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2002 F450 SD 7.3L
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Discussion Starter · #1 ·
I'm trying to get an idea of how the powerband works in these older trucks or even just how it's supposed to feel. This is my first diesel ever. I have recently gone over my engine and fixed all defective sensors, charge pipe leaks, leaking up-pipes etc. New filters and fluids. Basically got the thing running night and day better than when I got it with no codes. I do think it's about as good as it gets considering it was only rated at 250hp, but here's my question. I've noticed that power falls off at around 3,000rpm. Is this normal? If I hammer the pedal, it will go through each gear shifting at about red-line (3800rpm from the looks of it). But from about 3000rpm+ it's like there is no more power. It just keeps trying, but lags till the next gear. The turbo is boosting good at low rpm and takes it up to speed pretty good, but there is just no more pull at higher rpm. Is this just how they feel? Maybe the factory turbo just cant flow above 3000 rpm? Just trying to get a general idea.
 

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Discussion Starter · #2 ·
One thing I forgot to mention is the truck is pretty much bone stock. But I did think it was strange that after all my repairs, the final thing I did (and was looking forward too) was the bellowed up-pipe swap, and at the same time went back together with the 6637 air-filter mod. Of course the up-pipes themselves don't add power, but I thought for sure because it was an obvious leak that it would restore power and turn the turbine harder, but it actually feels just the same as before. Also the EBPV pedestal/turbo flap has been deleted since before I got it, another small thing, but supposedly would support more airflow. I can hear the turbo more from the air filter swap, but it's just noise, no more power. The turbo looked beautiful on the compressor wheel and had minimal shaft play. I don't have a boost gauge. Maybe that's what I should get next. But I'm wondering if it's just how these things feel.
 

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7.3L Power Stroke Diesel Specs & Info
Being stock you are likely running out of fuel and air past 3000 RPM. I really don't run mine past 2800 RPMs. KC turbo's has some good comparisons of different turbos and injectors relative to horsepower and torque.

Cj
 

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2002 F450 SD 7.3L
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Discussion Starter · #4 ·
Thanks for the link! The HP/TQ graphs show exactly what I'm experiencing. Power peaks and falls off right at 3000rpm. Having little experience with this engine I didn't know its characteristics. But these graphs show it's acting as it should and I haven't missed or messed anything up (y).

Now if I want more out of it, it's down to mods. Boost increase, chip, exhaust etc. Undecided if I want to go down that rabbit hole yet though.
 

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"that rabbit hole" gets expensive quick :).However, you are driving a 99+ so some of the mods are not required (like adding an intercooler).

Cj
 

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three things will wake that truck up.
a 4 inch free flowing exhaust, a "boost fooler" in the map line, and a 40 to 60 hp economy tune on a chip.
with the air filter you already put on, it will be a night and day difference.
i made the boost fooler i put on my 02 with a cheap harbor freight air pressure regulator. total cost for the regulator, fittings, and lines was under $15.
by setting the regulator to 21 psi or so, the computer will never see the added boost from the mods and not defuel the truck when boost goes higher.
with the old 60hp econo tune on my DP F5 chip, i can see 32 psi boost under heavy load.
normal unloaded driving boost is down around 10 psi.
 

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1970 - what injectors and turbo do you have in that truck (for reference)?

Cj
 

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I'm presuming that the truck that you are talking about is a F450?

The gearing in that truck is going to be fairly low and I am not sure on a 2002 but could it be de-tuned because it is a F450?
 

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1970 - what injectors and turbo do you have in that truck (for reference)?

Cj
whatever ford put in it when it was built.
engine has never been apart.
only thing done besides the chip, boost fooler 4 inch exhaust and air filter is intercooler boots, alternator, a/c compressor, and starter.
and normal PM stuff.
other than this it is all stock with 249k miles on it.
 

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2002 F450 SD 7.3L
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Discussion Starter · #10 ·
I'm presuming that the truck that you are talking about is a F450?

The gearing in that truck is going to be fairly low and I am not sure on a 2002 but could it be de-tuned because it is a F450?
Hey, wasn't sure if you were talking to me or 1970something. It is a F450 dually with the Dana 80 and 4.88 rear and 4R100 auto trans. I would think the gearing would be helpful for acceleration no? Not speed or economy, but quicker acceleration.
 

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Discussion Starter · #11 ·
three things will wake that truck up.
a 4 inch free flowing exhaust, a "boost fooler" in the map line, and a 40 to 60 hp economy tune on a chip.
with the air filter you already put on, it will be a night and day difference.
i made the boost fooler i put on my 02 with a cheap harbor freight air pressure regulator. total cost for the regulator, fittings, and lines was under $15.
by setting the regulator to 21 psi or so, the computer will never see the added boost from the mods and not defuel the truck when boost goes higher.
with the old 60hp econo tune on my DP F5 chip, i can see 32 psi boost under heavy load.
normal unloaded driving boost is down around 10 psi.
Hey, so far I have held back from exhaust and chip work. They may be next, but the things I've done so far have made a big difference:
The bellowed up-pipes
6637 filter
EBPV system delete
AIH delete and boost gauge ported to it's old location (Riffraff's port bung)
Waste-gate vacuum disconnect
Riffraff's boost fooler
Cleaned/wrapped the cold side CAC pipe with heat reflective tape
Flipped the CCV valve around and customized a catch can into the pathway to the intake. (I didn't like the way Riffraaff's kit just dumps to atmosphere). Not cool IMO
Not that it adds performance, but I put a 6.0 trans cooler in as well.

That's my list of mods so far. I do want to remove my CAC when I get time and do the simple green cleaning method. Judging by the pools of oily filth I cleaned out of the intake, spider, and CAC pipes, I'd say the cooler is pretty filthy inside.
I would be interested in seeing how a 4" turbo back system feels and a chip, but trying to justify the cost on a work truck I'll hardly drive is not very reasonable. I'll probably end up doing it though knowing myself.
 

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When you pull the intake apart, put a set of plenum inserts in. Riffraff should still sell them.they fix leaks around the tin intake plenum tubes by stiffening them up, and are 1/4 the price of bullet plemums.
 

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Discussion Starter · #13 ·
Good call, I did see my intake has been bent up and distorted in the past. Even had some odd silicone placement to try and seal the couplers. My couplers are in good shape and I don't see any reason for leaks after reshaping/cleaning the intake orifices. But if I get back in there again I'll address it with the inserts.
 
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