Using Dart's CCW (center counter weight) Crankshaft in OEM LS blocks
I found this info that might be useful posted elsewhere by
0HP RESEARCH
www.summitracing.com
keep in mind the stock LS crank is build without center counter weiights and the reason is that they are not required or very beneficial if the engines making less than 600 hp or stinning to under 6000 rpm,
if you want to push the ls series engine with turbos or nitrous the extra counterweight cranks are stronger and absorb abuse marginally better, especially if you used 4340 forged steel and intend to spin the crank over 7000 rpm ,you'll need to machine stock and some aftermarket blocks for additional clearances if you use center counter weight cranks
the guy linked below does a very good job explaining the issue
Dura-Bond LS Cam Bearing Sets
1999-2006 first design
position 1&5 bore 2.326 / 2.328
CH-10, CHP-10, CHP-10T
2003-2009 sec design
position 1&5 bore 2.346 / 2.348
CH-23, CHP-23, CHP-23T
2007-2013
position 1&5 bore 2.346-2.348
CH-25, CHP-25, CHP-25T
** All CH-25 sets will work in place of the CH-23 sets
I found this info that might be useful posted elsewhere by
0HP RESEARCH
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if you want to push the ls series engine with turbos or nitrous the extra counterweight cranks are stronger and absorb abuse marginally better, especially if you used 4340 forged steel and intend to spin the crank over 7000 rpm ,you'll need to machine stock and some aftermarket blocks for additional clearances if you use center counter weight cranks
the GM/GMC law suit on active fuel management engines
watch these video's, there's a great deal of info you might not know, info that should affect your choices and options you may want to avoid on used vehicles that lack of that info can easily affect the potential engine life span and expected durability issues there's a very serious built in...
garage.grumpysperformance.com
Cast, Forged, Billet, OE, aftermarket, stock stroke, stroker, de-stroked....when you think about it, the options for LS crankshafts are many and can sometimes be very confusing when building your next engine.
When we sit down with our customers we always want a good idea of what exactly they are trying to accomplish with the engine and what areas need to have more attention spent on detail work to make the end result more reliable.
As most of you know, the standard Chevy small block has not had a fully counter weighted crankshaft ever, even right up to the new Gen V engines the middle of the crank lacks these. For the OEM and most performance builds this can be over looked and not a mandatory item when building your engine. Even the 650 HP LT4 makes due with a std crankshaft build (although it is a forged piece). However, adding these back into the crankshaft will give you a better crank that will be more rigid, stable, and perform better in almost every way throughout the entire RPM range. This means longer bearing life, smoother engine performance, and less chance of vibration damage in most cases.
Here you can see the difference in this Dart CCW crank on the left vs a modern GM LSA crankshaft on the right.
Now, say you have decided that a CCW crank is right for you, and your build but you want to install this in your LS engine block....
There is a big warning! WILL NOT FIT OEM BLOCKS! While this is listed in almost every case you see, and for the home builder this is very true. The OEM blocks were never designed to accept one of these cranks and the added material of the center counter weights. That being said this is something we have done for a number of years without issue but it does require machine work to the engine block to do so.
OEM Thrust bearing main location
OEM Thrust bearing main location
As you can see there is a lot more material in the center part of the block as the extra machine work was not required given the OEM crankshaft has little in the way of material to hit any part of these areas. Not only the Dart but using a few billet CCW cranks we have measured the clearances needed and can easily machine iron and aluminum OEM blocks for the required clearance while retaining as much material for block rigidity as possible.
HPR machine work to clear CCW crankshafts
HPR machine work to clear CCW crankshafts
Once everything is machined and cleaned, your new CCW crankshaft will drop right in without issue.
Why is the LS Engine so good..
Good video discussion some key LS design and tuning topics. About halfway through is a good section stroker kits and piston skirt length.
garage.grumpysperformance.com
So for those wanting to use a CCW crankshaft but always thought they needed an aftermarket block, no need to fear, HPR has you covered!
1999-2006 first design
position 1&5 bore 2.326 / 2.328
CH-10, CHP-10, CHP-10T
2003-2009 sec design
position 1&5 bore 2.346 / 2.348
CH-23, CHP-23, CHP-23T
2007-2013
position 1&5 bore 2.346-2.348
CH-25, CHP-25, CHP-25T
** All CH-25 sets will work in place of the CH-23 sets
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