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2002 F450 SD 7.3L 4R100
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Discussion Starter · #1 ·
Okay, so as most of you know I installed a KC300x turbo on my 7.3 less than a week ago. I have given it several test drives and played with my PHP Hydra settings and I have come to a conclusion that there is either something wrong or the turbo is just disappointing in general. First I want to say "without blowing my own horn" that I am an ASE master technician and have worked as a tech for my entire professional life. I have turbo charged cars that were never turbo, and upgraded others before. Power and performance is nothing new to me. That being said, the turbo is correctly installed with no boost leaks as I have made sure at this point due to my current confusion.

I'll get straight to the point. Before this swap I was hitting 25psi on the 80hp setting and 30-32 psi on the 100hp setting on the Hydra. Now the turbo only hits 25 in both the 80 and 100 setting and feels lacking on the top end with either the same or slightly better on the low end. Before I contact KC turbos about this I am wondering if anyone has one of these installed and has had a different experience or an explanation for why this is. My turbo was worn out even! With chunks missing out of the compressor blades and rough dusting damage! I thought a 4" inlet and hefty waste-gated turbo would be a substantial upgrade. But it is literally the same or worse performance wise.

I also have several supporting mods too. 6637 filter, 4" turbo back exhaust, EBPV/AIH delete, bellowed up-pipes, boost fooler etc. etc. This turbo is supposed to be able to hit 40 psi as I understand it. I'm going for 35ish as a final goal though. 25 is just disappointing for a $1,300 investment that feels worse than my worn out stock turbo. I honestly feel like I'd have $1,300 back in my bank and be just as happy right now. I had such high expectations too.. Am I missing something here?
 

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Yikes! Sorry to hear that. The KC stage 1 I put in my truck has definitely made an improvement.. maybe the factory original was just that bad. The only thing I can think of is: is the wastegate opening when it shouldn't? What stage turbo did you purchase?

Cj
 

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2002 F450 SD 7.3L 4R100
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Discussion Starter · #3 ·
Just a stage 1 also. But the waste-gate rod is very hard to move unlike the oem one. So it should be holding boost fine. Don't get me wrong, the truck doesn't feel bad, just not better seemingly at all. I don't know if that's grounds for returning, but I don't want it if this is all it brings to the table..
 

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Discussion Starter · #4 ·
I was under the impression that it is supposed to be a drop in "plug and play unit", but before I scrap it, I'm going to have to play with the setup some by trying some turns on the waste-gate actuator rod. I came across a video of a tech demonstrating the need to do it on a KC turbo. I also have the red vacuum line plugged in as I was advised it should be on it, but unplugging it made my oem turbo work really well. I am nervous to do so, but I will try it unplugged and see how it goes and if necessary tighten the waste-gate rod as well. I want to be hitting 35psi on my 100psi Hydra setting and 30ish on my 80hp setting as my end goal.
After some research and reasoning I think my issue is having the red vacuum line connected.. Because psi stops at 25 in both the 80hp and 100hp setting now. Which means a computer algorithm is opening the waste-gate at that psi. I'll report back when I experiment with this.
 

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It would also account nicely fro the "flat feel" at the top end when the turbo should really be shining. I do recall reading a post that mentioned that Ford programmed the PCM to de-fuel above a certain boost pressure (hence the reason for boost foolers). Though with tunes I would hope that the tuner would have changed this. Perhaps it is hard coded in the PCM software. Please keep us posted!
 

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Discussion Starter · #6 ·
So all is well now. I disconnected the vacuum line to the waste-gate and it was similar to when I did that on the oem turbo. Now it reaches 35psi on the 100hp setting and low 30's on the 80hp setting. So 10psi more boost and the turbo is much more responsive and quick to spool up. It's performing the way I had hoped it would. I know I could get a little more out of it by playing with the rod, but I don't want to push the engine since 40psi is it's max rated safe psi. 35psi is good for me. It's strange, I was reading how some trucks don't respond at all to the line being on or off, and some do. Mine definitely does. Anyways, just wanted to update that it's working good and I wont be contacting KC or uninstalling.
 

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Good to hear you figured it out... I was sweating a bit given my original recommendation :).

Cj
 

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2002 F450 SD 7.3L 4R100
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Discussion Starter · #9 ·
Yes, injectors and internals are oem. They are the AD injectors as I understand it. I’m betting they are pretty maxed out at this point, but they are doing great with my setup. Not sure how they’d work with the 120hp and up tunes I’ve heard people use, but my hydra’s highest setting is 100hp. No hiccups or loss of power even at high rpm.
 

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2000 F-250 7.3 ZF6 Stage 3 205cc Hybrid Injectors KC300x77mm Hydra tuner with jellibuilt tunes.
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Okay, so as most of you know I installed a KC300x turbo on my 7.3 less than a week ago. I have given it several test drives and played with my PHP Hydra settings and I have come to a conclusion that there is either something wrong or the turbo is just disappointing in general. First I want to say "without blowing my own horn" that I am an ASE master technician and have worked as a tech for my entire professional life. I have turbo charged cars that were never turbo, and upgraded others before. Power and performance is nothing new to me. That being said, the turbo is correctly installed with no boost leaks as I have made sure at this point due to my current confusion.

I'll get straight to the point. Before this swap I was hitting 25psi on the 80hp setting and 30-32 psi on the 100hp setting on the Hydra. Now the turbo only hits 25 in both the 80 and 100 setting and feels lacking on the top end with either the same or slightly better on the low end. Before I contact KC turbos about this I am wondering if anyone has one of these installed and has had a different experience or an explanation for why this is. My turbo was worn out even! With chunks missing out of the compressor blades and rough dusting damage! I thought a 4" inlet and hefty waste-gated turbo would be a substantial upgrade. But it is literally the same or worse performance wise.

I also have several supporting mods too. 6637 filter, 4" turbo back exhaust, EBPV/AIH delete, bellowed up-pipes, boost fooler etc. etc. This turbo is supposed to be able to hit 40 psi as I understand it. I'm going for 35ish as a final goal though. 25 is just disappointing for a $1,300 investment that feels worse than my worn out stock turbo. I honestly feel like I'd have $1,300 back in my bank and be just as happy right now. I had such high expectations too.. Am I missing something here?
Is it a 77mm 1 a/r
 

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Discussion Starter · #11 ·

This is it. Stage1 and 84 a/r. You can read the specs you’re after.
 

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2000 F-250 7.3 ZF6 Stage 3 205cc Hybrid Injectors KC300x77mm Hydra tuner with jellibuilt tunes.
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This is it. Stage1 and 84 a/r. You can read the specs you’re after.
Odd what rear end? Also is it defueling at 23 psi
 

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Discussion Starter · #13 ·
Oh, I actually have no problems now, I have it working fine at 30 psi on my regular 80hp setting and around 35psi on the 100hp setting. Disconnecting the wastegate vacuum line was the key. It's just how my truck functions best.
 

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KC would've told you to disconnect the red line and clamp down the wastegate. So you made the right call there.

Also, remember that you now have a bigger compressor wheel making the same boost. So you are getting even more air into the engine than before, even at same boost levels. Sounds like you have her running right now.
 
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