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Vuolo2

Supercharged Monsoon?

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Vuolo2

Has anyone put a supercharger on a Monsoon 350?  I live in Denver and the elevation is killing the performance of my motor.  I have already tried three different props and still cannot get it to pull me at 36mph in my 2013 VTX.  This is supposed to be a cross over boat but if it can't pull 36mph how can it be considered a ski boat?

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oldjeep

Supercharger would require an ecm or tuner that doesn't exist for these motors.  What props have you tried that are incapable of 36 mph.  Mine tops out in the high 40s at sea level with a 1939, hard to believe there isnt a prop that would do the job. 

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mackie12

agree with @oldjeep, I hit 44 MPH at 3600' but I am in a response.....with an acme 515.

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RyanB

I can't speak for the speed of your boat, but I will tell you that if you swap out props for more speed, you will lose low end.  If your boat has plenty of power, a prop change is a great idea.

What you are describing is obviously a problem with our altitude.  There really isn't a substitute for a more powerful engine here.

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oldjeep
8 hours ago, RyanB said:

I can't speak for the speed of your boat, but I will tell you that if you swap out props for more speed, you will lose low end.  If your boat has plenty of power, a prop change is a great idea.

What you are describing is obviously a problem with our altitude.  There really isn't a substitute for a more powerful engine here.

The prop swap he would need is for more low end so that he can actually hit 36MPH with the reduced power that his engine puts out at altitude.  It will mean that he is turning a lot higher RPM's at 36 MPH

 

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dinovtx

Not sure if it is ideal for the situation but my 2014 VTX came from the factory with the tourque prorp "achme 2419". Initially I was thinking it was going to be way to  agressive for the boat but with the surfing we do it actually works out great. The boat does top out at about 38mph when it hits the rev limiter at 5350rpm's. I Don't run it that fast tipically max speed for me is 36mph where you will be turning around 5100rpms. We do burn more gas slolom skiing this way but still allows me to put a ton of weight and get a great surf wave out of the boat. If you can't get up to speed with this prop there must be someting else going on. I can get up to speed with 11 people in the boat at around 800ft above sea leval.

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Woodski

@Vuolo2:  You probably have to review supercharger installs on a small block Chevy in the hot rod community.  As noted, the biggest challenge would be the engine controller.  Depending on how it meters fuel, some options would include going with bigger injectors to compensate the fuel supply but you would need to know how the existing controller meters fuel to know if that would work.  Other alternatives to gain power or in your case simply to add airflow would be a more aggressive camshaft or 1.6 ratio rockers.

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RyanB
2 hours ago, oldjeep said:

The prop swap he would need is for more low end so that he can actually hit 36MPH with the reduced power that his engine puts out at altitude.  It will mean that he is turning a lot higher RPM's at 36 MPH

 

I guess that is not the way I read it.  I thought he meant that the boat will not physically run 36 MPH at WOT.  If you want more top end, you need more pitch.  Higher pitch would get more speed and less hole shot.

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oldjeep
12 minutes ago, RyanB said:

I guess that is not the way I read it.  I thought he meant that the boat will not physically run 36 MPH at WOT.  If you want more top end, you need more pitch.  Higher pitch would get more speed and less hole shot.

He will need to be more specific, but I read it as he is unable to hit WOT or 36 mph - which would be a typical issue at high elevation if you are running a speed prop rather than a more torquey prop

@Vuolo2 - it would help a lot if you could tell use which props you tried, what RPM and top speed you were getting

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mrothwell

I run my VTX 340 monsoon at 7000 ft and can easily hit 38+ with either my Acme 1235 or my OJ 475.  That said, I just picked up an OJ 945 to help my surfing at that altitude.

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Vuolo2

HI guys thanks for the input.  I am running aa ACME 1235 now which has been the best solution so far.  It will get to 36mph at WOT but when I start making my pass it drops 1mph each cut until 32mph which it can maintain.  This is not going to work for my skiing.  I have a whole race/hot rod crew willing to take on the project of adding extra horse power but as was mentioned in this thread they are not sure about the ECM controls.  We are wondering if we can tap into the controls and make adjustments or swap out the ECM completely for one we can tune or if anyone has done something like this in the past?

