I was reading a thread where some of the older Birds have a Red Series 92 engines in them. The horsepower and torque was less than the Silvers. On a diesel forum I read about green engines being a problem and then everyone skips to the Silver discussion. There is very little mentioned about the Red block. The silvers apparently have beefed up blocks, water pumps and head bolts etc. Are the Red blocks an engine to be wary of? Or were they ok and the shy sister to the mighty Silver?
The was a fuel miser somewhere in this time frame too. Late seventies to early eighties I believe. Looking forward to some of the responses on this. Seriously though what are the differences? Gary Our 82 has the Red motor it has 220,000 miles on it.
Detroit Diesel 8v-71 engine specs, bolt tightening torques, workshop manual, parts book and spec sheets for the 8v-71 Detroit Diesel engine. Skip to main content. Detroit Diesel 8v-71 manuals and specifications Diesel Engine manuals and specifications at Barrington Diesel Club.
Our 84 has the Silver motor it had 160,000 when it diedoverheated by PO. I can not see any visual differences other than color,water pumps have the same #'s cast into them I guess it could have been changed at some point. Both engines have the superchargers and turbos and internal intercoolers neither have the charge air coolers. For sure the Red motor in the 82 is a runner when we got to Sturgis pulling a 8,500 trailer it never complains about running along at 2300 rpm all day and night only stopping for food and driver changes. It's 1500 miles for us and we have made this run 2 times virtually non stop.
From my GM RTS days I remember the Green 6v92 became the Silver 92 around 1982. The talk then was a redesigned block that was beefier and had better water jackets for cooling. I beleive it is also when the DDEC was added too.;) 6V92 DD Silver engines began with the serial number F83425 any number after that is a Silver engine.
8V92 DD Silver engines began with the serial number F73594 any number after that is a Silver engine. Funny thing is I don't remember anything about a 'Red' version? When did DDEC start? Thankfully my 1985 Silver 6V92 is mechanical injection:rolleyes. When did DDEC start? Thankfully my 1985 Silver 6V92 is mechanical injection:rolleyes: Right fully so Ryan.
According to Detroit they produced DDECs since 1985 but that is not true. Detroit Diesel Electronic Control (DDEC®) Since 1985 Detroit Diesel has produced over 750,000 electronically controlled engines. DDEC V, the successor to DDEC 1,2,3 and 4, arrived as the most powerful electronic control system available on any heavy-duty vehicle engine.
The increased capability of DDEC V allows Detroit Diesel to offer vehicle owners a logical, simple and complete system of products and programs to assist with every phase of vehicle ownership. The combination of DDEC V and the new system of products and programs is known as the DDEC System. I had a DDEC II 6v92 in my 1982 GM RTS bus. Due to government regulations they derated it to 188hp, I'm thinking for polution control. IN fact sind the mid 80's the 2-stoke diesel is 'illegal' in Maricopy Country (All Phx area) due to its polution. I tried to register mine before the conversion and was told I could not AND I'd have to change out the engine to register it at all.:mad: Once it is converted then you can register it as an RV and get a waiver. It also had other undesirealbe programmed feature too, like 2-3 second delays on throttle responses.:mad: You know.
Don't want to jolt those passengers with any fast excelleration. Now the manual version back then you could easily get 350hp from the same setup. So wish I had bought one year earlier model.:mad: Here's the history I have on the DDEC; DDEC I Initially the engine was controlled by the DDEC I System, which was shortly after replaced by the DDEC II system which would last up to 1992. DDEC II Engine was available in ratings up to 425 hp (317 kW) and 1,450 foot-pounds force (1,970 Nm) of torque.
The engine proved extremely popular with fleet operators, and built a strong reputation for reliability and longevity. It was also available in a popular 'cruise power' configuration, which encouraged the operator to engage the cruise control function. During the normal use of the engine, 405 hp (302 kW) would be available, and when the cruise control was engaged the horsepower rating would increase to 425 hp (317 kW), as the engine was the most economical whilst the cruise control was engaged. DDEC III In 1992 the DDEC III system was introduced and was available in horsepower ratings up to 470 hp (350 kW), and this was due to revised camshaft timing, and other improvements.
Again, a 'cruise power' option was available, and the standard rating was 430 hp (320 kW), and when the cruise control was engaged the horsepower rating was increased to 470 hp. Again, encouraging operators to take advantage of reduced fuel consumption. DDEC IV 1997 Brought the introduction of the DDEC IV engine, and further improvements in the design of the engine, notably a wastegate turbocharger and engine management improvements provided increased horsepower ratings up to 500 hp (370 kW), and increased torque outputs to 1,650 foot-pounds force (2,240 Nm).
