Longer or shorter stroke on a turbo application?
9 Second Truck Club
iTrader: (17)
Joined: Sep 2006
Posts: 3,672
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From: Colorado Springs, Co/ Central, Ca
The factory 6.0L geometry seems to work really well for a med weight car on E85. For a really heavy car and or pump gas I think the 400 CI is a better deal because you will get farther with less boost and cyl psi. I too agree that the rod ratio is important on a turbo engine if you are limited on turbo MM. If there is no restriction on turbo then a shorter rod ratio and more CI can work really well. Same goes for the 317 head casting you will ultimately make more power with a 400" engine than a 364 CI due to the 400" not needing as much cyl psi to make the power. The higher psi 364 will lift head sooner.
TECH Fanatic
Joined: Jun 2013
Posts: 1,163
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From: Avon, Ohio
In theory-can you use a stock 6.0 rod/piston with a stock 4.8 crank in a 6.0, or would you need either
A) longer rod with OE or Aftermarket 6.0 slug
or
B) OE 6.0 rod length with Aftermarket "custom" piston with a lower pin height? (nice side benefit or a stronger piston!)
A) longer rod with OE or Aftermarket 6.0 slug
or
B) OE 6.0 rod length with Aftermarket "custom" piston with a lower pin height? (nice side benefit or a stronger piston!)
Thread Starter
Joined: Nov 2004
Posts: 998
Likes: 19
From: Rotterdam, New York
Thanks again everyone. I was also concerned about the 6.0 block sleeve length with a 4" stroke so better to stay on the safe side. I'm pretty sure I shouldn't have an issue spooling this turbo up with a stock stroke though since a friend of mine put an identical S484 on his bone stock 6.0 with a TU2 cam and at 3800 rpm on the 2 step with a transbrake boost was almost instantly 15psi. That's more than I will be able to hold down with my chassis, so as long as my converter is correct I should be fine. 
Restricted User
Joined: Mar 2014
Posts: 7,192
Likes: 109
From: Ohio
Positives and negatives can be discussed all day long.
The shorter stroke cranks are stronger because of more journal overlap, less rotating inertia, etc. This will give you a better rod/stroke ratio especially like in the 4.8 since it has longer rods. This means less rod angle, and less side-loading the pistons and the bores. A shorter stroke with a longer rod is a stronger combo.
Why is most of this irrelevant? You can get a 5" stroker forged crank with a pretty short rod to live at 3500 HP with today's metallurgy and machining. Strength will only play a factor in the extremes. It will all boil down to how you want your engine to behave.
Higher RPM and more top end? Go short stroker stroke. More low- mid torque and don't plan on spinning it to the moon? Nothing wrong with a 4" stroke. Realistically, either combo should be able to make or handle the same power
The shorter stroke cranks are stronger because of more journal overlap, less rotating inertia, etc. This will give you a better rod/stroke ratio especially like in the 4.8 since it has longer rods. This means less rod angle, and less side-loading the pistons and the bores. A shorter stroke with a longer rod is a stronger combo.
Why is most of this irrelevant? You can get a 5" stroker forged crank with a pretty short rod to live at 3500 HP with today's metallurgy and machining. Strength will only play a factor in the extremes. It will all boil down to how you want your engine to behave.
Higher RPM and more top end? Go short stroker stroke. More low- mid torque and don't plan on spinning it to the moon? Nothing wrong with a 4" stroke. Realistically, either combo should be able to make or handle the same power
