| Author |
Message |
Bill Teal (Teal) (63.184.97.60)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 02, 2002 - 11:07 am: | |
has any bus nut out there built or purchased a propane injection unit for there 8V-71 Detroit Diesel. I sure would like to know their opinion on the performance of the unit. |
Scott Whitney (66.82.32.1)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 02, 2002 - 12:18 pm: | |
Might search the GMC Busnut list on Yahoo for posts by George Lowry. He runs a Propane system, but it is on a Cummins.
Scott |
joe shelton (Littlewind) (67.241.228.31)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 02, 2002 - 12:22 pm: | |
I have tried to search the GMC Busnut list on Yahoo but always end up with about 1000 related posts. Am I doing something wrong? Maybe I should ask on the related Yahoo site. |
Mrbus (152.163.188.227)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 02, 2002 - 2:34 pm: | |
Joe,
Never had any desire to try the propane injection on my 8V71, but have had a lot of experience using propane on an Allis Chalmers diesel in an unlimited class pulling tractor. It definitely is a horsepower increase, but for what it takes out of an engine I would be reluctant to use it on anything other than an all out horsepower version that gets rebuilt after about two hours running time. It would probably be much cheaper in the long run to just convert to a larger rated engine, if you need that much power.
Gus Haag |
Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 02, 2002 - 8:59 pm: | |
I've been strongly considering it too, but in moderation... using much less propane than the max you could use, simply to decrease or eliminate smoke and maybe get that little "extra" needed on long grades for my old non-turbo Cummins 220. I'd like to hear any opinions. It seems that you can put quite a lot of propane into the engine and gain a lot of horsepower, at the eventual expense of a rebuild way ahead of schedule. But what about "just a little"...???
Cheers
Gary |
Don in WA (67.227.184.190)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 02, 2002 - 11:11 pm: | |
I was considering a system for a non-turbo diesel that would use two eletric valves and one or two regulators. First stage would come on at about half throttle for cruise and second at wide open. If using one regulator then adjustable inline valves to control flow. Would require considerable experimenting.
The systems used on turboed engines that use boost on the back side of the diaphragm give a proportional flow which would be hard to do non-turbo. Just like any hotrodding, you pays your money and you takes your chance. Might cost a little more to fix that a small block Chevy. |
joe shelton (Littlewind) (67.241.230.15)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 03, 2002 - 7:20 am: | |
Good reference info.
http://members.shaw.ca/k2pilot/Propane%20article.html
There are alot of posts on the yahoo gmc-busnuts site. Some dated around 5-30-02 and others 1-02.
I too am intrested for a little extra on the hills only. |
DON5050 (207.224.148.66)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 03, 2002 - 9:42 am: | |
add propane injection use only a little watch water temp very slowly incress presure when water temp starts to rise reduce presure a little whatch water temp there are several ways to hook up system if not over injected system is safe |
Bill Teal (Teal) (67.235.5.33)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 03, 2002 - 10:29 am: | |
I have built and installed a system like the one described in the post by Joe Shelton. It has two regulators and I have them adjusted to put out 5 to 6 lbs. pressure through a 3/16" orifice. When turned on you can see a small increase in smoke, but there is no noticable increase in power. the orifice might be to small, but I don't know how much larger to safely increase the orifice size,or pressure. Any ideas ???. |
Dallas Farnworth (216.98.68.82)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 03, 2002 - 4:12 pm: | |
Check out this site.
http://members.shaw.ca/k2pilot/Propane%20article.html
Seems to be worth while.
I've talked with George L. over on the GMC board and he's had good luck on his VT903 cummins.
Many years ago, when I was driving truck, we had some really small engines. The answer that one guy came up with was to put a propane torch tank with a rubber hose going to his air intake. He could climb the hills with 80K 20mph faster than the rest of us. Until the day that he cracked it too far...... think pieces and parts spread across Snowqualmie pass.
There are many companies that build propane enhancement systems for the 2 cycle detroits, just search for them at Google.
Dallas |
Jayjay (65.134.220.215)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 03, 2002 - 11:12 pm: | |
I spent some time on development of a system along with Bob Johnson, of Pahrump,NV. He recently e-mailed with a glowing report. It is set up on a kick-down type switch to only work on max throttle (i.e. hills) application. He says that now that the bugs are out that he just loves it. 3/8 tubing to a 1/4 in. orifice at 4.5 psi. He is currently in bend La Pine,OR, and may respond at B_joh@msn.com. Cheers...JJ |
Gary Stadler (Boogiethecat) (68.7.217.217)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 04, 2002 - 12:29 am: | |
It sounds too good...
I hear all these good reports, but I hear just as many comments of engines blown to smithereens, dead cylinders, etc. SO what is the real story behind all of this? Is it that these people just aren't careful, do too much of a good thing, or is it that it's a risky proposition at best and sane people shouldn't try it?