Thanks everyone for their replies. Especially Ed for taking some time away from the John's hoses and of course supervising the various naps. With no fan I might add. This seems to be one of those seldom talked about things. I have seen the red block referred to as IHC (has to be erroneous) which really bewildered me because to me that means International Harvester and as we all know that is not the case.
There are Red blocks out there for sure in stuff other than BB according to some posts I see on Diesel Forums. Randy the 'fuel pincher' was the 8.2 L and I agree.not DD's best effort. You find them in alot of Barths. The Fuel Squeezer I am referring to is a 6V92 and I know the red block was derated for some sort of reason. That is why I wondered if it was a fuel squeezer or if it was just not built as heavily. I have attached a DD Brochure so you can see what I am speaking about for the fuel squeezer.
Of course the engine in the brochure is Silver. Interesting to see what happens by changing the injectors. And as we know the life span. Oh one more thing look at the 100000 mile oil change interval on the brochure! Maybe Woody will have seen some of the Red blocks in and out of the Military over the years.
The 6v92 came out with a red block because the old Detroits had a reputation of leaking oil. There was an industry joke that stated: If you paint an oak tree Detroit green, it will start dripping oil'.' The original 6v92 had some oil leakage problems and the block was changed with s/n 6vf64412 in May 1980. The heads were changed with s/n 6vf72972 in October 1980. Bluebird had some red engines installed after these serial numbers but they were the new 'silver engines' regardless of color.
This information was given to me by a Detroit engineer after inquiry as I had a 1982 PT40 with a red engine and he assured me that it was the newer version even though it was red. There is no visual identifiers other than the serial number that I am aware of. I've heard and read several times about 'running 'em hard'. I usually cruise at about 1700 RPM. This gives me about 62 MPH. On hills, especially pulling my trailer, she run a steady 1800 to 2000 for the length of the hill.
I hate high RPM's. Plus if we cruise over about 1700, the fuel mileage drops. So what do they mean when they say run em hard.
During normal driving, I'll always run her out to about 2000 RPM with each shift. Is that sufficient. Any more than that and I feel like I'm over revving and beating on it. Changing my oil every 6000 miles and and not running her to death just feels better to me. I've heard and read several times about 'running 'em hard'. I usually cruise at about 1700 RPM. This gives me about 62 MPH.
On hills, especially pulling my trailer, she run a steady 1800 to 2000 for the length of the hill. I hate high RPM's. Plus if we cruise over about 1700, the fuel mileage drops. So what do they mean when they say run em hard. During normal driving, I'll always run her out to about 2000 RPM with each shift. Is that sufficient.
Any more than that and I feel like I'm over revving and beating on it. Changing my oil every 6000 miles and and not running her to death just feels better to me. Don, I am no expert but I have been lead to believe that 'keeping your foot in it' hence, mashed to the floor is where 2 stroke Detroits like to run. I think that is why they put air throttles on 'em, all or nothing:p Our 6V92 likes to be run hard and not babied at least during acceleration plus, we love to heard the roar of the flow through muffler:) Keep the proper oil in it and changed properly and let her rip;). I've heard and read several times about 'running 'em hard'. I usually cruise at about 1700 RPM. This gives me about 62 MPH.
On hills, especially pulling my trailer, she run a steady 1800 to 2000 for the length of the hill. I hate high RPM's.
Plus if we cruise over about 1700, the fuel mileage drops. So what do they mean when they say run em hard.
During normal driving, I'll always run her out to about 2000 RPM with each shift. Is that sufficient. Any more than that and I feel like I'm over revving and beating on it. Changing my oil every 6000 miles and and not running her to death just feels better to me. I'd like to know too Don. 'Run 'em hard' and 'keep your foot in it' doesn't really say a lot. Are we saying don't lug the engine, or are we saying keep the revs up for cooling, or is there more to it?
We all know what lugging an engine is and we know that no engine likes to be lugged. No two-stroke dirt bike I've ever owned liked to be lugged. No 4 stroke air cooled Porsche I ever owned liked to be lugged. (2-stroke bikes load up, and 4-stroke Porsches like the cooling). So neither 2 strokes nor 4 strokes like to be lugged, but it seems that 2 stroke diesels are more susceptible to serious damage from lugging.
