| Author | Message | ||
| David Hartley (Drdave)
Rating: N/A |
An argument is brewing over this topic. I have been told that an 8V92DDEC engine gets the air supply for the air compressor system after the turbo compresses the air and before it goes into the blower. I have never found ANY air compressor feed line being taken anywhere other than after the filter and before the inlet for the turbo. Or in some cases completely separate from the engine air such as on older GMC coaches. From everything that I have seen I cannot fathom that anyone would tap the turbo output to supply the air intake on the air compressor. Right or Wrong and Please Explain so that I am not the only one... Dave.... | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
Dave, I have worked on heavy equipment for my primary occupation since 1992. I have never seen or heard of such. Everything I have ever seen the compressor either has it's own breather or gets fresh air from a tap on the air filter side of the turbo. I don't believe you could produce any or enough boost if you try to take air from the pressure side of the turbo. The compressor would take all or most of the boost. I would have to see a "FACTORY" setup to believe it would work. FWIW, Dale | ||
| Merlin westphal (Merlin)
Rating: N/A |
Well I don't know what to tell you guys!! Every big rig I have had with a 4 stroke engine had the compressor inlet on the intake manifold (thats between the turbo and engine)so the compressor is pre charged. My 8v 92 ta the intake is in one of the inspection ports on the side of the block. pre charged also those turbos put out way more air than the engine can consume. | ||
| PMS Rating: N/A |
Many later Cummins engines use pressurized intake air to feed the air compressor. All of our ISC 8.3 engines are plumbed this way. If you feed pressurized air to the compressor it will be more efficient. The turbocharger on a diesel engine produces much more boost than the engine really needs,that is why many engines run waste gates on the turbo. Also reducing boost pressure lowers NOx in the exhaust. | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
First, 8v92ta is a 2 stroke. The arguement is a 8v92 2 stroke. Kinda don't compare to 4 stroker. Second, I highly doubt that DD would design that setup in the "inspection port" to allow oil, unburnt fuel, and the sludge that forms in the airbox of a 2 stroke to be allowed to enter the compressor intake. 4 strokes are different no oil or unburnt fuel or sludge in the intake. And no those particular turbos are not designed to put out way more air than the engine can consume. If it was KABOOM, because someone somewhere would over boost without it being designed to not over boost. If it was that kinda turbo setup it would have a wastegate. The non wastegate turbos are designed for the exact amount of boost and cfm required to supply that engine without the KABOOM. | ||
| J.L.Vickers Rating: N/A |
Second, I highly doubt that DD would design that setup in the "inspection port" to allow oil, unburnt fuel, and the sludge that forms in the airbox of a 2 stroke to be allowed to enter the compressor intake On the 6/71 inline for the PD4104 the air compressor inlet air was piped from a airbox cover to the air compressor inlet. JLV | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
Here We go again, An old 6-71 1950's NON Turbo is not a later model 8v92DDEC. After DD figured out that it caused problems they stopped plumbing them in that way. So I would bet they wouldn't do it on a 8V92. If you need reference I can find that bulletin. I believe I may have it at work Also they stopped plumbing the airbox drippings back into the oil pan (same reason). If yours is still that way I would change it. | ||
| David Hartley (Drdave)
Rating: N/A |
Ok, Look like we have the horns of a dilemma forming. Seems the 4-strokers allow for it in the design. Us 2-strokers don't and don't have excess turbo boost to waste for pre-charging the air compressor. We can't spell "waist gate"  The clarification question is pertaining to Detroit Diesel 2-Stroke engines, IN the DDEC electronic version of the 8V92TA engine. To reitertate, Air pulled from section after the turbo and before the roots blower. The issues of air box dirt & oil do not apply. Maybe if someone has a leaky turbo seal then the oil part would apply but I wouldn't want to follow him very far! This is fun and educational already. | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
"The issues of air box dirt & oil do not apply." AAHHH, but they do with the guys saying they have an inspection port tap. LOL. I know what you are saying Dave. Just pulling your chain. LOL. This is fun! | ||
| David Hartley (Drdave)
Rating: N/A |
