Quote:
Originally Posted by jt20
I just spoke w/ C Sean Watts. The difference is in the size of the bore in the pintle. You will NOT notice significant gains on a 617 turbo until above 4k rpms. The 265 allows greater fuel flow in this range / faster delivery. Up until then, he says theyre is no preceptible diff. The 265 does make a difference for the 603 though.
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The bores are
almost the same, the SD 240 has a hole in the pintle. The 261 and 265 don't, they have a facet cut between the shoulders. The design intent between the two (261 and 265) is emissions. The 265 came out with the aluminum heads and trap oxidizers.
BOTH feed the same displacement engine but the OM 603 (stock with the SD 265) can turn higher RPM. I try to stay under 4K with mine but I'm still keeping the 265s, as I have found no reference to back date fitting for newer motors, only update fitting with older motors.
The bottom line is EITHER 261 or 265 are a good improvement over the 240.