Disappiontment In The Mountains

dieseldoug

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Got the old girl (91 F250 7.3 with Banks turbo) ready for our first winter trip south from Washington to Arizona. The E40D was rebuilt with all the new bells and whistles. Running gear was serviced as needed, and new tires added. So, off we went.

All was fine on the first leg from Seattle, WA to the mountains in southern Oregon. Then we hit the first long 6 % grade, and the climb was downright embarrassing. By the time we reached the top of our first of many the best I could do was 35 MPH in second range at about 2800 RPM.

Now I probable could have done 5 MPH more by slamming up against the governor, but really didn’t see the point in pushing that hard to gain so little. During the climbs I stayed in third range until the exhaust temp. hit 1000 degs., which was over the 900 I try to stay below.

On the flat and up a slight grade I could maintain 58 to 65 MPH depending on whether or not I was able to stay in overdrive. I learned that 58 was a much better choice, and my 7.3 was happier at higher RPMs.

Here’s my problem. I like the 29’ fifth wheel (7500# dry, about 8000# loaded) we now tow, and have no problems on local short trips. But the mountains are much more than I can handle.

I know I can get more out of my engine with more boost, heavier head bolts and so on. But, I’ve already sunk a bunch in the Banks, and don’t want to waste more on what may be a marginal power plant.

I love the truck and engine / transmission combination as it is. But, maybe it’s just not enough for what we plan to do.
 

snicklas

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I hate to say it, but unfortunately that is what I would expect out of an IDI. It sounds like it is close to stock plus a turbo. So you are doing good there, however, these trucks were designed in the mid to late 80's and your 91 built in the early 90's when the National Speed Limit was 55 MPH. So your truck performing well at ~55 is what it was DESIGNED to do. That is why it gets the best fuel economy at or below 55, and tows the best at or below 55, because it was never designed to go faster for the most part. That is why at 65-70 most say it sounds like the IDI is just screaming along, because well, it is.....

It is not just the IDI. It is is all the vehicles. I have 2 wonderful examples from both sides of the 55MPH "fence":

My 03 6.0 PSD Excursion. Was designed and built when the National Speed Limit had been raised to 65 or 70 depending on where you were. My Ex, I could hook my 5000lb TT to its back end, get on the interstate, set the cruise at the posted speed limit, turn on the A/C in 90+ degree weather and just drive. It would hold the speed fine at 65 - 70, and get decent fuel economy. Running empty, guess where it seems happiest to cruise..... about 72 MPH..... I have gotten 21mpg hand calculated at that speed on a long summer run with the A/C on max staying nice and cool.....

My 91 VW Jetta, just like your truck, was built to go 55. I daily drive it to work, with about half of the trip on the interstate 70 - 55 since I enter the Indy area, it is 55...... but doing 70 on the interstate in 5th gear it is SCREAMING!!!!! It is loud, obnoxious and generally pissed off about it. It will do it, but its not happy. But, slow down to 55 - 60 it quiets right down, gets fairly civilized and will just purr right along at that speed very happily. Knowing the era of the car, that is exactly how it would expect it to act.

I have been around the IDI's for a long time and have always heard: An N/A IDI will tow anything you want at 45MPH. A Turbo IDI will tow anything you want at 55MPH. But that is exactly what they were designed to do, because of their age. I would say a stock 460 from the same era probably would give the same performance, with less fuel economy.....

I know the IDI can be "hopped up". Look at what Heath has done, and Mel is doing...... so you can get it to do better. But, expecting an IDI to keep up with the new trucks out there, at the current speed limits is something the IDI was not designed to do. Sorry, not trying to put down the IDI, I will have one in the future, heck technically I do in the Jetta, but I know what to expect. They do a great job..... people are just trying to ask them to do something more than they were designed to do. Apple to oranges, but same as someone putting a 100+ HP tune on a 6.0 and blowing the heads off it, and then calling it junk. No you broke it, you pushed it past its design limits and it broke....... somewhat the same thing... push it past its design limits and it doesn't perform the way "you" want it to......
 

icanfixall

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What can you tell us about the fuel system. Now many miles are on it. Has the pump or injectors ever been changed. Figure around 125,000 miles for good life on the pump and injectors. If the pump was changed did you time the engine. What are the differancial gears. A set of 3.73 or 4.10 will haul what you have easy. Also did you turn up the pump when the turbo went on the engine.
 

theguruat12

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That sounds a little off to me, the part where you're going up a grade. You weren't towing this time, I think from reading your post? I can do a long grade, empty and unloaded, keeping 65 ish in my 6.9 with a non-wastegated Banks kit, hitting around 4.5 lbs of boost. Maybe it's just the difference in transmission (I have a T-19) and altitude, but that just seems a bit low to me.
 

reklund

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Need pyro location, boost numbers, timing numbers, etc. to make a good judgement overall.

