Over the winter I added the hardin drive shower to my bravo 1 454 mag. I thought I used the template correctly to drill the holes. I guess not. It's further back then it should, close to my propwash. (See pic below as this isn't my 10th post yet) I'm wondering if there is any performance loss in this location. I'm not getting any more cavitation then I was in certain circumstances then before. I added this and changed my plugs to iridiums and lost 300 rpm. Which it 10 mph for me.

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#10

Summer89,

I can't imagine adding a drive shower pickup would cost you RPM. If it were causing cavitation, conventional wisdom says you'd gain RPM, but not necessarily speed. I'd go back to standard plugs and see if the RPM come back.

For the record, I wouldn't think iridium plugs would cost you any RPM either, but others way more knowledgeable than me may chime in with empirical testimony otherwise. I'd also think that pickup would be high and dry, other than prop wash, at a speed anywhere near where you've lost RPM. Hence, my advice about the plugs.

Thanks. Brad.

I had a simrek style cooler on mine from the previous owner. I switched to the hardin marine style and reused the hole from simrek and had no issues, I think mine is even further back than yours from a quick look at the picture

Would it be impractical to suggest just removing the shower pickup and re-test? Is it possible in changing plugs a wire is loose or reversed with another? Perhaps tugged on the wire too hard and dislodged the cap from the wire?

I just put copper vpowers in it. I'm gonna try the plugs first. All the wires were new with the plugs. Put a new msd cap and rotor on it last year. Checked timing at 36. And if it doesnt work. I'll pull the cooler off and see. I hope to test this weekend. I was just wondering from everyone's experience if they think the shower could have any affect on performance since it's in the wrong location

Besides that the bolt should be on top (i.e. reverse the nut and bolt and put the screw side underneath it looks fine to me. The reason to flip the bolt is because the other side is simply smoother and in the water, you don't want the water to shake the bolt loose.

I'm betting you have a loose plug wire, bad plug, etc. that shower isn't scrubbing 300 RPM but a dead or partially dead cylinder certainly would.

Summer89,

I don't know if the mounting tab for the drive shower pickup will allow for it, as it's very likely they are at least tack welded to maintain orientation of the pickup, but I could see swapping ends with it, bolt for tube. Otherwise, I stand by my initial statement: I can't imagine anything behind the prop causing cavitation, and it's hard to imagine the pickup even being in the oncoming stream of water at WOT. It is my understanding that these pickups are "dry", and just catch water slinging off the blade tips, at any speed much beyond planing speed, especially after trimming it out a bit.

Plugs are a very likely culprit, especially if the change occurred in conjunction with a plug swap. Double check firing order and wire end connections. I can fully attest to missing cylinders resulting in decreased RPM at any given throttle position.

Thanks. Brad.