Jurassic Park

rzucker

Well-known member
The 2 stroke dinosaurs are back on the road. It's spud harvest season here and I have seen a bunch of well preserved older Detroits on the road lately, Mostly 10 wheelers with all manner of 71 series engines. Puts a big smile on my face.
Got a call this morning about an 8V-71 "no start" and went to check it out. Checked the E stop and it wasn't tripped, bent a brazing rod to put into the fuel pump weep hole and could feel the shaft turning so the blower drive was good... then I saw white smoke near the starter, Bingo, an airbox cover lost a stud and dropped down to uncover most off the opening. A bead of gasket eliminator and a 5/16" bolt and it's wailing away again once more.
 

Steve Frazier

Founder
Staff member
I hated the 71 and 53 series back when I was driving, so much work shifting and noise without much to show for it. I smile today when I hear one in the distance, a sound from a bygone era. I'd like to be able to buy a truck with an 8V71 and 13 speed just to start and listen to now and then LOL!
 

rzucker

Well-known member
I hated the 71 and 53 series back when I was driving, so much work shifting and noise without much to show for it. I smile today when I hear one in the distance, a sound from a bygone era. I'd like to be able to buy a truck with an 8V71 and 13 speed just to start and listen to now and then LOL!
Honestly Steve, in the day the 8V71N pretty much ran with the 335 Cummins and the 12V71 ran the early 400 Cummins into the ground. lt took Cummins and Cat quite a few years to hit that honest 475 HP mark that the 12V71 held. The Cummins KT was close but heavy.
 

JasonG

Well-known member
Yeah, harvest season around here brings out the old iron.
I love the sound of those 2 strokes, well, from outside the cab ☺
 

BoxCarKidd

Active member
I hated the 71 and 53 series back when I was driving, so much work shifting and noise without much to show for it. I smile today when I hear one in the distance, a sound from a bygone era. I'd like to be able to buy a truck with an 8V71 and 13 speed just to start and listen to now and then LOL!
I have no use for a 53 in a truck!!! Went and started an old Detroit yesterday. Double blockage, a well hidden Racor, and trash in an elbow. I worked at this one a bit and surly I was the first guy? No rush when ever you get around to it.
Big Rickie's 8V71 Astro would do 92's on a good day. Can 5 million Gray Hounds be all wrong?
 

rzucker

Well-known member
Yeah, harvest season around here brings out the old iron.
I love the sound of those 2 strokes, well, from outside the cab ☺
I ran an old GMC 9500 for 290,000 miles, 8V-71 power but it had the fat Donaldson mufflers on frame mount brackets, nice and quiet in the cab. Had a good sound too.
 

rzucker

Well-known member
I have no use for a 53 in a truck!!! Went and started an old Detroit yesterday. Double blockage, a well hidden Racor, and trash in an elbow. I worked at this one a bit and surly I was the first guy? No rush when ever you get around to it.
Big Rickie's 8V71 Astro would do 92's on a good day. Can 5 million Gray Hounds be all wrong?
In the mid 90s I worked on a fleet of 10 wheelers that had 6V53s and 653 Allison transmissions, They ran 52K gross loads. They were loud and slow, Did I mention they were loud. They were loud, But they got the job done. The same trucks are still running today.
 

Steve Frazier

Founder
Staff member
I imagine it was a worthy engine when it was introduced, my experience with them was at the tail end of their run, late 70s to early 80s. The company I worked for had some trucks with 6/71 and 8V71 in them with 13 speeds vs Macks with 237 and 300 Maxidynes in them. I don't have to tell you which were less work to drive. I wore headphones in the Detroit trucks, I could actually hear the radio in the Macks. It's an engine I loved to hate! At the same time 300 and 350 Cummins were becoming popular, they were smooth and quiet compared to Detroit.
 

BoxCarKidd

Active member
The last ones I was around were 1994 off road 425 8V92's. They did a great job. Worthy when it was introduced caught my eye. So when were they introduced? What did the GM cast in letters stand for? A little gray area?
 

rzucker

Well-known member
The last ones I was around were 1994 off road 425 8V92's. They did a great job. Worthy when it was introduced caught my eye. So when were they introduced? What did the GM cast in letters stand for? A little gray area?
Dunno about the casting letters, but I remember in '78 the word about the 92s was out, the 430 was the hot number. But I have driven a 500hp+ 8v92. It was hard on drive tires and fuel if you weren't careful.
 

Truck Shop

Well-known member
Late 70's early 80's there was a guy out of Indio Calif that ran a V12 salt water chevy in a Mack Superliner. The V12 was built buy a marine shop in Long Beach.
The cab and sleeper was painted black. It had a very racist name painted on the hood {I will not say what it said}. But I can say that truck flew, I was passed buy him twice.
Once at Shasta and at Biggs Junction going south up the grade. I know he was a hobby trucker because no body else could afford the fuel, tires, transmissions and rear
drives.