Can anyone tell us why this is so? Is it heat or is it oil pressure or is it both or something else entirely? In any case I'll put forth the following definition of lugging an engine, or on second thought, it might be easier to define when you're not lugging the engine. How's this: You're not lugging an engine when fuel delivery is matched to the engine's hp at a particular load and rpm.
This means that lugging requires over fueling for a particular load and rpm. This also means that you can lug an engine at any rpm short of bouncing it off the governor, in which case the governor backs off fuel delivery. I'd also say that it's impossible to lug a modern electronic engine such as the one in my '02 (DDEC IV), even if I load completely down to 1300 rpm's, WOT. All that's required is that the DDEC not over fuel it.
One of the issues with operating any shaft with plain bearings at a low rpm is a lack of hydrodynamic oil pressure. The oil pump only supplies fresh oil to the bearings, it is the rotation of the shaft that provides the pressure to keep the shaft and bearing from rubbing. The hydrodymanic pressure increases with shaft speed - too low a speed and the pressure will not be adequate to keep the two from rubbing (very bad!!!). Experienced it first hand in my first job - green engineer at a power plant start-up. We had large fans that fed combustion air the the boiler.
The amount of air was controlled by fluid couplings that varied the speed of the fans to match the required air flow. We had several instances of bearing failure on the fans. It was determined that at very low loads, the fans were not rotating fast enough to keep enough oil pressure in the bearings to keep the shaft and bearings apart. Solution was to limit how slow the fans could run and to also increase the viscosity of the oil. It is the combination of high load and low rotational speed that makes 'lugging' very bad on engines.
Also, as David says, on air cooled engines it is also the amount of cooling is reduced. Hey Ryan, your muffler looks more like the resonators that Shane and I have on our coaches. Straight thru.
No back pressure. I try not to let her lug down.
On the hills I usually just let the engine/tranny do the job they were intended to do. Sometimes she doesn't seem to downshift soon enough then jumps into TOO low of a gear. RPM's go to 2200 then she shifts into the proper gear for the hill. Doesn't happen that way all the time though. But I seldom have to manually drop a gear or two. I think a manual trans is much more susceptible to lugging.
But an auto seems to take of that problem. I'm just uncomfortable screaming at top RPM for extended periods of time. On long hills, I'll climb at 2000 PRM's in whatever gear is appropriate. On level ground I'll run 1700. One of the issues with operating any shaft with plain bearings at a low rpm is a lack of hydrodynamic oil pressure. The oil pump only supplies fresh oil to the bearings, it is the rotation of the shaft that provides the pressure to keep the shaft and bearing from rubbing. The hydrodymanic pressure increases with shaft speed - too low a speed and the pressure will not be adequate to keep the two from rubbing (very bad!!!).
Experienced it first hand in my first job - green engineer at a power plant start-up. We had large fans that fed combustion air the the boiler.
The amount of air was controlled by fluid couplings that varied the speed of the fans to match the required air flow. We had several instances of bearing failure on the fans. It was determined that at very low loads, the fans were not rotating fast enough to keep enough oil pressure in the bearings to keep the shaft and bearings apart.
Solution was to limit how slow the fans could run and to also increase the viscosity of the oil. It is the combination of high load and low rotational speed that makes 'lugging' very bad on engines. Also, as David says, on air cooled engines it is also the amount of cooling is reduced.
Oil, oil, oil. That is why as we all know, straight 40 weight is of the utmost importance with 2 stroke DD's. Viscocity rules:eek: Jim hit the nail on the head. David is right too in that the Detroits just seem to want to get up and go lick a fast car or a 2 stroke dirt bike (those were the days!).
Cruising is cruising but getting there is the point here I guess? Don yes, I was trying to be nice and use the word 'muffler'. It really is a straight through resonator and it has a nice 'bark' when we stand on the go pedal;) Love the sound, funny watching people turn their heads as we drive! NASCAR powered bus they must think. Ryan, I know what you mean about the 'bark'. Unique sound from those 2 strokers. And the sound with my Jake Brake engaged is, well.awesome!
Even truckers look up and take notice. So far no smokies have. Hope it stays that way. The post from Jim talked about the importance of oil viscosity.
The oil I'm using righ now is Amolie. Low ash (0.90). Designed just for 2 stroke DD's. They also have a straight 50 made for 2 strokes. If one is doing a lot of highway driving, and especially in hot weather, I wonder if the 50 is a viable choice. FWIW- I've put about 98,000 miles on my coach. It had 89,000 on it when I purchased it in 2004.
