Originally Posted by kvogt (Post 4405578)

My buddy Rick has a 43 No-Tech that had EFI 598s in it build by Eddie before he went on his own. After a few years Rick rebuilt the motors lowering the compression and added 10-71 blowers. The boat responded well and ran 92 at about 5700 -5800 rpms. After 4 years of running that combo the motors came out. Rick worked with Marine
kinetics to update his cam from the original efi cam. Back into the water looking for 6000 rpms and 95 mph he went. Nope The boat went a best of 87 at 5600 rpms.

The boat was tuned right, both motors pulled the same - didn't make sense

Rick contacted Bob for guidance. Bob's response was Rick was running the wrong oil (50 wt). How could that make sense, The same oil had been in the boat for over 5 years. The old motors with the same lifters ran fine with the wrong oil.

We though maybe the exhaust needed to be better so. The next year Rick invested in new exhaust. Going from CMI E-tops with 1 7/8 runners to Stainless Marine Gen 3 with 5 inch tails. Result - exhaust temps dropped a little but no real speed change.

This year (out of frustration and friends making fun of his slow boat) the motors are out again for a cam change. Not with marine kinetics.

First cam that ran well was a Crane 651 with 1.8 rockers on the intake. Bobs cam was larger with 680 lift. Third cam - we will see how it runs. The 651 cams are on the shelf not for sale.

Originally Posted by Boatally Insane (Post 4405584)

That's why I shared my results with you on F/B about changing my cam timing..

Who knows if the power steering pump or seawater pump starts taking exponentially more HP to turn once over a certain RPM....
We never ran it without the belts to check as it didn't matter, wasn't going in the boat without them.
We retarded the cam timing 4°, made more power on the top where I wanted it, and moved on.. :)

Originally Posted by kvogt (Post 4405578)

My buddy Rick has a 43 No-Tech that had EFI 598s in it build by Eddie before he went on his own. After a few years Rick rebuilt the motors lowering the compression and added 10-71 blowers. The boat responded well and ran 92 at about 5700 -5800 rpms. After 4 years of running that combo the motors came out. Rick worked with Marine
kinetics to update his cam from the original efi cam. Back into the water looking for 6000 rpms and 95 mph he went. Nope The boat went a best of 87 at 5600 rpms.

The boat was tuned right, both motors pulled the same - didn't make sense

Rick contacted Bob for guidance. Bob's response was Rick was running the wrong oil (50 wt). How could that make sense, The same oil had been in the boat for over 5 years. The old motors with the same lifters ran fine with the wrong oil.

We though maybe the exhaust needed to be better so. The next year Rick invested in new exhaust. Going from CMI E-tops with 1 7/8 runners to Stainless Marine Gen 3 with 5 inch tails. Result - exhaust temps dropped a little but no real speed change.

This year (out of frustration and friends making fun of his slow boat) the motors are out again for a cam change. Not with marine kinetics.

First cam that ran well was a Crane 651 with 1.8 rockers on the intake. Bobs cam was larger with 680 lift. Third cam - we will see how it runs. The 651 cams are on the shelf not for sale.

Originally Posted by mike tkach (Post 4405625)

i am not a cam expert but if the 651 cam made more power with the 1.8 rockers on the intake side the 651 is way wrong for the engine.all though i am a big fan of the 651 cam i believe it is not even remotely close to correct for a 598.