That said, I bought a complete spare cummins 220 for my bus so I can try the propane thing and if the worst nightmare happens, I have a fallback albiet not a fun one... (I'm definitely gonna try this) but aren't there things that you could watch like exhaust temp, etc that could clue you to the fact that your happy powerburst is about to render your hard-earned coach into tow-truck fodder? I'm really wanting some first hand experienced comments on both sides of the fence...what was the true reason that the ones I hear blown up did that, and how long have the sucessful ones been running?
Cheers!
Gary |
JayJay (65.142.15.116)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 04, 2002 - 1:18 pm: | |
Gary, we didn't get to spend a lot of time on development of the system while we were in Vegas. We used the old ether hole in the blower housing to feed it in. Definitely watch for high temps(oil,water,exhaust) I spoke with him a few days ago and he said it was doing fine. Remember that his system is only engaged during max throttle applications, and thus only for short periods of time. Perhaps a few minutes of moderate HP increase, but definitely NOT a Nitrous Oxide drag-racer type boost. Just a smooth,steady increase, though I'm sure you could use more pressure to increase the gas flow and get that, along with the short engine life that I worry about for my bus. Use metal braided lines inside the engine compartment, and some sort of remotely controlled (solenoid operated) start/shutdown mechanism.Keep it well vented too. Bob had a homemade "steersafe" rig installed that I liked, and I'm going to put on the 4905 along with the propane boost. Will let you know how they turn out as development continues. Cheers...JJ |
Tom Caffrey (Pvcces) (64.114.233.138)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 04, 2002 - 11:53 pm: | |
Gary, I don't have any experience with the propane boost like you were asking for, but I have a few comments that may shed some light on the subject.
First, an absolute limit to the horsepower you can get from any kind of engine will be the amount of air it can breathe. If it runs out of oxygen, it will act just like you if you were to run uphill until you run out of oxygen.
Second, one of the characteristics of an injection pump, injectors and the pump timing is the rate at which fuel burns. What happens if you mix fuels is that the burn rate is affected. I believe that diesel burns fairly slowly, even when compressed, so a fairly advanced injection timing is used.
What happens if propane has a faster burn rate or changes the burn rate of diesel when they are mixed so that it burns faster will depend on whether the timing was advanced enough to provide maximum power for the fuel consumed.
If the engine was running slightly retarded, and mixing the fuel speeded up the burn, then you could get a real noticeable improvement in power.
What happens if the timing is already advanced to the point of maximum performance and then you speed up the burn? Then cylinder pressures would spike before top dead center and performance might suffer.
If the engine is not designed to stand the increases in pressure, then you might have early damage.
One reason that a Detroit 2 stroke might increase its performance with propane is because of the scavenge air that is pushed through the engine by the blower as the piston passes bottom center.
If there is a lot of scavenge air, then there is some extra oxygen available to burn the propane and produce extra power. If there is not much spare scavenge air, then the boost might be less, and the smoke more.
One of the reports mentioned best improvement on moderate throttle. Since diesels normally run very lean until heavily loaded, moderate throttle performance could be good, while WOT performance might mean just a little more smoke.
From the above, you can see there are a lot of variables that would affect the outcome. I think that you might be able to get some ideas from the engine makers and from some research on how the pressure cycle is managed in different brands and configurations.
Just food for thought.
Tom Caffrey PD4106-2576 |
RJ Long (Rjlong) (24.127.74.29)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 05, 2002 - 12:09 am: | |
Gary -
George Lowry, who's a frequent contributor on the Yahoo GMC bus-nuts group, has a propane system on his 4106, which he's repowered w/ a Cummins 903. However, I believe he had the system on the 8V71 before the transplant.
He will be more than happy to share with you his real world experience with it, but he's travelling right now, headed for the FMCA director's meeting.
There was quite a threat going on the GMC board awhile back about this, you might log on and search for the thread, as they aren't lost like MAK's bbs.
HTH,
RJ
PD4106-2784
Fresno CA |
Carl R (65.148.107.67)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 05, 2002 - 2:28 am: | |
Tom Caffrey has about the same thoughts on this as I do. As they do to everything else, the laws of physics apply to diesels and engines, gas or diesel, typically run out of oxygen before the fuel's completely burned up. Now a two stroke Detroit might put out a bit more power with the propane because it's supercharged, but I'd be real skeptical that propane would add any appreciable power to a four stroke engine. The best ways to get more power out of any engine all involve getting more air through it. Porting, bigger valves, different camshafts, high flow exhaust, super/turbocharging and nitrous oxide for extra oxidizer. Once there's additional air to support burning it, then more fuel can be added to produce more horsepressure. I'd love to see some dyno numbers before and after one of these propane installations. Anything else is just conjecture.
Take care,
Carl |
Don KS/TX (63.15.244.65)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 06, 2002 - 2:31 pm: | |
George never had his propane system on his 8-71 RJ, only on the Cummins. He is a dealer for the Bully Dog system and loves it on his Cummins, but I am not as convinced. As an old trucker, I know for a fact that if you can add power and increase mileage as much as claimed without any ill effects, every cross country truck on the highway would be using one. I sort of agree with Carl, something just don't add up. |