If everything kept the same as far as bolt ons. Both engines carburated with the same induction system (of course properly sized) what would be the horsepower differences between a maxed out 12a with 150hp in just bolt ons, no porting and a 13b with the same mods and no porting?

12a = 150hp
13b = ???

thanks

 

with a lovely delorto or 50 weber i'd guess 160-170 for the 13b

 

RB says 179 hp for the 13B with Dellorto and RB exhaust, 154 hp for the 12A.

So that's a 25 hp difference, which sounds reasonable to me.

 

yeah ... generally speaking, you can assume a 30 HP difference between the two of them, tit for tat.

 

ok cool, thanks guys...

 

How about torque? I heard people say that the 13b will feel a lot more powerfull becouse of it's higher torque output / curve.

 

Good point! The torquiness of the 13B definitely makes it feel more powerful, especially the '74-'75 motors which have the largest stock ports of the 4-port 13Bs.
-WG

 

I think it is important for every to note though that once porting is induced and especialy ratical porting the difference between the 2 narrows a lot. In really radical set ups they are usualy only 10-15 HP appart.

CJG