6V92TA DDEC Overheating

Topic: 6V92TA DDEC Overheating (Read 2831 times) previous topic - next topic

Re: 6V92TA DDEC Overheating

Reply #25 – October 26, 2013, 11:36:47 pm

Quote from: Dave M – October 26, 2013, 09:51:22 pm

For sure, If you have a Jake Brake setup, it does not matter if you have the best muffler or a straight pipe, the use of the exhaust brake is forbidden,

Guess I was talking from a practical standpoint, believe Kent said you couldn't hear his J. Brake due to muffler. Don't think this would be the case with straight pipe.

Re: 6V92TA DDEC Overheating

Reply #26 – October 27, 2013, 12:23:08 pm

Hahahaha! Dave is my hero!

I only bought a Foretravel because I've always wanted a two cycle Detroit Diesel. It's the ultimate engine. I've never liked any diesel engine except the two cycle Detroit. I love the sound and the power. It's so drastically different than today's Cummins powered coaches. I like to stand out from the crowd. Have you noticed today's Cummins coaches have that cheap sounding little high speed gear reduction starter on them but the Detroit has cool sounding full size starter motor... and then when it fires up everyone looks over at me and sometimes they ask if I've got it on high idle or something. A guy asked me if I had a 12 or 16 cylinder engine the other day. It's kinda like when I start up my 1965 Chevrolet with the big direct drive starter motor and straight through exhaust and everyone turns around to see what car made that cool sound.

Re: 6V92TA DDEC Overheating

Reply #27 – October 27, 2013, 01:03:45 pm

Here's a couple of videos for all the 2cycle detroit lovers out here especially for Pierce and any any other firemen on the forum. It's music to my ears! Enyoy!

Jerry aka Murph

WLHVFD 1988 Seagrave Engine 482 Takeoff 6v92 - YouRepeat WLHVFD Engines 484 and 482 (6v92) Departing - YouRepeat

Re: 6V92TA DDEC Overheating

Reply #28 – October 27, 2013, 01:04:39 pm

Quote from: Dave M – October 26, 2013, 08:48:11 pm

Also would get rid of that muffler, go with the resonator, free up the engine, never ran a 6V-92, but the 8V-92 at 600+ hp loved the resonator. Running with a straight pipe is way too harsh, just adding the resonator cuts the harshness way back to a useable non complaining level. As mentioned the reduced heat, both engine compartment and engine exhaust temp.
It is a win win.

Dave, Back when resonators were first being discussed on the Forum, the subject of a resonator on a 6V92 came up and I remember that the advice was that it would be way too loud. I understand for you that's probably not true. What's your estimate of what the "average" person would think?

Re: 6V92TA DDEC Overheating

Reply #29 – October 27, 2013, 03:24:19 pm

Since we're way off topic I'd like to take this opportunity to point out that my 6V92TA DDEC doesn't experience any overheating, even climbing steep Rocky Mountain grades at high altitude. My radiator is less than a year old though, and I presume the average coach this age has a much older radiator. I didn't experience any overheating with the 23 year old radiator even climbing steep grades in the Appalachian Mountains. I always watch the temperature gauge as I climb steep grades... Now that we're back on topic briefly, has anyone else noticed that the turbocharger on the 6V92TA really screams at high altitude? I presume the thinner air at high altitude allows the turbine to hit a much higher rpm than it does in denser air at sea level. Normally I can't even hear the turbocharger at sea level. Also I noticed I get a little puff of black smoke out the tailpipe for a moment when I take off from a standing stop at high altitude. After a second or two the turbocharger spins up to speed and there's no more smoke. I normally never see any black smoke at sea level, even when I mash the accelerator from a standing stop. I don't notice any power loss from sea level to 10,000' elevation. I'm at 7,000' currently in Santa Fe NM. I love the multistage turbo/supercharged engine, though I admit I never considered high altitude use when I bought the coach. It's just one more cool thing I discovered after I bought it. My previous experience with a diesel engine on high altitude climbs was 25 mph in the slow lane at 10,000' but my 6V92TA is way more advanced than that other diesel, which was a Ford... still can't believe I drove a Ford, hopefully nobody saw me... it definitely WASN'T mine!

