Diesel engine success in our G cars..

[KrisW]

Hello all,

I have had some interest in diesel related stuff so I thought I'd open this up in case anyone else has had questions or concerns. As I remember more or get new info I'll keep adding it here.

First, what I have;

Currently the car is an 80 Cutlass Supreme (factory Ca car, factory diesel car)

The current engine specs:

1985 DX casting diesel block with factory roller cam

1979 heads from a pickup truck application (these heads use the older style Roosa Master pencil type injectors with fuel return lines and are supposed to be good for 10 horsepower over the later Delco injectors)

The crank and rods are from a 1979 Eldorado but it's hard to tell the actual year because so many were upgraded with the better Goodwrench 350 diesel crate motor by warranty later on. Only my Cutlass had an original "D" block that the factory had not snatched up!

aluminum intake from a 1981 non EGR car. I modified the intake by drilling into the water passage at the left rear so that I could bring a hose to connect the rear water passages of the head to the front to try to equalize the cylinder head temperature throughout. I have found this to be the number 1 problem that these engines (and later 6.2 engines) suffer from. The back of the head gets hotter than the front and heat cycles more in one place. This causes the head bolt to stretch and break and then the head gasket blows... It doesn't matter what bolts or how good they are, they all break. You have to use studs and you have to equalize the temp.

The injector pump was custom made by me. It is a housing from a 1979 Eldorado with the guts from a cold weather application 6.2 diesel with a 4900 rpm governor.

I am using premium Fel-Pro gaskets that are .030 oversize to drop the compression a tad. I am using Milodon Studs in the heads and the mains.

This engine has been in a 1973 Jeep 4x4, a 1977 Suburban, and my Cutlass. I think it will go in my 93 Chevy pickup next and a good 350 Olds gas engine will go into my Cutlass... I don't know!!

 

[85 Cutlass Brougham]

Good luck is all I can say! If you have figured out how to make this engine work well for you I applaud your efforts. I like diesel engines myself, but the ones I like are German as they seem to have built the best over the years. Have you ever considered a turbo installation for it? The Mercedes OM617 3 liter turbo diesel that saw duty in the late 70's-mid 80's Benzes was a 3 liter turbo diesel with 126hp, about the same as the 5.7 liter GM diesel. The non turbo version of that engine made 88hp. Makes you wonder what kind of performance you could get with a turbo on the GM?

Also, the truck 6.5 turbo diesel is a bolt in as far as mounts and transmission pattern are concerned for a Small Block Chevy. It has it's share of problems, but may be worth considering as an alternative to the old Olds based engine.

 

[ryanwitski]

just don't use the 5.7L diesels. those are converted gas blocks AKA junk. if you had a big budget and a custom ECM (like megasquirt but for diesels) get the duramax, I have seen them pull a little over 1000 ft/tq with stock drive train and med/high difficulty mods.

 

[KrisW]

just don't use the 5.7L diesels. those are converted gas blocks AKA junk. if you had a big budget and a custom ECM (like megasquirt but for diesels) get the duramax, I have seen them pull a little over 1000 ft/tq with stock drive train and med/high difficulty mods.

I think that ignorant statement says it all.

I am running 5.7L diesels. I can get them nearly for free because so many ignorant people just give them away. THEY ARE NOT CONVERTED GAS BLOCKS. If you really don't know what you are talking about, you probably shouldn't post.

All of the diesel blocks have a big "D" cast into the sides. The first ones used from 1978-1980 had just this D on the side under the number 350. The main webs in the bottom of the block are not strong enough for diesel use and they are only machined for a flat tappet cam. This is still a good block to convert for use as a gas engine if you want a large cubic inch Olds Small block. These blocks use the same main saddles as a big block olds. You only need to use a shorter connecting rod to run them.

The next block started sometime around 81. They have a "DX" cast under the number 350 with a flat tappet cam. They also use a stronger crankshaft.

The last block was in production from 82-85. It also has a "DX" cast under the number 350 and is machined for a roller cam. It was actually cast by Detroit Diesel in the same foundry with the 6.2 diesel. This is the preferred block to use for diesel applications.

There were also V6 diesels and 260 V8 diesels made in these same time frames. They need only head studs to survive forever.

If you have an 81 or newer 5.7 (or Goodwrench crate engine) all you need is head studs and a coolant line from the back of the head to the front of the intake where the thermostat is. These two mods will allow that engine to live a long, productive life.

As I stated before, my modded engine will probably go in my truck next. I may build another stocker from my engine stock pile to run in the Cutlass again.

 

[beeterolds]

just don't use the 5.7L diesels. those are converted gas blocks AKA junk. if you had a big budget and a custom ECM (like megasquirt but for diesels) get the duramax, I have seen them pull a little over 1000 ft/tq with stock drive train and med/high difficulty mods.

