| Author |
Message |
J.C.B. (Eagle)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, May 08, 2006 - 6:59 pm: | |
I have a friend that has a 1990 Eagle Model 15 with a DD6V92TA and a mechanic told him that it does not have a fuel modulator and has F85 injectors. This unit does not smoke. Was wanting to know if the above facts are possible. The injectors are 9F85's rather than F85's. Any input would be appreciated.
(Message edited by eagle on May 08, 2006)
(Message edited by eagle on May 08, 2006) |
Greg Peterson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 8:36 pm: | |
Looking at the 92 service book it looks like the 9F85 were used in Calf. certified 6v92. Rating is 320hp at 950LB-ft torque. Turbo is a TV-7511 with an A/R of 1.23. Injector timing is at 1.520.
It should have a rack delay unless some one removed it. If the engine orginally had smaller injectors than the turbo probably has a much smaller A/R ratio. This would make the turbo spin up fast at take off but might choke the engine up at high RPM and burn more fuel without making the correct horsepower.
I have recently spent much time researching injector and HP interaction in 2 stroke diesels.
It is a lost art that is difficult to get any info that is even close to correct. Get your engine serial # and call a Detroit Diesel Distributor. They can tell you what injector and turbo your engine was built with orginally. They will likely be no help in changing it to some other power rating. They told me that would be treated as an engineering problem at $150 an hour.
The high power setup for the 6v92ta is 9G90 injectors.
350 HP at 1020 LB-ft torque. Turbo is TV-7511 with A/R 1.08. Injector timing 1.466.
If you have a TV-7512 turbo use a A/R of 1.23. and injector timing of 1.480. Torque drops to 995 lb-ft but you meet 1989 emission standards.
There are many combination of things that will work but if you don't due them correctly you will burn more fuel and not get the rated power.
Good Luck. |
Geoff (Geoff)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 9:24 pm: | |
I would think that a 1990 bus would have a DDEC engine so it would not have a mechanical injector size number, but maybe it was built outside Federal EPA requirements and actually has an MUI engine. Anyway, Greg has some great advice on turbo and injector sizing/matching. I might add that the small A/R numbers on turbo housings is not only good for quick boost on takeoff, but they supply more than adequate air when underway. For example, I have an turbo A/R of .95 on my 6V92TA with 9G90 injectors and don't smoke under full power in the flats or in the mountains. A 350HP 6V92TA normally has a 1.08 A/R, so the .95 is a little better, but personally I would try the 1.23 and see how it does before I spent the money on a replacement housing or turbo.
--Geoff
'82 RTS AZ |
Greg Peterson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, May 09, 2006 - 11:03 pm: | |
The research I have done has indicated that large injectors with a small A/R ratio cause much higher exhaust backpressure. This caused increased emission of the NOX pollution. As the years went by the turbo on the 8v-92 went from a TV-8511 to a TV-8513. If you look at the complex Garrett flow charts it looks like the main difference in these turbochargers was the ability to flow more air with less turbo backpressure. In the end one of the reasons DD could not meet the pollution standards was the inability to completely scavenge the exhaust from the engine.
Geoff… I wonder with that small A/R ratio if you are really hitting 350hp. You must have very high exhaust backpressure that would translate into high supercharger pressure. This is one reason DD went to the bypass supercharger because they were blowing out the rings.
Anyone else have any information please chime in. The info I got was from being transferred to many different people at DD. I finally got that “old two stroke guy” who is about to retire and has been put on the series 50 lines. He was the only one that had any reasonable information. Seems like all the experts have retired or are dead. I could tell I was in trouble when the Kid checking my engine serial number tried to convince me that I really had a DDEC engine not a MUI.
P.S. Geoff is correct, the last certified MUI engine was built in 1989 according to DA Book. The DDEC engine injectors are very different part #.
Greg |
J.C.B. (Eagle)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 10, 2006 - 7:52 am: | |
This was a replacement engine. This coach was used as a shuttle from VA to D.C. and the charter company replaced the original engine with this one. It came with a factory warranty. It has less than 25000 miles on it. |
Geoff (Geoff)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 10, 2006 - 9:01 am: | |
The proof is in the pudding, Greg. If I am running 9G90's and not producing black smoke under load then I am getting plenty of air. The difference between a 1.08 A/R and .95 A/R is not that great. My understanding is that the reason Detroit went to a by-pass blower was the mechanical blower was restricting the turbo output.
Getting back to the original question, I don't see how your friend's engine doesn't have a throttle delay or fuel modulator and not smoke on takeoff. Maybe the mechanic doesn't know.
--Geoff |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, May 10, 2006 - 10:05 am: | |
IIRC, the blower bypass was explained by a DD rep at an early BC Convention (Laughlin?) to be a energy saving mode. The turbo in some engine ranges was supplying sufficient airflow to render the blower's contribution "surplus", Turbo being driven by "free" energy, the supercharger taking energy from the crankshaft.
(Just a "first impression" thought blurb that popped into my memory upon reading Geoff's comment) |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 11, 2006 - 5:36 am: | |
"In the end one of the reasons DD could not meet the pollution standards was the inability to completely scavenge the exhaust from the engine."
Yet the newest engnes all use EGR as the required method to lower "polution".
FAST FRED |
Marc Bourget
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 11, 2006 - 6:55 am: | |
EGR is used to reduce conbustion chamber temps which, in turn, reduces NOx generation.
The biggest problem with diesel engines, pollution wise, is particulate generation. This can be controlled adequately.
