AFR 521

My 521 with AFR 280s goes on the dyno tomorrow. The heads have had some work done to them as well as the intake. Running a solid Roller setup with mid 270s at .050 and .730 ish lift. I am running the 4150 manifold with a 1050 4150 style carburetor. Compression ratio is 10.5 so it is a pump gas deal for my boat. Hoping for 700 and change.

Seems like a pretty reasonable goal, good luck. I treated the dyno session of my 547 as the birth of a child, happy and healthy was the end goal.

TPayne366 wrote:My 521 with AFR 280s goes on the dyno tomorrow.  The heads have had some work done to them as well as the intake. Running a solid Roller setup with mid 270s at .050 and .730 ish lift. I am running the 4150 manifold with a 1050 4150 style carburetor. Compression ratio is 10.5 so it is a pump gas deal for my boat. Hoping for 700 and change.

sweet build, details and pics of the boat !!

I was only able to attend about an hour of the dyno this morning, when I left it was making 717HP @6400 with 650+ ft lbs almost the whole pull. Have not gotten final dyno sheet, but heard final was 737HP @6500 with a super flat torque curve. Will post all build details and dyno sheets when I get them.

very nice !!

Very similar to my engine. I have a pump gas 521 with AFR 295’s. 11.5:1. AFR Dom intake with an 1150. Solid roller 260/270 .700 lift. It made 760@ 6500 and 660Tq from 4900-5900. It ran the best with 30* total timing. Good luck with yours.

I have a 521 10.5 comp with afr 315 heads...I run mine round 34 timing...never tried less