Good morning everyone,
I have an 87 F-350 6.9 w/an ATS turbo. I recently changed the differential gears from 4.10 to 3.55. What a difference ! I can now actually drive on the highway. My only problem is the egt while towing a 5000 lb trailer. I have purchased a stage 1 water injection kit, that should arrive in the next few days.
My question is....... The hobbs style switch that these kits come with are vacuum actuated. The vacuum on an idi is constant. You cannot use your vacuum pump system for these kits. The so-called techs at these sales outfits are younger than my truck, and can't answer a simple question. Where on a turbo charged 6.9 can I install the Hobbs switch???????? As always, any help would be greatly welcomed.
Peter A.

 

You need to find the source of the heat. What are your egt and where are they measured. With the 3.55 you going to be slow accelerating. With that kit you will be covering up the problem. 5000 should not be a problem. How big and what type air filter? How big is exhaust? Are you pipes wrapped? How much boostime? Water temp? Oil pressure? Transmission temp? Are you ga guess mechanical or electric

 

EGT will climb to 1100 if I keep my foot in it. I have mechanical gauges, 3" exhaust water temp runs at 190, oil pressure 45lbs. I don't have any egt problems on flat land towing. Only when I get into the Sierra foothills and start climbing to the top. 7250 ft.

 

The trucks can be turtles going up hill. So you are going to use the kit for the hills.? 1100 is at the upper limit. For your switch you could get an el3ctric vacuum pump they are not that expensive. You could wire a toggle switch to turn it on off . It will shut itself off. Works with out a tank

 

This won't answer your question and might seem a bit off topic but it's really not.

I have basically the same truck but it's F250 non- turbo with 3 inch exhaust as part of the original Banks Power Pack set up. I'll be towing that much (5k) in hot weather, over mountain ranges and haven't even considered having any problems with EGTs.

Basically I just have a couple of simple questions (for anyone who can answer) and some comments.

I logically assume that a turbocharger raises exhaust gas temperatures right at the source (in the cylinder during combustion), especially under conditions like you are describing. How much of a difference that might be while towing up a long grade as you described would be interesting to know if anyone wants to make an estimate or logical guess.

Secondly, the pyrometer or "probe" on a turbo should be installed right before the exhaust enters the turbo ("turbine in") and as strange as it seems, the EGT is hotter there than it is in the exhaust manifolds! Unless I am reading the following wrong - see bold type:

Source: Exhaust Gas Temperature Basics - Diesel Power Magazine

My question with the above (important for further discussion below), is how long is the turbine-in piping (average) between the end of the exhaust manifolds and turbine in?

It appears to me that it must be at least as long as the exhaust Y on a non-turbo engine and probably longer, right? Yet the average EGT is higher at "Turbo In" than at a point inside a single exhaust manifold.

Did I understand the quoted text correctly?

Comments:
The placement of the pyrometer in a non-turbo engine is not that important. It certainly doesn't have to be in the exhaust manifold or next to an exhaust valve to give you accurate and usable EGT readings and it's better NOT to have it in the exhaust manifold.

On my Banks Power Pack system designed by Gale Banks (who I'm certain knew as much as most engineers in this field) the pyrometer "probe" is just below the connection of the exhaust Y to the first section of exhaust pipe. That is probably closer to the manifolds than the temperature probe at "turbine in" on the turbo engines. I perceive that with the velocity and volume of the of the exhaust gases from the exhaust manifolds through the 'Y' to this point below the Y, EGT is not going to decrease enough to make a significant difference on where the probe is placed, eg: = such as "below the exhaust Y connection" as Gale Banks placed it, compared to in the exhaust Y or probably the worst place directly into one manifold where most people think it needs to be.

In further support of that, another quote from that very knowledgeable article:

Me says: The turbo creates resistance to flow, increasing as RPM increases, converting that energy to boost, absorbing heat and reducing EGT at the "turbine out" side.

If you removed the turbo from that exhaust circuit the temperature difference in the before and after points in the exhaust would be about zero. What I am trying to illustrate is that changes in EGT in the piping beyond the ends of the exhaust manifolds whether it's 2 feet or 4 feet is insignificant

Further, for a non-turbo engine it would be better to place the "probe" below where the Y comes together and even below where it connects to the exhaust which is where mine is located. Either of those locations is comparable to the location on a Turbo engine at "turbine in" which if my understanding is correct is the hottest average EGT. It's NOT inside one exhaust manifold.

Last note on that and then a final comment about EGT:

Related to physical metallurgy which studied and I used to be well versed in, I don't like the idea of drilling and tapping into a cast iron exhaust manifold due to creating "notch defects" which are a source point for cracking when the metal is under physical stresses. The threads are notch defects. The stresses acting upon those defects are caused by thermal expansion and contraction, (plus some tensile stress) and combined with the properties of dissimilar metals (if they are dissimilar) being threaded into it. Even though the cast iron is soft (when machined or at higher temperatures), it's also brittle when cooled.

