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A DF25A and a DF30A have the same bore, stroke, compression ratio and valve size, essentially the same motor, so where do they get the extra 5hp? Hotter cam? injector size/programming? Curious minds want to know!
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Any/all of the above.
For as long as I can remember, manufacturers have had engines with the same basic specs producing several different HP to give them the range coverage required.
In the old days it was usually things like carby sizes, jetting and porting in the inlet and manifolds. Sometimes it was as simple as linkages on the carby being placed slightly different position I remember a Tohatsu 30 that could be upgraded to 40 just by repositioning the throttle linkage to a different hole and changing the timing a couple of degrees!
With the new engines it can be things like ECU mapping, valve timing and valve systems like VVTI or equivalent, manifolds, injector sizes, etc. All can be pretty expensive items to replace.
Many have asked the question about whether it's worth trying, on the new EFI 4 strikes, to get the extra HP by changing a few things. It's rarely if ever as simple as that any more. It is rarely practicable or financially worth the trouble. Better off just buying the higher hp version in the first place.
And unfortunately outboards are not big enough volumes to make it worthwhile for many "performance chip" companies to turn their attention to developing chips for them. -
I figured as much. I too have seen the same over the years, also on tractors. I was just curious if anyone knew the specifics on this motor.Comment
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