- Aug 17, 2010
- 1,589
- Boat Info
- 2008 44 Sedan Bridge
2017 Avon 380DL RIB w/ Yamaha 40
2022 Sea-Doo GTX LTD
2020 Sea-Doo RXT-X
- Engines
- Twin QSC-500 HO
turning 4800 on one and 5000 w.o.t. on the other
This is interesting. Before I purchased my boat last fall, the mechanical inspection and survey revealed the starboard engine was running 320RPM higher at WOT. The marina did a compression test with the following results:
Port side engine: 4350RPM WOT
1 180 2 180
3 180 4 180
5 180 6 180
Stbd engine: 4670RPM WOT
1 195 2 195
3 195 4 195
5 195 6 180
~ 44MPH (speedo)
They stated both engines were within spec, and the compression difference may or may not cause the RPM gap. The props are the originals with no signs of impact. They then did a full tune-up to see if it would close the gap. It did, to about 150RPM and they felt there was no problem so I proceeded with the deal. Boat runs perfectly.
Is it typical for the engines to be out a bit? Could it simply be a prop being out of spec accounting for the delta? Anyone have an opinion about the compression difference?