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  #11  
Old 02-14-2018, 05:13 PM
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Originally Posted by C'roy78stroker View Post
Just something that came across my mind. I was try to think of a negative to this hypothetical scenario. The ones I could think of would be a drop in torque, added expense for a *shorter* rod, or block deck machining depending on the amount of de-stroking. What drew me this direction was if we had a smaller displacement engine but fed it the same fuel, for sake of max effort, 400/400's and then also ported the cylinder heads... Would the HP numbers go up any higher? Or would we still be breaking even do to fuel and air remaining constant? Just a thought, but I'd like to hear some speculation.
Fixed. The expensive part would be the machining on the crank for the different throw travel. Then youd still run into fueling limits with the heui system.

At which point, you'd be money ahead to look into a different platform. Maybe somewhere along the lines of jdelaney' s post. 6.7l is probably about where you'd end up in a destroked situation with a 7.3 block anyway, lol.
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  #12  
Old 02-14-2018, 05:18 PM
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The limitations with heui to move mass amounts of fuel is trying to actuate them quick enough to hit an ever shrinking injection window as engine speed increases. Where was commonrail does not rely on moving high pressure oil to inject fuel. With a big bore engine you can put in bigger valves and let it breathe and with short stroke you can spin it faster. However swamps has already had their commonrail 7.3 past 6K rpms if i remember correctly.
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Last edited by superpsd; 02-14-2018 at 05:21 PM.
  #13  
Old 02-14-2018, 05:28 PM
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Originally Posted by superpsd View Post
The limitations with heui to move mass amounts of fuel is trying to actuate them quick enough to hit an ever shrinking injection window as engine speed increases. Where was commonrail does not rely on moving high pressure oil to inject fuel. With a big bore engine you can put in bigger valves and let it breathe and with short stroke you can spin it faster. However swamps has already had their commonrail 7.3 past 6K rpms if i remember correctly.
Yes there's nothing keeping a 7.3 from spinning rpm other than the ****ty heui setup. The mechanical and common rail guys are spinning them as fast as any other motor.
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  #14  
Old 02-14-2018, 06:49 PM
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Quote:
Originally Posted by superpsd View Post
The limitations with heui to move mass amounts of fuel is trying to actuate them quick enough to hit an ever shrinking injection window as engine speed increases. Where was commonrail does not rely on moving high pressure oil to inject fuel. With a big bore engine you can put in bigger valves and let it breathe and with short stroke you can spin it faster. However swamps has already had their commonrail 7.3 past 6K rpms if i remember correctly.
This is precisely what I was trying to say. P-pump will solve this problem.

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  #15  
Old 02-14-2018, 06:49 PM
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Yes there's nothing keeping a 7.3 from spinning rpm other than the ****ty heui setup. The mechanical and common rail guys are spinning them as fast as any other motor.
Exactly! I think Cory at CNCFab has kits in the works.

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Last edited by ja_cain; 02-14-2018 at 06:59 PM.
  #16  
Old 02-14-2018, 06:58 PM
C'roy78stroker C'roy78stroker is offline
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And if you sit down and compare prices between a mechanical and top end heui build, almost everything offsets each other until you get to the front cover. Those suckers are very pricey.
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Old 02-14-2018, 08:14 PM
JDelaney JDelaney is offline
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Well, the 7.3L is already pretty square and has a pretty good rod ratio so I don’t think decreasing displacement is going to help a whole lot. Air flow and HEUI limitations are roadblocks. Maybe a 4 valve cylinder head and higher volume HPO system would yield greater returns?
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  #18  
Old 02-15-2018, 01:10 AM
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About halfway thru this thread, Morgan answered my question about changing the 7.3 stroke. http://powerstrokearmy.com/forums/ar...p/t-55394.html
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Last edited by PsdPullerJr; 02-15-2018 at 01:13 AM.
  #19  
Old 02-15-2018, 03:14 AM
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Originally Posted by C'roy78stroker View Post
And if you sit down and compare prices between a mechanical and top end heui build, almost everything offsets each other until you get to the front cover. Those suckers are very pricey.
I bet there is a lot of maching on that bad boy.

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  #20  
Old 02-15-2018, 03:56 AM
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Quote:
Originally Posted by PsdPullerJr View Post
About halfway thru this thread, Morgan answered my question about changing the 7.3 stroke. http://powerstrokearmy.com/forums/ar...p/t-55394.html
Good thread. I remember reading it back in the day. Basically confirms everything I understand about destroking. The part about shorter dwell time on the destroked motor was a good revelation too. All that back and forth about head flow numbers and then Dave blows it up at the end. Lol! I plan on visiting their shop one day for sure.

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