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      09-11-2025, 09:20 AM   #5
PerformanceEngSolutions
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Drives: 2008 135i M Sport
Join Date: Oct 2024
Location: Massachusetts

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Quote:
Originally Posted by scratchgolf135 View Post
I understand there were some revisions to the HPFP along its lifecycle. Does this include such upgrades to match those?
The latest factory pumps are up to index 5 now. I’ve rebuilt -01 through -05 pumps and haven’t visually seen any differences. Without precisely measuring the internal components, since all of the components visually appear to be the same, it’s tough to say what the differences between indexes are. However, I will say that after rebuilding them I’ve seen all indexes perform more or less the same.

Otherwise, the only upgrades we perform are the addition of a backing ring and retaining ring to capture the rotary seal for increased rotary seal longevity and the use of Viton o-rings on the fuel side for E85 compatibility.

Last edited by konstat; 09-11-2025 at 09:21 AM..
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