Re: 6V92TA DDEC Overheating

Reply #30 – October 27, 2013, 10:58:17 pm

Dave,

Have the pump below the alternator on the passenger's side. Probably about the same spot as yours. Was your stock muffler a five incher on your larger Detroit? Wonder if the 5 inch muffler works on ours but would be restrictive on the 25% bigger displacement engine you had?

Jerry,

I can tell right away that is not a 350hp engine. It left the stop sign like a rocket. Would think it was turned up to 450hp or more. Our 8V-71s had 285hp, no turbo and a 4 speed plus CL manual trans. The automatic keeps the boost up when it shifts. Impressed with that fire truck. Probably has about 5000 lbs of water on board too.

Scott,

Your 300hp engine does not have the same cooling requirement as the 350hp engine. Ours does not overheat but on long grades with high outside temps in summer, I have to back off and gear down to keep it no higher than 200 degrees. Santa Fe is 7000 feet or higher depending where you are in town and without a wastegate turbo system, the horsepower and cooling requirement are about 75 percent of what they are at sea level. Yes, they do leave a little black smoke taking off at altitude but nothing like a mechanical diesel. With a waste gate, you can keep full horsepower to over 7000 feet. The point where the boost starts to drop is called the "critical altitude" and the power starts to drop off above this altitude. But we don't have a waste gate on ours so we start to lose HP as soon as we leave sea level. Assuming you are at 7500 feet with your 300hp Detroit in Santa Fe, your radiator only has to cool 225 horsepower. Plus, the temperature lapse rate will drop the temperature 3.5 degrees for every thousand feet above sea level so the ambient won't be a as much of a challenge as is would in Las Vegas. I never had to have AC on any home in Santa Fe but Albuquerque is a different story.

Geared starters save weight, never a bad thing, especially when you have to R&R one.

Would like to hear from anyone who has had their DDEC reprogrammed for more HP.

Pierce

Re: 6V92TA DDEC Overheating

Reply #31 – October 27, 2013, 11:43:37 pm

When I first bought our coach in 2001, I took it into DD for service plus a dyno test (it's a rear radiator 300 hp 6V92). Without me even asking the tech told me not to think about increasing the HP as it wouldn't be allowed by DD. He told me the change goes through DD's computer system which would dis-allow it. I have no idea if he was telling me a line or not. He did tell me the way to drive it is to floor the pedal and let the DDEC and ATEC decide on shifting.
I didn't know then but know now that the rear radiator has all it can handle. And because the 350hp 6V92's of subsequent years needed to have the 700 series transmissions it make me think my 648 might be at it's limit too. I concluded if I want more HP, I need to buy another coach.

I did have an overheating problem with my coach but I seems to be unique to my coach and have never figured out why. Over the years I've talked with a lot of U300 owners (with rear radiator 300 HP engines) and none ever seem to have problems I've had. I've replaced the radiator, water pump, and thermostats- all to no avail. I verified the fan speed, pulled the blower to inspect the intercooler for blockage and even added a turbo and exhaust blanket. After years of using a misting system on the radiator, I added a second radiator on the drivers side using electric fans (75 amps total). In the most severe conditions the temp will still get up to 210 -which is right at the max operating limit (as defined by DD). Others have mention the driver as a cause, but with the DDEC, there's no such thing as over fueling it and the ATEC won't let you lug it. On 6%+ grades, its running at about 2100 rpm at about 37 mph (in I think 3rd gear?, maybe 2nd?) but the mister is no longer required. I removed the battery isolator and have the fans on the house battery. When I need full power (up a grade) I make sure the boost switch is off. I figure I'll remove alternator HP burden going up hill and then turn the boost switch on when HP isn't needed on the downhill.

Re: 6V92TA DDEC Overheating

Reply #32 – October 28, 2013, 12:36:57 am

They should be able to reprogram the DDEC II but you would need 5234775 injectors ($200 plus each) plus a different turbo housing with an A/R (area to radius) ratio of 1.23 (from 1.08). At least $1500 in parts. Or could buy the eBay 6V-92TA 400hp Seagraves fire truck engine ($1500) with anti-freeze in the oil and use the parts or fix it.

