fire crater or step head

I just got to thinking about the two pistons for a 560 c-263. The fire crater gives more HP I believe, but does it use more fuel? Does any one know? I put step heads in the last tractor I overhauled but is the fire crater better? The step head performed very good, It almost made my 706 with the 282 dyno'd at 71 hp look bad because it didn't run away from it.

I dont recall that IH called the pistons in anything Fire Crater after the 450 series, they had std altitude, hi altitude & LP.

Rodger, in a perfect world fuel use is a function of air fuel ratio so cubic inches of the engine determines the amount of fuel used. A 263 should use x amount of fuel at x rpms wheter it is 5 to 1 or 10 to 1 compression. you may need better grades of fuel but useage should be about the same.

Fuel use improves with efficiency of pumping and thermodynamics of the combustion chamber.
Higher compression improves the expansion ratio. Thus the burning fuel has a greater percentage of volume to expand into from a smaller chamber. The surface to volume ratio of the chamber amounts to the relationship between the TDC volume compared to the surface area exposed to that volume, ie, if the chamber were perfectly cpherical, it would have least surface/volume, if thin areas and convoluted surfaces are present it has more surface to volume. Minimal surface area allows less quenching of the flame and more complete combustion. Strange shapes can produce higher unburned HC and lower net output.
BUT-- squish areas and shapes do (or can) contribute to turbulance in the chamber and somewhat better combustion than open chambers.
The reality today in newest technology engines provide direct injection. This allows a correct easily ignited mix at the plug with fuel free air near the surfaces reducing unburned HC, and making a gas engine nearer diesel in efficiency and far better in HC emissions and far fewer soot particulate issues.
I wpould go with the piston that has the least surface area, but highest compression. Jim

I agree with all below statements,

In our drag motors,we have always strived to use the flattest topped piston we can get away with.

What has been stated already,the only reason for a domed piston is to increase compression.In some of the newest Pro Stock engines I have got to be around,The dome is getting almost un noticable,compared to that big LUMP that used to be on them 30 yrs ago !!!!! There is kind of an art to getting a good,effecient combustion chamber.If you raise compression VIA a piston dome,you start having issues with flame travel,scavenging,ect.If you start raising compression VIA reduction of combustion chamber around the valves,you start diminishing the flow characteristics of the heads from "shrouding "the valves.Let alone cam profiles,valve diameter,ect. WAY too much details to post on here,and this is WAY long winded answer,probably alot irrelevant! lol

I know we are talking about older,lower RPM tractor engines here,but the same applies.