You may be a good candidate for an intercooler- it made a world of difference on mine. I used to tow frequently through the NM and CO mountains, albeit not a giant 5er, but I was and still am happy with the performance from my old IDI.

I just crank up the radio to drown out the noise from under the hood and drive by the pyro. My engine has never been apart, aside from valve cover gasket replacement.
 

Black dawg

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Like said already, need to know pyro location. If if is before the turbo, you are leaving alot of power on the table only running 1000 degree max. My normal load that I haul (right about 18k gross) will show 900 deg on the pyro on flat ground.

Dont worry about your headbolts if it is a 7.3
 

chris142

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do you have 3.55 gears? if so 4.10's would make a huge improvement
 

FordGuy100

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Towing 6K, with 1500~lbs in the bed, I was able to hold every single grade between Texas and Oregon at 55mph. In fact, if I could hit any grade at 65mph, I could hold that speed in 4th (direct) gear. Anything less than 60mph (up 6% grades) I would loose speed in 4th gear, downshift into 3rd, and then could accelerate back to around 62mph and hold it there (governor).

You may have a an extra ton over what I had, and less aerodynamic. But, you should have been able to do better than 25mph. I'm fairly certain that I could do a 8K load and hold speed up hills. Any more than that, downshifting into 3rd would be required to hold 50+mph.

If I were you, I would wire up a torque converter lockup switch. That way, I could lock the converter in 3rd and march up any grade at a decent speed, while on the governor
 

79jasper

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I agree that an intercooler would help.
My suggestions are, straight pipe exhaust, and freer flowing intake.

Sent from my SM-T537R4 using Tapatalk
 

dieseldoug

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Thanks guys. Very interesting. Here are more of my specifics. E40D with 1 / 1 in 3rd, pyro. after the Banks, 4.10 dif., no inner cooler, 174,000 original miles. Both the transmission and dist. fuel pump are recent rebuilds. The Banks is waste gated. I turned up the fuel delivery 1/4 turn when I installed the Banks. In 3rd range on the 6 % I'm pushing just over 5 psi on the boost.

I have not checked timing, and definitely should. I'll get that done before the next trip.

By what you have all said I can tell I'm babying my truck under big loads. That's cause she's my baby. I've done nearly all the work on her myself, and don't want to break anything. ANYTIME I go over 950 on the pyro. I back off, and never run over 2800 RPMs. Maybe I'm treating my pit bull like a lap dog. What do ya think???? Can I kick her in the butt once in a while?
 

theguruat12

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ANYTIME I go over 950 on the pyro. I back off, and never run over 2800 RPMs.

I hold mine at 3300 RPM when I'm on the interstate at 78 MPH for about 7 hours when I go back and forth from Tucson and Albuquerque. I don't really like to hold the engine at that speed that long either, but IIRC according to others on here (towcat is one, if I remember correctly), it's perfectly alright to run these engines at the governor all day long. Although I have to say, even though the engine is screaming the entire way, it doesn't really seem to have an issue with it.
 

icanfixall

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Stll sounds odd that you have no power with the replacement fuel system and turning up the pump. With 4.10 gears you should be pulling a lot better than what you posted. Might want to check the gears and be sure they are actually 4.10. Just loft a rear wheel. Make a mark on the inside of the tire and a mark on the drive shaft. then turn the drive shaft and count the turns watching the tire mark make a completer turn. You will have just over 4 turns of the shaft for one turn of the tire. As for the pyro location and being a Banks wastegated turbo. I'm thinking you have the wrong idea of where the pyro actually is located. The heavy cast iron part of the exhaust is the before side of the turbo. The thin steel pipe going to the muffler is the after side of the turbo. I have never seen a waqstegated Banks have the pyro after the turbo.
 

Diesile

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5 degrees of advance with the rented meter turned both of my '94 factory turbo trucks into really responsive rigs. Both w/o coolers
and near stock pumps.
 

FordGuy100

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My bet is timing is off. How are the injectors?

If your pyro is after the turbo, then yes I would limit it to 900-1000*. The lower the rpm, the higher the EGT's on my truck when pulling. These engines when designed were put on full load at the governor for a long period of time, do not be affraid to run it up 3300-3800rpm's (depending on the pump, thats generally the governor range).

5psi of boost pulling those grades is also way low. Really if the wastegate is set properly you should be at 7-8psi. This leads me to think you have an exhaust leak, or bad timing (probably retarded). Call me crazy but I have had the wastegate blocked on mine for around 20k miles, so every grade I hit I was over 15psi.

An intercooler, better timing, and boost around 12psi would probably give your truck a kick in the nuts.

How tall is that 5th wheel?


The most pleasant (minus fuel consumption) towing for me up grades is 3rd gear. I never had to worry about EGT's (1100-1200* but my thermo is in the exhaust manifold) and it would never loose speed.
 
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