I think that ignorant statement says it all.

I am running 5.7L diesels. I can get them nearly for free because so many ignorant people just give them away. THEY ARE NOT CONVERTED GAS BLOCKS. If you really don't know what you are talking about, you probably shouldn't post.

All of the diesel blocks have a big "D" cast into the sides. The first ones used from 1978-1980 had just this D on the side under the number 350. The main webs in the bottom of the block are not strong enough for diesel use and they are only machined for a flat tappet cam. This is still a good block to convert for use as a gas engine if you want a large cubic inch Olds Small block. These blocks use the same main saddles as a big block olds. You only need to use a shorter connecting rod to run them.

The next block started sometime around 81. They have a "DX" cast under the number 350 with a flat tappet cam. They also use a stronger crankshaft.

The last block was in production from 82-85. It also has a "DX" cast under the number 350 and is machined for a roller cam. It was actually cast by Detroit Diesel in the same foundry with the 6.2 diesel. This is the preferred block to use for diesel applications.

There were also V6 diesels and 260 V8 diesels made in these same time frames. They need only head studs to survive forever.

If you have an 81 or newer 5.7 (or Goodwrench crate engine) all you need is head studs and a coolant line from the back of the head to the front of the intake where the thermostat is. These two mods will allow that engine to live a long, productive life.

As I stated before, my modded engine will probably go in my truck next. I may build another stocker from my engine stock pile to run in the Cutlass again.

350 diesel blocks are their own monster as you pointed out...they have 3inch mains like the big block Oldsmobile fat webbing around the mains...super thick cylinder walls....for a Gas engine..superbadass!!! sadly the Olds diesel wasnt all that successful because it was "based" on the Oldsmobile 350 small block...and loved to crack heads and blow gaskets...hard starting..and just plain unreliable...it was not converted as stater prior.. However with enough time care and patience. you can put together a good daily driver...

I have an old Peterson book where they replaced a beat to sh*t 327 chevy out of an El Co and installed a lightly turbocharged Olds 350 in its place...its actually a good read... If u lower the compression of the 350 from 22ish-1 to about 17-18 you can get some revs out of it...and throw a turbo on it with some real boost.. :shock:

 

[megaladon6]

i still say put a bmw 330d in a g-body. stock they make 230hp and 370tq. up the boost some, bigger injectors and a re-flash or chip and that thing will MOVE plus, with the lower front weight it will handle better. another option, since it will actually be in the us soon, is the VW 3l v6 tdi.

kris: what do they do about the distributor hole. is something still driven by the cam or is it just sealed off? can you upgrade the cam at all?

 

[85 Cutlass Brougham]

How about a Mercedes Benz OM 603 or OM 606? They had some "Issues" but supposedly the ones that got the recall and better rods are very good. Plus, they made decent power from the factory and were turboed with efi and a DOHC head. Plus, unlike the BMW 330D, they were sold in the US when new over a number of years and models. They replaced the OM617 in 1986 IIRC. Besides, If I could get a 330D, I would want the whole car not just the engine. IMO, the E46 coupe is the best looking BMW of all time.

 

[megaladon6]

why put a low power, low efficiency engine in? the new bmw and vw v6's get MUCH better power and efficiency and are more reliable (they have a cool common rail system now). i don't want a bmw with 42+ modules but they do make a decent diesel motor.

 

[85 Cutlass Brougham]

I am not talking about the w123 engine here ( the OM617). I am talking about the one that replaced it. Then again, have you seen the new GM diesel for the future that Hot Rod has a pic of this month? It's an odd one with the intake on the outside of the vee and the exhaust in the center of the engine with a VNT turbo and intercooler? It's worth a look because it is so unconventional. I have nothing against the BMW 330d! I would rock one if it were available in this country. I was just proposing a more readily available alternative. Then there are the new Blue Tec diesels that are a joint development effort between VW and Mercedes-Benz that are supposed to come out shortly.I have not read anything on them yet, but look forward to seeing what these two titans of diesel can come up with.

On a swapping note, the GM 6.5 turbo diesel found in light and medium duty trucks will bolt to SBC mounts and has the same transmission flange. It may be a viable alternative to the typical gas swaps into a dead diesel G or B body car. The only drawback I can think of is weight as diesels weigh more than gas engines do. This engine also has a reputation for bad injector pumps, and I have heard that GM did sort of a silent recall on them. The new pumps are supposed to be better. A friend of mine has a Chevy 1 ton crew cab with this engine and GM did the repairs for free because of this.

 

[KrisW]

kris: what do they do about the distributor hole. is something still driven by the cam or is it just sealed off? can you upgrade the cam at all?

They run a vacuum pump that still drives the oil pump from the cam, just like a distributor...