- Location
- sunbury ,ohio
Here is a good link to some quick nozzle boring anybody can do . http://greenhulk.net/forums/showthread.php?t=31518&highlight=nozzle+boring
Nozzle Boring ''How To ''
- Thread starter blaster800
- Start date
- Location
- So. IL
That is pretty neet I never thought about doing it like that. But I drop mine off at the local machine shop and they turn it on a lathe during lunch for $15
I've read several threads where people have bored their oem nozzles to 85+mm from stock bore size. So a small increase in diameter of the nozzle orifice should theoretically make the resistance to flow decrease by a power of 4 (since Resistance is proportional to length (unchanged) and inversely proportional to radius to the 4th power). Is there a proven "break even" point, with nozzle boring, that due to pump output the decrease in resistance doesn't provide any more benefit in actual thrust produced from ski? I assume the stock diameter is matched well to stock pump/impeller/engine specs so where is the optimal diameter for ski's of various stages of modifications? In the end...is it worth discussing?
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Idok
F1pro
- Location
- Nations oldest muthaF+++kin city
we did a couple with a bore master
did you run them? any seat of pants impressions after use?
I tried doing this with a rental ridge reamer from autozone and made a total hash of it on my 750 nozzle. The big difference is that the Lisle ridge reamer works like a hone where the entire tool turns. The other kind of ridge reamer is more common and it locks down on the cylinder and the very top spins cutting the ridge making it almost impossible to use it on a tapered nozzle.
Actually the bottom end yank is exactly what this mod is for. Even though my 750 boring was a straight ghetto boring, it was immediately noticeable. I plan to do it to my SJ but I have done so much internal modding to that thing, I wanted to get a good baseline before adding the little things like nozzle boring, flow control valve, etc.
#ZERO
Beach Bum
- Location
- Florida - U.S.A.
The stock nozzle has a 1.5-degree taper and needs to be machined on a lathe.
Boring the nozzle straight through will make the pump less efficient.
If you would like to have your reduction nozzle bored out the right way, send me a PM.
Boring the nozzle straight through will make the pump less efficient.
If you would like to have your reduction nozzle bored out the right way, send me a PM.
stanton
High on jetskis.
- Location
- atascadero,ca
I think most people have found that 85/85.5/86mm is the limit depending on the other components in their pump---pump cone, impeller design/pitch, general condition of stator vanes, intake grate type. 85mm is a pretty safe bet, beyond that you may have to change some other stuff around to prevent cavitation.
There are a couple of 701-760 SJs in our group that use old style Pro-Tec nozzles straight bored to 85mm. They make noticably more thrust without cavitation problems. So much so that I cant understand why theres not a huge demand for aftermarket nozzles. Keep in mind that the nozzle must be bored straight for a bilge siphon to work. Use a mill and turn table to leave the stock siphon or just install a tube like Kawasaki does.
the ww cone does almost the same thing but a different way. basicly makes more room for water to go though. i`m thinking if you got big hp you don`t want to open to much because you loss thrust pressure . thtust is your power and i don`t know were the cut off would be . that cost money
#ZERO
Beach Bum
- Location
- Florida - U.S.A.
You would notice even more of a difference with a taper bored nozzle.
When these nozzles are bored straight by the time you reach 85mm the back section hasn't even been cut.
The stock nozzle has a taper bore on the inside and outside of the aluminum casting and the stock bilge siphon works fine.
Why not just use a lathe with a boring bar and a carbide tip and cut it on an angle?
- Location
- South Florida
Is this worthwhile with a wetwolf cone? Or is it too much?
The main reason that Superjets work so well for freestyle is because of the pumps inlet to outlet area ratio and the low impeller pitch required to load the engine. You will start seeing the same problems that plauge kawasaki pumps if the nozzle gets too big. Dont expect a siphon to work in a tapered nozzle unless it is located flush with the outlet or is large enough to remove the taper effect. There must be more area behind the tube to get good pressure differential. A larger tube in a straight nozzle is why Kawasakis setup works so well. Tapered vs straight is really splitting hairs, I could not feel any differences for a given diameter. The radar guys may find some gains.