But then it would overheat with the rear radiator.

Pierce

Re: 6V92TA DDEC Overheating

Reply #33 – October 28, 2013, 12:55:05 am

John, do you have a 600 series transmission that locks up? Lock up drops the trans temp a lot and with the trans/engine heat exchanger, it takes a fairly decent thermal load off the engine too. Lock up is like having 50-75hp more.

I can really see it in city driving with a lot of first and second gear work. Trans temp goes up in a hurry when I'm out of lock up.

I have turned on the front dash heater to cool it on occasion.

Pierce

Re: 6V92TA DDEC Overheating

Reply #34 – October 28, 2013, 01:17:18 am

John,

Read your post again. 2100 rpm and 37 mph is in second gear lockup in ours. Has shifted twice so it seems like third but is second gear. Third is good to 57 mph and fourth to 82 mph.

Low tire pressure will cause the engine to work harder, run hotter.

Pierce

Re: 6V92TA DDEC Overheating

Reply #35 – October 28, 2013, 08:28:13 am

Quote from: Pierce & Gaylie Stewart – October 28, 2013, 12:55:05 am

John, do you have a 600 series transmission that locks up? Lock up drops the trans temp a lot and with the trans/engine heat exchanger, it takes a fairly decent thermal load off the engine too. Lock up is like having 50-75hp more.

I can really see it in city driving with a lot of first and second gear work. Trans temp goes up in a hurry when I'm out of lock up.

I have turned on the front dash heater to cool it on occasion.

Pierce

Yes, it has the lockup (3rd and 4th). I did put in a large (24" x 23") oil to air cooler for the transmission but it didn't do too much. Put it in just before the stock heat exchanger to give the engine the coolest transmission oil. Later, when I installed the 2nd radiator, I had to removed it because I just couldn't fit both in the same space.

I used to run the dash heater too before I installed the misting system - but I could never really tell the difference with it on - there's just so much heat to reject. That was also when I was only using the OEM temp gauge. I replaced it with a digital which was better, but I now have a VMS unit and it's a good 8 degrees cooler than digital dash gauge. So my problem was never as bad as I originally thought but numbers I posted above (210) are with the VMS. For my vintage engine there is no shutdown for engine overtemp, but there is a fault code list for overtemp which I have never had trigger on my engine.

Re: 6V92TA DDEC Overheating

Reply #36 – October 28, 2013, 08:30:15 am

Quote from: Pierce & Gaylie Stewart – October 28, 2013, 01:17:18 am

John,

Read your post again. 2100 rpm and 37 mph is in second gear lockup in ours. Has shifted twice so it seems like third but is second gear. Third is good to 57 mph and fourth to 82 mph.

Low tire pressure will cause the engine to work harder, run hotter.

Pierce

I do pressure checks on tires before each day's run - I run at least 10 psi over placard - 90-100psi (placard is 80 psi).

Re: 6V92TA DDEC Overheating

Reply #37 – October 28, 2013, 10:20:22 am

Dave,

I remember in the old days, ALL Mexican buses were Detroits, either with a GM sidewinder setup or fore and aft like Dina, Solex. The latter always just had the two exhausts go straight down (looked like 4") and then made a 90 out the back on each side w/o muffler. They did sound a bit like they had a "cam" at idle but above that, it was like a NASCAR green flag start. U.S. buses were almost all Detroits but had mufflers.

And speaking of exhaust, has anyone noticed the difference between European truck exhausts and those in the U.S.? They run all truck pipes down toward the ground. Must figure the particulates will settle faster but you have to roll up the windows and put the air on recirculate to avoid breathing it.

John,

My knowledge is microscopic compared to Fire Department, bus company mechanics. They could easily have a tip that might solve your problem and are usually really friendly. One other thing, have you ever checked for products of combustion in the cooling system? I bought a 3.4 Jag sedan with a new 327 chevy in it. The owner could never keep it cool and had replaced the radiator and tried several other fixes after the engine conversion but to no avail. The day I bought it, I tried torquing the heads and found they were well below specs. After tightening them, I never had a problem and it ran cool as a cucumber.

