Detroit Diesel 2 stroke- 92 series vs 71 series

[TomC]

Yes, I enjoyed driving the 8V-92TA. When I got my next truck, it had a Cat 3406B-I had to relearn to shift all over again.

8V-92TA has a lot of preventative maintenance. You change the oil at 10,000 miles. At 100,000 you run the rack and adjust valves. 200,000mi run the rack and adjust valves and roll in rod and main bearings. 300,000 you run the rack and adjust valves and rebuild turbo, blower, governor. 400,000 you run the rack and roll in rod and main bearings. 500,000 usually ready for engine overhaul. Fuel mileage average- 4.8
Compare to the Cat 3406B. You change the oil at 12,000 miles. Every 100,000 adjust the valves. At 500,000 roll in rod and main bearings, injector tips. 1,000,000 or when needed overhaul engine. Fuel mileage average- 5.6
Compare to the new Detroit DD engines. You change the oil at 50,000 miles. Adjust the valves at 100,000, then every 500,000 after that. Overhaul at 1,200,000 miles. Fuel mileage average- 8.
Good Luck, TomC

[luvrbus]

s.

Only reason I mention this is that the 12V71 hp & torque figures aren't that different from an 8V92TA, so you might be able to come up with some rough heat load numbers that could help with your extrapolations.

.

FWIW & HTH. . .


The DD application manuals and engineering bulletins have the heat rejection numbers in the manuals needed for the 2 strokes.The 8v92 replaced the 12v71 mostly because of the HP to weight ratio the 12V71 really never made it's mark in the trucks it was to heavy a 8v92 weighs 2306 lbs and the 12v71 a whopping 3502 lbs for about the same hp and torque rating
 

[Dreadnought]

The DD application manuals and engineering bulletins have the heat rejection numbers in the manuals needed for the 2 strokes.The 8v92 replaced the 12v71 mostly because of the HP to weight ratio the 12V71 really never made it's mark in the trucks it was to heavy a 8v92 weighs 2306 lbs and the 12v71 a whopping 3502 lbs for about the same hp and torque rating
 

Thanks! Where can I get hold of these manuals?

Would save me from extrapolating!
I found data on a CAT C15 (485 Bhp), a Cummins ISX and a DD15 engine and their heat rejection numbers- (all between about 140-200 kw to coolant) and I was trying to get a 'feel' for typical numbers. If I get direct numbers from DD about the 8v92 so much the better!

[luvrbus]

In the application manual DD used a simple formula 2250 BTU for ea HP setting on the 8v92 TA engine almost twice as much for a 500 hp 8v92TA as compared to the 60 series with 500 hp 

[Iceni John]

I have friends who have sized up radiators and cores so I could probably come up with a rule of thumb as to what radiator core would dissipate what.

Is there a simple way to determine a radiator's heat rejection ability that us busnuts could use to know if our cooling systems are adequate or not?   I recently completely replaced my entire cooling system in an effort to address some serious overheating, and while my new setup is much better than before I still wish for slightly lower coolant temperatures.   I'm toying with the idea of adding a second smaller radiator to help in hot weather, but I've not been able to find a single radiator maker who can quote plausible heat rejection numbers for their radiators.   Is it really that complicated?

Using Detroit's formula of 2250 BTU/hour per HP, my 277 HP engine should need 10,400 BTU/minute of radiator capacity.   When I turn on my 150,000 BTU/hour heaters I see a noticeable drop in coolant temps, so if I could achieve the same results with a second radiator I'll be happy.

John

[RJ]

Does the MC6 with 12v71 have just ONE radiator on the Left hand side or in this radiator in addition to the two that are there on the MC5s?

Just one, HUGE, radiator on the MC-6, LH side, hydraulically-driven fan.

Scott's bus is currently stored about an hour away from me.  Next time he's in town, if I go with him, I'll measure it for you.

FWIW & HTH. . .

[luvrbus]

When I was running twin turbos on the 8v92 in the Eagle I had Atlas in Texas build me a radiator for it the dimensions where 42 inches tall X 47-1/2 inches wide with 9 rows of tubes, with a 13 blade 31 inch dia variable pitch plastic fan and I could still heat it if not careful on a long grade
   

[HB of CJ]

Since all the knowledgeable guys are here, if you ran a proper sized turbo and instead of dumping the cooled charge air into the blower what would happen if the turbo boost air got instead dumped into the air box inspection cover(s)?

