Thread: Good RPMs / Bad MPHs
04-11-2011, 11:07 AM #1
Good RPMs / Bad MPHs
I d like to ask advice to find out why i have lost 2mph at same rpm over the last few months
My set-up is 07 RXP (170 hrs), 8.600 ECU reflash, ET140 charger, 50" injs, Riva rrfpr @59psi, 4" front air, XS IC with HKS BOV, Riva open loop kit, Riva grate & 255 plate, 83 ring, 15/20R untouched
Air & water 90F then and now
I used to gps +79mph @8.400 rpms (best 79.5), now i can only get +77mph @8.400 rpms
I tested with 82 ring and it got worse: rpms were down only 50 to 8.350, but speed went down to +75mph
I would understand the speed loss if rpms were down on par but they stay solid...
Carbon seal, wear-ring & pump-shoe were all replaced less than 10hrs ago.
Compression check showed 130 across the 3 cylinders.
What do i do now?
04-11-2011, 01:11 PM #2
04-11-2011, 08:33 PM #3
04-11-2011, 11:00 PM #4
04-12-2011, 03:35 AM #5
Ring/prop clearance seems ok when looking into the pump with a flash-light,
the wear-ring is new...
do you recommend i pull the pump for inspection?
When the dealer changed the shoe, i asked them to align engine too, they wouldn't have bothered checking it if i didnt mention ... i remember they put 2 shims under each rear mount, that seemed a lot...
If it was a boost leak, rpms would be down too, correct?
so we can narrow it down to a pump or alignment problem?
04-12-2011, 06:47 AM #6
I did notice something unusual after dealer replaced pump shoe/ wear ring /carbon seal,
after the first ride i found this black carbon line all around the inside of the hull at the level of the seal, see pic attached.
It s everywhere, at the bottom of the hull, on the sides, even on the inside of the seat.
At first it was a very thin fine line like laser-etched, now it s thicker & blurred, i havent cleaned it so i could show it to them next time.
Is this a sign of bad alignment?
04-12-2011, 07:08 AM #7
04-12-2011, 08:06 AM #8
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