Ive been trying to decide which route im giong to go with on my new motor (all of my considerations will use a resleeved ls2 block). Kevin at Race Engine Devolopement thinks you can go with as high as a 4.190" bore on the Darton resleeved ls2 block. One of my considerations is a 446 ci combo with a 4.150" bore and a 4.125" stroke. Although ive heard (not sure if its true or not) that anything over a 4" stroke isn't as solid as a 4" stroke. Is this true? If so, why? Would I be better off going with a 433 ci (4.150" Bore, and 4" stroke) or even a 441 ci (4.190" Bore, 4" stroke)?

 

not if you get a LS7X Warlock block... (Check out the new GMHTP website article) Not sure about the LS2 block.

 

I'm no expert, but my engine is just fine after almost 2 years with a 4.125 stroke.


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Yeah, the Warlock block is a little expensive though.

 

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They have been using 4.125 stroke cranks in their 427's iron blocks for years

 

I believe Eagle offers a forged 4.100" stroke crank for $1k or less. Something to think about if you're on a budget.

Just remember, you're pulling the piston pretty far down below the bore with these big strokes. I personally would stick to 4.00" unless you're willing to go with a taller deck block.

 

No need to go with a taller deck when you can use a longer sleeve. My LS-2 block is a 4.150" bore with a 4.185" stroke crank. When ordering the block, we specified that the sleeves be longer for the added stroke. Steve then mentioned that they have now released a longer sleeve that is good for 4.250" strokes.

The only time you don't want to add stroke is when you are not increasing the bore. If you plan on going 4" or better bore, the 4.125 will be fine. With 4.150"+, you could go with a 4.185, like mine, or even a 4.250" if you wanted. It really just depends on the application. Just try not to get to far "over square".

 

How far is too "over square"?

 

why dont you go 4.125 bore with a 4.00 stroke that yeilds 427?

 

Would these be the sleeves that race engine developement is using?

 

Just looking for extra cubes (without going to radical) I guess.

 

thats not radical......

 

Some people run the 4.125" crank in stock blocks. That's about as far over square that I would even think about, and then, I wouldn't reccomend it for a large power adder application. So I would say no more than .250" more stroke than bore.

Yes, Steve at RED did my block. I'm not sure if the longer sleeves are standard now, or if you still need to request them. I know they did cost me a little more. From my understanding, Steve can use the LS-2 or LS7 sleeves in the LS2 block. The LS-2 is capable of a safe 4.150 bore and the LS7 is capable of 4.190. I would have gotten the LS7's, but they weren't avalible at the time. I say get the LS7/4.190 sleeves and a 4.185 or 4.250 stroke crank and pack in as many cubes as possible.

 

i have been running a 4.125 crank in a stock bore for 2 years now, just took the motor apart and putting the crank in my new iron block. the thing has taken quite a bit of spray with no signs of problems to the bores or pistons when it was disassembled.

 

the aluminum block is 4.125 bore and the stroke is 4.000 for 427 , the iron block is 4.070 bore and a 4.100 stroke for 427

 

What lots of people look for is the rod to stroke ratio. The longer the stroke with the same length rod shortense this ratio. The shorter the ration the greater the angle the rod has compared to the cylender when the rod turns around and heads up or down. This greater angle loads the side of the cylinder wall harder as the rod ratio gets smaller. You can see how this can limit the amount of HP and RPM the engine can handle before causing cyl. problems. Usually you can correct this when you lenghten the stroke by also lenghtening the rod. But then you run out of deck height.

Lots of different engines in the past have run strokes greater then 4", and they were all stocker cranks that lots of people hopped up over the years. A good example would be the Pontiac 455 (one of my favorites due to the fact I use to race them all the time). It had a stoke stoke of 4.212 (I think) and a bore of 4.150 (or something like that) and the rod length was something like 6.8 or so. Mine was stroked with a factory Nodular cast iron crank out to 4.250, bored .060 over and I ran reworked, heat treated 421 forged steel rods (about 20 somfin years old) that were shy of 6.8". I turned the engine all the time for 2 years to 7500rpm, ran 10's regularly in it, and wound up selling the engine to a friend who is still using it today in his race car (freshend up several times over the years). Point is yes you can run longer stokes then 4", I would think that due to the block deck height, rod length, and piston pin placement that we have with our LSx engines, 4.125 might be all we can get in it without shorting the rod length.

Also food for thought, the industrial engines I work on all the time like the Waukesha AT series, has 16 cylinders, about 10" bore, and 10.5" stroke. Granted it only turns 1000rpm but it makes over 4000 HP, I have no idea how much torque, and runs 24/7/365. But it does have one long ars rod in it. Think it weighs about 75 pounds!!!

 

I'm still running a 6.125" rod with my 4.185 stroke, but after that, I don't think there would be any room left.