Max boost for a 7.3L IDI N/A
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Junior User
Joined: Jan 2009
Posts: 89
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From: Reno, NV
Max boost for a 7.3L IDI N/A
Bone stock, using a factory turbo from a '93 F-250, what is the maximum COMPLETELY SAFE boost I could push into a N/A 7.3L IDI? I heard the N/A motors have weaker head gaskets than the 7.3L IDIs w/ factory turbos had... I may end up droping a N/A motor in place of the turbo motor due to head issues on the turbo motor. The exhaust system is not stock, but everything else is.
Basically I'm looking at getting this truck, and it looks like it would be a lot cheaper (very important in my case) to simply drop the N/A motor in rather than drop a new set of heads on the motor in the truck. I have heads for it off a totally differnet N/A motor, but I still need to buy the gasket set, valley pan, and head bolts if I fix the motor in the truck. Droping the N/A motor (which is 100% complete) in place, seems like all I would need to get to get it running is filters and oil.
Basically I'm looking at getting this truck, and it looks like it would be a lot cheaper (very important in my case) to simply drop the N/A motor in rather than drop a new set of heads on the motor in the truck. I have heads for it off a totally differnet N/A motor, but I still need to buy the gasket set, valley pan, and head bolts if I fix the motor in the truck. Droping the N/A motor (which is 100% complete) in place, seems like all I would need to get to get it running is filters and oil.
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Junior User
Joined: Jan 2009
Posts: 89
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From: Reno, NV
I guess I will make sure it doesn't go over 10 then, because if the head gasket blows, I'm kind of SOL. No money... Actually, is it safe to hold it at this boost for a few minutes? See below...
How about max SUSTAINED EGTs (at the manifold, and after turbo), because we have a hill that I have to climb both ways every day, and its about a 30% grade for 2 miles. I want to be able to maintain 70mph. Truck that I might get has a 5 speed. So far every vehicle I've ever had has had to be about pinned all the way up to do it. None were diesels though...
How about max SUSTAINED EGTs (at the manifold, and after turbo), because we have a hill that I have to climb both ways every day, and its about a 30% grade for 2 miles. I want to be able to maintain 70mph. Truck that I might get has a 5 speed. So far every vehicle I've ever had has had to be about pinned all the way up to do it. None were diesels though...
Posting Guru
Joined: Jul 2004
Posts: 1,627
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From: West Valley Utah
30% grade? Are you sure? Do you have any idea how steep a 30% grade is? On a 70 mph highway?
That could be used for a "you aint gonna believe this" truck driver story. Here goes- well I was driving this 2 lane back country road in the Rockies. Started up this big ol hill that so steep I had to turn on my windshield wipers cuz antifreeze was coming out of the radiator cap n running all over the windshield.
30% is like REALLY REALLY steep on a 70 mph road. Did I mention that 30% was real steep? Just making sure!
On a long pull, when loaded, I like to keep egt's 1100-1150. I'm talking pulls that are 5,6,7 plus miles long and 5% plus grades.
That could be used for a "you aint gonna believe this" truck driver story. Here goes- well I was driving this 2 lane back country road in the Rockies. Started up this big ol hill that so steep I had to turn on my windshield wipers cuz antifreeze was coming out of the radiator cap n running all over the windshield.
30% is like REALLY REALLY steep on a 70 mph road. Did I mention that 30% was real steep? Just making sure!
On a long pull, when loaded, I like to keep egt's 1100-1150. I'm talking pulls that are 5,6,7 plus miles long and 5% plus grades.
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Elder User
Joined: Dec 2006
Posts: 559
Likes: 4
From: On a farm.
Why my truck was newer, I uses 1050 as my maximum sustained (pre-turbo) temp. Now that it's 23 years old, I use 950. I usually made 10+ psi boost. With a few changes since, i sometimes see up to 14 psi (non-wastegated Banks, 1st generation unit circa 1987)
Used to cross the Rockies a lot in this truck, many times with a big camper on back or a 30-ish foot trailer in tow (sometimes both the camper AND the trailer). I fooled with the fuel rate to get where I didn't get the rocket-like jump of EGT at the first minor hill. That worked out to be a little more than the Banks recommended "emissions" setting of 1/4 turn of the fuel screw (which Banks advertised as a 30 % increase in power) and the "non-emissions" setting of 3/8-turn, which was touted as a 50 % increase. My Banks kit instros recommends never exceeding 1150 degrees.