I usually run it wide open (anyone who's followed me can attest to that:) Usually, that's around 2050 RPM's @ 72 MPH. I average around 6.2 mpg at that speed and see hotter oil temps (220 or so), but the oil tests don't appear to show any abnormal wear metals and other base compounds in the oil are pretty much within spec. I've never pushed it, but I'm guessing that the redline is around 24 or 2500 RPM's. My governor starts to restrict at about 2250 RPM's. FWIW- I've put about 98,000 miles on my coach. It had 89,000 on it when I purchased it in 2004. I usually run it wide open (anyone who's followed me can attest to that:) Usually, that's around 2050 RPM's @ 72 MPH.
I average around 6.2 mpg at that speed and see hotter oil temps (220 or so), but the oil tests don't appear to show any abnormal wear metals and other base compounds in the oil are pretty much within spec. I've never pushed it, but I'm guessing that the redline is around 24 or 2500 RPM's.
My governor starts to restrict at about 2250 RPM's. Shane, What if you powered back to 65 mph and lightened up on the go pedal to match fuel delivery with the work the engine is doing? Would this do any harm? FWIW Ed said in his post at the beginning of this thread he runs his red block 2300 all day. Now I thought that was a bit quick but maybe with the 6V not. It does have 220M on it. I am not familiar and Ed sure is!
As for 'run em hard' I have a philosophy that has served me well over the years (decades) and I have done it all diesels I have driven. And I do it on my Duramax I have now.This is several million miles as I started doing 135,000 miles a year when I was 20 years old. Did that for awhile until I was well into my thirties. I really listened to the older guys who were credible and paid attention to what they said. I believe that made me more money than you can believe in maintenance cost savings. What I do is cruise very much like Don suggests at a comfortable RPM for fuel mileage, comfort, wear etc. BUT when it comes time for a hill and boy, I am surrounded by mountains then I work that engine the way it was meant to be worked and run it at or closest to peak torque RPM and or HP depending on the situation.
Mostly peak torque, but for passing then peak HP. You should read the tables for your engine and know where this is. You can usually feel it to.
For torque it is where she 'hangs in' on the tach most times. This keeps the motor clean and well seated IMHO. And I never let the pyrometer go over 1100 and try to keep it 1000 max most of the time depending on where your sensor is. I also manual shift the transmission to get the speed and RPM I want looking at the hill ahead of me.
I must admit the Allison is pretty good at this by itself.I know what gear my rig will need by what grade it is and most of you probably do too! Most of this is all in the planning. One thing I am glad to see is that there were more red blocks than we thought out there. I tend to agree with Gary.
I drive mine on cruise at 1950 RPM which is about 69 - 71 MPH depending on load and winds. It seems to be a sweet spot for my 8V92 as far as fluid temps go. Uses about 1 quart in 5-600 miles that way.about 3 quarts after a 1600 mile run to east coast. It gets about 5.5 - 6 MPG without hills. Doesn't leak but doesn't like dirty air, dirty fuel, sluggish radiators, and I don't go past 8,000 mile very often on oil changes. I also have a SOAP (Scheduled Oil Analysis Program) that costs me about $11.00 per sample at the lab and I buy them 6 at a time. I have also decided to pull the radiator and drop the top and bottom every 5 years to check it completely now that I am driving it more.
Labor intensive, but gives me peace of mind - I want it to go to 300K+ and it has 180K on it now. I tend to agree with Gary. I drive mine on cruise at 1950 RPM which is about 69 - 71 MPH depending on load and winds. It seems to be a sweet spot for my 8V92 as far as fluid temps go. Uses about 1 quart in 5-600 miles that way.about 3 quarts after a 1600 mile run to east coast. It gets about 5.5 - 6 MPG without hills.
Doesn't leak but doesn't like dirty air, dirty fuel, sluggish radiators, and I don't go past 8,000 mile very often on oil changes. I also have a SOAP (Scheduled Oil Analysis Program) that costs me about $11.00 per sample at the lab and I buy them 6 at a time. I have also decided to pull the radiator and drop the top and bottom every 5 years to check it completely now that I am driving it more. Labor intensive, but gives me peace of mind - I want it to go to 300K+ and it has 180K on it now.
Hey Bob, Good maintenance. I think a good philosophy on the coolant for ANY 6V,8V 3208, series 60, Cummins or what have you engine on a Bluebird. Not a highway truck is.
