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Old May 23rd, 2017, 02:08 PM
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Default Re: Toro-Flow- G.M. vs. Cummins

Originally Posted by BobBray View Post
It is a strange reference in that the 348/409 were gasoline engines, and the dispute was more to do with oversquare diesel engines. Oversquare really doesn't work too well for diesels, as you stated it's difficult to build compression (vitally important for a diesel!) and I question if it puts undue stress on the crank and rods compared to undersquare diesels. In any event, there have been very few oversquare diesels.

You know, back around 1980 when Detroit Diesel introduced the 8.2L 'Fuel Squeezer', I initially thought it was some sort of a revised Toro-Flow!
The V-6 GMC's took over-square to a new level when they came out, allowed for big valves for good breathing, sturdy blocks, crankshaft, etc. The fact the Toro flow was such a good engine with the few changes they got proves how tough a gas engine the big V-6's were. No other manufacturer had as good of service from their converted gas engines.

I had the misfortune of driving an early '80's F-700 with an 8.2L. I loved the truck. Was like driving my F-150 except for the air brakes. Put a boat load of miles on it too. Had a 1000 mile day with that truck. All except about 15-20 miles in the state of Iowa. Poor truck only had a 40 gallon fuel tank so fuel stops came every 260-270 miles. 7 mpg was pretty good in my opinion for a truck running 60-65 mph grossing 30,000-40,000#. When we switched to the gas V-8 powered IH Loadstar with 100 gallon gas tanks I lost 5 mph and about 4 mpg, I averaged about 3 mpg. Anyhow, the 8.2 had some unusual type of injection system, different that any other engine. It was tough to find someone good to tune them up. It would drop a cylinder within a week or two of spending a week at the dealer, then drop another cylinder, then a third, finally a forth over the span of a month or two. By then it was only able to bobtail 35-40 mph back to the shop. In about 8-9 months it was gone. Guy who was a DDA service tech explained the injection system to me years ago, and why it was so fussy. I put 350 to 375 miles on that truck six days a week pulling a 45 ft trailer every foot of the way.

I checked specs on several diesel engines I thought might have been square or over-square but they all were under-square. Only the IH gas engines converted to diesel kept their under-square bore&stroke. Engines like the 6.9L & 7.3L ID I and various PSD's were just barely under square.

Anyhow, I enjoyed the article, and always enjoy discussing truck engines, what worked and what didn't, because in the 100+ years of truck engine development, just about everything has been tried with the possible exception of pure rocket power. Lots of gas turbine powered trucks in the late 1950's and 1960's. Chevy, Ford, IH, and others.
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