The ZR1 oil filter has been long touted as an upgrade for the KLDE. I have used it since 2006 and ever since I have had a recurring problem, an oil leak on the filter body. I have always resigned the leak as something elsewhere on the engine, Id wipe it off and think its so insignificant its not worth digging into.
Until recently I was repairing a power steering leak under the motor and this time I wiped the drop away and began fixing the power steering leak. After about 30-45min of repairing the leak i noticed the oil drop had returned on the filter. The engine hasent ran in over a week, so this is a leak with no oil pressure.
This time I was able to see where the oil leak came from, it was the seal of the oil filter. The filter is tight and put on correctly, yet it leaks with no oil pressure.
This is where I decided it was time to dig into this issue, especially after close inspection of the seal it appears the outer edge of the oil filter gasket seal is riding on the tapered edge of the filter housing.
Below are the specification differences between a stock KLDE oil filter and a Corvette 1994 ZR1 oil filter. As you can see they are practically the same filter but different in dimensions, most notably in this situation the gasket seal.
Here I measured the filter housing to determine if the ZR1 Filter is at all possible an upgrade. A larger filter doesn’t improve much if the flow characteristics are the same or worse.
The ID of the body is roughly 1.70″ and OD roughly 2.80″.
“roughly” because both edges of the inner and outer are rounded. Roughly is the measurement of the flat part of the surface.
Here is the measurement’s of the ZR1 filter, as shown the outer edge of the seal is wider then the outer edge of the filter housing. This is obviously why the filter always seeps oil from the seal ( in my case) A quick comparison of the stock filter below shows the inlet holes of the filter are the same quantity but actually smaller then the stock filter. There is actually more void and material obstruction compared to the stock filter.
Here is the measurement’s of the stock filter, as you can see they are closely matched to the filter housing and the outer edge of the seal is much smaller then the outer edge of the filter housing. It is a smaller filter by comparison but the technology of oil filters is a bit more advanced then they were 30yrs ago. Shown here is a WIX XP filter.
Conclusion
Based on the measurements ive taken I feel comfortable claiming the ZR1 filter is not an upgrade, at best its a filter option that fits good enough but not well.
The claim that it can flow better or filters better because its larger doesnt hold well either because the ZR1 filter ( any filter) is sized according to the filter housing inlet and outlet. I do not have access to a ZR1 but its reasonable to assume the filter housing of a ZR1 has a much larger inlet.
In either case I have decided against running a ZR1 from here on out because of the possibility of a filter seal blow out. It has never happened in 20years for me but its possible with .08 of the seal not actually sealing.
