Curious about where would be the best area & in which manifold to place a EGT probe on a dual exhaust 671 Detroit
Spec tells us that EGT for the 671 naturally aspirated engine is 900F.
What would be a cautious high temp?
I've added propane injection and am curious of any variations in EGT.
A probe in 1 manifold is not going to be much help,you should be 870 F with N65 injector's @ 2300 rpm 1100 F is toast at a long period of time.The propane injection I won't go there ;D
2 stroke engines flow a lot of air and being 2 stroke, just don't have the big power jolt 4 stoke engines have. With a non turbo 6-71, if you stay at a N65, you don't have too much to worry about burning anything. 7G75 on turbos. I had a 8V-92TA with 9A90 and was told an pyrometer was not necessary. Don't waste your time, effort and money on a pyrometer for a 2 stroke engine. Good Luck, TomC
2 strokes have a higher EGT than a 12.7 series 60 by over 100 degrees.TomC I have never saw a V manifold that didn't have a boss to tap for a probe.Just reading from between the lines I think this guy wants to monitor his EGT using propane which is probably a wise choice on his part
I appreciate the feedback guys. Want to keep the old girl ticking like a fine watch. Thanks
Main thing, don't run it below 1500 at full fuel on the grades. If you turbo it, it'll run like an Na 8-71. Best thing we did to ours.
Thanks for all the feedback, this beats the Encyclopedia Britannica! Remember them...LOL
I've decided to go with a dual gauge (info attached) and a probe in each manifold. Found a nice source for pyrometers & much more - Hewitt in Huntington Beach CA. They even had their Tech/Engineer on the phone walking through it with me. Sometimes the piece of mind portion of things is priceless.
On huge Diesels on ships and in generating stations, they use a pyrometer on each cylinder. Also they use a tachometer on the turbocharger. Both of which we don't use in trucks and buses. Good Luck, TomC
Make sure they have the proper extensions to reach clear to the drivers area. The ones I've seen need special resistance wire.
I got ripped off for years buying the harness wire from pyrometer gauge manufacturers,then I found out you can buy it at about any pottery supply that sells kilns for around a dollar a ft
A follow up on my pyrometer project
I ended up tapping both manifolds
I went with an "old school look" double read pyrometer
Looking forward to getting it on the road, feeding it some propane
And see what its doing?
An update on 671 NA propane injection. Did a small dry run towing a 6000# toad for the 1st time since installing propane injection and pyrometer/thermocouples. The most substantial noticeable change (w&wo propane injection) is a slight increase in power and top end with propane. As far as EGT, couldn't get the temps to quite touch 900 degrees - probably due to Florida's flat terrain. Very noticeable increase in power when pulling overpasses and small upward inclines (holds speed in high gear). Propane pressure is set at 8-9 psi (when flow is off) with 1/8" entry into air flow just ahead of blower. Pressure drops approx. 3 psi when flow is turned on. Not a whole lot of difference in smoke out tail pipes with and without. I'd like to bump the pressure to ten psi (probably as a max). One term being used in propane injection dialog is "pinging". I know what it sounds like - but should the driver be able to hear it from the drivers seat or should taking a listen be closer to the engine? In general I'm pleased with the modification, especially with the added toad weight. Looking forward to some mountain driving...
Impossible to hear on a diesel, and knock sensors will not work..first sign is holes in pistons.. not as bad with low pressure....btdt...rdw
Quote from: gg04 on March 16, 2016, 07:30:58 AM
Impossible to hear on a diesel, and knock sensors will not work..first sign is holes in pistons.. not as bad with low pressure....btdt...rdw
;D yep pole vaulting over piss ants
Quote from: gg04 on March 16, 2016, 07:30:58 AM
Impossible to hear on a diesel, and knock sensors will not work..first sign is holes in pistons.. not as bad with low pressure....btdt...rdw
rdw?
Pinging,prefire knocking... detonation from pressure..rdw
You may need larger feed lines. How about water injection while you are at it to provide combustion cooling? It keeps exhaust temps under control on my 6.5 pickup with power chip. Mine is variable with boost and flow control.
