Engine/Transmission (1998.5 - 2002) Dang it, I still can't decide - need more advice

[Boondocker]

I think what I need to do is just belly up to hook my truck to a trailer and do my own testing.

Better yet Justin, hook up that trailer, hand the keys to your wife, and you just nap in the right seat while she tows up the hill I'm not diss'n your missus, maybe she's as savy a driver as you. When I let my wife drive, I sleep with both eyes open if you know what I mean.



Now let's talk about engine safety. Where do you want engine management control - driver or automated? Sure, you and I can manage the balancing act, controlling the pyro needle with the right foot, and probably find it one of the enjoyable challenges of vehicle operation (sick). The thing is, I already do that. Adding another ~60 HP (M1. 6 --> M4) is clearly not recommended with a stock turbo... which is where this discussion started. So it seems, the best case is, more fuel + more air = still driving by the pyro like I do now.



I guess the bottom line for towing is, there is no advantage to more power because of the trade-off of higher EGT risk, which restricts you from using all the available power. More power is just for fun - blowing smoke (not fun in my book) and blowing by the unsuspecting



I suppose I could add power, then set the Smarty on half power - yuck!



Neil

 

[Hohn]

Yep, I drive by the pyrometer and try to limit it to 1150-1200 degF on the long grades. :{

Rusty

Actually, I'm proposing you give it the pedal to sustain 30psi and look at EGTs, which is slightly different than going WOT and backing off to 30psi.

If EGTs are the same at 30psi before and after the injector installation, then my point is somewhat proven.

Of course, this ignores the large psychological factors.

 

[RustyJC]

Actually, I'm proposing you give it the pedal to sustain 30psi and look at EGTs, which is slightly different than going WOT and backing off to 30psi.



If EGTs are the same at 30psi before and after the injector installation, then my point is somewhat proven.

Justin,



Just for you, I'll try to remember to run this little test next time I'm pulling the 5th wheel. :-laf



Rusty

 

[Hohn]

Better yet Justin, hook up that trailer, hand the keys to your wife, and you just nap in the right seat while she tows up the hill I'm not diss'n your missus, maybe she's as savy a driver as you. When I let my wife drive, I sleep with both eyes open if you know what I mean.

Now let's talk about engine safety. Where do you want engine management control - driver or automated? Sure, you and I can manage the balancing act, controlling the pyro needle with the right foot, and probably find it one of the enjoyable challenges of vehicle operation (sick). The thing is, I already do that. Adding another ~60 HP (M1. 6 --> M4) is clearly not recommended with a stock turbo... which is where this discussion started. So it seems, the best case is, more fuel + more air = still driving by the pyro like I do now.

I guess the bottom line for towing is, there is no advantage to more power because of the trade-off of higher EGT risk, which restricts you from using all the available power. More power is just for fun - blowing smoke (not fun in my book) and blowing by the unsuspecting

I suppose I could add power, then set the Smarty on half power - yuck!

Neil

My wife will never drive the truck without it on "24V Valet"- AKA Smarty's half power. She's not very experienced with the truck, and it shows in her driving-- but she gets better each time.

I agree with your point that more fuel is of no advantage when you're not towing.


But my whole point is that you can run a larger injector for that remaining amount of time when you are NOT towing.

Now a guy like Rusty would probably not benefit at all from this, as his truck is pretty much 99% tow duty or just weekend trips to warm the oil.

But someone else who rarely tows need not go with a tiny injector to accomodate the 20% of the time that they might tow.

If you have safe temps at 30psi, and can pull your trailer up the grades you face at 30psi, then it doesn't matter whether you are stock or have Mach 6s-- if you limit the fuel used, the risk is gone.


Like I said before, RESPECT the fueling you have, and there will be no problems. If you can't pull the grade at 30psi, downshift to where you can-- just like when you were stock.


If you have enough turbo for 350hp of safe towing, then as long as you use <350hp, you'll have no problems regardless of injector size.



I'm not saying that everyone run out and install Mach 6s in their trucks. I'm not arguing practical application or how it plays out in reality-- I'm talking THEORY and PRINCIPLE. .