I suspect the better reason for the emergence of 4 stroke engines is their superior BSFC, Brake Specific Fuel Consumption, They "extract" more work per gallon of gas - in land vehicle applications. The large ship engines, which are two stroke, hold the current record for efficiency, at or close to .5 as compared to .384 or thereabouts for cars/trucks. |
J.C.B. (Eagle)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, May 11, 2006 - 8:02 am: | |
Thanks Greg and Geoff for the information.
The engine is a rebuilt engine from DD but is an MUI. The coach was probably built in 89.
Thanks again guys. |
Marc M
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 12, 2006 - 1:14 am: | |
I need a little education please.
What is a DD "MUI" engine?
The letters TA that you guys are throwing around. I'm assuming the "T" stands for the turbo'd version of the engine. What does the "A" stand for, and I don't want to hear aftercooled. If I have a Turbo'd engine, does that automatically indicate that somewhere down in there I have an aftercooler ??
I'm assuming the injectors have an external marking on them so I can determine which ones they are.
My 8-92 smokes all the time, so in reading this post (and others like it), I'm assuming that I need to start looking at the existing injector / turbo combo. |
ned sanders (Uncle_ned)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 12, 2006 - 8:31 am: | |
2stroke detroit diesel and smoke.
I think black smoke means you are making power. the more black smoke the more fuel you are burning so the more power the engine is making.also more heat because that is what an engine is"a heat source".Larger injectors and more air equals more smoke. look at your exhaust pipe and the farther away before you see the smoke tell you how much heat and power you are making.
uncle ned
"huggy bear"
4104 With 6v92 |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, May 12, 2006 - 10:06 pm: | |
Hello Marc M,
6V92-TA = 6 Cylinder, V Configuration, 92 cubic inches per cylinder, Turbocharged, Aftercooled
[Edit] Almost forgot: MUI = Mechanical Unit Injector (this is different from an electronic injector like what is currently used in 4-strokes). This piece contains all of the required parts to regulate and inject fuel into the individual cylider (minus the constant fuel delivery which is taken care of by the fuel pump).
DDEC (AKA DDEC II, DDEC III...) = Detroit Diesel Electronic Controls
Black smoke means that you are not burning all of your fuel (basically you're generating a heck of a lot of soot). You see this a lot when you are at altitude and the air is thinner - or if a trucker's idea of gentle throttle modulation is smashing the accelerator through the floor off every green light and gear shift. This can also happen if your injectors are not sized correctly for the load the engine will experience, or the fuel rack (which controls the MUI's) is not adjusted correctly.
Blue smoke after the engine warms up means you are burning oil. This can either be bad rings, bad blower seal, or bad turbo seal.
White smoke when it's cold outside (sub 40 degrees) just means that you're running a two stroke - and its cold outside. However, if it's not cold outside, then you're probably leaking water into your combustion chambers. This can be bad ring seals around the injector, a cracked head, or a blown head gasket.
To check if you have an after cooler (after you've determined that you have a "-TA" or "-TTA" engine), follow the water pump outlet down the cross-over pipe (the one that feeds water to the other side of the engine) - if you see a split to a flat plate under the roots blower, that's an Aftercooler. Also, the aftercooler's part number should appear on the engine's build plate.
I have not seen an engine that had just an after cooler with no turbo...
Cheers!
-Tim
(Message edited by Tim STrommen on May 12, 2006)
(Message edited by Tim Strommen on May 12, 2006) |
Greg Peterson
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, May 13, 2006 - 2:00 am: | |
Geoff is one of the best sources of two-stroke info around. Geoff you should write a book before you die on how to hot-rod an old two-stroke.
Here is some more two-stroke trivia that I have found in my spare time.
I found some interesting information by looking at some of the old EPA records that were filed by inventors in the late 1980 time frame in order to improve particulate emissions.
Some of the submissions to the EPA used converters and DD was very concerned about exhaust backpressure.
“DDC noted that increased backpressure will
cause increased engine out smoke and increased non-volatile particulate
levels. It would also cause increased cylinder and exhaust temperatures and
have a deleterious effect on engine durability.”
Another interesting change on the later 92 engines was the reduction of the port length in order to increase the power stroke for more efficiency. The angles of the ports were also changed. The change to the port optimized the swirl of the air coming into the cylinder for less smoke and better efficiency.
Marc’s explanation of the bypass supercharger is exactly DD explanation to the EPA of its function. Some old two-stroke experts say that this was part of the engine life improvements that went with the silver engine changes. I did not find any real proof of this claim.
If you look at the tune-up specs in the service manual the setting for a rack delay or a fuel modulator are given for many different years of engine certification. The fuel modulator seems to be a superior system because it is based upon the air box pressure. Yet, most engines seem to have the rack delay. It seems to be difficult to find used parts for a fuel modulator.
In a few more years Geoff book could be like the “ Dead Sea Scrolls” except for Two Cycle diesels. |
Eagle 10
Unregistered guest
Posted From: 152.163.100.138
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 11, 2006 - 9:33 am: | |
I have a hole in the driver's side exhaust manifold on my 1984 Eagle 10 6v92 turbo. Do I need to remove the radiator to get it off? Can I get at it from under the coach? Any things I should be aware of before starting the project??? |
Richard Bowyer (Drivingmisslazy)
Registered Member
Username: Drivingmisslazy
Post Number: 1607
Registered: 1-2001
Posted From: 66.168.162.246
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 11, 2006 - 5:36 pm: | |
Eagle 10, it might be a good idea to start a new thread for your question. It kinda gets lost down here at the bottom of another subject.
Richard |