360 vs 318

Tech Question


raymond courchesne, sherbrooke, QC, canada, 1988 chrysler 5th ave 318

Why as often the case, do you recommend replacing a 318 ci bya 360 when it comes to upgrading the performance of the 318? Engine Quest isproducing a wonderful cast iron head part #CH318-b for the application. Haveyou read Engine Masters article about the rebuilding of the 318 with a 425hp without stroking it? I would be glad to read your consideration on thispoint.



I’ve been using EQ heads for years and will continue to do so. Their headsare for 318s and 360s – same head, the “sameness” applies to OEM Magnumheads.

OK, my rationale:

> #1 The engines weigh just about the same and are identical overall size
> #2 The swap is generally a cinch
> #3 Spun to a higher RPM, yes, the 318 can make close to the same peakpower as the 360, true (remember, the 0.090 larger bore of the 360 willshroud the valves less, allowing for better breathing). But the 360 willalways win by a wide margin when it comes to torque, and even moreimportantly, the “area under the curve” is a whole lot fatter. That long arm(stroke) makes for a much pleasanter “driver”, especially vs. a cammed-up318 which will really suffer at low end and mid-range.
> #4 That fatter torque curve will also be a much better “fit” for towing, atall axle ratio, or overdrive /lockup gear. In a daily-driver there’s nocontest.

I have never said to toss out a perfectly good, low-leakdown 318, and I haveno objection to hopping it up, the same applies to a 273, for that matter.But if the engine is tired, needs a bore job, etc., and needs to come out, Isee no rationale for not swapping the 360. Cores are dirt-cheap, and therebuild is priced the same. I expect to get 425 HP out of a stock-shortblock360 very soon, for a total cost of under $2,500, including the engine, maybeunder $2,000. It might make even more power, we’ll soon see. Put a stoutclutch between the crankshafts of a 425HP 318 and a 425HP 360, however, andthe 360 will spin the 318 backwards with ease!

You have an M-body, right? A 360 Magnum, preferably with the OEM SMPI, andan OD tranny (A518 or 46RE), would put an ear-to-ear grin on your face!


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