You drain the radiator once a year and replace the coolant. That way you are replacing and percentage (it depends on the coach.chassis heat, primus or aqua hot on volume) on a timely basis. Does not cost that much and you will not have to be concerned about SCA and cavitation. Cavitation is a killer. This eliminates that pretty much.
Of course do the test. Cheap easy good PM!! When it comes to Bluebirds is IT IS ALL ABOUT the preventive maintenance. We know they are built to go a very long way.
The trouble is time gets in the way. It is about how we guide and care for them along the way. THAT is what creates value. GREAT stuff here guys, We all seem to be on the same page. Seems like no one really 'babies' their 2 strokes. And like Gary said, cruise in the comfort range for mileage, run 'em up the hills and keep 'em in their sweet spot.
I also found that by keeping my cruise RPM at 1700 to 1800 I use less oil (as well as optimal mileage). I love it too when others say they don't go to 10,000+ between oil changes. I've always said oil is cheaper than an engine job. I usually go 6000 to 7000 MAX between changes. And I like what was said about opening up the radiator every few years. This winter while I'm in the southwest I'm gonna pull mine and probably have it re-cored. Some of the cooling fins down in the lower corners are corroding away.
I want to find out if there is some sort of 'high capacity' cooling design that may replace the original style. Anyone have any experience in this? I’m far from a V92 expert but here’s my 2 cents worth. When I bought my first V92 powered Bird I asked the mechanics a lot of questions whenever I was at a Detroit Diesel shop picking up supplies. The condensed version of their words of wisdom about what would kill a V92 were “if the coolant temperature EVER gets above 230 degrees the liner O-rings are shot and if you lug the engine you will shorten it’s life” Their definition of lugging was “if you can’t accelerate on a hill you’re lugging the engine”. They also advised “if you can’t keep the RPM above 1500 while pulling a hill you’re in the wrong gear” I think the 8V92 in my 91 has a design range (for hill climbing) of about 800 RPM so that puts the operating window for hill climbing between a low of 1300 RPM and high of 2100 RPM. The middle of the range puts you at about 1700 RPM.
Having owned a Bird with a mechanical 6V92 and mechanical Allison transmission and a Bird with an 8V92 DDEC and electronic Allison transmission - there’s a world of difference in how well they stay in that 800 RPM window on their own. The 8V92 DDEC and electronic Allison transmission pretty much take care of keeping my 91 in the design RPM hill climbing range (usually stays between 1700 and 2000 RPM on a steep climb) - I'm not sure that I could even force it to lug unless a hill was too steep for 1st gear. I often had to manually shift my 84 ½ to a lower gear on a steep climb or it would drop well below 1500 before it would downshift on it’s own. This is just a guess but. Maybe lugging a V92 is worse than lugging a 4 stroke engine due to the way the engines work. On a 4 stroke engine the pistons push the exhaust gas out of the cylinders and then pull in fresh air.
On a 2 stroke Detroit there are no intake valves and the only thing that pushes the hot exhaust gas out of the cylinders and pushes fresh air in is the air pressure from the turbo charger and/or the blower - so it seems to me that you would need to keep the RPMs up on a 2 stroke Detroit to boost the pressure to purge the hot exhaust gases from the cylinders and to supply lots of fresh air for combustion when climbing a hill. Shane, What if you powered back to 65 mph and lightened up on the go pedal to match fuel delivery with the work the engine is doing?
Would this do any harm? Dave- when I travel down I-95, that's about where I cruise- 65 MPH.
Mileage increases to around 6.4 or even 6.7 once. I've checked it by filling up at the Carmel Church VA flying J and then again at the one in Brunswick, GA. Oil consumption is about the same at 65 or 70, but I tend to use alot more down below 60- the engine is 'lugging' at around 1400 RPM's at that speed.
When ascending steep grades, I will shift to the lowest gear that will allow me to hold the pedal about 1' off the floor. Usually, this is first or second gear. The revvs stay up around 1900 or so and the cooling fan is on override. Temps will stay down around 185 or so in the cooling system, but oil will rise to 220 or 225. Tranny cooler usually is around 220 or so. On a recent trip to WY and back, we used around 5 qts of 40W oil over the course of 4500 miles or so.
I seem to be using alot less oil now, than when I first purchased the coach. Could it be possible that the rings have finally 'seated' after 190K miles?
