331 vs. 347
- Thread starter wishihadastang125
- Start date
Durability - (albeit slight, the rod ratio on a 347 causes more side wall load on the cylinders than the 331)
Performance - Although the 347 has more displacement and the ability to make more overall power, the 331 is more "rev happy" and will spin up a lot easier. Not to mention that it’s better rod ratio actually keeps the piston at the top of the stroke a little longer for a more efficient burn than other designs.
Cost - the 331 is a slightly less expensive kit and doesn't require notching the cylinders in order to clearance it's rotating assembly.
Performance - Although the 347 has more displacement and the ability to make more overall power, the 331 is more "rev happy" and will spin up a lot easier. Not to mention that it’s better rod ratio actually keeps the piston at the top of the stroke a little longer for a more efficient burn than other designs.
Cost - the 331 is a slightly less expensive kit and doesn't require notching the cylinders in order to clearance it's rotating assembly.
Black331Stang
Active Member
wishihadastang, i am currently building a 331 after a long decision process, and i mean long. i wasnt sure which but then i realized that the trade offs werent worth it for the 347. All that was said by Gearbanger (nicely said), also that it could burn oil from the minute u start it and that it suposedly has a shorter life b/c of stress. Even if is beleived by some (who say its all false or its been corrected) and not others (people who think it does burn oil, etc) i just didnt think it was worth it for what? maybe 15-20 HP?? thats what most told me the difference would be on 2 identical motors but one with a 347 and one 331. Good luck and i hope this made your decision easier
the 347 will be a torquier engine, capable of seeming a bit 'beefier' from lower rpm's. this is best appreciated in a street car, not a drag car. not sure if there's a huge SOTP difference b/w a 331 and a 347, similarly equipped though. I'd build a 347 since there's no replacement for displacement, but i can definitely see where the lower wear rate and better revvability of the 331 would be an asset
I thought for sure this mess would of died by now. the myth that 347's burn oil, that the ring land intersec's with the pin etc etc. Does this 347 piston look like theres any intersec problem?. me don't think so.
347 Piston
Technology has come along way since the days of the crawford 347's.
Scott
347 Piston
Technology has come along way since the days of the crawford 347's.
Scott
runningmole
Founding Member
If 347s were that bad, companies would stop putting them together because of dissatisfied customers.
I chose a 331 for reliabilty, I'd use a 347 if I was building a track car, but my car is for a daily driver.. I did not want to take the chances, plus 10-15 hp can be maid up with a power adder, so why worry about 10-15 hp.. That doesnt mean anything for a street car unless it was track car.. And since it is a street car why worry about it, you'll blow the doors off of 95 % of the cars on street.. Cops wont catch you :oD ... put on a A trim if funds are limited, thats 80-100 rwhp right there.. Your engine will love you !!
Sam8950
Founding Member
I plan on buying a 347e from CHP. They seem to have conquered most of the problems previously associated with 347s.