I love Banks Power take on propane injection "save the propane for the cook stove" ;D
I love my little extra hp I get from my propane. It keeps both my buses from loosing momentum on grades and hills. I've seen bent rods and holes in Pistons on 71 engines not using propane. I use propane and have yet to bend a rod or put a hole in a piston so it must be better than diesel. :) just using the logic
Seriously the amount I use and the way it's used it's not a big deal as a few people try to make it out to be. A 10-15hp boost is nice and worth it to me. If used in higher heat situations and with a lot more gas yep I would agree it would be harmful but fogging in small amounts does not effect the timing, does not increase the engine temp, and yet gives a little more power. It's not a $ diesel fuel saving effort. My buses could not even go up a simple overpass without loosing 5 mph or more and with the propane I keep up my speed. I can cross a long grade at 50-60 instead of 20-25. I can accelerate up steep hills with it when without it I loose speed. i would even lean towards the idea that the benefits out way the negative side effects. I love my results. Only warning is don't use too much, and don't operate your engine like its not a 71 series, all the 71 limitations still apply as far as lugging, temp range, etc. Used in a small limited capacity and in my 3 years of real world using propane, on two different buses it works. Yes Clifford just saw an engine that was destroyed possibly and probably from propane. But that is not apples to apples as that system used more than 10x the amount of propane and added even more with higher boost. It's not the same at all.
I had a compromised cooling system this past summer and I could run 10mph faster at 5 deg cooler than I could without the propane on. I don't remember the exact numbers but it's documented on my website and it was dramatically different like that. For example I was 190 at 50mph without propane but if I turned the propane on my temp would drop and I could go 60mph and maintain 185. If it turned the propane off the temps went up and I had to slow down. If and or when I blow up or destroy an engine I will be sure to post about it. Until then I'll be safer in the right hand lane going much closer to the speed limit instead of under 1/2 or 2/3 of what is the posted speed on grades and hills. Anyone that says a bus is better going 22mph up a grade is dumb. It's Better for the bus but not better for your safety because of the semi's behind you are closing at you 40-50 mph faster and not paying attention. Same thing with "I can see and enjoy the scenery when I'm going slow". Good, go slow on a side street or frontage road, not the Interstate and keep your eyes on the road and traffic not the scenery anyways. Using propane has benefits along with the risks... That's all I'm saying. Around a $150 investment is what my system costs and it works!
The propane debate has last 50 years it comes and goes it will destroy a engine I have seen it more than once.Electronic engines have a more control for the time of injection the old manual 2 stroke engines don't you flip a switch it's there.
Sooner or later it will take a toll, first you get 1 weak cylinder pumping a little oil then it's down hill from there.
Scott's little system is nothing new it's been around long when people would draw the system on a big chief tablet and pass it around to others long before the internet and YouTube.
The engines will usually blow at full throttle when it's low on oxygen and you flip the switch.
I don't understand why propane you can achieve the same affect with air and have full time power but people like to get outside the box and I am ok with it just not for me
I recall some stuff from long ago discussions...
No matter the fuel, you need oxygen to get it to burn.
Is there any "spare" oxygen present in the cylinder before the propane is added?
If there's a bit of smoke, indicating unburned fuel, is all the oxygen being used up?
The propane has a cooling influence on the burn. Cooling the burn has advantages all the way back to the end of WW2, with the first water injection used to good effect to get the heavy bomb loads off the runway.
Are we being fooled? Is it the cooling, not the burning, that is giving the modest improvement?
Would water injection accomplish similar effects to the propane in our 2 strokes?
I miss the engineers that used to haunt the bus boards and the chat rooms, back when the internet was shiny and new...
happy coaching!
buswarrior
It is replacing fuel. When you are on the governor and turn the propane on, the fuel racks dial back maintaining rpm. It is the propane giving you more power and in smoke situations my exhaust smoke dissapears and or lessons greatly when the propane is turned on. I firmly believe it gives a more complete burn of the fuels too. I think it adds to better performance for a few reasons not just adding a fuel. Cooling, increasing o2 via density, the propane is more evenly mixed already with the air in the cylinder Allowing the diesel to burn better and cleaner when it ignites. It works for me. I've experienced it first hand make my bus Getty up and go! I was about to roll backwards down a steep hill with my automatic screaming full throttle and when flipping on the propane I went right up it and the mosquito fogging disappeared.
Quote from: Scott Crosby on March 17, 2016, 02:12:58 PM
It is replacing fuel.
I rest my case that is what put Bully Dog out of the propane injection business Propane is like CNG it has no upper cylinder lubrication diesel engines are required to have.Just be with careful it,I have a 92 series here that is complete junk due to propane use that went astray with a factory installed kit
It's less than 10% and I only run it on grades and hills. If it was on full time and at a larger amount the lubrication would be effected but not as much as the low sulphur fuel is effecting it. Any fuel additive for lubrication will be a benefit above and beyond any small reduction from the propane.
