Okay guys, i know this si going to sound dumb and i should know the answer myself considering..... But here goes, is there a difference in LENGTH between a stock stroke piston and a stroker piston?
Dont shoot!
- Thread starter Deuce4935
- Start date
The wristpin is moved up according to the rod length and difference in stroke, but as far as the overall height I believe they're typically the same.
Taking a 383 piston, 5.7" rod for example... you use half of whatever the stroke is because half of it moves the piston up in the bore, and the other half moves it down (not sure if you got that part, some understand it & some don't). The difference in the two is 0.27" (3.75"-3.48"), and since we're working with a 5.7" rod you only use half of the 0.27" (0.135"). If you were running a 6" rod you would move the wristpin up another 0.3", the reason is the piston will be 0.3" higher in the bore, whether it's at TDC or BDC...
Part of the reasoning behind a 6" though comes in everywhere between TDC and BDC. The piston moves faster up & down the bore, there is also less cylinder wall loading... these are just a few details, the topic is kind of like turbo vs. supercharger, everybody has an opinion and will build their engine different. There isn't quite so much of an advantage comparing a 5.7" to 6.0" rod, but when you look at a stock 400 rod (5.565") vs. 6.0, that rod/stroke ratio looks a whole lot more enticing.
Taking a 383 piston, 5.7" rod for example... you use half of whatever the stroke is because half of it moves the piston up in the bore, and the other half moves it down (not sure if you got that part, some understand it & some don't). The difference in the two is 0.27" (3.75"-3.48"), and since we're working with a 5.7" rod you only use half of the 0.27" (0.135"). If you were running a 6" rod you would move the wristpin up another 0.3", the reason is the piston will be 0.3" higher in the bore, whether it's at TDC or BDC...
Part of the reasoning behind a 6" though comes in everywhere between TDC and BDC. The piston moves faster up & down the bore, there is also less cylinder wall loading... these are just a few details, the topic is kind of like turbo vs. supercharger, everybody has an opinion and will build their engine different. There isn't quite so much of an advantage comparing a 5.7" to 6.0" rod, but when you look at a stock 400 rod (5.565") vs. 6.0, that rod/stroke ratio looks a whole lot more enticing.
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Im still stumped. But i'll explaine what im trying to accomplish. I have a stock vortec 8100 which has the 4.25 bore and a 4.37 stroke and it runs a 6.697 rod. I want to bore it out to 4.50. So im just trying to figure out if i can use any 4.50 bore bbc piston with this combo or will it require me to order custom pistons.
Are they capable of going out .250"??? Most any SBC I've seen is lucky to get .100", but then again since it's a BBC it may have more room to grow. If the deck height and stroke are the same the same as the older BBC, then you should be able to use the same pistons... UNLESS there is a difference between rods (crank pin/wrist pin on old vs. new). I'm only saying this because I know very little about BBCs, and I don't know how much interchanges between different years.
Its a tall deck block if that helps and other the internals are pretty much the same as traditional bbc other than the crank having a reluctor and the heads are designed similar to the gen3 sbc.
