Power loss. 318 Vs 340 manifolds

Power loss. 318 Vs 340 manifolds

Use the 318 manifolds.,

http://www.moparmusclemagazine.com/...pp_0307_mopar_crate_engine_exhaust/index.html

For our baseline test, we fitted the 360 with the lowest of exhaust low,a set of stock small-passage 318 iron exhaust manifolds. Bolted to themanifolds was a set of 21/4-inch head pipe extensions 24 inches long. Soequipped, the 360 put out a respect- able 311 hp at 4,600 rpm and 403lb-ft of torque.

We moved up a notch from the early 318 iron manifolds to late 360 ironlog-style manifolds. The 360 manifolds are nothing to look at, but theinternal passages and outlet are significantly larger than those of the318 pieces. Power was up a little, moving to 314 hp and 407.1 lb-ft oftorque.

Our final test of factory iron was a set of rare and expensive early 340high-performance manifolds. With the 340 exhaust, the 360 inched up to 315 hp and 409.1 lb-ft of torque, which represented very little gain onthis engine.

furz4 said
One of the Mopar mags did a test on a 300 HP crate 360 starting with 318 manifolds all the way up to TTI headers. I think the spread was like 28 HP. If I remember correctly the hp manifolds were about 11 hp better then 318 and 7 betther then basic 360 logs. Will try to find it and link it here.