Truck Shop
 

rzucker

Well-known member
Late 70's early 80's there was a guy out of Indio Calif that ran a V12 salt water chevy in a Mack Superliner. The V12 was built buy a marine shop in Long Beach.
The cab and sleeper was painted black. It had a very racist name painted on the hood {I will not say what it said}. But I can say that truck flew, I was passed buy him twice.
Once at Shasta and at Biggs Junction going south up the grade. I know he was a hobby trucker because no body else could afford the fuel, tires, transmissions and rear
drives.

Truck Shop

Geez, It's been awhile. I was contemplating calling the shop today to see if all was well. Busy?
 

BoxCarKidd

Active member
No replies so looked to answer my own question and will list my hearsay facts first.
A retired Navy guy that helped me some started in subs, graduated to pilot, and was an electrical engineer. I thank he said GM originally stood for Gray Marine and General Motors bought them out. Walkipedia tells a different story, you can read it there. He may have been talking about larger engines in boats, trains, generators and such. I do not know.
Another guy that helped me some retired from Cummings. He said Cummings dumped the two stroke after their race car days at Indianapolis and such. The condition of the engines was so bad after they completed the races they were not worthy of commercial production. GM wanting to get into the diesel business started with what was thrown away. You can find some info on that in the same place. Only car to run in Indy that never made a pit stop.
Please excuse my for spreading hearsay. I will try to refrain from it in the future.
 

rzucker

Well-known member
No replies so looked to answer my own question and will list my hearsay facts first.
A retired Navy guy that helped me some started in subs, graduated to pilot, and was an electrical engineer. I thank he said GM originally stood for Gray Marine and General Motors bought them out. Walkipedia tells a different story, you can read it there. He may have been talking about larger engines in boats, trains, generators and such. I do not know.
Another guy that helped me some retired from Cummings. He said Cummings dumped the two stroke after their race car days at Indianapolis and such. The condition of the engines was so bad after they completed the races they were not worthy of commercial production. GM wanting to get into the diesel business started with what was thrown away. You can find some info on that in the same place. Only car to run in Indy that never made a pit stop.
Please excuse my for spreading hearsay. I will try to refrain from it in the future.
Uhh. NO. Gray Marine used GM 71 series engines to build their own branded power packages just like OMC and Volvo used the old 350 chevy rebranded as their own marine power packs. Never heard the Cummins 2 stroke story before, could be true. But after 35 years of heavy equipment repair, I doubt the 2 stroke was a throw away design. Millions of Detroit Diesels powering heavy equipment of many different makes tends to prove otherwise.
 

Longhood

Well-known member
the old 2 strokes said General motors diesel on them, the early ones had a centrifugal blower instead of the more common roots blower. Pretty sure that General motors designed their own engine, Cummapart is pretty handy at buying other peoples designs, like the Case/copy of a Caterpillar 5.9 that sold so many crappy wrapper "trucks". Detroit powered almost everything for a while.
but they were lazy in truck applications at higher altitude. I had an 8V71N in a Ford LT9000, with a 5&4, it had big injectors, but a 270 cummins would spank it (somebody probably messed with the pump on the 270 )
 

rzucker

Well-known member
I have seen Detroit rocker covers stamped "General Motors Diesel", "Detroit Diesel", and even a 6-71 that was stamped "GMC" in the old 50's style truck emblem script, probably out of a 50's GMC truck. Still all built by the Detroit Diesel division of General Motors. The centrifugal blower was used only on the early 6-110 engines and discontinued after it was discovered that overspeeding the engine blew up the impeller and destroyed the engine. (it turned 10X the crank speed)
 

BoxCarKidd

Active member
I can not post links and such but if you look at Wakipedia Cummings at Indy there are pictures and mention of 2 strokes. Maybe that was Car and Driver: When Cummins assualted Indy.
 
Last edited:

rzucker

Well-known member
I can not post links and such but if you look at Wakipedia Cummings at Indy there are pictures and mention of 2 strokes. Maybe that was Car and Driver: When Cummins assualted Indy.
Not a whole lot of info about the actual 2 stroke engine but it does mention the driver "stripped the gears" and that ended the Cummins experiment with the 2 stroke engine.
In the long run, the 4 stroke is more fuel efficient but the 2 stroke packed more power into less cubic inches before the turbo came along. Ergo the 475 HP 12V71N at nearly the same displacement as a 250 Cummins... Big difference in power there. And even when Cummins was struggling with the small cam 400, Detroit had the 430HP 8V92 that could actually run at 500HP when the warranty ran out and you had it rerated.
Yeah... I kinda miss the 2 strokes.
 
Top