Diesel conversions

[Big J]

I noticed FSJeeper's post in another thread where he mentioned that a number of them in Texas had found doing Diesel conversions solved their fuel economy problem using the GM 6.2/6.5l.

My Chero doesn't get too bad of gas mileage on the highway, even with 33's and 3.07 gears. I'm actually fairly impressed, but it is still fairly expensive, especially when it costs me over $50 Canadian each time I fill up.

If you see this post FSJeeper, could you fill us in on what you know about these diesel conversions? You mentioned BBC, and something else... what is this?

Is doing a diesel conversion a good option, or should I just buy an Toyota BJ60!!! ;)

[Rogue]

B ig B lock C hevy

[Big J]

Thanks RogueStar... I've never had a BBC.

Here's a fairly informative (related) link if anyones interested:

http://www.62-65-dieselpage.com/mileage.htm

[joe]

You Canadians are lucky to have the BJ series LC's available. The dsl LC's were never imported to the US :(
I would check into stuffing the BJ motor in your FSJ. It'll be slow through the gears but that's what'cha ya got the stir stick on the floor for ;)
And you don't need speed in LO range anyway and the mpg's(kilo's per litre?) will prolly be better on the hwy than what you'd get with the 6.2/6.5 GM motor? The 6.2/6.5 dsl's aren't bad motors but not really good either. But if I could find a 6.x for a reasonable price I'd consider one for my truck. IMHO any dsl is better than any gas motor...well except that POS 350 GM psuedo dsl. After I get the rest of the x-case stuff I need for my 2.4L MB dsl swap into my CJ I'll start figuring what dsl to use in my Wag and truck. ;)
FSJeeper I too would be greatful for any info on the 6.x dsl swap.

[OBX-AUTOMOTIVE]

DID SOMEONE, IN THE LAST YEAR,SAY...THAT THEY ARE LOOKING FOR A SMALL DIESEL!!! WELL!!! EBAY HAS A 2.2 NEESOON WITH 17000 MILES FOR 300.00....I THINK IT'S AN 82??..LOOK UNDER NISSAN TRUCK ON EBAY...AS YOU KNOW!!I CAN'T POST LINKS :confused: :confused: :D

[Rogue]

how about finding an old Scout Travelall with a diesel engine and pulling out the whole drivetrain?

[joe]

Originally posted by RogueStar:
how about finding an old Scout Travelall with a diesel engine ?That may be possible in FL but Nissan dsl Scouts are really rare up here in WA. Heck gaso Scouts are rare here...FSJ's up the wazoo but not many dsl Scouts. ;)

[Rogue]

i''ve only ever seen 1 diesel scout, my uncle in pennsylvania owns it, just figured that with the problems with mating engines to AMC only bellhousings and the fact that a Intl Travelall is approx same wheel base, it would be relativly easy to retrofit

[joe]

Yeah it would be a nice swap. Perhaps a bit weak nippled for the added weight of a FSJ(?) but it would be a great motor. We still gotta solve the big prob of finding dsl Scout donors though. ;)
Your uncle wouldn't be into contributing/donating to a worthy FSJ experiment would he? :D

[Rogue]

i'll definetly ask next time i see him ( this hunting season ) oh and here is something interesting I just found out somewhere else International Travelalls with 401 engines are indeed AMC 401'S!!!!!! :D

[joe]

The 258 inline sixes in Cornbinders are also AMC motors. smile.gif

[FSJeeper]

The 6.2/6.5 diesel swap is easy, can be cheap, and very practicle. To make the swap, you just need adapter motor mounts, switch your radiator ports, figure out an engine oil cooler setup, either adapt the jeep drivetrain, or go with Chevy, bolt it in and go.

In a very heavy M715, the engine I have got 20mpg and has the power of a big block chevy and tons more torque, all at a lot lower rpm. Mine makes max torque at 1900 rpm and max power at 2500.

They are reliable. There is no carb or dist to tune.

[joe]

Originally posted by FSJeeper:
In a very heavy M715, the engine I have got 20mpg and has the power of a big block chevy.FSJ'r you're getting 20 mpg's in a M715/6.2 combo????
What axle gears did you switch too? I can't imagine stock 5.88 gears being compatable with a 6.2? ;)
Give use some details on your runnung gear please.

[FSJeeper]

Axle gears were 4.56 and it had an eaton gear splitter overdrive.

I am putting it in my chop top Wag/M715 project which will be a lot lighter. Have added a ORD doubler to the drivetrain.

lol, a 6.2/6.5 would not live with 5.88's.

[joe]

Thanks for clearing that up FSJ'r. ;)
With the 4.56/OD set up what size tires did you use? That'll give me an idea of what you're overall effective ratio is. I knew 5.88's and a dsl was just an explosion looking for a place to happen... ;)
I'm running 4.09's in both truck and wag and don't want to swap or loose the grunt factor. What's your thoughts on a 6.2/4.09 gears?