I have never seen a tapped hole right through a cast iron exhaust manifold (from the factory). Only on ears or a boss that was created in the casting especially for that purpose never going through the exhaust manifold itself. I might be overly concerned (probably - focusing on finer details like this are part of my nature) but....
there is probably a good engineering reason why there are not tapped holes directly into cast iron exhaust manifolds and I would say it's to prevent cracking.

Now onto my last comment. Sorry this is so long:

1,100 deg. F. exhaust gas temperature is not going to melt pistons as some people have feared. The pistons and cylinder walls (and head) are cooled and do not reach the temperature of the exhaust gases. Don't mark this as absolute fact but I believe that in one of these engineering research documents (I think it was testing IDI diesel engines and I may have that one here) when EGT reaches 1100 deg. the piston temperature is only in the 700+ deg. range.

That is plenty hot but it's not going to "melt pistons." Probably you don't want the pistons to get over 700-800 degrees for other reasons (higher piston temperatures could be a result, in part from engine overheating) and 1100 deg. EGT is just a good safety mark to start paying attention. I'll see if I can find that document (and others) in my folders or bookmarks. (I collect a lot of this stuff)

In all the discussions I have seen debating where to place the temperature probe on N/A engines, it's always by drilling into the manifold.

I think that the evidence presented above strongly supports putting the temperature probe BELOW where the two pipes meet in the exhaust 'Y' which is equivalent to the location on Turbo piping or below the connection of the exhaust Y to the exhaust, the difference between temperatures at those two locations being to small to be significant or even measurable on an EGT gauge.

If ANYBODY sees anything questionable or disputable about the information I presented from the outside source OR in my personal comments, please bring attention to it with a contrary opinion.
The last thing I ever want to do is give incorrect or wrong advice.

Thanks for reading it

 

Uh-oh. I re-read what I just posted and it looks like I've hijacked your topic to go in another direction. I did not intend that. I was and am interested in water/methanol injection. It's a topic that I don't think has been posted here in a long time and something I remember people talking about decades ago. Maybe 1970s. Or from "old timers" who knew a lot about engines and how to drive.

Towing or driving any kind of big vehicle over mountain ranges is very important and that is what I meant by "knowing how to drive" because most people now days don't know how to drive anything big in those situations.
Now-days the "old timers" is "us" so we have to know this kind of stuff.

What kit did you order and any special reason for that choice?

I am curious in case I ever need to, or could benefit from using water/methanol injection on my truck. From what little I remember it's quite simple. I'll have to look into that further later tonight when I have the time and MAYBE I can help answer your question.

One thing I won't be doing is installing a turbo. I don't want the extra expense, work of installing /maintaining a turbo. I don't mind going slow, I love to be on the road watch the scenery and listen to everything related to the vehicle performance with no distractions (no radio except sometimes late at night when I'm tired) and going slow is even better for those things and fully enjoying the trips between Point A and B.

Same rear end gears as yours, sterling 10.25, 355 gear ratio.

WHAT TRANSMISSION DO YOU HAVE?? I read the other posts you started but didn't see that mentioned. Mine is a C-6

I've probably read most if not all of the discussions in this sub forum about EGTs since the forum first went online. A few related to towing up grades.

I don't recall if reaching 1100 deg. is normal for a 6.9L turbo engine under those conditions, Is it?

I don't know if there is anything else that can be done to change that. Less of a lead foot?

Too late now but:
What about going slower? You may not get a chance to try it now, BUT if you do the calculations in the difference in time that it takes to get to the top, I'll bet you'll find that the tiny amount of time saved will not make a difference in your trips. If that means lower EGTs, that equals LESS STRESS a more pleasant drive, a better trip and being in better condition when you get to point B!

I learned that a long time ago, driving across country and in cities. I did the arithmetic for different situations a number of times and the perception of saving time is mostly imaginary and rarely significant. Speeding didn't save enough time to be worth it and that is relative to the situation of speed while towing up mountain grades.

 

Disregard my question about your transmission. I saw in another topic that it is a C6 automatic.

 

I've found that EGTs are related to either over-fueling or retarded/advanced timing.
Often, tweaking the timing a little will result in lower EGTs and better fuel economy(because perfect timing means the engine isn't fighting itself as much, using less fuel to maintain the same work.

If you are seeing smoke from the tailpipe when climbing, you are giving it too much fuel. Plain and simple.
If you need the extra power, you'll want to use a better turbo - the stock turbos tend to produce a lot of backpressure and heat when giving you decent boost(12+PSI), so going with a better turbo will net you increased power and less EGTs.

I'm honestly not sure on the water meth issue; I think it's more of a stop-gap measure myself(good for passing, dyno runs, really short term use) because you will use a lot of it.
Also you have to be careful about how much you use, and getting it vaporized - you don't want to hydrolock or something.