If you have the discipline to manually impose limits on the truck that are no longer there, then you can have safety.

I'd recommend you restrict the driving priviliges to those who also have such discipline

 

[Hohn]

Thats hitting the nail right on the head. You don't WANT to pull your foot off - you HAVE to.

Actually, I *want* to lift my foot off the pedal, knowing I can't afford a new engine

 

[ThrottleJockey]

Injector size is the key to it ALL.



When you tow with a stock injector, the fuel is metered somewhat by the hole size. Imagine filling a bucket (the combustion chamber) with, let's say, balls, until we have, say 16 pounds of "fuel".



Bear with me Stock injectors 'fill' the bucket with 16 pounds of GOLF balls, say 64 golf balls 1 at a time. The golf balls represent fuel.



Go with a big injector and you change the size of the fuel charge, even at limited throttle actuation.



Your golf balls changes to a bowling ball, albeit it is still only the SAME amount of fuel in both examples, (our fictional 16 pounds) we are filling our combustion chamber with ALL the fuel SOONER. Imagine dropping a bowling ball into a bucket. Boom.



Now we have all this fuel in the combustion chamber and NO AIR to burn it all because we still have our stock turbo and the backpressure is keeping the valvetrain from scavenging the exhaust and we get higher EGTs than we want while towing.



Air in. Air out.



I personally want a Phat Shaft 66 with a 16 sqcm wastegated housing, and I'm a Hotshotter.

 

[Hohn]

If you have 16# of fuel in both cases, how can one be running out of air and the other not??16# of fuel is 16# of fuel-- right? This is all happening with all the valves closed, so the amount of air in both cases is the same, right?

I think what you are alluding to is "rate of discharge. " In other words, once pop off pressure is reached and the injector opens, how much time will it take for X amount of fuel to flow into the cylinder and the injector to close?

We need to think of this in terms of a timeline (in milliseconds or maybe even microseconds) and how cylinder pressure rises as time passes-- and how does rate of discharge affect this?

I'll tell you *my* theory:

Cylinder combustion is just like any other combustion, only it happens in a much shorter timeframe. You can model cylinder combustion in super-slow motion using a campfire.

With combustion, you want the progression from tinder to kindling to main fuel to happen as fast as possible without gettting to the main fuel too fast and putting the fire out (or causing smoke).


On our VP44 trucks, the quantity of fuel injected is determined by HOW LONG the bypass solenoid in the pump is held closed. Initial injection pressure is determined by injector pop-off, no matter whether you have stock sticks or Mach 7s.

Many people have a mistaken concept of how pop-off pressure works. Some people think that the injection pump builds up all this pressure, and then the injector pop, and relieves all the pressure. In this case, the pop-off pressure is the highest pressure achieved.

But what happens in reality is that the injection pump builds pressure up faster than the injector can relieve it. The injector opens at the pop-off, and pressure CONTINUES to rise because the pump can deliver fuel faster than the injector can flow it. That makes sense, given the comparatively large 7mm plungers (on an HO) in the pump compared to the miniscule surface area of the nozzle holes.


Now, as you increase the flow rate of the injectors, you get to the point where pump capacity does not exceed injector flow rate by enough of an amount, and overall efficiency suffers because pressure drops too far too soon.

But you're talking about HUGE injectors at this point-- well over 150hp sticks for an HO, and well over 220hp sticks for the SO with the larger (7. 5mm) plungers.



Bringing in all the fuel SOONER only matters if you bring it in so incredibly fast that combustion barely occurs, if at all. In our campfire analogy, this would be like trying to light a tree stump with a Zippo.


But the difference in particle size between a large injector and a small one is much closer to the difference between flour and sugar than the difference between sawdust and a tree stump.

But there IS a difference. Most of us have been around sawdust more than once. Look at the sawdust made by a chainsaw-- it's somewhat coarse and it's not much of a "dust" , as it's more like "shavings" or "chippings".

How does that compare to the sawdust produced by finish sanding? Obviously, the sanding dust is MUCH finer, and it's so small it hangs in the air like a vapor-- unlike the chainsaw product which falls right to the ground.