I’m far from a V92 expert but here’s my 2 cents worth. When I bought my first V92 powered Bird I asked the mechanics a lot of questions whenever I was at a Detroit Diesel shop picking up supplies. The condensed version of their words of wisdom about what would kill a V92 were “if the coolant temperature EVER gets above 230 degrees the liner O-rings are shot and if you lug the engine you will shorten it’s life” Their definition of lugging was “if you can’t accelerate on a hill you’re lugging the engine”. They also advised “if you can’t keep the RPM above 1500 while pulling a hill you’re in the wrong gear” I think the 8V92 in my 91 has a design range (for hill climbing) of about 800 RPM so that puts the operating window for hill climbing between a low of 1300 RPM and high of 2100 RPM. The middle of the range puts you at about 1700 RPM.
Having owned a Bird with a mechanical 6V92 and mechanical Allison transmission and a Bird with an 8V92 DDEC and electronic Allison transmission - there’s a world of difference in how well they stay in that 800 RPM window on their own. The 8V92 DDEC and electronic Allison transmission pretty much take care of keeping my 91 in the design RPM hill climbing range (usually stays between 1700 and 2000 RPM on a steep climb) - I'm not sure that I could even force it to lug unless a hill was too steep for 1st gear. I often had to manually shift my 84 ½ to a lower gear on a steep climb or it would drop well below 1500 before it would downshift on it’s own. This is just a guess but. Maybe lugging a V92 is worse than lugging a 4 stroke engine due to the way the engines work.
On a 4 stroke engine the pistons push the exhaust gas out of the cylinders and then pull in fresh air. On a 2 stroke Detroit there are no intake valves and the only thing that pushes the hot exhaust gas out of the cylinders and pushes fresh air in is the air pressure from the turbo charger and/or the blower - so it seems to me that you would need to keep the RPMs up on a 2 stroke Detroit to boost the pressure to purge the hot exhaust gases from the cylinders and to supply lots of fresh air for combustion when climbing a hill. John, As usual I think you are right on with your assumptions. The 2 stroke Detroits rely on the volume of incoming air for combustion and to purge the cylinders on the exhaust stroke.
They 'tend' to have lower ex. Temps than 4 strokes because of this-If the RPMs are kept up. I have observed about the same parameters as you with my 91 on hill climbing. I think the DDEC & Allison combo do an excellent job of keeping the engine in it's optimum RPM range. I like to cruise at 1750 ( 65 mph ). Seems like its sweet spot, and after seeing the graph that David posted, I can see why.
I also like to keep the cruise control on as much as possible. I've never seen any written proof, but it sure lays into a hill a lot better with the cruise on. Seems like an extra 50 hp. Numerous times when climbing a hill, I've to kick it out of cruise due to traffic & there's no way I could maintain the same pace with the go pedal.
I also agree with the comment that was made about listening to what the old time drivers have to say. My FIL has been an OTR driver for over 40 years, and most of that time was with a Detroit. He has a 74 KW with a 12v71 in it that he bought new. He retired it 25 years ago and just plays with it now.
It sees 4500 RPM on a regular basis, for 15 to 20 seconds at a time, so running a 2 stroke against the governor doesn't bother me much. Over all I think there is a lot of good info here. Keep the oil changed, keep 'em cool, and keep 'em wound up- they should have a long & happy life!! I have a Bosch Automotive Handbook in front of me and it lists the following operational differences between two and four stroke diesel engines. (They're not specifically looking at Detroit two strokes, just two strokes in general): Two stroke advantages as compared to four-stroke: Simple engine design, Low weight, Low manufacturing costs, More favorable torsional force diagram Disadvantages: Higher fuel consumption, Higher hydrocarbon emissions (due to cylinder scavenging), Lower mean effective pressure (which means lower volumetric efficiency), Higher thermal load (no gas exchange stroke) Poorer idle behavior (higher percentage of residual gas) Some of this may explain the sensitivity to 'lugging'.
The higher thermal load may result in higher oil temperatures which has an effect on viscosity, and the lower mean effective pressure may relate to what John Wyatt said about air flow at low rpms. From the curves it does look like HP drops off rapidly with decreasing rpms. Could this be do volumetric efficiency dropping off relative to a four-stroke? I have a Bosch Automotive Handbook in front of me and it lists the following operational differences between two and four stroke diesel engines.
