Why are turbo SRT-10's stroked to 522 CID?

steveoviper

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Just currious when engine builders build the SRT-10 engine they bump them up just to 522 CID? If you are going to go thru the bother of providing more inches, why don't they go bigger?

I've seen many builders pick this size for natural asperated and turbos. What is so magical about this number?
 

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Nothing magical. Its just an arbitrary number that is a "large enough" increase to accomodate the majority of engine wear seen on most cores that would be coming in for a rebuild. Realistically, for big-power builds, the small increase in cubes is negligible, the priority is the overall strength of the block and sleeves. The more material you remove, the weaker the block becomes, and the less power it can handle without distoring [which increases the rate of wear]. For longevity, it is generally better to utilize more boost and less cubes than vice-versa if considering the same block platform.

We prefer to stay even closer to OEM cubes than 522 if possible, only going towards 522 if neccessary, though we wont go much larger before we require the block to be reworked before use.
 

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Why not De-Stroke then?:dunno:

For the sake of argument, lets ignore aftermarket cranks and cylinder sleeves;

1. The maximum thickness of the cylinder liner would be its strongest condition. In this case, this would be a cylinder in an un-bored, original condition.

2. In order to De-Stroke (or Stroke) a stock crank, you will have to offset grind the crankshaft, and as a result weaken the crankshaft compared to its stock counterpart.

As you can see, both boring over, stroking, or de-stroking would casue a weakened condition when comparing apples to apples. The strongest configuration is OEM cubes, not more, not less.

Now, if you are bringing aftermarket parts into the equation, I am not going to deny that a smaller-bore liner is going to be stronger, but you have to look at the whole package: a Viper engine with stock thickness liners will run out of torsional rigidity before the stock liners have a problem. In reality, there isnt much to be gained here without other reinforcement- and it would be an interesting endeavor to put that kind of power down to begin with.

Next up, if including aftermarket cranks, sure- you could increase the stroke without a strength penalty as you are starting from a blank capable of being machined full journal size right off the bat. On this same note, there are other things to be considered here: Due to the deck height of the Viper block, you only have so much "length" to work with between the rod length, liner skirt, counterweights, and piston compression height. If you increase the stroke too far, you will end up with a piston that has to be downsized both on compression height and skirt design, not to mention it will be getting increased side-loading to boot. This type of a design has its own can of worms that becomes an increasingly large problem with increasing strokes. Eventually, you will get to the point of having an engine that will wear itself out in no time flat.
 

Jroc

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I always wondered about de-stroking the car so we could rev higher (7.5-8k). Nothing would be sicker than being boosted with all that rpm in there.
 

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I always wondered about de-stroking the car so we could rev higher (7.5-8k). Nothing would be sicker than being boosted with all that rpm in there.

Its not just the stroke, it is also the large bearing journal size of the viper. While the larger sizes are great for handling the power and torque, for high RPM, you will get into trouble with linear bearing speeds as well as oiling related issues.
 
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