Just got back from Jay's dyno running the 418 I assembled for the GT40 replica I am building.
Thanks to Brent for helping me select and procure the components and sciencing out the cam. I wanted a pump gas engine that was fairly docile, easy on the stock valve train. rpm to about 5500 make 425 to 450 horse and a lot of torque.
360 105 block .030
428 1U crank
Scat FE rods
Diamond pistons
10.25 compression
Total seal rings
Morel hydraulic lifters
Comp 3/8 push rods 7.70
Lykins spec'd Comp Hyd roller. (Cam card attached)
Edlebrock heads from Jay's Car Craft engine, unported
Rocker Arms Unlimited stock rockers with end stands
Comp 914 springs
Performer RPM knockoff intake manifold ported by Joe Craine
800 Holley double pumper
We made a total of 13 dyno pulls, ran at different rpm ranges, we did a timing loop, and tested 3 carb spacers
The best run was what I call a hero pull which is cold water and hot oil that netted 439.5 hp and 497 torque. Power numbers under more normal dyno conditions were 433.1 @ 5600 and 490.6@3700. We made one pull from 3000 to 6100 just to see where the power dropped off and to get a complete profile of the power curve. As you can see in the graph, it took a dive at 6000. I think this was loss of valve train control. I purposely went with a modest spring to lessen stress on the rocker assembly . Since this engine will never see that rpm things will be just fine. I did not set out to fine tune the engine to extract the last few horsepower The carb was slightly rich but we left it alone.. I mainly wanted to see what the engine combination would do, check for leaks and any mechanical gremlins. No need to flog it further.
Comments: I am quite surprised by the performance of what i would normally consider a tiny cam.. Brent and I discussed my goals and I went with his recommendation even though I would have dialed in more intake duration.. Kudos to Brent he knows his stuff..