Particle size is important here because it's related to atomization of an injector. The smaller atomization of a smaller injector hole produces a finer particle which burns faster (and hence, more completely).

But on the other hand, the larger injector makes somewhat larger particles, but provides more time for them to burn.

Returning to our sawdust example, the sanding dust would burn faster than chainsaw dust, but I can probably burn 10# of each in the same amount of time if I burn a pound a minute of the slower dust instead of . 8lb/minute of the finer. Follow me?

So a larger injector NEEDS more time to burn because of the lower atomization. However, it GETS more time to burn because of the larger flow rate the brings ALL the fuel into the cylinder in less time.


The two factors tend to cancel each other out-- but may slant one way or the other depending how far in either direction you go.


In my particular case, I've seen an almost perfect balance of this. When my truck had stock injectors, I got 16mpg around town, and 20 on the hwy.

I now have 150hp injectors from Don M installed, and I still get that same 16mpg in town and 20mpg hwy. How can this be?


Now, I can tell you with full certainty that the larger injectors are less efficient at idle. The fuel odor in my exhaust is MUCH stronger with these large injectors than it was with stock injectors, and half again or so stronger than it was with the DD2s.

This is visible at night, as well-- at low engine speeds and low workloads, I can see a steady haze in the trailing headlights until the engine is FULLY up to temperature.

But at higher workloads, the injector efficiency recovers. This is proven by 1) the consistent hwy mpg and 2) the consistent EGTs on the hwy.


The hotter the engine is running (working harder) the more efficient the larger injector becomes. I'd expect that a Mach 4 injector would actually give BETTER mpg towing a moderate load (EGTs steady at 1000 or so) than even a stock injector would.


Air in and Air out doesn't really matter in this case becase we are talking injector efficiency, and airflow for our scenario is kept constant.

JMO

 

[nps]

Actually, I *want* to lift my foot off the pedal, knowing I can't afford a new engine

OK - remember that thought when you finally hook up to a trailer and, ascending a large hill, come up behind a durapuke pulling a similar sized trailer.



Oh, and BTW your theory sounds plausable, but ignores turbo drive pressure factor alluded to by ThrottleJockey. This factor would suggest that the higher boost pressures acheived with larger injectors would in fact cause an increase in EGTs. But if you constrain the boost pressure to remain within the turbo's map, then I think your theory is sound.



Think either way the bottom line is that bigger injectors makes it much easier to get into trouble when towing for a variety of reasons. We haven't even talked about the effects of a 3rd gear launch hooked up to a 15k# 5er. :-laf

 

[Hohn]

Amen on the psychological factors... If we had a nickel for every time our egos made us do something foolish... .


Anyway, my whole point is there IS no increase in drive pressure because you're using the SAME AMOUNT of fuel and making the SAME power!

Again, a stock engine making producing 200hp (say at 90% "throttle") and one with mach 4s making 200hp (at say 60% "throttle") are going to have similar if not identical EGT.

I actually take a sort of perverted pride in towing slowly and extra carefully when I do tow (quite rarely). I probably have higher EGTs empty than towing, just based on driving style!

BUT, having large injector and not going full throttle is part of my personality.



For example, I am an electric guitar player. One piece of equipment I have is a Mesa-Boogie guitar preamplifier that can generate a LOT of signal gain. So much so that the included instruction manual actually says "USE COMMON SENSE. DO NOT TURN THE GAIN ALL THE WAY UP". Why did they design this preamp with the capability of generating more gain than someone could use?

It's simple. Different guitars will be connected to this preamp, and each of them will have different limits as to how much gain can be used before the sound just goes really bad. For example, a vintage Telecaster or Stratocaster with low-output pickups won't sound as good at high gain as a modern guitar with high-output pickups. That's why the hard rock guys use these "hot" pickups, and and the blues guys or guys who play clean tend to prefer the tone of low output pickups.

By designing the preamp to give huge amount of gain, you can cover all the bases. (and all the basses in your band, too, hahahaha).


