97 PSD Defuel ?
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97 PSD Defuel ?
97 F350 CrewCab 29k miles. ZF 5 spd. Gear Vendors underdrive. Ford Intercooler retrofit, 3" downpipe/4"exhaust and muffler. SuperChips performance tune.
Unloaded at 3000rpm and 18psi boost the EGT reading drops off sharply from 600 degrees. After gear shift it steadily climbs back. Yellow zone on tach starts at 3400 rpm. No error codes. EGT (mounted in downpipe at turbo) only reaches 800 when pulling 26' 102" wide car hauler van at 75 mph in double overdrive (5th gear and Gear Vendors unit engaged)
Some sort of defueling going on ?
Unloaded at 3000rpm and 18psi boost the EGT reading drops off sharply from 600 degrees. After gear shift it steadily climbs back. Yellow zone on tach starts at 3400 rpm. No error codes. EGT (mounted in downpipe at turbo) only reaches 800 when pulling 26' 102" wide car hauler van at 75 mph in double overdrive (5th gear and Gear Vendors unit engaged)
Some sort of defueling going on ?
Post Fiend
Joined: Apr 2004
Posts: 12,835
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From: Silver Lake Dunes, MI
so unloaded at 3k and 18psi the temps drop off from 600 to what? is this as a shift happens? you top temps of 800 sound about right with an IC and double overdrive. These trucks don't defuel so thats no happening.
also Holy crap you have a 97 with 29,000 miles on it! wow!!
also Holy crap you have a 97 with 29,000 miles on it! wow!!
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Yeah - the mileage is correct. Bought it last year from a California Lawyer who hauled horses around.
When I see the EGT starting to drop I shift. Gets down to about 450 and then starts to climb again. Have had 2 different Banks gauges showing the same thing. I have a 94 non-PSD without an intercooler and never see this happening.
When I see the EGT starting to drop I shift. Gets down to about 450 and then starts to climb again. Have had 2 different Banks gauges showing the same thing. I have a 94 non-PSD without an intercooler and never see this happening.
Post Fiend
Joined: Apr 2004
Posts: 12,835
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From: Silver Lake Dunes, MI
my guess and this only a guess cause I am not even sure it works this way but as you see the temps dropping you are hitting the sweet spot for the turbo where its most effiecent pushing air. as a turbo get less effiecnt it starts to push heat and not so much air. so you are moving thru the sweet spot to higher boost limited and start to pump more heat. then you shift and start the cycle over again.
it the drop after a shift or in the middle of a gear then the temps raise then you shift up to the next gear? Sorry i am just trying to see the sequence of events going on.
it the drop after a shift or in the middle of a gear then the temps raise then you shift up to the next gear? Sorry i am just trying to see the sequence of events going on.
Post Fiend
Joined: Apr 2004
Posts: 12,835
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From: Silver Lake Dunes, MI
I would say that sounds ok. as long as your not loosing power when it does that it probably just an air flow thing. maybe some one else will chime in. I run an automatic so maybe its phenomeno that happens with high rpm shifts
FOREIGN GURU
Joined: Jul 2006
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From: Celaya, Gto. MX
29K miles on it. !!!! WOW !!!! 
Congrats.
IMHO You should change the pyro to a preturbo location (in the exhaust)
Congrats.IMHO You should change the pyro to a preturbo location (in the exhaust)
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Thanks. I've done a few Banks installs and their instructions for an after-turbo EGT claim that a 300-350 decrease at the exhaust is reliable. They advise to keep temp below 1100 at this location. Never had a problem yet. Have you had an experience that says otherwise ? I'm an old dog that is always willing to learn new tricks.
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Post Fiend
Joined: Apr 2004
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From: Silver Lake Dunes, MI
the biggest reason for Pre turbo mounting is its more accruate reading of what the true exhuast temps are. The reason for a pyro is protecting the pistons and not the turbo so its closer to the action.
FOREIGN GURU
Joined: Jul 2006
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From: Celaya, Gto. MX
Postmaster
Joined: Apr 2004
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From: Ellensburg, Washington
Sorajt- I have heard this from a couple people as well as having seen it happen in my truck, and I remeber posting this in a thread once, and it was about how the more RPM's the motor spins the lower EGT's you'll see. It was a while back but if I remeber right its has to do something about the truck taking in more air and consuming all the fuel in the cylinder. I could be way off but im pretty sure thats what someone said. Good luck!
Cowboy Steve
Cowboy Steve
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