Detroit Diesel 2 stroke- 92 series vs 71 series

[Iceni John]

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

The present 3/4" feed from the engine for the heaters goes to a coolant booster pump, then to some 3/4" hard pipes that go to the front and all the way back to the radiator's lower return pipe into the water pump inlet.   My idea is to have valves to select coolant flow to either the heater loop or to the additional radiator, but not to both at the same time.   I'm hoping the present 1"-to-3/4" coolant supply has enough flow force to avoid needing a booster pump for the additional radiator, especially if I use a larger 1.25" return back to the water pump;  the pump is sucking the return as much as pushing its outflow.   I definitely don't want to introduce any cavitation with this extra circuit.

Has anyone here done anything similar to this?   I want just a small amount of extra cooling for those rare occasions when the temperature gauge keeps creeping up, but I really don't want to use misters.

John

[lvmci]

John, I'm thinking about making the driver side engine bay door into a grill, like eagles and the MCI six and 7 combo and go directly from the outlet and inlet pipe on the driver side of the engine adding continuous Cooling because of living in the desert, Tom...

[Brassman]

I'd think that if you have done everything to get your coolant temp down but still have problem that maybe you have a combustion gas leakage into your coolant. That can cause some strange effects, like loss of coolant pressure and high temps.

[daddysgirl]

Reading all of this had led me to another question (I'm sorry. I wish I wasn't as inquisitive)
You all are describing some different ways to cool the coolant, and I personally think there are various thoughtful ways to accomplish this.

So this question is on the other end of the temp spectrum...

I'm a fan of exhaust wrap because it works. BUT...Because the entire issue is reducing overall heat, what could be done to better channel/address the exhaust?

I've seen buses with the rear doors louvered, different ways of adding extra ambient air to the engine compartment. My issue with this is that if it is not done correctly, (on the ease coast at least) you end up with a wet engine compartment and that leads to rust/corrosion. Or if the outside temp is too high are you really helping the situation?
On a coach, the engine compartment contains more than just the engine, and electrical components don't like water. So... what about helping cool everything by addressing the other side...the exhaust?

[lostagain]

The freer the exhaust flow, the more heat goes out the pipe. The less exhaust restriction, the better. Since I replaced my muffler with a resonator, I think I run cooler. Wrapping also helps getting the exhaust out faster, because the hotter it is, the more it expands, therefore the faster it goes out.

Outside air, drawn through the rads, is cooler than what is inside the engine compartment, even on a hot day.

Regarding the electrical components getting corroded, they already are getting most air on a rainy day, or worst in the winter, so a little more by increasing the flow wouldn't make a big difference. Replacing rusty switches and the like is a normal maintenance thing anyway.

JC

[lvmci]

I think we're way off Dreadnaughts thread. All the DD gurus have always written about pushing a 2 stroke and the heat that creates. My engine can idle for some time and not heatup, so I  dont think the more complex issues are my heat problem with mountain driving. Every direction from LV is mountains to go over and those mountains that dont amount to a hill of beans in the winter, but in summer I keep my eyes glued to the temperature gauage as the bus climbs and so does the gauge. Im going to recore or rod out, the two big size radiators on my 8V92T 102C3. Ive added sprayers and listend to Clifford, Gary and the rest of the knowledgeable bunch on driving technique, all their suggestions have led to my successful driving over the mountains. But I  want to increase the horespower, as it is at the minimum horsepower rating right now. Observing the different solutions is not only interesting, but will lead to more fun while driving my big bus. You guys are great and once again, thanks for your kindness in advising all of us new to diesel, tom, lvmci...

[lvmci]

My observations about coastal bus lines is the tremendous suction on the two radiator systems on MCIs, is that's where to look for corrosion, rust when looking for problems when searching for a new bus. So I dont think protection from outside salt air is posible on those models. lvmc...

[Geoff]

The present 3/4" feed from the engine for the heaters goes to a coolant booster pump, then to some 3/4" hard pipes that go to the front and all the way back to the radiator's lower return pipe into the water pump inlet.   My idea is to have valves to select coolant flow to either the heater loop or to the additional radiator, but not to both at the same time.   I'm hoping the present 1"-to-3/4" coolant supply has enough flow force to avoid needing a booster pump for the additional radiator, especially if I use a larger 1.25" return back to the water pump;  the pump is sucking the return as much as pushing its outflow.   I definitely don't want to introduce any cavitation with this extra circuit.

Has anyone here done anything similar to this?   I want just a small amount of extra cooling for those rare occasions when the temperature gauge keeps creeping up, but I really don't want to use misters.

John

I added an extra radiator using the 1" heater hose that used to supply the passenger heating system.  The coolant pump moves the coolant through a heater core that measures 1' by 3' and uses 3 electric 12v fans with a 190 degree switch. The RTS has a screen in the roof so that is where the extra radiator is mounted.  With this system I was able to quit running the water sprayers on the main radiator.  350HP 6V92TA.

--Geoff

[Iceni John]

Geoff, good to hear that my idea's not so whacko after all!   The Ford radiator is between 3 and 4 sq.ft core size and has 3 rows, and I want to fit as many fans as space allows, ideally two 16" or maybe four smaller ones on a shroud.   I would let the coolant flow through it all the time, but have the fans switch on at 195 degrees.   It sounds like we're on the same track here.   If it drops temps by just a few degrees, I'll be happy.

I think I already have a low-restriction Donaldson muffler (it's loud!), and I'm also thinking about wrapping all the exhaust pipes to keep the heat inside them.   I don't think I have an exhaust leak into the coolant, but I'll check it anyway.   Keeping these old 2-strokes cool is never easy.   Sometimes I'm tempted to put in a Series 50, but those engines leave me cold (so to speak).

Thanks, John

[Geoff]

I should mention that the heater core I used was designed to run high up so it has a small air bleed hose with a check valve going down to the main radiator.  Without the bleed hose you would probably get an air lock.

--Geoff

[luvrbus]

Here is some food for thought,the water pump on a Detroit is 67 GPM @2100 rpm and takes very little wear on the impeller to diminish that flow.It marine use the raw water pump is 107 GPM over the the exchanger on a 6v92 with 70 dgree water   

[Oonrahnjay]

Here is some food for thought,the water pump on a Detroit is 67 GPM @2100 rpm and takes very little wear on the impeller to diminish that flow.It marine use the raw water pump is 107 GPM over the the exchanger on a 6v92 with 70 dgree water 

      Is there a different design water pump with an alternative part number that could be fitted to a DD 2stroke in a bus?  If so, would a larger (50%+) flow be a benefit to someone who is having overheat problems?

[lostagain]

I thought I heard that if the coolant flows too fast through the rad, it doesn't have time to cool. So maybe a faster pump is not the answer?

JC

[Lee Bradley]

My 8v92 has a one inch line off each bank and two returns in the lower radiator line. No reason to switch between the radiator and heater if you want to run off both sides of the engine. 

[kyle4501]

I thought I heard that if the coolant flows too fast through the rad, it doesn't have time to cool. So maybe a faster pump is not the answer?

JC

Too fast thru the radiator doesn't make sense to me - isn't it is going the same speed thru the engine?

What makes more sense to me is lower pressure at the pump inlet causing tiny 'air' bubbles to form in the coolant - that reduces the coolants ability to transfer heat. . . . . It takes a lot longer for that 'air' to go away than it did to form.
Changing a properly designed system seems to always present unexpected opportunities. 


BTW, I have a technical paper on my coach that states the cooling system was designed for the coolant temperature to stabilize at 125F above ambient at full power. Would be great if they all came with that information.