So, back to trucks. By installing larger injectors you can have BOTH good towing performance AND superior performance when empty.


The penalty for this flexibility is that you MUST respect what a lack of discipline can do. For my preamp, turning it all the way up could wipe out $2200 worth of vacuum tube electronics.

On the truck, it's even more expensive. All the more reason to be super cautious when towing...

In the end, it's all up to personal preference. If you want to treat your truck like a Ronco Showtime Rotisserie (i. e. "set it and forget it"), then go right ahead. It's very safe and you'll be happy.

But if you're willing to invest a little more into it (discipline and attentiveness),then there are rewards to be had

 

[RustyJC]

Think either way the bottom line is that bigger injectors makes it much easier to get into trouble when towing for a variety of reasons. We haven't even talked about the effects of a 3rd gear launch hooked up to a 15k# 5er. :-laf

Or a WOT acceleration run through the gears on a short freeway entrance ramp to get up to the 70 MPH merge speed - with my 16K GVWR 5th wheel in tow. (Hint - don't look at the pyrometer! ) :-laf



Rusty

 

[NoSeeUm]

{snip}



I guess the bottom line for towing is, there is no advantage to more power because of the trade-off of higher EGT risk, which restricts you from using all the available power. More power is just for fun - blowing smoke (not fun in my book) and blowing by the unsuspecting



{snip}

After thinking about it allot, Boondocker spells out where I am at. Thats because I often consider that no modification is required to begin with. The Smarty, by itself, meets all my needs and the rest is just for fun.



I had no clue there was such a radically different opinion about how to do this. What kept me from moving forward was that I really would have liked to install the M4's and keep my E-Brake. However, it seems most resonable to pick which the way works the best for you and go with it. As you get about the same Hp in the end. At pretty close to the same price.



Other than tapping the pump wire, what is the biggest point of contention?



Jim

 

[RustyJC]

Again, a stock engine making producing 200hp (say at 90% "throttle") and one with mach 4s making 200hp (at say 60% "throttle") are going to have similar if not identical EGT.

OK, I'll buy that. EGTs at a steady-state 70 MPH Interstate cruise with the 5th wheel in tow aren't significantly different between the stock HO injectors and the DD2s. I have, however, lost between 0. 5 and 1. 0 MPG when towing with the DD2s. I'm sure part of that is because I use the additional power, but some of it is probably related to the less efficient atomization of the extrude-honed DD2s as well - too bad EDMs were just in their infancy when I bought the DD2s.



Rusty

 

[Hohn]

After thinking about it allot, Boondocker spells out where I am at. Thats because I often consider that no modification is required to begin with. The Smarty, by itself, meets all my needs and the rest is just for fun.

I had no clue there was such a radically different opinion about how to do this. What kept me from moving forward was that I really would have liked to install the M4's and keep my E-Brake. However, it seems most resonable to pick which the way works the best for you and go with it. As you get about the same Hp in the end. At pretty close to the same price.

Other than tapping the pump wire, what is the biggest point of contention?

Jim

OK, well I re-read your lead post Jim, and I think I've lost sight of the forest for the trees.

You made it clear that you don't to worry about EGTs-- the "Ronco" approach (set it and forget it).


The more I think about it, the more I think you'd be a perfect candidate for Mach 1 injectors.


I installed a set in a friend's truck back in Cheyenne. He has an 01 6sp similar to mine, but tows a lot. He already had an EZ installed.

The overall results were very impressive. Most impressive was the smoke-- or lack of it. These were SUPER clean, even in 6000 feet elevation. SOP power showed that these M1s (rated at 65HP) were just as strong as my DD2s (rated 75hp).

Moreover, EGTs are never a concern-- even towing heavy at somewhat high elevations. He's well within the limits of the stock turbo, which he wanted because he too has a brake and wants to keep it. He bought a water/meth injection kit, because he wanted to play with it, not because he really needed it. That, and he's SUPER cautious about EGTs, preferring to keep everything under 1200, even towing heavy in thin air.

Most impressive is the fuel economy. On a trip to SD running empty, he was knocking out a steady 22-23 mpg, hand calculated. That's stellar for a 4x4 imo.