I shudder to think about that 15.5 cu ft/min air compressor sucking turbo air away from the starving engine. Then I think about that remote idea of the compressor blowing its valves and 120 psi air backfeeding into the engine.. ( I know there's a check valve guys )!! or the compressor losing a head gasket and engine coolant running up into the blower intake and into the engine. Ouch! Are we having fun yet? | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
120 psi of boost. wwweee hhhhaaaa!!!!!! Better tighten the ole 5 point harness and put on a helmet! | ||
| Tim Hoskinson (Tdh37514151)
Rating: N/A |
Dale the 671 had the air intake to compressor out of the inspection cover from the 40s thru the 70s. This was not a short term method. Worked very well. Volumes of compressed air from turbos and blowers are far greater than the intake volume of a air compressor the size of those use in this aplication. The compressor would have no chance of scavenging enough volume to starve the engine of intake pressure. Tim | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
Tim, You are correct on the 6-71 compressor configuration until the 70's, But a bulletin was issued to move the compressor intake to the air filter housing plumbing. I believe it stated DD was concerned with the airbox oil, unburnt fuel and sludge issues entering the compressor. I can tell already I am going to have to dig out the paperwork. The ORIGINAL question is about a 8v92 turbo engine compressor taking the air from BETWEEN the turbo and blower. So NO it won't starve the engine of airbox pressure, BUT it will take precious BOOST from a TURBO. As DrDave pointed out a 700 series compressor pumps 15.5 cfm and that compressor will be robbing boost to get that air. Unless you have a turbo that has been designed to provide this you are loosing boost. If you have a turbo that does this it will have to have a waste gate for the times the compressor isn't demanding air from your boost circuit to keep boost continious. If not you will over boost. | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
If anyone has ever had just a loose connection or a pinhole in a turbo boost circuit they will tell you it doesn't take much of a leak to loose every pound of boost | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
Now add something to the mess... Consider what will happen when you have your compressor taking air after the turbo, and you add a propane injection system to your mess... (which if you read the "how to", they tell you to inject the propane BEFORE the turbo... ) NOW we're having fun... nothing like a good explosive mixture of propane and air to pump up those good ol' brake tanks with!!! | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
Forget the 5 point and helmet I posted awile ago. We gonna need some of them space suits. Any Busnuts have experience flying a bus in space??? | ||
| niles steckbauer (Niles500)
Rating: N/A |
I believe famous bus driver Ralph Kramden's wife Alice took many "trips to the moon" | ||
| Ian Giffin (Admin)
Rating: N/A |
Dale, Yes...  Ian www.busnut.com | ||
| David Hartley (Drdave)
Rating: N/A |
The only thing missing when I looked at it is that giant airbag between the driver and windshield! Oh about the size of a king size waterbed Does that big nose constitute a "crush" zone or just something else to scoop up hondas? Gee, Just think.. All that work just to hang those neat headlights | ||
| Dale Waller (Happycampersrus)
Rating: N/A |
I can't wait till I can get the chance to go to one of the rallies. I would go Busnuts trying to look at all the coaches. I really have to admire the bodywork involved with that look. Wonder how it handles reentry? | ||
| Gary Stadler (Boogiethecat)
Rating: N/A |
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| Artboy
Rating: N/A |
I had recently aquired a 35' GMC transit bus. It is quite the experience! I drove it to a fueling station to top off. OMG! $96 for diesel! (this was last year and not even a whole tank..) ouch. well, .. better check the air pressure. you know, improve milage and all! I began filling one tire. (BTW: all tires were in the 45-50 psi range and showing it.) 50 cents for air per cycle. I put about $3.00 in and was still filling the one tire. I did some quick math. "let's see. 6 tires, combined with exponential decay of added air pressure per cycle (if the darned thing could even do 100 P.S.I.! [big difference between a honda tire and a truck tire!]) "Add column A to column B.. carry the 1.." I estimated it would take about $60 in quarters and about 5 hours to fill all tires. "no F'ing way. I did notice that there was a ball valve and an air connector in the engine compartment (not sure if OEM but what the heck!) I went to hardware store and got an air hose and a tire fitting. cost me about $25 and half hour to fill. (took half hour because whoever installed the last set in the back didn't line up the tires and I had a tough time even removing the valve caps on the inner set! ..but that's another rant.) |