Pierce

Re: 6V92TA DDEC Overheating

Reply #38 – October 28, 2013, 08:36:58 pm

I have been considering programming up my 6V92TA. It seems to me that if I go from the stock 300 HP to 400 HP, it's not like the trans and radiator will see this power all of the time, just when I lay into it, say to accelerate to merge on a freeway.

Going down the freeway with the cruise on at 70, I don't see that the engine will be putting out any more HP than it does now to maintain that same speed. The heat generated should be the same.

So, I don't see the harm in doing this. For sure, I will want to watch temps on a long grade, and if necessary, downshift and work the engine a little less till I top the hill.

Re: 6V92TA DDEC Overheating

Reply #39 – October 28, 2013, 09:11:24 pm

Peter,

You probably saw the Seagraves fire department video. What a rocket! It probably had an engine like the one for sale on ebay. Would be a good deal even if you just used the turbo housing and injectors. Detroit 6V92TA Ddec 400 Horsepower Engine Motor | eBay Not sure if just programming the DDEC would do it.

The 517hp ladder truck engine would be even better but would probably break the trans.

Would find someone really savvy on Detroit 2 cycles before I went too far. Sure would be nice to send some coolant up front. Perhaps down the left center and through the back of the generator compartment. If you moved the AC condenser, you could stick a wide but short aluminum radiator from the left to right grill with a couple of fans and then do the same below with the removable plates out of the way. Would have to get rid of the two hitch receivers. Mounts would be pretty easy and no body work to do or grills to install.

Probably could take some $$ home from unbelieving Monaco owners. They sure are fun.

Will follow your progress.

Pierce

Re: 6V92TA DDEC Overheating

Reply #40 – October 28, 2013, 11:25:07 pm

My 300 horsepower rear radiator 6V92TA totally outran a new bus with a big Cummins and a tag axle without a toad today on the steep grade climbing up from Espanola to Santa Fe. The big bus was right behind me and floored it to get a run for the hill but he didn't even make it up beside me before he started losing ground and fell back about 1/8 mile by the time I cleared the top of the grade, then he flew past me on the other side of the hill course. I had my cruise control set at 60 mph just like always and didn't get any run for the hill, just let the DDEC do its thing like usual... Someone please explain to me why I need more power?

...I'm not averse to paying Stewart & Stevenson $50 to turn up the power but I've driven my coach all over the country and never needed it. I honestly can't see any power loss, even at 10,000 feet.

Re: 6V92TA DDEC Overheating

Reply #41 – October 29, 2013, 06:17:11 am

Scott:

Great story. On our last trip we were climbing up the hill coming out of Duluth going back to Minneapolis. My son down-shifted into third, and spun up the turbo to 2000 RPM just as we hit the bottom and put the pedal to the metal. We lost about 100 RPM on the hill, and held 1900, topping the hill at about 50. The Detroit sang it's song all the way. Cars passing on the left gave us a good look going by.

On your question, who needs more power...(you're missing the point)...

My wife asked the same thing... It's the fun and excitement of modifying something to go faster!

Re: 6V92TA DDEC Overheating

Reply #42 – October 29, 2013, 10:08:38 pm

The new coaches get heavier and heavier every year. I'm told the new coaches are now up to 50,000-60,000 pounds, or in other words, more than twice the weight of my coach fully loaded, which it never is of course. I've never had any coach pass me climbing up a steep grade, and I've driven it all over the country in the year and a half since I've owned it. The 6V92TA is a real strong performer, which is why I bought it... that and the fact that it's the ultimate diesel engine.

Re: 6V92TA DDEC Overheating

Reply #43 – October 30, 2013, 02:50:59 pm

Quote from: rpettway – October 24, 2013, 05:14:51 pm

Dave, do you or anyone else know of anyone on here that has modified their 6V92 to say 400hp? Could the Allison HT 746 ATEC transmission handle that much hp?

