsessories would help.Finding a good used engine is very tough. War wagon got one from here:http://www.boyceequipment.com/ They garentty them to be good but are not truck turbo engines. You would have to add all the turbo hardware.Or diesel depot has decent prices on remans http://www.dieseldepot.com/parts_home.html
My plan, in my head, included a 4l80e overdrive tranny to help the mpg and lower rpms. TCM out of a 92-93 to control it:thumbsup:
 
Add the parts cost back into the 6.5 of injectors, pumps, etc and the realistic fuel economy... You may be better off leaving the 454 alone and keeping the extra power when you need it.

Otherwise make sure a better non GMx turbo is in the plan or going N/A for max mileage non-towing.
 
the tow rig is my 87 land yacht (pics/details in my garage), 454, sm465 1 ton dually. swapping over to a diesel in that body style (would go mechanical injection) would be very simple, expecially since the truck already has the hydroboost system. issues would be the fuel tanks (either clean or replace), the ac box has fitment issues with a 6.5 turbo and requires modification, and i believe the motor mounts are different from a 454 to a 6.5L (correct me if i'm wrong). would stick with a manual tranny.

a 12 valve would be very nice, however the added expense of tranny/t-case would be more than i am wanting to spend.

getting rid of the 87, not an option. plan to keep it around a long time as my tow rig, just looking at options for better fuel economy. if the best i can get is 10-12mpg than thats the best i can get. just looking at options to go with that will suit what i'm aiming for.

did fuel economy with the 6.5 drop off alot in the past year? the last time i drove the yukon (6.5L, not driving because of injectors) i was getting 23mpg highway at 70mph (empty). either going to sell the yukon as is but considering pulling the motor out of it, overhaul and add some upgrades while its out, and swap it over. would cost at least 3k to do.



just an overview of what the truck is used for and what i would like it to do. the dually will be used as my tow rig, pulling around some misc trailers with cargo up to 12k pounds (2 offroad trucks on a goosneck trailer, maybe a few times a year). i want this truck to be around for a long time, easy to work on, and able to pull what i ask of it without breaking on me. i'm familiar with having to slow down on long steep grades and dont have a problem with that to keep from overheating. as the truck currently sits it does all that and meets my wants with the exception of fuel economy, lacking in that department but thats to be expected with a 454. hence the reason i'm looking around for options within a reasonable price range.
 
well, comparing a Yukon to a 1 ton (or equivalent)/dually is kinda apples and oranges.

Given the same vehicle weights, tires, gears etc...you can expect better mileage from the 6.5.

How much better depends on how much you load it down.

Given a 1 ton dually with 4:10's, I would think anything between 15-20 MPG would be good enough to actually "brag" about.

If the Yuke is toast, just pull the drivetrain out and slip it into that classic body style. You'll have pretty much all the parts you need at your disposal. Injectors aren't that bad. I just received the 8 injectors I ordered from Dennis off ebay for a couple bills (sure beats cummins/duramax/powerstroke prices!). Pm if you want Dennis' ebay seller name. I'd recommend him, he did right by me!

Be warned though:

6.5 blocks seem to crack with shocking regularity. The block in the yuke might be running right now, but it may be harboring some nasty cracked main webs and you just don't know it yet....

Cheers
 
with that no OD tranny.. 3 thing need to happen
1; OD tranny NV4500, range box for a sm465
2. taller gears
3. taller tires.

BTW th400 and 4l80s run the same tail shafts and output shafts as i understand
 
cracks would be a big concern, the yukon's 6.5L has 155k miles on it so the possibility is definetly there and no way to tell unless i tear the motor apart. also is there any way to fix the cracks if there are any? the rest of the yukon is not bad, needs paint and the rear axle rebuilt along with a few other minor repairs but certainly not destroyed, hence my hesitation (but seriously considering) with pulling the motor out.


the 87 dually is sitting on 35" tires (as i bought it) so it helps the rpm's significantly. eventually would either upgrade to a 5 speed or a gear vendors overdrive unit as well. although the th400 and 4L80E are good auto's its not my preference, call me stubborn but i prefer to shift my own gears.

anywhere in 15-20mpg unloaded i'd be happy with. pulling a heavier load and getting around 10mpg is ok, just want there to be more than a 1mpg difference between loaded and unloaded haha. if i do swap to a 6.5L td in the 87 it will get a 4" exhaust, turn up the injection pump, and eventually add an intercooler. maybe upgrade from the gm series turbo to the att one that i've read about here. would not be going for big torque, just some extra power and to help keep the motor cool when it has to work.

good info and keep it coming please.
 
red said:
the 87 dually is sitting on 35" tires (as i bought it) so it helps the rpm's significantly. eventually would either upgrade to a 5 speed or a gear vendors overdrive unit as well. although the th400 and 4L80E are good auto's its not my preference, call me stubborn but i prefer to shift my own gears.

good info and keep it coming please.
Click to expand...

4.10 wit 35" and a non OD tranny are 70 mph is 2800
4l80 OD is .75 put you about 2000rpm
nv4500 cant rember but its ..7-.8 for and OD

if you dont have a OD tranny cruising rpm is going to be limited to maintain mpg
 
Don't forget to check with the county emissions station for advice on your conversion. Here in Davis County, we only have to pass a visual and a dyno smoke density test. I'm not sure how strict the visual is, or how they'd react when your vin comes up as a gas engine.

My truck gets 15-ish mpg at 75 mph between Bountiful and Lava Hot Springs -- empty with 4.11 gears and stock tires.

Don't forget the 454 is rated to tow ~2000 lbs more than the 6.5. I don't think it's a power issue; I think it's probably a cooling issue.
 
Last edited:
Well towing a 24" cargo trailer through some extreme hills gets me 35 MPH and 43 MPH with the turbo and screw turned up. MPG does not change with screw/turbo turned up and still sucked at ~7.5 MPG +- .5MPG. A 4.7L POS V8 gas 2010 dodge got 6.9 MPG.

I did not slow down due to overheating. I slowed down due to lack of power. 4 speed auto.

Your Old Body Style should not have the airflow issues that cause us lots of cooling problems.

A good diesel tow rig is picking up a 1993 with factory mechanical injection and factory no kitty. I posted a local one today... Then you can go through lots of cash fixing it up. Then blow up the engine and pick up a used military surplus 6.2 engine...
 
Pruittx2 said:
how bout just poppin the cash for a gearVendors unit to overdrive the piss out of that 454.
Click to expand...

thats something i'm looking at as well. going off the price from their website it would cost me about 4k since i have a 4wd. also looked at a ranger overdrive unit (cheaper), but the max power its designed to take is 420ft/lbs so i'd be sitting close to its max in stock form. dont know of any other add-on overdrive units.

on a side note i also found a 93 k3500 6.5L 5 speed up near where my home station is for a good price. truck is in bad shape but the pricetag is worth the tranny alone and would give me the 4wd nv4500 that i could pull out. would be an excellent starting point to get my rpm's down so i could see where my mpg improvements will start at. also provides another 6.5L that already has the mechanical injection pump that i could tear apart and see if its worth rebuilding (if fuel economy improvements arent enough with the 5 speed).
 
correction on the gv price, about 3,000 brand new. would be an improvement that can be added to the end of the drivetrain (wont be restricted to that tranny or engine if those later change) and allow for much better rpm's at 70mph. been looking and other than the US gear splitter (no longer in production) its the only one that would survive the torque. found some used and a new in box unit for quite a bit cheaper than new, none that were attached to my t-case model though. contacted gv to see if the adapter can be purchased seperate.
 
You must log in or register to reply here.
Back
Top