318 cranks • The Dodge Challenger Message Board

by **redelliott** » 11 Dec 2003 6:19

hi everyone
is a 340 cast crank stronger than a 318? with all the 318 build ups lately
how much hp can they take?

by **dave-r** » 11 Dec 2003 8:54

As you probably know the 340 and 318 cranks are the same and interchange.

However the 340 was always a forged crank. I will have to look up what the 318 crank was but even if it is cast I would not worry about it. A 318 is never going to make more power than the cast crank will take.

by **redelliott** » 11 Dec 2003 16:21

72/73 340's have cast cranks also most 318 except maybee some early heavy trucks. i guess my question is will a 318 cast crank hold up in a 340 build around 400hp / 310hp at the wheels?
thanks

by **dave-r** » 11 Dec 2003 18:50

I beg your pardon Sir! You are right.

Yes now I look in a book I see the 340 crank was forged up to 1972 and cast from 1973 although I bet there was some overlap on the dates.

I don't know how much power a 318 or 340 cast crank will take but i would bet it is a lot more than 400hp. More like 500-600 I would guess.

RPMs are the limiting factor. If you want an engine that makes its power at 6000-8000 rpm you need to look at a better (lighter) crank and con rod.

by **redelliott** » 12 Dec 2003 5:23

thanks for your reply. i never considerd high rpm as a factor

by **117** » 18 Dec 2003 0:12

When I redid my 73 3forty Direct Connection recomended shot peening my cast crank. Since the motor did'nt have a lot of miles, and I was'nt planning for a lot more horsepower, I decided to not turn the crank of shot peen it. Shot peening may be an option for you though.