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oldjeep
7 minutes ago, Vuolo2 said:

HI guys thanks for the input.  I am running aa ACME 1235 now which has been the best solution so far.  It will get to 36mph at WOT but when I start making my pass it drops 1mph each cut until 32mph which it can maintain.  This is not going to work for my skiing.  I have a whole race/hot rod crew willing to take on the project of adding extra horse power but as was mentioned in this thread they are not sure about the ECM controls.  We are wondering if we can tap into the controls and make adjustments or swap out the ECM completely for one we can tune or if anyone has done something like this in the past?

When you say WOT do you mean factory defined WOT (4800-5200 RPM), or that you have the throttle pushed all the way forward?

 

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minnmarker

The altitude must be making a significant difference.  I have a 1235 on a 21LSV (w Monsoon 340) and top out at 42 mph.  No problem skiing at 36 mph with the PP.  Surf at 10.7 mph at 2900 rpm.  800 feet.

Maybe there is a Super or Turbo charger that just adds enough boost to get the engine inlet to sea level pressure so the current MAF sensor and ECU thinks it is at sea level and engine performs "sea level?"

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Vuolo2

WOT pushed down and running 5100rpm.  Yes I am looking to get the motor to run more like it would at sea level but at around 7000ft.  WE lose about 10-20% performance at this elevation I'm just trying to get that back.

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oldjeep
Posted (edited)

I guess I'd start looking for another boat, or swap in the optional 6.0L that was available for your VTX.  Even assuming that you can figure out a way to cobble a supercharger onto an MFI 5 engine, it would likely cost as much as a complete engine swap.

If you google around, the idea comes up pretty frequently and I think there have even been threads here about it.  Have yet to see anyone actually follow through on it, so if you do take lots of pictures.

Edited by oldjeep

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Vuolo2

That's a bummer.  I have a group of friends who can do the supercharger and the tuning for about $4500 but we are still worried about the ECM and our ability to tune the motor.  Has anybody tried it?

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oldjeep
1 minute ago, Vuolo2 said:

That's a bummer.  I have a group of friends who can do the supercharger and the tuning for about $4500 but we are still worried about the ECM and our ability to tune the motor.  Has anybody tried it?

The ECM is MEFI 5 or 6 in a 2013 (check the tag on the ecm).  You would have to google around for a tuner.  The Mefi4 and older are a little more prevelant

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minnmarker

At 5000 feet you only need about 3 psi boost to get to sea level.  Maybe an electric duct fan?  Might be an interesting (and easily reversible) project.

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oldjeep
Posted (edited)
4 minutes ago, minnmarker said:

At 5000 feet you only need about 3 psi boost to get to sea level.  Maybe an electric duct fan?  Might be an interesting (and easily reversible) project.

LOL, this reminds me of the guys that sell bilge blowers to Honda kids on ebay as electric superchargers

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1311.R1.TR7.TRC1.A0.H0.Xelectric+supercha.TRS0&_nkw=electric+supercharger&_sacat=0

Edited by oldjeep

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Vuolo2

yes we figured 3-4lbs of boost on the supercharger would do it too.  not sure what you mean by an electric duct fan???

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Vuolo2

thanks.  I will check out the tuner software and make sure which one we need.  perhaps call the company to see if it is compatible with the Indmar systems.

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minnmarker
14 minutes ago, Vuolo2 said:

yes we figured 3-4lbs of boost on the supercharger would do it too.  not sure what you mean by an electric duct fan???

Something like this https://www.amazon.com/Johnson-Pump-America-54124-Blower/dp/B002IV533I/

I have NO idea if it would work or provide enough flow/boost but it might be worth a try for $85.  Maybe the manufacturer has cfm specs you can compare to the engine air flow?

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Nitrousbird

These threads come up every year and I have yet to see a single person do it.  

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justgary
11 hours ago, minnmarker said:

Something like this https://www.amazon.com/Johnson-Pump-America-54124-Blower/dp/B002IV533I/

I have NO idea if it would work or provide enough flow/boost but it might be worth a try for $85.  Maybe the manufacturer has cfm specs you can compare to the engine air flow?

Hmmmm.  I'm thinking it would be a restriction at WOT.  It's late, so my math might be wrong, but a 5.7l engine is about 0.2 cubic ft.  At wot and pumping the engine displacement every two rotations, you are looking at about 523 cubic ft per minute.  

That pump is rated around 115 or so, meaning you would have a restriction (negative pressure) beyond high idle. 

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