 

I have owned this truck for the last 24 years. It was primarily used as a ranch truck until 4 years ago, when I started doing some serious mountain towing. The pyrometer probe is installed at the bottom of the Y pipe. The differential was changed to 3.55 to keep the engine rpm from being topped out at 60 mph on the highway. Yes I can tow at a slower speed, and the people behind me can get as bent as they want! I ordered a Devils Own Stage 1 customizable system to attempt to lower my egt. I don't care about more power. I have a tool box in the back of the truck, and this is where I will be installing the pump along with a 5 gal tank. Steep two lane mountain roads at 35 mph are the problem. That's where the egt starts to get touchy. Now............ back to my question. Does anyone out there know where to mount the Hobbs switch on a 6.9 w/ATS turbo. The water injector is mounted directly into the top of the pressure chamber.
Sorry for being so abrupt, but we were getting far away from my actual question.

 

I think I figured it all out a couple of hours ago plus exactly who you can contact and how to contact them (several people) who can give you the exact answer but I am way too tired at 3:40 AM to concentrate enough to try to type it.

I'll get back to it sometime later this day (Sunday) with some good advice (I hope).

 

Firstly, what is your timing set at? What pump are you running?

Secondly, an intercooler would be a more prudent way to keep EGT in check. Once and done, no extra fluid to maintain and no electronics to fail. Only worry about extra consumables and complexity once you've done the basics.

Also, I've come to accept driving by the pyro is just how it goes with an IDI when towing in hilly terrain.

Since you seem set on going with water/meth injection though, waht criteria do you intend to trigger the injection off of? EGT, boost, and accelerator position are options that come to mind. EGT would probably be ideal, I'd think you could do something with an arduino and a thermocouple to activate a relay. Probably could do it more simply with basic electronics as well as a microcontroller is probably overkill for such a simple task. This seems the most direct way to address the concern, rather than assuming or chasing it by triggering off some other criteria you don't care about.

You mention a vacuum switch, which makes no sense to trigger using that. Diesels don't make vacuum. I did google "hobbs switch" as you mentioned that as well, and it seems to be a pressure switch. If you want to trigger off a pressure switch you just need to plumb the switch into the intake after the turbo. I don't understand what's to misunderstand about that? Pressure switch triggered above x psi to activate the relay for the water/meth pump. By then EGT will already be high and at slower speeds depending on gear and load you may have to set it to inject for far more duration than you'd need.

Do you know what you're trying to accomplish? Let us know so we can help you.

 

Auber Instruments makes a decent digital EGT gauge(thermocouple gauge) that's programmable to both use any type of thermocouple you might have(usually K type), as well as high/low limits which drive a relay output.
This is a simple solution - simply set your temp range for the water/meth and it'll close the relay contacts when you get there.
I'd probably also use a second method in series - either a manual ON switch or a boost pressure switch to keep 'edge conditions' from causing a problem(say engine dies in the middle of the road - you don't want the water/meth to continue to pump into the dead engine due to the EGTs being high still).

I second this.

 

Yes, an intercooler would be a better { and much moe expensive ] way to go, but I'm trying to keep things simple. I do in fact drive with a constant eye to the pyrometer when towing.I understand that a diesel does not make vacuum. The installation instructions that come with the kit say to " connect the switch to a vacuum source." This is obviously meant for gassers. The switch is in fact an adjustable pressure switch designed to detect boost pressure. This gets me {once again } back to my original question. Where to install the pressure switch ? The programable EGT gauge is a very interesting possibility, but I would rather stick with the supplied parts in the system before attempting to re-engineer it.To tell you quite honestly, I don't know where the timing is set. I have never touched it in 24 years. I have an original
{ to Me } Stanadyne pump, and yes..... I could probably throw a new pump and injectors in. I hesitate to do this because the truck only has 97000 miles on it, and other than the high EGT runs sweet.
And yes in answer to McRobb's earlier post........ It pushes black smoke under load. It always has. It also gets rotten milage. I probably would benefit by turning down the fuel a bit, and playing with the timing But, that is for another day and another dollar spent.
I know that project creep will bite me in the butt if I start messing with the pump at this time.

 

So an old stock pump not turned up or anything and timing set 97k miles and 30 years ago? Step 1 is set the timing, I'd go for 9* at 2000 RPM. It's probably at least a few degrees retarded which will make EGT higher. You may be chasing a problem that doesn't exist. If you're worried about money (intercooler) you should be checking the timing annually or at least every 20k-30k miles. When I changed timing from 6.5* to 9* it resulted in about 3 MPG better. That's huge when you're starting at 8.25 MPG.

 

I purchased this truck from the original owner, who had just had the ATS turbo installed at the ford dealership in Sacrament, Ca where he had purchased it. In the years that I have owned it, I have only put 7600 miles on it. That means that the timing and pump were adjusted to accept the turbo not more than 10000 miles ago. Your suggestion on the timing check is valid. Are you sure that 9 degrees at 2000 rpm is correct for a 6.9 w/turbo ?
Peter A.