With 4.09 and 33's that put's my effective ratio at about 3.55 Any idea what GM ran for axle ratio's with the 6.2's?

D*mn...I like fuel oil burners :D

[FSJeeper]

The ideal cruise rpm for a 6.2/6.5 is around 1800-1900 rpms. A lot of people I know running GM diesels run 4.10's with 33"-35" tires with no OD transmission. At 70mph, you are at the top of your rpm range and at 55 mph you are closer to ideal rpm range.

My truck has 39.5's and with the eaton OD/gear splitter and 4.56 gears, I can criuse at 70mph at 2000 rpms which is right where I want to be.

[FSJeeper]

GM ran 4.56 gears in their CUCV Blazers and 1.25 ton trucks which has the 6.2. Top speed is 55 and that is pushing it.

Diesel powered civilian trucks came with a variety of ratios from 4.56 down.

[joe]

Thank you for the reply FSJ'r...ya pretty much told me everything I wanted to hear. :D

[Big J]

Any idea what my 3.07's and 33's would be like with a 6.2/6.5l diesel?

It does sound like a pretty easy swap... Advance Adapters has bellhousing adapters and mounts, or I guess you could build your own stuff.

[joe]

Originally posted by Big J:
Any idea what my 3.07's and 33's would be like with a 6.2/6.5l diesel?Play with this a bit:

rpm = (mph x axle ratio x 336) / tire dia

If ideal cruising rpm's for the 6.2 is as FSJ stated above you should be right in the ballpark for no-load hwy cruising(maybe a bit on the weak side?).
Towing though you might want lower gears and I'd think even w/o towing you'll prolly have to drop a gear pulling a hill.

[FSJeeper]

You are right, in the M715 with no load cruising, it is right on, for towing, maximum power is at 2,500 which means you don't use the OD. You are also right in that if it were a stock 6.2, it would be on the weak side. My engine has a lot of modifications including a custom banks wategated turbo that spools up really quick. At 2000 rpms I have tons of torque.

The Wagoneer/M715 project I am building is strictly a toy and will be trailered to locations. Will see little highway use. It will not tow anything except for stuck Fords, Chevy's and Dodges that can't keep up with a FSJ.

[Big J]

Are there any special considerations when mating a diesel with an automatic? Will a diesel perform well with an automatic?

Any suggestions for finding these engines? I noticed there were a couple on ebay. What am I looking at having to pay for one of these engines?

[FSJeeper]

The GM diesels that came with autos have a special low stall convertor and HD valving. You can't use a gas tranny witout the diesel convertor and mods. This includes the Turbo 400 and 700R4. They run well with autos.

Down here they are very easy to find. Lots of people swap out the diesel for a gas engine and just give them away. I see them go for $100 on the Chevy board all the time. You just need to shop around. If you would like, I think I could probably round up a complete 6.2/Turbo 400 and NP208 setup with low miles for less than $1000 out of a military truck. The military ones are the best J series engines, have no emisssions, and have about 10HP more than a civilian model.

Someone said these are not very good engines. The 6.2 engine is the base the new Chevy duramax is made from. Izuzu engineers gave them 4 valves per cylinder, etc.

There are a lot of tricks to these engines. You can easily crank up the injection pump at least 10% on a stock engine and get noticable power and MPG increases. Add a turbo, and wow. Intercool it and pick up another 10 to 20% increase in power and mileage. These mods increase the reliability and efficiency of the engine, not add more stress to the engine.

The engine I have is basically no budget buildup. Too much to list, but it has had extensive blueprinting and complete balancing from the vibration damper to the pressure plate. A lot of wieght taken out of the reciprocating assembly which allows it to rev quicker, pennisular teflon/ceramic top pistons, crank and rods, shot peened, polished and nitrided. Head were ported and high flow valve job. Gear cam drive that is advanced 4 degrees. Custom injection pump and wastegated turbo.

Go to the diesel page and you can see how you can get 300 HP plus without propane injection which is what my rebuild was based on, and taken a bit futher.

If you run a 6.2/6.5 at very high RPM's without doing custom work, the rods tend to sling out the side of the block. Trick is to keep rpms down and these things last forever.

I have pics and a list of the parts, mods, etc. that were doen to the engine. Hopefully, I can get a friend to put a website together for me.

[Stolen76]

I have got a pretty good source for a direct drop in on the 6.2, Watch ebay, the guy runs them on there some times. He can set you up with a 6.2 with the GM tranny and a warranty for around $1300. avasalv@mylink.net Jamie Avant, The Diesel Depot 800-553-8192.

I've been trying to save up to get a Cummins 4BT from him. I found a few pages on swaps with this engine into "flying brick" type vehicle (bad aerodynamics). One of them was into a Dakota, I emailed the guy and he was getting in the low 30's mpg without a load.

