what the difference between the 7.3's?
Hotshot
Joined: Dec 2006
Posts: 14,069
Likes: 17
From: Melbourne, Ky
The engines themselves are basically the same. The 94.5 to 97 has a manual/mechanical fuel pump, smaller turbo, different type of injectors, (single shots), and different IDM' and PCM's to control them. The early 99's are a little different from both of them, but I don't know the specifics. All the engines up to sometime in the year 2000 have forged rods. The later ones have PMR's which don't hold up as good under higher horsepower.
Also, there is about 25hp difference between the older ones and the newer ones. the California models are a little stronger. Manual tranny trucks have 25 more hp than their automatic counterparts.
Also, there is about 25hp difference between the older ones and the newer ones. the California models are a little stronger. Manual tranny trucks have 25 more hp than their automatic counterparts.
Postmaster
Joined: Sep 2007
Posts: 4,195
Likes: 6
From: Medford Oregon
Here is a good article on the differences ...
Ford's Power Stroke Diesel History - Diesel Tech - Diesel Power Magazine
Ford's Power Stroke Diesel History - Diesel Tech - Diesel Power Magazine
Thread Starter
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Postmaster
Joined: Nov 2009
Posts: 4,556
Likes: 0
From: Crapy southern New Jersey
The engines themselves are basically the same. The 94.5 to 97 has a manual/mechanical fuel pump, smaller turbo, different type of injectors, (single shots), and different IDM' and PCM's to control them. The early 99's are a little different from both of them, but I don't know the specifics. All the engines up to sometime in the year 2000 have forged rods. The later ones have PMR's which don't hold up as good under higher horsepower.
Also, there is about 25hp difference between the older ones and the newer ones. the California models are a little stronger. Manual tranny trucks have 25 more hp than their automatic counterparts.
Also, there is about 25hp difference between the older ones and the newer ones. the California models are a little stronger. Manual tranny trucks have 25 more hp than their automatic counterparts.
Playing in the Dirt
Joined: Oct 2005
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From: Southwest Georgia
Last edited by plowhand; Dec 20, 2009 at 07:37 PM. Reason: spelling
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Lead Driver
Joined: May 2007
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From: Belair md
you are backwards on teh turbo statement, the 94-97's have a larger turbo. thus why we dont have wastegates on them.
but to make it simple,
mecanical vs electric fuel pump.
angle of attack in hpop is different,
intake manifold are larger on sd's
turbo is wastegated on sd
intercoolers on sd's
single shot vs split shot injectors
but to make it simple,
mecanical vs electric fuel pump.
angle of attack in hpop is different,
intake manifold are larger on sd's
turbo is wastegated on sd
intercoolers on sd's
single shot vs split shot injectors
Hotshot
Joined: Jul 2003
Posts: 12,177
Likes: 40
From: Newport, WA
The reason the 97 Cali models are a little stronger than the other OBS trucks is that they got the larger AB code injectors, 120cc split shots that the early 99's have. The other OBS trucks have AA 90cc single shot injectors.
Hotshot
Joined: Jun 2007
Posts: 10,008
Likes: 7
From: Austin, TX
you are backwards on teh turbo statement, the 94-97's have a larger turbo. thus why we dont have wastegates on them.
but to make it simple,
mecanical vs electric fuel pump.
angle of attack in hpop is different,
intake manifold are larger on sd's(on late '99-'03, Early '99 had same intakes as the OBS)
turbo is wastegated on sd(with diff. compressor wheel and housings and prone to compressor surge)
intercoolers on sd's
single shot vs split shot injectors(single shots were 90cc and splits were 120cc)
pistons- SD had lower intermediate ring groove with bigger ring
crankshaft
SD cam doesn't have the mechanical fuel pump mojig
OBS- 100V IDM..... SD- 120V IDM
OBS pcm reads the MAP by frequency instead of voltage like the SD
but to make it simple,
mecanical vs electric fuel pump.
angle of attack in hpop is different,
intake manifold are larger on sd's(on late '99-'03, Early '99 had same intakes as the OBS)
turbo is wastegated on sd(with diff. compressor wheel and housings and prone to compressor surge)
intercoolers on sd's
single shot vs split shot injectors(single shots were 90cc and splits were 120cc)
pistons- SD had lower intermediate ring groove with bigger ring
crankshaft
SD cam doesn't have the mechanical fuel pump mojig
OBS- 100V IDM..... SD- 120V IDM
OBS pcm reads the MAP by frequency instead of voltage like the SD
we can do anything to the OBS that can be done to the SD's. chips, injectors, turbos, regrind cams(gotta use an SD cam), pistons, rods, girdles, etc. hahahaha
Hotshot
Joined: Jul 2003
Posts: 12,177
Likes: 40
From: Newport, WA
tatsch your list isn't all correct. Only early 99's have 120cc splits, late models have 140cc splits.
Early birds have a 110v IDM, late models have the 120v.
Early 99 compressor wheel, aka wicked wheel, same as OBS
Early 99 has a w/g turbo, but it is physically smaller than the late turbo even though the A/R is the same
Early birds have a 110v IDM, late models have the 120v.
Early 99 compressor wheel, aka wicked wheel, same as OBS
Early 99 has a w/g turbo, but it is physically smaller than the late turbo even though the A/R is the same
Hotshot
Joined: Jun 2007
Posts: 10,008
Likes: 7
From: Austin, TX
tatsch your list isn't all correct. Only early 99's have 120cc splits, late models have 140cc splits.
Early birds have a 110v IDM, late models have the 120v.
Early 99 compressor wheel, aka wicked wheel, same as OBS
Early 99 has a w/g turbo, but it is physically smaller than the late turbo even though the A/R is the same
Early birds have a 110v IDM, late models have the 120v.
Early 99 compressor wheel, aka wicked wheel, same as OBS
Early 99 has a w/g turbo, but it is physically smaller than the late turbo even though the A/R is the same
Hotshot
Joined: Jul 2003
Posts: 12,177
Likes: 40
From: Newport, WA
Very true, I wasn't aware of that stuff either. I wonder if the change to the crank came with PMR's? Any chance you have access to an SD forged rod block to compare an OBS, SD forged, and SD PMR crank?