Heavy Duty Engine Thermal Break Downs

[Dreadnought]

A previous thread delving into some engineering technical details about the 71 series and 92 series 2 strokes started to head towards the direction of cooling. It covered some good ground. For this reason I thought I would start this one. Thanks to Luvrbus- who posted

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 

and gave what Detroit quote from their old application manuals. How does an 8v92 stand vs modern heavy duty engines? I thought I would post some break downs, at rated power of
-a Series 60
-an ISX and
-a CAT 15 litre
I picked engines that were around the 500 bhp mark and all this is based on measured engine dynomometer data


Thanks to the relationship to the S60 that luvrbus posted we can then work out how many KWs and therefore BTUs the 8v92 rejects to its coolant. First of all- the Series 60
The 34.8% "Other"- a lot of that is exhaust heat
What I found of 2 stroke diesels is that their exhaust tend to run cooler than 4 strokes because the blower bypasses or pushes so much air through. The 8v71s in particular, scavenge much better at higher rpm than lower (scavenge- the supercharger is blowing well during the scavenge cycle or overlap period). This is why an 8v71 will black smoke if you labour the engine- at lower rpms the blower isn't scavenging as well (the danger of continually labouring the 71s is that the soot finds its way into the oil and in extreme cases you can 'ring jack'). The EMD 2 stroke train engines do the same on the dyno.




Next is an ISX



And Finally

a CAT 15 (The CAT 15 was sold as a Navistar/International Maxxforce 15 briefly with combustion and fuel system mods)



The series 60 rejects 158 Kws to coolant (or radiators).
This works out to 8985.30 BTU/min

For 500 Bhp-the 8v92= 1125000 btu/hr= 18,750 BTUs/min. About twice the amount of the S60- as was originally stated- so that's verified.

My target is to one day get 550 bhp from an 8v92. Therefore I will need to dissipate 20,625 btu/min- basically TWICE what my 8v71 makes now.

I haven't worked out a relationship of what radiators reject what yet. I have a simulation package that may have that info.

I phoned up Griffin radiators, who I've worked with in the past and who supplied me a custom radiator for my 700 bhp Dodge Challenger project and he said he could custom build radiators when the time comes. In addition the other thread talks about additional radiators.

I'm not urgently on this right now as my 8v71 is fine and I don't intend to change it for probably another 10 years. I have to finish my Challenger and Jaguar projects before then.

Other ways to help with the high heat-to-coolant situation of the 8v92 is to

Improve combustion- the combustion of the 8v92 just judging by the bowl design and the poor bsfc numbers and the amount of air the engine needs to burn cleanly is probably slow and inefficient. If I could, I would increase the injection pressure as much as mechanically possible (I wouldn't go common rail, I like the mechanical set up), change the piston design to a re-enterance bowl and change the injector holes/angles to suit.

Porsches used to ceramically line their exhaust ports on the air cooled engines to not 'thermally overload' the cooling fins, but what if this starts to break off and go into the Turbo etc

[oltrunt]

Good read and info.  I didn't know about the Porsche ceramics.

Jack

[Dreadnought]

Good read and info.  I didn't know about the Porsche ceramics.

Jack

You're welcome- it's a lot of effort putting those posts together and it's nice when it's appreciated

[daddysgirl]

It's VERY appreciated...said she who didn't realize her question would hijack your other post.
I'm sorry. And Thank You 

[Iceni John]

I haven't worked out a relationship of what radiators reject what yet. I have a simulation package that may have that info.

If/when you can present that info here (in a form understandable to rank amateurs like me!) I would be most interested to read it.   With your knowledge of the more theoretical aspects, and others here who have many decades of wisdom from hands-on bus wrenching and real-world use, this forum is an invaluable resource.

Thanks, John

PS  -  I had the pleasure of visiting your namesake when it visited Rotterdam in the 1960s, and even at my tender young age I was impressed with how relatively spacious it was inside compared to the usual diesel-electric subs.   I also visited the Savannah when it was in port there  -  two nuclear vessels visited before I was twelve years old!

[Dreadnought]

If/when you can present that info here (in a form understandable to rank amateurs like me!) I would be most interested to read it.   With your knowledge of the more theoretical aspects, and others here who have many decades of wisdom from hands-on bus wrenching and real-world use, this forum is an invaluable resource.

Thanks, John

PS  -  I had the pleasure of visiting your namesake when it visited Rotterdam in the 1960s, and even at my tender young age I was impressed with how relatively spacious it was inside compared to the usual diesel-electric subs.   I also visited the Savannah when it was in port there  -  two nuclear vessels visited before I was twelve years old!

Ive never seen the nuclear sub (S101) hms dreadnought but I'll bet it was something to behold!

[buswarrior]

Thank you.

Science and solid engineering experience were foundational in both bus boards in the past.

It needs to be here in the present and the future.

Droolers belong on social media, we need smart peeps on the Boards!!

There used to be a guy.... exactly this stuff was in his head, used to get on the chat over at BNO from Japan... he had been "loaned" to one of the big boys over there... our evening was his mid day break...

If only I paid more attention and wrote some of it down...

happy coaching!
buswarrior

[TomC]

Simple-the 8V-92TA is the hardest engine to cool. As shown here, the coolant heat rejection is also an indication of engine efficiency. The new DD engines are so efficient, Freightliner went with aluminum 2 row radiators and was able to reduce the size of the radiator.
I have a 1200 sq/in radiator 6 row with constant run 8 blade fan on my turbo'd 8V-71 and still need misters on over 90 degree days on a long pull. Good Luck, TomC

[gg04]

Bob Sheaves,  Got loaned to GM to make the Isuzu diesel into the Duramax for the American market..he did the development on the 50 and 60series..talked me out of using a series 50.rdw

[buswarrior]

YES!!!

Where is Bob these days?

Most of us still owe him many adult beverages from those very interesting chatroom days.

happy coaching!
buswarrior

Bob Sheaves,  Got loaned to GM to make the Isuzu diesel into the Duramax for the American market..he did the development on the 50 and 60series..talked me out of using a series 50.rdw