New IDI Story In Diesel World

[The_Josh_Bear]

@PwrSmoke Great article! Thanks for the share. I enjoyed that and learned some too.

Question about the following statement:

The engineering target was for a moderately priced V8 diesel in the 400-450 cubic inch range, making 165 net horsepower at 3200-3500 rpm.

That RPM range was used by Ford, but weren't all the IH engines turned down to around a 2500 rpm redline? I have no experience with the IH versions, just read on here a lot and that seems the case. If so it seems silly for them to target an RPM they didn't even come close to using.

-Joshua

 

[PwrSmoke]

@PwrSmoke Great article! Thanks for the share. I enjoyed that and learned some too.

Question about the following statement:

That RPM range was used by Ford, but weren't all the IH engines turned down to around a 2500 rpm redline? I have no experience with the IH versions, just read on here a lot and that seems the case. If so it seems silly for them to target an RPM they didn't even come close to using.

-Joshua

Nope. Per engineering documents, interviews with surviving people from the era and SAE paper 830381 (whichoutlines the development of the engine from an engineering perspective), their engineering target was 3200-3500 for maximum power. But that was before design and testing. In the end, 3300 rpm became the maximum rated full load rpm. Bear in mind that there are different ratings for different applications. Non-commercial automotive is the highest and that's what Ford used. Passenger cars and light trucks always get the maximum rated power... often called "maximum intermittant"... though each company may have a slightly different way of expressing it. Commercial automotive is almost always lower and in the case of the IH 6.9 it was 155 or 165 hp at 3000 rpm. That would be the intermittent rating. If the engine was to be used in a stationary or marine applications, neither of which was common for the 6.9, you would get into continuous rating, meaning at what rpm and power setting can the engine run essentially forever without undue harm. There is where you might see a 2500 rpm rating or something close to it. I haven't seen any documentation on stationary applications but have seen a couple of retired units. There were several marine applications, inboard and I/O. In the marine realm, they generally had two ratings, pleasure boat and work boat, with pleasure being whatever the maximum rated for the base engine (sometimes a little more due to having unlimited cooling) was because they knew they would only be used intermittently at that output. The workboat ratings are lower and closer to the continuous ratings. I have found only a few references to marine use of the 6.9 but I know they were out there. Mercury was pushing a marinized 7.3L PSD I/O in the mid '90s with a 300hp pleasure boat rating. WOuld like to find more industrial and marine documentation for the 6.9/7.3.

 

[The_Josh_Bear]

Thank you! New wrinkles in my brain...

 

[Dieselcrawler]

Glad to see ya stop in Jim, and great article!