Thread: Sonic Boom Stage 2 Results
04-12-2009, 10:35 PM #1
Sonic Boom Stage 2 Results
Due to the huge amount of work involved in the creation of 43mm overbored throttle bodies, i have been hard at work getting yet more performance out of the standard 40mm bore design.
All previous sets have only had the throttle shaft screws trimmed flush with the throttle shaft on the back side where they protrude from the shaft.
I have now done extensive throttle blade and shaft work, with great results. The throttle shafts are very thick, which leaves plenty of material to remove, and not compromise strength or safety.
The screws themselves are very hard, at least grade 5 and probably grade 8, as it takes a carbide cutter to cut them.
They are then (peened) or staked into place by Yamaha, which makes them IMPOSSIBLE to take out. The only way to remove them is drill them out. And its a bitch, trust me.
Stage 2 will offer hand trimmed throttle shafts and screws flushed with trimmed shaft on both sides, and radiused throttle blades on the rear of the leading edge blade.
I have been able to remove .050 from each side of the shafts, and still this leaves a portion of the screw head intact so clamping force will not be changed on the blades.
Totaling .100 now being removed from the shafts, this greatly enhances airflow even more, and allows more air in, similar to overboring.
1mm = approx .040, so this is removing approx 2.4 mm from the total shaft diameter.
I hate to post numbers, because everyones results will vary. But, we are all motorheads and live and die by the numbers, so here is what i had.
Standard stage 1 sonic booms 7200-7210 rpms.
Stage 2 Sonic Booms, 7230-7240 rpms.
This is on my Rossnemo ported 06 1300 NPV ski.
30 rpm increase and .6-.7 speed increase over stage 1 sonic booms with a dynafly impeller.
Have been testing them for the last month now and results are steady.
Updates to existing sets will be very affordable at 110.00...
This work is all done by hand, very tedious and time consuming.
Yes the results even surprised me... No i wont guarantee the same for you.
Results will vary. Just letting everybody know there is more out there with the standard 40mm diameter if you want it, and now its affordable. The 43s are so labor intensive it makes them almost cost prohibitive to make.
I will be doing a back to back test soon on my 1390 with a 40mm Stage 2 set against a set of my 43s and will post the results.
I fully expect the Stage 2 40mm set to outperform the 43s due to increased velocity of the 40mm diameter. We will see.......
Pics show a Stage 2 set i just finished.
Shoot me a PM or call me for more info.
04-12-2009, 10:41 PM #2
04-12-2009, 10:45 PM #3
My 40mm kick ass just like they are! Oops did I say ass?
04-12-2009, 10:47 PM #4
Edit to add....I will update mine after season is over, no doubt.
These bad boyz work.
04-12-2009, 11:14 PM #5
- Join Date
- Jan 2006
- Lake of the Ozarks
Ross - what kind of turn around time on the retro fit? I really like the ones I have, but always looking to upgrade.
04-12-2009, 11:17 PM #6
I needed those pics Ross.They will go up soon! Have you did the same mod to the 43's yet?
04-12-2009, 11:31 PM #7
- Join Date
- Oct 2006
04-12-2009, 11:44 PM #8
04-12-2009, 11:47 PM #9
04-13-2009, 07:05 AM #10
- Join Date
- Feb 2006
Speaking of 43s - what EFI settings did you end up with on your 1390 with the 43s? I know you had it maxed, but you indicated you were going to lean a bit to see if there were gains.
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