He ordered the M1s while I still had my DD2s, and that sealed the deal for me-- I was going to buy some Don M injectors, not a doubt in my mind. I was extremely impressed with them-- the combination of clean and power is amazing.

For a tow rig, I don't think I'd even go as big as the commonly-loved 1. 6s. You just don't need that extra fuel.


~~~~~~
Now you're probably wondering why this guy who just spent a lot of words justifying Mach 4s is now recommending Mach 1s

First, I wasn't really trying to say that M4s SHOULD be used for towing, just that they CAN be. Also, high EGT is not a forgone conclusion, because there IS a driver present who has some say in how the vehicle is operated, and thus the EGTS that result.

But I lost sight of what you want your truck to do and be.

I've also found in life that I'm much happier if I err to one extreme or another with many choices. For example, when I buy tools, I will buy either the best of a kind in existence (that I can afford, anyhow), or I will buy the cheapest piece of junk I can find. I find that I'm often pleasantly surprised by how well the cheapies work, and never disappointed with the expensive stuff.

So, as it related to injectors, I would tend to go small (<70hp) or go really big (150 or more). So, if you want to be safe-- it's best to be REALLY safe so you can truly put your mind at east. Or if you accept that YOU are the only thing standing between you and danger, go as big as you think you will ever want to.


How many of us are on our first set of injectors?

 

[nps]

How many of us are on our first set of injectors?

I am - 1st and last set. Got better things to do with the $$.

 

[Boondocker]

How many of us are on our first set of injectors?

Did you mean first injector upgrade or stock injectors?



stock

RV 275

F1 Mach 1. 6



The M1. 6 run higher EGT towing than the RV 275s. I can't say how much higher, as I don't run it higher, it just gets there quicker.



Neil



P. S. I still think I need a bigger turbo. The question is, do I size it for M4s

 

[darkhorse]

How many of us are on our first set of injectors?[/QUOTE]



I went from stock to Mach 1. 5's. That with an APB gave me more power than I could use but I got curious about the reports of the Mach 4's. I ended up with Mach 3. 8's. The power delivery is much smoother than with the box turned up on the 1. 5's. A DZ 14 keeps things cool enough for what I do & I can keep my Banks Brake.

 

[NoSeeUm]

{snip}



How many of us are on our first set of injectors?

I am still running stock injectors.



Jim

 

[Boondocker]

I just wanted to say how much I've enjoyed this thread. It's relevant to me, educational, a good read, and joined by some of my favorite people on the board. This is what makes my TDR membership so worthwhile.



Right on guys!



Neil

 

[SnoKing]

The more I think about it, the more I think you'd be a perfect candidate for Mach 1 injectors.

Hohn are we on to something here. I run Jammer 1's, Comp in the EZ and full DTT transmission and my truck tows great. I need to can the HY35, but no one will give me their old HX35-12W. I too want to retain my turbo mounted EB. Only EGT issue I have are at high RPM in the mountains when pulling hard in 3rd gear at 60+ MPH. HX35 should help that. I am retiring the end of June and afraid to tell DW that I want a new turbo, after the 8K (most with DTT - transmission, Comp and Jammers) I spent on the truck the year before last. Maybe Bill and Stefan will dust off an old one and send it to me as a retirement present!



SNOKING

 

[ThrottleJockey]

GREAT post Hohn!



I wish you were right. Your'e not, in regards to towing, but your'e close.



I know Mach 4's are too big without turbo matching consideration. (Twins?)



Injector size is hugely important in towing because of the "T" word I dare not utter in this thread. It will ruin this conversation and I for one, am enjoying this discussion.



By the way Hohn, when you are ready for your towing study, I have the perfect model I can swing by your house on my way to Seattle/ Tacoma.



Teton is rolling out their new Reliance Royal 40 as we speak.



It has a GVWR of 24000 pounds. CDL Class A only. I rolled one across a CAT scale. It only actually weighs 20485 empty. They sit on 3 axles and the hitch weight is 4600 pounds. :-laf