Velocity stack inside stock airbox?

[joeschuit]

It will be many months before I can water test this, but the wheels are in motion. Stock 62t airbox/flame arrestor base is milled flat and a 3d printed velocity stack using the original mounting holes. I turned some stainless bushings as to not crush the plastic when tightening the bolts. Main shape for the stack is a 7 degree taper, 3/16" radius at the top, and 2" overall height. I'm hoping this will give me the increased airflow similar to an aftermarket flame arrestor, yet have the benefits of the stock flame arrestor for water intrusion. My plan is to get some stainless mesh and form it over the ends to maintain the backfire resistance. If this works well, it would be a cost effective option for people with stock 38's that are looking for a bit more. In previous projects, I've done testing with pla and gasoline, doing full 24 hour submersion with no effects. The lack of fuel residue in the airbox makes me think vibration will get to the printed stack before fuel would. I can make a reinforced version 2 in that case.

 

[khaos]

If you print it with PETG fuel will not be a factor at all.

Following.

 

[restosud]

Very nice but why?
There are no performance gains to be had.

 

[Big Kahuna]

sandwich the mesh below the Stack where it bolts on to the lower Airbox assembly.

 

[Quinc]

Looks great! looking forward to seeing the outcome.

 

[Jhucke]

Very nice but why?
There are no performance gains to be had.

Airbox always seems to be an area where people really hope and want there to be easy gains made, but if you ride enough skis, you know this is never the case. Maybe it will reduce water ingestion on an already pretty good air box for this matter, but that's about it. Good science project though.

 

[Big Kahuna]

Airbox always seems to be an area where people really hope and want there to be easy gains made, but if you ride enough skis, you know this is never the case. Maybe it will reduce water ingestion on an already pretty good air box for this matter, but that's about it. Good science project though.

It may be like some of the small things you do on a stock class SXR. No one product makes the package, but when you take the sum of all the small parts added you get a great package. Just one part of many that can make a ski run really good..........

 

[waxhead]

Ha ha, this is funny. I have been looking at the very same thing you have been looking at. Not in the same instance but in another model of jetski.
Did you know that a set of 46s with the riva adapters will rev 70 rpm higher than a set of ada. The reason being that the riva has a nice round edge versus the ada which has a sharp edge.

 

[VXSXH20]

Ha ha, this is funny. I have been looking at the very same thing you have been looking at. Not in the same instance but in another model of jetski.
Did you know that a set of 46s with the riva adapters will rev 70 rpm higher than a set of ada. The reason being that the riva has a nice round edge versus the ada which has a sharp edge.

Way to go wax, trending soon on FB marketplace .... guys digging out old faded riva adapters and marking them up 300 percent!

 

[kevbo]

Very nice but why?
There are no performance gains to be had.

Many carb mods fall under this category but it doesn't stop very many from spending lots of money on the subject.

 

[joeschuit]

I liked the idea of trying the low profile version, less of velocity stack and more of a rounded lip at the base of the carb inlet. I'd be able to machine this type out of aluminum easily with little waste. Total height is .365" and fits under the oem flame arrestor screen. This should accomplish what I was thinking of, getting rid of the hard edges at the mouth opening. I also noticed the airbox carb holes are about 0.050" smaller than the carb opening. 38.95mm to 40.20mm, so I can open that up as well.

 

[maxboost]

I liked the idea of trying the low profile version, less of velocity stack and more of a rounded lip at the base of the carb inlet. I'd be able to machine this type out of aluminum easily with little waste. Total height is .365" and fits under the oem flame arrestor screen. This should accomplish what I was thinking of, getting rid of the hard edges at the mouth opening. I also noticed the airbox carb holes are about 0.050" smaller than the carb opening. 38.95mm to 40.20mm, so I can open that up as well.

Got to love being a machinist and a motor head

 

[joeschuit]

I've got more time and tools than money, so I end up spending much of my time in the shop doing silly things like this. Machined out of aluminum and everything bore matched.

 

[bored&stroked]

There is a reason they make stub stacks for 4 barrel carbs.

 

[MTRHEAD]

Many carb mods fall under this category but it doesn't stop very many from spending lots of money on the subject.

Can’t tell you how many things I’ve tried to get more rpm on my stock spec SJ. This is one of them! I will say I did make one for my SXR that really improved it. I’ll post pic later after I find it

 

[Storbeck]

I've got more time and tools than money, so I end up spending much of my time in the shop doing silly things like this. Machined out of aluminum and everything bore matched.

I like this one. I've had schemes to 3d print almost exactly this but never got around to trying it.

 

[Speleopower]

Humm...I would not mind a short piece to stick up inside the airbox to keep any water splashes out of the carb or maybe slow down the water so there is just a tiny bit getting into the carb.

 

[MTRHEAD]

Found what worked the best on my stock class SXR. Back yard cobbling 15-17 years ago

these were the ticket on stock Seadoos about 20-25 years ago

 

[Jhucke]

Found what worked the best on my stock class SXR. Back yard cobbling 15-17 years ago

these were the ticket on stock Seadoos about 20-25 years ago

Isn’t there a bit of a hood mod you can do for airflow to get rpm out of stock class sxr’s too? That’s more or less ahem, (il)legal?

 

[Big Kahuna]

Found what worked the best on my stock class SXR. Back yard cobbling 15-17 years ago

these were the ticket on stock Seadoos about 20-25 years ago

Forgot all about those! Wish westcoast was still around...