Again, kind of a general question without knowing the intended application. I don't have any 383 experience as I never cared for the combination. However I have a lot of 406 experience which is somewhat transferable. Depending on application I use either a 5.7" or 6" rod. There is some potential increased performance with the 6" rod. You can read about piston dwell time and the like. However with the 6" rod all of the pistons that I have looked at the oil ring will be up into the wrist pin and require a ring bridge. This is not a concern for me for a race engine that will see regular maintenance. I don't want that concern, not do I need the potential HP increase, in a street engine. So for the street I use the 5.7" rod.
who's pistons are snapping? if one is cheaper go that way, if your after high rpm power maybe the 6" (pistons can be shorter-lighter) some say better breathing with a long rod. there is a HP difference, lots of dyno tests on the web to look at,
Your theory..... not an engine builders. Lots to concider about detonation. Engine temp, timing, compression ratio, cam timing, piston dwell at TDC, fuel mixture, fuel octane. If any are not done right.... you can get detonation.
Yeah, my experience is with a 406. I went with 6" rods. It was my understanding it resulted in a more optimum rod ratio. My guess is in most applications either length will work well. Both much better than the 5.56 rod used in the 400 motors. I am guessing you will have a wider choice of pistons and compression ratios with the 5.7 length.
Rod length for the same stroke of engine has all to do with the concept of rod angle and the side pressure the piston puts on the cylinder wall. It has not one ******** thing to do with detonation. The concept being that if you reduce friction by changing rod angle you gain what amounts to free horsepower. Rod length isn't going to affect piston deck height on a stroker unless you **** up though. you choose pistons with the correct pin height to get the piston top at the right height. From a HRM article on 383 strokers. Rod LengthThere's much more to stuffing a longer-stroke crank into a small-block Chevy than just making sure the crank will clear the block. In the Origin of the Species sidebar, we outlined how the total height of the rotating ***embly should compute to be roughly the same height as the engine's deck height. While a short rod like the stock 400's 5.565-inch piece will work, the angularity is rather harsh. A shorter rod pushes the piston into the thrust surface side of the cylinder wall, causing unnecessary friction and wear. Plus, short rods tend to expose more of the piston skirt out of the bottom of the bore at bottom dead center. This can cause durability and piston noise issues. Most 383 small-block stroker packages prefer the stock 5.70-inch-long 350-style rod, but there are also advantages to going with a 6.0-inch rod. A longer rod further reduces rod angularity during the combustion cycle, which reduces the side load on the piston and cylinder wall. But despite all the theories about long versus short rods, there is no solid evidence to suggest that there is significant power to be gained by using a longer rod. All is not rosy with a long rod combination, however. Longer rods move the wristpin closer to the ring package. In tight situations, the wristpin overlaps the oil ring, requiring a support rail. This reduced compression height also creates less piston stability at higher engine speeds because of a shorter piston skirt length. The following chart outlines the three popular rod lengths and piston compression heights based on a 3.750-inch stroke. All these rod-length and compression-height combos will produce an overall ***embled height of 9.008 inches, which allows roughly 0.017-inch piston-to-deck clearance with a stock deck height of 9.025 inches. In this example, the 6.00-inch rod requires a compression height of 1.133 inches (SRP's 6.00-inch rod pistons use 1.125 inches). The height is close to the bare minimum of 1.000 that most piston manufacturers recommend, which is why the 5.700-inch rod is so popular. Longer rods are also heavier and can affect the overall bob weight of the rotating ***embly. When mixing and matching parts, you'll want to avoid spending extra money to balance the system. This means that if you buy the crank individually, make sure the overall bob weight of the rods and pistons match the crank's designed bob weight. If you screw up here, it will cost big bucks to balance the crank.
There were some long rod pistons back a number of years ago that had the pin up in the oil ring area and had ****ons if that is the correct term in the pin holes with grooves for the rings. I remember
That would depend on how long his long rods are. I was reading on 302 Ford but there are longer than stock rods and then there are real long rods that require the pin up in the bottom oil groove. Stock 400 small block rods are shorter than 350 rods to keep the stock pin height down a bit. 5.565 rod length for 400 = 383 crank and 5.7 for 350.
Look up the episode of engine masters where they did the dyno tests on rod lengths. Best i recall there was no substantial difference on the 383 they tested.
Deuces... I thought it was a Mercury engine.. We use a 6” with a 3.75” stroke. with a 3mm oil ring in the pin area. Works good comes off the corner hard. Doesn’t like 7200 ..
Excellent explanation. My take, the higher ring land and extra cost are more suited for race engine. Drivers or street engines will do quite well with 5.7 rod. The power gains from 5.7 to 6.0 rods are in very optimized engine combos, you wont see the difference in a typical street engine, too many compromises. 5.7 rod 383 combos are very cost friendly, spend the $ difference on better heads.
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