Can anyone out there tell me the actual size of the over 500 cubic inch IH diesels used in semi tractors and if so are the injectors the same size as the 6.9 etc [threads etc] and do they put more fuel through. In other words can they be used in modified 6.9/7.3? Larger injectors have been used for years to increase hp in diesels and would be superior to cranking the pump if available.

 

I have a 1982 school bus and it has a 9 liter V-8 IH motor. If I use 444 for the 7.3 and do the calculator thingy it comes out to 547 cubic inches.

 

Hi, thanks for the come back. Its been a while so I about gave up. Is the school bus diesel? My dad was a long haul trucker in the 60's and talked about the IH v8's as quite fast so I thought maybe the injectors might be bigger but still fit our 6,9/7.3s. Do you know if they do? Thanks.

 

The 9L is actually a gas converted 545 around a 180 horse. Fuel Chewer not the most powerful animal they ever came up with. You would find it in mostly medium duty applications school buses 6 wheel dumps 18,000 lb class. Anything you would find a 3208 CAT in basically about the same size and horse power range. One thing I did like about the 9L it was one of the best cold starting diesels I have ever come across. On the coldest days no glow plugs just an ether assist (never used) spin over bang running. EPA killed those dogs and they were heavy drank fuel etc. They always sounded pretty tough though.

 

Ok, so what did the road tractors use? Dad drove an old B69 Mack for Hemmingway back then and he talked about the "new V8 Haybinders" as though they would really haul. The guys all cranked the pumps on those Macks till the flame just bounced off the pavement to get the most power from them. Even at that he got a comendation for 475,000 miles with no major work on the engine. Even with the Mack really hauling the IH would scream on by so they must have had something. Remember a 300 Cummings was quite the rig back then so we have come a ways.

 

I'd guess that if they were v8s in IH road tractors, they were Detroit Diesels, which IH used plenty of. The classic "318" 8v71 was common. There also were the 92 series engines and I imagine the 12v71 would move a truck in a manner that could be described as "screaming on by".

Ken

 

The old Mack motor was a 237.
Can you imagine starting a cross country trip with a 73,000 pound rig that only had 237 HP?
Here in WV when pulling the mountains a person could walk as fast as the truck would go.
So when the 8V71 Detroit with 318 HP was passing you it felt like you were in reverse.
Shortly after that they added a turbo to the 318 and bumped the power up to 350.
The Mack drivers just watched the tail lights fade in the distace.

The 12V71 engine did rule the road for a while, but Cummins soon retaliated with the KT600 and took the road back.
They did not sell that many of them, but you only had to see one to realize it owned the highway.

Back in the early 80's I ran an 8V92TTA for a million plus miles.
That engine was a true Screamin Demon Detroit.
When you normally drove an I 6 motor like the Cummins or Mack and most of the Cat engines that are governed to 2100 RPM, a V8 motor turning 2800 RPM sounds like it is screaming when it goes by.
That engine is also probably a lot of the reason I don't hear to good any more.
There were not many trucks that could pass me on the hills, but I always had flashing red and blue lights in the rear view mirrors.
The truck was fast, the cop cars were faster though.

I also have to point out the engine was not very fuel efficient, at higher altitudes it was common to see flames above the stacks.
All the fuel in the exhaust would still be burning when it left the stacks.