The 6.2 is a good motor, plenty of parts out there. You'll probably have to add a leaf in the front end for the extra weight. 200,000 miles out of a well maintained motor is pretty normal. If you want to get up around 500,000 miles before a rebuild, look into the Cummins 4BT. Same weight as a 360 AMC, but you would be looking in the range of $2,500 for the engine and GM400 tranny at about 100,000 miles on it. Not too bad I guess when you consider that it still has 80% of it's life left before the rebuild.

[Stolen76]

One other thought on the mpg value of an inline diesel... the fleet shop I ran in Alabama we had 20 trucks with 550 hp, 1650 torque detroit diesels in them. We hauled paper maxed out at 80,000 lbs. gross weight. With our fleet averaging 40% idle time (running engine going nowhere !) our fleet averaged 6.7 mpg running up the eastern seaboard and through the mountains out west. When you consider the lack of aerodynamics, high idle time and the extreme weight, that's not to bad.

Put it into perspective...
80000 pounds divided by 550 hp is a hp/weight ratio of 1:145.
If you consider the GM 6.2 at 160hp moving a 4,000 pound FSJ the ratio is 1 hp per 25 pounds.
I know they have many more gears, but when you consider that a 6.2 is an FSJ would have 6 times the power comparatively you could esily get 3 times the fuel economy which would put you at least in the 19 mpg range.

[joe]

FSJ'r, it's been a long time since I've owned a Blazer(civy model) so if I remember correctly the x-cases are pass side drop? I'm guessing this also holds true for the CUCV's?
Man if ya ever get your picks and info about your rig up on the web please pass the link on to us. I'd be interested for sure. Thanks for all the info.

[243]

The TH400 uses vacuum to modulate shift points, how does this work with a diesel?

[FSJeeper]

The GM has a vacuum pump located where a distributor would be on a gas chevy engine. At the top and back of the block.

The CUCV's have a passenger side drop tcase.

[Big J]

Are these engines from military vehicles being converted to gas as well, or do they get upgraded? So, with low miles would be drop-in reliable, or would they be intended for rebuild?

I'm also curious about what side the output yokes on that NP208 come out.

It sure sounds like a pretty good conversion. It would definitely be different having my Cherokee, or any FSJ sound like a diesel!

FSJeeper, I'll give that 6.2/TH400/NP208 some thought. Even in Canadian funds, that would still be fairly affordable for me. Shipping would be a little extra. Do you come across these military units very often?

[FSJeeper]

The military units have a passenger side drop on the tcase. The Turbo 400 they have are the strongest 32 spline model. Some of the CUCV's, the model 1028 came with a NP205 with 32 spline inputs and outputs. I have never seen one of these military trucks with more than 45,000 miles on them, and most are below 20,000.

The military does not convert them to gas, civilian guys do. This is the same engine the Hummers use. Parts are plentiful and cheap on the surplus market.

The Cummins 4BT and 6BT are definitely superior
engines. I have a HO Cummins in my daily driver truck with the 6 speed NV4500, it performs excellent and I get 20 MPG with it. Problem with these is that they are very expensive to buy, and parts are very expensive.

The guy who built my eninge had it in an M715 and came across a deal on a Cummins 6BT so sold me his engine and put the Cummins in it. He has seriously modified it it to the point he is twisting up 1410 driveshafts when he gets down on it. If you can get a deal on a Cummins, that is the way to go.

[FSJeeper]

The military units have a passenger side drop on the tcase. The Turbo 400 they have are the strongest 32 spline model. Some of the CUCV's, the model 1028, came with a NP205 with 32 spline inputs and outputs. I have never seen one of these military trucks with more than 45,000 miles on them, and most are below 20,000.

The military does not convert them to gas, civilian guys do. This is the same engine the Hummers use. Parts are plentiful and cheap on the surplus market.

The Cummins 4BT and 6BT are definitely superior
engines. I have a HO Cummins in my daily driver truck with the 6 speed NV4500, it performs excellent and I get 20 MPG with it. Problem with these is that they are very expensive to buy, and parts are very expensive.

The guy who built my eninge had it in an M715 and came across a deal on a Cummins 6BT so sold me his engine and put the Cummins in it. He has seriously modified it it to the point he is twisting up 1410 driveshafts when he gets down on it. If you can get a deal on a Cummins, that is the way to go.

[FSJeeper]

oops, I meant NV5600, not NV4500

[Stolen76]

the th400 behind the diesel is essentially the same except for:
heavy duty clutches and bands
low rpm lock up torque converter
manual shift valve body (rpm shifted)

[Stolen76]

BTT,
hoping for some more on this topic !

[Mikel2]

BTT! smile.gif

[Mikel2]

BTT! smile.gif