jetboat impeller suggestions 215

[tiderider]

OK thanks. I was referring to the exhaust outlet in the transom that was prone to water intrusion. You're saying the new style OEM waterbox over the riva box?
The only real function I require of the tstat is to "work" which it does. If it does indeed wear faster, thats just something ill deal with down the line.

If your concerned about the J on the water box. Simply replace it with a newer water box which no longer have the J pipe. There are ZERO performance gains with exhaust, get one used from any PWC for a few bucks... Free flow sounds awesome in my opinion. Simply replace the resonator with I believe a 9 1/2" Straight piece of 2.5" aluminum tube with beaded ends and 4 straps.

[njallday18]

You'll need to lighten your valves, replace the springs if they are old, replace the stock retainers with titanium and replace the flywheel bolts to spin more then 8400ish..

Yea thats what I thought. Thanks. Thatll be down the line.

[njallday18]

If your concerned about the J on the water box. Simply replace it with a newer water box which no longer have the J pipe. There are ZERO performance gains with exhaust, get one used from any PWC for a few bucks... Free flow sounds awesome in my opinion. Simply replace the resonator with I believe a 9 1/2" Straight piece of 2.5" aluminum tube with beaded ends and 4 straps.

Thats the plan. It would need the new style manifold as well if im not mistaken. I believe my current exhaust is "free flow" Thing sounds beastly. These are second tier concerns atm. Prop and SC build are what id like to get done before end of may.

[connorrxp]

That's a pretty cool set up you got there, just to clarify some misinformation. Your t stat is totally fine, thermostats set the temperature floor not the ceiling, lower temps will help with knock on a hot summer day and throttle response, your oil temps will still be high enough even at a 160 t stat to lubricate your bearings and rings properly. Next, you do not need to lighten valves to run over 8300, you can run stock valves all the way to 9k the valve seats are the first to give, but you would need retainers to spin over 8400 "safely" and springs and retainers for anything over 8600, for reference racers used to do stock valve train to near 9k and cross their fingers and are usually fine now we can run 9k with retainers cuz the rules changed. What will break on your engine at possibly even 8300 rpms are the flywheel bolts. You could do the 15/20 but I think your rpms will be a tad low in the summer but you can always pull a couple mill out of the impeller and get some of that rpm back, impros, skat track or Jerry that has the online store would all be able to point you in the right direction on what the exact impeller you'd need.

[njallday18]

That's a pretty cool set up you got there, just to clarify some misinformation. Your t stat is totally fine, thermostats set the temperature floor not the ceiling, lower temps will help with knock on a hot summer day and throttle response, your oil temps will still be high enough even at a 160 t stat to lubricate your bearings and rings properly. Next, you do not need to lighten valves to run over 8300, you can run stock valves all the way to 9k the valve seats are the first to give, but you would need retainers to spin over 8400 "safely" and springs and retainers for anything over 8600, for reference racers used to do stock valve train to near 9k and cross their fingers and are usually fine now we can run 9k with retainers cuz the rules changed. What will break on your engine at possibly even 8300 rpms are the flywheel bolts. You could do the 15/20 but I think your rpms will be a tad low in the summer but you can always pull a couple mill out of the impeller and get some of that rpm back, impros, skat track or Jerry that has the online store would all be able to point you in the right direction on what the exact impeller you'd need.

Thanks bud I appreciate the compliment. Its been a fun project for sure.
That's pretty much what I was thinking tstat and pushing over 8300. Trying not to touch internals til its absolutely needed. Lets see how well this prop spins before the SC.
Most likely going with the 15/20. Shave a bit if need be.

[njallday18]

just an update. 15/20 works quite well. Definitely better on holeshot. Top end is 2-3 mph increase but will should spin better in chillier conditions.