Used to cross the Rockies a lot in this truck, many times with a big camper on back or a 30-ish foot trailer in tow (sometimes both the camper AND the trailer). I fooled with the fuel rate to get where I didn't get the rocket-like jump of EGT at the first minor hill. That worked out to be a little more than the Banks recommended "emissions" setting of 1/4 turn of the fuel screw (which Banks advertised as a 30 % increase in power) and the "non-emissions" setting of 3/8-turn, which was touted as a 50 % increase. My Banks kit instros recommends never exceeding 1150 degrees.
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Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
This hill is 15% grade at the camera position and goes to 32% right in front of the blue/white house on the right.
An IDI will not run 70 MPH up a hill that steep two miles long, turbo or not.
With a 133 inch wheel base, 30% grade has the front tires 40" higher than the rear tires.
And yes, that is a steep hill.
70 MPH down a 30% grade, hope you don't ever have to stop, because the brakes will be on fire before it stops.
Bone stock 7.3 NA, I would keep the boost under 15 PSI.
7.3 turbo head gaskets did have a bit stronger fire rings and the head bolt torque was a little higher.
EGT on a hill that steep and long should be 1050 to 1100 max.
An IDI will not run 70 MPH up a hill that steep two miles long, turbo or not.
With a 133 inch wheel base, 30% grade has the front tires 40" higher than the rear tires.
And yes, that is a steep hill.
70 MPH down a 30% grade, hope you don't ever have to stop, because the brakes will be on fire before it stops.
Bone stock 7.3 NA, I would keep the boost under 15 PSI.
7.3 turbo head gaskets did have a bit stronger fire rings and the head bolt torque was a little higher.
EGT on a hill that steep and long should be 1050 to 1100 max.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
West Virginia
My house is about 250 feet to the right of the blue house where the hill is even steeper.
That nice streak in the photo was where a Mercedes SUV was driving down the hill and a chunk of concrete was under the left front tire.
The anti lock brakes sensing the left front was not turning and the lady driving could not stop.
So she was heading for the curb, and almost rolled the vehicle when she got up against the bank, but at least when the right front went over the curb the left front bounced across the concrete and she got stopped.
Our hills are not usually that long, but we have many that are very steep.
Interstate and US highways are 13% or less.
State highways are under 20% most places.
County roads and city streets, there are many that I can not pull a trailer up in 4x4 when the blacktop is hot.
Truck just sits there chewing up blacktop with all four tires.
My house is about 250 feet to the right of the blue house where the hill is even steeper.
That nice streak in the photo was where a Mercedes SUV was driving down the hill and a chunk of concrete was under the left front tire.
The anti lock brakes sensing the left front was not turning and the lady driving could not stop.
So she was heading for the curb, and almost rolled the vehicle when she got up against the bank, but at least when the right front went over the curb the left front bounced across the concrete and she got stopped.
Our hills are not usually that long, but we have many that are very steep.
Interstate and US highways are 13% or less.
State highways are under 20% most places.
County roads and city streets, there are many that I can not pull a trailer up in 4x4 when the blacktop is hot.
Truck just sits there chewing up blacktop with all four tires.
Post Fiend
Joined: Nov 2003
Posts: 21,285
Likes: 15
From: Nutter Fort, WV
Gonna be awful hard to make the 90 degree corner right behind the camera position at anything above 10 MPH though.
Joe, go park your crew cab with the bottom of the front tires 53" higher than the bottom of the rear tires.
Now you have an idea how steep that hill is at the top.
Joe, go park your crew cab with the bottom of the front tires 53" higher than the bottom of the rear tires.
Now you have an idea how steep that hill is at the top.
Laughing Gas
Joined: Mar 2006
Posts: 1,083
Likes: 1
From: Fitzpatrick Alabama
Yeah, I had a buddy that was working near you Dave in Flemington, he said the hills there were something like us Alabama folks had never seen. 30% is a lot, reminds me of a time when we were in the hills of North Arkansas going down a huge hill toward the Buffalo river Low Water Crossing, my buddy had a late 90s Crew Cab Chevy, by the time he got to the bottom his brakes were smoking heavily, and he didn't have a trailer or anything behind him.