Post by: radryan on October 18, 2019, 05:47:41 AM
Post by: 08chevyguy on October 18, 2019, 07:41:26 AM
Sent from my SM-J727T using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
Post by: FordLover on October 18, 2019, 09:55:50 AM
Sent from my LG-TP450 using SoCal Jet Boats mobile app (http://r.tapatalk.com/byo?rid=201)
Post by: radryan on October 18, 2019, 10:41:14 AM
Post by: radryan on October 20, 2019, 07:30:09 AM
Got the jet cut in. Back plywood cut @@nd custom spoiler installed. Lol
Post by: mash on it on October 20, 2019, 10:43:50 PM
Started life as a 18ft kona. Took 2ft out of the center and 6ft off the length.(http://) berkeley jet with place diverter, powered by a gsxr 600. Not sure what that combo will do but we'll see. Plan on keeping the 6spd tranny in play
First, I'm not a motorcycle guy.
Second, the gsxr 600 makes between 90 and 110 hp, @ ~13,000 rpm, depending on year. These figures are from the interwebs.
For a Berkeley pump, with a "C" cut impeller, (the smallest impeller with a detailed chart, from JBP) requires 92 hp @ 3300 rpm, and 110 hp @ 3500 rpm. This is pump shaft rpm.
With the gsxr transmission, 3rd or 4th gear might achieve 3500 pump shaft rpm, with an engine rpm of 13k rpm.
A "C" cut, as well as a "D" cut impellers are not as efficient as an "A" or "AA" cut impellers.
With trying to compare a mini jet boat to a 18' jet boat, it's difficult at best. Let's try.
My boat, 18', Sbc 350, Berkeley "A" impeller, at 4000 rpm, is roughly 45 mph, ~ 228 hp.
With a "C" cut impeller, 228 hp would be about 4500 rpm. The volume of thrust (water) would be similar. So would the speed. (A @ 4000 vs C @ 4500).
2700 rpm is about the slowest I can keep on plane. Somewhere around 22 mph. With a theoretical C impeller thats about 3000 rpm.
Even if your mini jet boat is half the weight, with a "C" cut impeller, at 3500 pump shaft rpm, 35 mph would be full throttle. Possibly 40, but I doubt it, just a wild azz guess. Remember, to achieve 3500 pump shaft rpm, the gsxr will, WILL, be @ 13,000 rpm.
I would go one of two (or 3) different ways-
Keep the Berkeley, and put in a light engine, with double the hp (Think Subaru flat four? 3100 60° GM V6? Ford 2300 turbo?)
Or keep the gsxr, remove the Berkeley, and use a suitable jet ski pump.
Or use an entire jet ski engine and pump. (The aluminum mini jet boat guys have been doing this for years)
I hope this helps.
Others might have more insight than I do.
Dan'l