'99 & up 7.3L Power Stroke Engine and DrivetrainDiscussion of the 99 & up 7.3L Power Stroke diesel engine and drivetrain in the 1999-Up Super Duty trucks and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 7.3L Power Stroke engine.
I too like the Fumot valve but I find a 203 thermostat to not be a needed item. Unless you needed a thermostat anyway, although 203 costs about 5 times what a reg thermostat costs and I am not sold on 8 degrees making that big of a difference. But some will claim 25 extra HP and 2 more mpg.
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NChornet said, "But some will claim 25 extra HP and 2 more mpg."
I've searched this site's active and archived files about higher temperature operation, most commonly enabled by restoring the 1995 203 degree specification thermostat value to newer engines which were fitted with 195 degree thermostats ONLY to improve nitrous oxide emission values at a clear disadvantage to their thermal efficiency. I've also read a lot about this issue as it relates to non NaviStar diesels. Your statement is the only example I recall claiming even close to "25 extra HP and 2 more mpg."
Please provide a citation by which we can verify that anyone ever made such a claim. I've seen consistent references to small incremental gains, typically translated into about 0.5 mpg maximum gains on these trucks, and then only when they are fully warmed. Frankly, that's a LOT! We can easily estimate miles traveled and fuel burned before 203 degree conversion cost is fully recovered by fuel expense saving. After that, fuel expense savings would be a permanently flowing gain.
This change produces small but 100% consistent MPG improvements while marginally worsening nitrous oxide emissions. Power gain at any fully-warmed throttle setting does exist. But those incremental changes are very small so they can only be measured through sensitive tests. That power gain is much too small to be noticed through "seat of the pants" acceleration comparisons.
As a certifiable MPG contest participant for about 4 decades, I will install an engine temperature changing system into my recently acquired 2000 truck. By far the easiest way to do that well would be to buy one of these aftermarket 203 degree adapters. A thermostatically-controlled electric-motor-driven plunge valve with dash-mounted adjustable temperature threshold control would allow exploring the full range of performance differences thermostatic controls can produce. Creating and enjoying devices like that is only well suited for people who love exploring maximum efficiency just as drag strip contestants enjoy exploring ways to minimum their elapsed times. I've done both and the fun from testing limits in both performance arenas feels similar.
You're wrong to attack 203 degree thermostat replacements. Your claim that others claim "25 extra HP and 2 more mpg" sounds exactly like "putting up straw man to knock down" because that claim does not square with any credible previous reference I've read about this issue.
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Lightest 1995 Standard Cab PowerStroke F-250 with factory "Camper Package," no AC, 5-speed, Conklin ParaSynthetic Oil with MolyLube, oversized 10-micron filter, Randy's Ring & Pinion aftermarket 3.07 ratio running in Royal Purple, Stanadyne always in fuel, tires @ 100 psi, nearly zero friction brake adjustments, 203 degree thermostat enables higher engine efficiency than 195 degree units, front end precisely aligned with minimal toe-in to reduce friction, lowest rolling friction F-250 I've seen. 2-axle trailer tires run 110 psi generating less rolling friction than lower pressure tires. Infrequently carried slide-in camper is an older all-hard-side Siera pop-up. Hard sides seem more secure than canvas connected pop-ups when up and never have canvas mold problems. Pop-ups push less wind than fixed height slide-ins.
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