DD 8V71T specs. What components went into turning 435 hp to 462 hp in later years?

[oscarvan]

"Honey, can I get an old fire truck?"
THE LOOK
"But it has a Detroit Diesel in it"
THE LOOK LEVEL 2

That's where I quit.......

 

[madhatter1]

How does one change blower speeds when the center to center dimensions / diameters of the camshaft drive gears, the blower drive gear and the blower drive quill shaft center are fixed?


View attachment 42106

You can call Spacely Sprockets or Cogswell' Cog's. Either will have a full matching set.

 

[kelpy]

That appears to be the only way!!

 

[Avenger]

I guess the notes in the DD Field Service Data Book are wrong then?



May be a 92 Series thing, but there are definitely different blower drive ratios on some applications.

 

[Captain Ralph]

Uh Oh, one of the real books.
All hail da book.

 

[Glory]

The 462 hp engines used a faster blower and 120 injectors. 462 HP 8-71s were OE on some of the Pacemaker MY in the 70s.

 

[kelpy]

I guess the notes in the DD Field Service Data Book are wrong then?

View attachment 42128

May be a 92 Series thing, but there are definitely different blower drive ratios on some applications.

Nice reply. I never referenced the notes in the DD Field Service Data Book in my post. I was just curious what is altered to change the ratio. It is hard to read the photo image. What parts in the gear train are changed out according to the notes in the DD Field Service Data Book? That is only a 37 H.P. gain over the stock 425 H.P. 8V-71 TI found in thousands of boats.

 

[Captain Ralph]

Nice reply. I never referenced the notes in the DD Field Service Data Book in my post. I was just curious what is altered to change the ratio. It is hard to read the photo image. What parts in the gear train are changed out according to the notes in the DD Field Service Data Book? That is only a 37 H.P. gain over the stock 425 H.P. 8V-71 TI found in thousands of boats.

37 hp gain?
Are you talking shaft HP or SAE flywheel HP.
You could be talking about the same engine and tune.
The sales guy used the higher number of course. All other real boat issues are in shaft HP.

Even if different engines are in discussion, the same metric (apples and apples) must be used.

 

[kelpy]

I would have to assume it is HP rating at the flywheel since Detroit Diesel had no idea what gear the boat manufacturer was going to place behind, or in my case, in front of the engine. You will have to tell me how they were rated back in the 70's. The OP's original question was how a DD 8V-71 TI got from 425 HP to 462 HP from the factory. I still don't know how they gained the 37 HP. My question was how the 71 series blower drive gear ratio was changed to increase airbox pressure. See post #19.

 

[oscarvan]

My question was how the 71 series blower drive gear ratio was changed to increase airbox pressure. See post #19.

Guess it would have been a variation on this theme:

 

[luckydave215]

There are many ways to hot rod an engine. It is simplistic to just say "burn more air and fuel". There are a lot more ways than that to increase output. The most basic is to increase compression ratio (boosts low end torque), and move the torque curve higher in the rev range (peak torque occurs at higher rpm) to increase horsepower.
Why limit yourself to simply changing injectors?
My engines have NA pistons (compression ratio increase), bigger injectors, different cams and cam timing, different blower drive ratio, bigger turbos, etc etc etc.
When going for more output the competent engineer will change everything.