(They're not specifically looking at Detroit two strokes, just two strokes in general): Two stroke advantages as compared to four-stroke: Simple engine design, Low weight, Low manufacturing costs, More favorable torsional force diagram Disadvantages: Higher fuel consumption, Higher hydrocarbon emissions (due to cylinder scavenging), Lower mean effective pressure (which means lower volumetric efficiency), Higher thermal load (no gas exchange stroke) Poorer idle behavior (higher percentage of residual gas) Some of this may explain the sensitivity to 'lugging'. The higher thermal load may result in higher oil temperatures which has an effect on viscosity, and the lower mean effective pressure may relate to what John Wyatt said about air flow at low rpms. From the curves it does look like HP drops off rapidly with decreasing rpms.
Could this be do volumetric efficiency dropping off? David, They missed one of the best advantages. Dave- when I travel down I-95, that's about where I cruise- 65 MPH. Mileage increases to around 6.4 or even 6.7 once. I've checked it by filling up at the Carmel Church VA flying J and then again at the one in Brunswick, GA. Oil consumption is about the same at 65 or 70, but I tend to use alot more down below 60- the engine is 'lugging' at around 1400 RPM's at that speed.
When ascending steep grades, I will shift to the lowest gear that will allow me to hold the pedal about 1' off the floor. Usually, this is first or second gear. The revvs stay up around 1900 or so and the cooling fan is on override. Temps will stay down around 185 or so in the cooling system, but oil will rise to 220 or 225. Tranny cooler usually is around 220 or so. On a recent trip to WY and back, we used around 5 qts of 40W oil over the course of 4500 miles or so. I seem to be using alot less oil now, than when I first purchased the coach.
Could it be possible that the rings have finally 'seated' after 190K miles? Fascinating stuff Shane.
Your experience shows how the engine runs better under load at high rpm - uses less oil, oil temps climb but stabilize. Maybe it's premature to say, but the oil temps do seem to run higher than mine. Mine are typically 15 deg over water temps. I just posted some stuff which I think supports what you're saying. In any case, these engines very much have a preferred operating range and style. Funny, I have a message asking me if I prescribe my previous post driving style view for 2 strokes but when I look here in the thread that post is no where to be seen. I have had a freakish day as my logic board went kaput on my computer.
Then when I took it into to Apple I also took along my old Nellie Belle Powerbook G4 I bought about nine years ago to get updated OS in it that is supported. Thinking I'd limp along with that until we figure out the rest. Naturally I have everything backed to the hilt. No big deal really. Well the gal take one look at Nellie and says your hard drive is about to crash. It is warning you of that.
After nine years that little computer has finally given up or thinking about it anyway. No complaints, as that thing has made me a good living and I had alot of fun with it too. How many 9 year old laptops do you see?
They are fixing the other one at NO charge even though it is past warranty at 4 years old. 1100 dollar fix. Now who doesn't like Apple?
I think it is great. So I sit and type this on my new iMac ( first desktop I have had in 10 years) and I look at the BIG screen with HIGH resolution and I am in MAC NIRVANA! Ok now that I vented I am saying that I have driven my diesels the way I described. The newer V engines with DDEC can probably be driven that way too. The older ones you have to watch and I probably would not pull them down to 1300RPM.
Your gauges ( especially the pyrometer ) will tell you if what your doing works. OK I have to go look at more photos on the BIG screen!
The two forums have good information. Look in the FILE Section, Detroit Diesel topics. Changing the thermostats isn't hard. You may want to change the fuel hoses while the coolant tubes/hoses are removed. On 9/28/07, jesupbill wrote: How hard is it to change the thermostat in my 84PT40 6V92?
Is there one or two thermostats? Thanks Bill Garlen Jesup, GA 84PT40 - Curt Sprenger 1987 PT38 8V92 'MacAttack Racing' Anaheim Hills, CA Non-text portions of this message have been removed. Hi Bill, There are two on the 6V92 and the kits are available at DD/Allison's parts counter. Make sure that you get new gasket kit too. Since you are draining upper part of the system- have the DD shop make you some new silicone hoses for the upper radiator pipe and the crossover pipe. There are drains on the two bowls. The large cross-pipe and pipe to the top of the radiator will have to drain through the bowls.
A funnel and vacuum hose worked great for me- I drained the anti-freeze through a coffee filter in a small funnel, put a hose on the end of the funnel and put the anti-freeze in a clean 5-gallon bucket. I checked the pH and nitrates and re-used it. I reduced my thermostats to 170 degrees and have had no problems since 2005 running a little cooler.
Shane Fedeli 85PT40 Hershey, PA - In, 'jesupbill' wrote: How hard is it to change the thermostat in my 84PT40 6V92? Is there one or two thermostats?