I never jump into the fray, but I'm feeling risky today so I'll just say this, I know nothing about propane injection on diesels, but I've done a ton of research on propane as a fuel for my twin Honda EU3000is generators. They have a propane kit for them. A recent thread by a guy who bought one of these generators new and ran it on propane was very interesting. Basically, he tore the motor down after the genset died (6000 hours) and realized that the propane fuel system caused it to run too hot and ended up killing the motor. He pulled the system and is running gas only now after installing a fresh honda motor. Probably completely unrelated, but generator owners are reporting shorter lifespans running propane.
off topic, the delicate balance between fuel economy and lean burn is the devil with compressed gas fuels.
At Big Transit with the CNG Cummins engines long ago and far away, run them rich, get poor fuel mileage, run them lean to get better mileage, burn the exhaust valves and snap them off.
I'll bet the generator propane things will be related.
happy coaching!
buswarrior
That's all fine but I don't think it really applies or matters much when the propane is only a 10% mix used for one min here and three min there. Total usage is probably averages to two min per hour of running.
It all adds up anyway you slice the pie,propane is a dry fuel I recall the old 549 IH V8's and the 534 Ford V8 you had to retard the timing a lot to keep one from flying apart every 40,000 miles when using dry fuel back then it butane
My bus's will continue to work because I use 40wt cf2 oil... That's the answer to everything working right from what I've read. :)
If I break it I won't even complain about it. It's been that good to me and such a benefit to have the power with the flip of a switch that I don't care at this point. I wonder How many years I need it to continue to work before people will believe it works?
You're a living science experiment Scott :) and if anyone is gonna feel comfy breaking down the motor and building it again, it would be you. Keep reporting back your results. Sorry OP for how much this thread drifted :)
Sent from my iPhone using Tapatalk
LOL this debate has been going on since the 60's it just pops up from time to time like every 7 or 8 years, it was a running soap opera in 2007 on the Detroit Diesel Yahoo Group page for a long time
Wow and the conversation goes on... It's all better than the average bear! I'm actually enjoying all the communication. I hope we all are. As far as I'm concerned It's all good...I first asked the questions and now have everything installed. I'm willing to feed it a blend and monitor it at the same time. Heck I (& I know we all) have done things with our bodies we shouldn't have so why not mess with the engine a little. I've been doing my vitamins for decades and so has the ole girl. 40 wt delo 100, fuel additives to compensate for the new bio-diesel, stop leak on occasion for a small headache, & on & on. The 53 has 7 to 9 million miles on her. A 69 repower that's been tuned probably twice since then. I'm considering the propane injection part of her vitamin regimen. we're only 2 years apart. It'll be fun to see who can outlast the other...It's all good
The first time I ever saw Propane injection was when I had brown hair working for Stewart and Stevenson in Houston in 1960.A trucker came in with a engine problem. I noticed a bottle of propane beside his seat and hose hooked to the blower pipe stand.
Being young and dumb I ask what is that for he grins and tells me that is my "topper" and said what is a "topper" he told me when you see a hill you turn the bottle on and the 8v71 tops the hills like they weren't there.
I thought to myself yea like we have a lot of hills around Houston,he left and I pulled the left head off, he came back the next day to check on his engine, he walked over to me and ask did you find the trouble son.
I laid the piston and rod out for him to see and told him your "topper" did a good job it took the piston,liner and rod out.
I'll never forget him he said damn son I must have forgot to turn it off he laughed and said fix her up son I got cows to haul.The boss made me remove his system and they explain to him they would not warranty the work with it connected and he was ok with he even gave me a 10 dollar tip
A true story only a trucker could come up with a name like "topper"
Hey luverbus, at least I followed your advice and tapped both manifolds, thanks for sharing...
I look at it like this I don't care one way or the other because it's your bus,your engine and your money, I just won't use it I never saw good results with propane injection
10-4, I know what your saying. If I screw my engine up it's my own fault. The benefit is the small boost if gives. I'll be able to monitor the ole' girl with & without injection & make my conclusions and decisions. I'm conservative by nature so I probably won't overdo things but its a blast walking the turtle a little faster - although we never needed "fast". Some people ask "why carry such a heavy toad" (over 6000#) It's such a nice resource to have, It's our secondary camper (full size P-U with camper shell) then there's the dog - so its more room all the way around. We've always liked to tent camp off the path the coach takes - with this Alaska trip coming up - any camping we do away from the coach will not be in the house of cloth! It will be in the truck or a lodge. Common sense kicks in there. We'll save tent camping when we get back to the lower 48... As far as the injection goes - it's more to offset the toad weight than anything. Periodically when we're not carrying the toad - it feels like were in a race car - well not quite but you know what I'm saying - right?