Dave, I would not do anything to that 6V92 Detroit, that Detroit diesel does not recommend. The 6V92 is a dinosaur in today's standards, it is a 2 cycle diesel, by pumping too much fuel you are definitely going to run into overheating problems at low rpm's. Anytime you have a mechanical diesel and you're going to put more fuel to it make sure you have a pyrometer installed on the hot side of your exhaust. Any of 71 series 92 series Detroit's are noted for burning fire rings due to internal combustion chamber high temperatures. They are great reliable engine as they are. But do yourself a favor do not let any shade tree mechanic get into that governor and pump system or put oversize injectors into it. Because all you're looking for is throwing $10,000 out the window. Your new or engines of today you can squeeze a lot more horsepower out of them, at the ECUs have failsafes programmed into them to eliminate the chance of over fueling that causes overheating problems, they also are equipped with air to air cool air going into the engine, which keeps your internal engine temperatures down.

Re: 6V92TA DDEC Overheating

Reply #44 – October 30, 2013, 09:41:17 pm

These are DDEC engines, which are electronically controlled. You have to take it to a Detroit Diesel service center such as Stewart & Stevenson and have them plug their hand held computer into the DDEC computer to raise the horsepower. There's no need to change injectors or turbocharger or anything, just pay the man the money. The only issues would be the condition and capacity of your radiator and the maximum amount of power your transmission can handle. Ask Stewart & Stevenson's Allison transmission shop before you have their Detroit Diesel shop turn up your horsepower. You'd be okay to turn a 300 up to 350 but you probably wouldn't notice much if any difference in performance. Fire engines were usually 450 horsepower, so that would probably be a reasonable horsepower to aim for, but you should already be able to outclimb any coach on steep grades if you're lightly loaded, so what's the point? The new coaches weigh twice as much as yours and get heavier every year and they've probably hit the wall at 600 horsepower now. They'd probably need over 700 horsepower to pass you climbing a steep grade... just saying

Re: 6V92TA DDEC Overheating

Reply #45 – October 31, 2013, 10:12:25 am

Quote from: RATC1956 – October 30, 2013, 02:50:59 pm

Dave, I would not do anything to that 6V92 Detroit, that Detroit diesel does not recommend. The 6V92 is a dinosaur in today's standards, it is a 2 cycle diesel, by pumping too much fuel you are definitely going to run into overheating problems at low rpm's. Anytime you have a mechanical diesel and you're going to put more fuel to it make sure you have a pyrometer installed on the hot side of your exhaust. Any of 71 series 92 series Detroit's are noted for burning fire rings due to internal combustion chamber high temperatures. They are great reliable engine as they are. But do yourself a favor do not let any shade tree mechanic get into that governor and pump system or put oversize injectors into it. Because all you're looking for is throwing $10,000 out the window. Your new or engines of today you can squeeze a lot more horsepower out of them, at the ECUs have failsafes programmed into them to eliminate the chance of over fueling that causes overheating problems, they also are equipped with air to air cool air going into the engine, which keeps your internal engine temperatures down.

In order to require a pyrometer on a 2-cycle Detroit, you would be talking about a boat installation with an additional couple of hundred horsepower or more on a 6V-92TA. I know that some 5.9 Cummins PU owners with chipped engines see 1250 degrees on hills. We stopped adding fuel at 1100 degrees on 4 cycle diesels to stay on the safe side in the old days. Plus, they smoked a lot with too much fuel.

2 cycle diesels use a huge amount of air and it would be very unusual to see an EGT reading of above 900 degrees. They have both the big supercharger as well as a turbo plus 4 exhaust valves so the air really whistles through them. With the low exhaust temperature, they produce a different set of compounds and is probably the reason for the "Greyhound Bus Station" smell we all got used to in the 50's. The high volume of air is another reason to check the "tell tale" air cleaner restriction gauge frequently. I replaced ours with visible lines for the amount of restriction. That way, I can plan for an air cleaner change rather than waiting for the indicator to suddenly change to red.

Like Dave said, too far advanced injector timing has been the cause of piston/ring failures in the mechanical days. We had a Jaguar customer that did most of his own maintenance but ran too much advance and put holes in the pistons.

Pierce

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