Thanks Bill Garlen Jesup, GA 84PT40. Thanks Shane, Here's what happened. My coach has never run hot. It sits at 190 except sometimes in the mountains of North Georgia, Alabama or Tennessee it will heat up some.
I live in South (hot) Georgia. Mostly no long trips as I still work full time; trips around South Georgia, Florida, etc. Yesterday I decided to replace the last remaining older tire on the tag.
I went to pick up the coach and drove it home, about 1 mile, and when I pulled it in I heard a boiling sound coming from the passenger side of the engine. It was not making the same boiling noise on the driver side. That is why my first guess was thermostat.
I usually have found most parts I needed at NAPA because we have a lot of log trucks in this area with Detroits. He has 180s in stock but not 170s.
I don't think he will have the gasket kits either. I am also worried it could be a water pump. Bill Garlen Jesup, GA 84PT40 - In, 'sfedeli3' wrote: Hi BillThere are two on the 6V92 and the kits are available at DD/Allison's parts counter. Make sure that you get new gasket kit too.
Since you are draining upper part of the system- have the DD shop make you some new silicone hoses for the upper radiator pipe and the crossover pipe. There are drains on the two bowls. The large cross-pipe and pipe to the top of the radiator will have to drain through the bowls. A funnel and vacuum hose worked great for me- I drained the anti-freeze through a coffee filter in a small funnel, put a hose on the end of the funnel and put the anti-freeze in a clean 5-gallon bucket.
I checked the pH and nitrates and re-used it. I reduced my thermostats to 170 degrees and have had no problems since 2005 running a little cooler. Shane Fedeli 85PT40 Hershey, PA - In, 'jesupbill' wrote: How hard is it to change the thermostat in my 84PT40 6V92? Is there one or two thermostats?
Thanks Bill Garlen Jesup, GA 84PT40. Hi Bill, I replaced all hoses, water and fuel pump earlier this year. It was a bear of a job- but good preventative maintenance IMHO (I had the $$ and time to do the job now vs. On the road somewhere). The water pump will 'weep' when it is bad. Mine old one was fine- there really aren't too many parts in them to go bad. If you have an inkling to do the water pump, now is the time to do the fuel pump and thermostats too- otherwise you will be draining the system twice.
I have what they call a 'walking' pump- take a picture of yours to the DD parts counter- yours could be a 'standing' pump. They also had put a plug in my new one where the heater hose is connected- have them remove it for you. I could not remove mine with a 1/2' impact wrench.
If they are nice, the DD shop will make new hoses for the pump an no cost. If you get the parts, we could work on this at the RATS rally. I hope to get there.Shane - In, 'jesupbill' wrote: Thanks ShaneHere's what happened.
My coach has never run hot. It sits at 190 except sometimes in the mountains of North Georgia, Alabama or Tennessee it will heat up some. I live in South (hot) Georgia. Mostly no long trips as I still work full time; trips around South GeorgiaFlorida, etc. Yesterday I decided to replace the last remaining older tire on the tag. I went to pick up the coach and drove it home, about 1 mile, and when I pulled it in I heard a boiling sound coming from the passenger side of the engine.
It was not making the same boiling noise on the driver side. That is why my first guess was thermostat. I usually have found most parts I needed at NAPA because we have a lot of log trucks in this area with Detroits. He has 180s in stock but not 170s. I don't think he will have the gasket kits either.
I am also worried it could be a water pump. Bill Garlen Jesup, GA 84PT40 - In, 'sfedeli3' wrote: Hi BillThere are two on the 6V92 and the kits are available at DD/Allison's parts counter. Make sure that you get new gasket kit too.
Since you are draining upper part of the system- have the DD shop make you some new silicone hoses for the upper radiator pipe and the crossover pipe. There are drains on the two bowls. The large cross-pipe and pipe to the top of the radiator will have to drain through the bowls. A funnel and vacuum hose worked great for me- I drained the anti-freeze through a coffee filter in a small funnelput a hose on the end of the funnel and put the anti-freeze in a clean 5-gallon bucket. I checked the pH and nitrates and re-used it.
I reduced my thermostats to 170 degrees and have had no problems since 2005 running a little cooler. Shane Fedeli 85PT40 Hershey, PA - In, 'jesupbill' wrote: How hard is it to change the thermostat in my 84PT40 6V92? Is there one or two thermostats? Thanks Bill Garlen Jesup, GA 84PT40.