I'm thinking of some sort of clapper valve to keep charge air from coming back out through the blower.

[Dreadnought]

Is there a simple way to determine a radiator's heat rejection ability that us busnuts could use to know if our cooling systems are adequate or not?   I recently completely replaced my entire cooling system in an effort to address some serious overheating, and while my new setup is much better than before I still wish for slightly lower coolant temperatures.   I'm toying with the idea of adding a second smaller radiator to help in hot weather, but I've not been able to find a single radiator maker who can quote plausible heat rejection numbers for their radiators.   Is it really that complicated?

Using Detroit's formula of 2250 BTU/hour per HP, my 277 HP engine should need 10,400 BTU/minute of radiator capacity.   When I turn on my 150,000 BTU/hour heaters I see a noticeable drop in coolant temps, so if I could achieve the same results with a second radiator I'll be happy.

John

I'm pretty sure there is , but I don't know what the rule of thumb is right now. I have to confer with some old friends...

[zubzub]

Since all the knowledgeable guys are here, if you ran a proper sized turbo and instead of dumping the cooled charge air into the blower what would happen if the turbo boost air got instead dumped into the air box inspection cover(s)?

I'm thinking of some sort of clapper valve to keep charge air from coming back out through the blower.

[daddysgirl]

Andrea,, probably the reason you perform so well is the location your in.. the 8V71 does very well near sea level but runs out of breath quickly above 5 or 6 thousand feet.>>>Dan

Yes, at sea level, I'll get a ticket if I'm not careful. However, I've been from VA to CA and back, and all over the mountains...I remember 6200 feet, and 7000 a few years ago, and the bus didn't struggle. THAT is what I don't understand.
I like Toms turbo setup, but I just finished tearing out and reinsulating the rear interior, over the engine compartment, as the beginning of the re-rebuild process. It's going to be a while before I worry about the engine. But I will be sending Tom a message or two before I start that process.

[lvmci]

Hi All, when I was searching for a bigger bus, there was an MCI9, that had 2 additional radiators inside where the side engine doors were on either side and it was an 8V92. I think he said it was from Saudi Arabia.  It was in central texas. He said it never overheated no matter how hard he pushed it. Clifford how would you route inlet and outlet pipes, inline with the upper radiators? lvmci...

[Branderson]

At risk of sounding like an idiot.  I noticed that nobody is talking about the 6v92 (which is what I have).  Is that a dinosaur?  I'm curious on how much of a difference in speed/power between the 6v vs 8v. I guess it shouldn't matter to me really b/c I don't plan on changing engines unless I do something stupid and ruin the one I have.

[Iceni John]

lvmci, my idea for a second radiator for my 6V92 is to use the existing 1" coolant outlet on the driver-side of the block that presently supplies the two heaters.   (Curiously, the heaters are supplied through 3/4" hoses and pipes, so presumably a 3/4" flow rate is sufficient for 150,000 BTU/hour heat dissipation;  the 1" outlet now immediately reduces down to 3/4".)   If I ran a 1" line to the radiator and a 1.25" return line back to the existing radiator lower return pipe into the water pump, I'm hoping I wouldn't need a coolant booster pump like my heaters now have.   I've found a 3-row aluminum radiator for a Ford Excursion which is the largest that will fit, and if I used two shrouded 14" or 16" Hayden electric fans would they draw enough air through it?   So, the big question is, what is this radiator's heat rejection ability?   I would also need to know the total CFM of the fans and the static pressure, and the coolant flow rate.   If this radiator matches the heaters' 150,000 BTU then it's worth doing, but if it doesn't then I won't bother with it.

The more I learn about heat dissipation the more complicated it becomes!   I know that what's theoretically possible doesn't always work so well in practice, and intuition doesn't get you very far.   Nothing's easy.

John  

[lvmci]

Hi John, does it go toward the driver and cabin heat? Where does it return to the block? Is it also 1"? tom, lvmci...