btt

Reworking 496 manifolds by CNC
 

We were already to release a CNC'd program for upgrading flow on the original all aluminum Merc 496 exhaust manifolds when the "boys' at Mercruiser decided in 2006 to start using an all iron exhaust manifolds instead of the nice aluminum units, which made spreading the long term costs and trouble of our exchange CNC program an unprofitable curve. Considering for single engine applications the Dana actual header manifold can be purchased in complete kit form for about $2600 polished and they produce about 20 more horsepower than our CNC'd stock manifolds its kind of a "no brainer"! Buy a quality aftermarket exhaust like Dana or CMI and loose the stock manifolds (especially the heavy new iron versions) if you really want a reasonable power increase and serious better looks!

Best Regards,

Ray @ Raylar

I took mine out. Sounds much deeper, like a 500, I like the exhaust note. I picked up about 1.5 mph. Pretty good for $0invested.

As an update to the question of turbulator removal, here's a link to some actual dyno results.

http://fullthrottlemarine.com/496%20...%20Article.htm

Bob, as always thanks for the information. Thanks also for having a great shop so close to home. You guys do great work, and at very reasonable rates. Its been a pleasure doing business with you guys. BTW, finally hit the magical 70+ on the GPS, and it was 90 degrees.