need more power on 2011 speedster 150 (155)

[Rae]

Was having cavitation issues with my speedster 150 (155 hp). It would run 40 mph @6900 rpm on a lake at 4400' elevation. I know the elevation is a factor.
I just bought the solas impeller 11/19 upgrade and a new wear ring. I took it out to the same lake today and noticed the cavitation is pretty much gone and got the boat up to 41-42 mph but it seemed to top out at 6340 rpm. So its nice to see the speed bump a little and not needing as much rpm to do so which tells me everything is fine, but im just lacking in the horsepower department, which brings me here. I am trying to figure out what i can do to increase my HP so i can get the rpm's back up and let the boat go even faster. The rev limiter is at 7600 rpm btw, which im not coming close to. I have no idea if adding a supercharger to get to 215 hp is even an option with the normal rotax 4-tec or if it is, is it a big ordeal to do? im already running a KNN cold air intake. Just wondering if there are some other upgrades to get back that 25-35hp im losing from elevation?

 

[RustyBucketBay]

I asked a similar question about a week ago in the modify section. Can you upgrade a challenger 180 215hp to 260hp. No replies yet. But some digging would lead to yes. Apparently there’s someone with a good write up on Facebook doing this to scarab boats. I’m not on FB so can’t confirm I asked same question on jetboater.net

TLDR seems possible here’s some videos from my own digging that may shed some light. The 2nd 2 are from the channel 3ftdeep some really detailed vids and tear down guides. Check the descriptions within for parts.

Parts needed to upgrade HP on 4tec

How to install inter cooler on 4tec

Supercharger upgrade and how to remove install

Best of luck on the power hunt.

 

[Rae]

Im running a non supercharged engine.

 

[MacSeaDoo]

The short answer is that anything is possible with the right amount of money.

Having a normally aspirated engine at elevation usually works out to around 3% per 1000 feet. For you that would be around 15%. That brings you to around 131HP.

Now that being said, a supercharger is gear driven and provides a linear amount of pressure vs RPM. They will suffer the same loss but are starting at a higher output.

The only free lunch typically with altitude with forced induction is turbocharging. It will still have losses but they will not be in the same range depending on the setup.

To be honest, I would assume there are turbo kits out there for your 155 NA but I am not sure the return on investment would make sense.

If you need more speed, your best bet would be to sell your machine and find a SC model. I say this because the pump for the SC model and the NA model are different. I think you would be just dumping money into something that you will never get back.

 

[ZRX Guy]

Good try on the prop pitch, but you are lacking the air. Mine is a little under par @3k', but nothing I'm gonna worry about. I can still get about 47mph. Haven't had it at sea level yet. Even on my bike in the avatar, I live at 3000'. I took it to a trackday years ago at about sea level. It turned into a little monster on me...LOL!!!

 

[Franky Flash]

You need to change your intake grate, check with SOLA on their site. You can also build a fresh air intake that will help.

Last year I did the same thing my old impeller was a 13-21 pitch. Thaht make me lost about 800rpm and 4mph, but I gain a lot of torque at low speed (yummy!). So I change my intake grate, my fuel from 87 to 94 octane, my oil from ordinary oil to full syntec and put a cool air intake...now I am back at 7200rpm and 48mph.

My boat is a 2004 Sporster with a 155Hp 4tec, altitude 1000'

 

[Rae]

You need to change your intake grate, check with SOLA on their site. You can also build a fresh air intake that will help.

Last year I did the same thing my old impeller was a 13-21 pitch. Thaht make me lost about 800rpm and 4mph, but I gain a lot of torque at low speed (yummy!). So I change my intake grate, my fuel from 87 to 94 octane, my oil from ordinary oil to full syntec and put a cool air intake...now I am back at 7200rpm and 48mph.

My boat is a 2004 Sporster with a 155Hp 4tec, altitude 1000'

94 octane? Never even seen that. I run 87 with an octane booster. I already use full synthetic oil and a knn cold air intake. Haven't done an intake grate and not sure what that would do.

 

[Franky Flash]

94 octane? Never even seen that. I run 87 with an octane booster. I already use full synthetic oil and a knn cold air intake. Haven't done an intake grate and not sure what that would do.

it will pressurise your intake with a rotating non turbulent flow of water and keep your intake always charged (no air in the turbine between 2 waves), the airfoil section allows more water flow consistently into the pump to eliminate cavitation and improves hook up ability.
Total thrust boat = intake pressure + thrust delivers by your turbine.

 

[Rae]

it will pressurise your intake with a rotating non turbulent flow of water and keep your intake always charged (no air in the turbine between 2 waves), the airfoil section allows more water flow consistently into the pump to eliminate cavitation and improves hook up ability.
Total thrust boat = intake pressure + thrust delivers by your turbine.

Doesn't seem like solas makes a grate for the 2011 model. Any idea if I can use an older model's grate? Also, is it really OK to use a higher octane in the engine?

 

[Franky Flash]

the grate that Solas make for your boat is the SS0206 (i find this by doing cross-referenced searching with the no. 271001561 part to see on what seadoo pwc it fitt and compare the list with solas's list)

Higher octane seem to work fine for me (but maybe it is just in my head) anyway in my shop manual BRP write to use at least 87 min. but they do not give any number for the highest grade that you can use.

 

[Rae]

Just looked up the grate. Are you sure it will fit a 2011 speedster boat? looks like its for an actual jet ski. I know a lot of parts are reused for different craft but i just wanted to make sure before i pull the trigger on it.

 

[Franky Flash]

Just to make sure , write an email to solas?

 

[Rae]

Just to make sure , write an email to solas?

I did some cross referencing. It does appear to be the right one. Im ordering it.

 

[Digdog]

I think you have too much impeller, you should be around 7400 rpm which is where most of your horsepower is.

 

[Rae]

I think you have too much impeller, you should be around 7400 rpm which is where most of your horsepower is.

At sea level maybe. I can only get to 7400 out of water. And the previous impeller was the oem one. Im also achieving a slightly faster speed at less rpm with the new impeller.

 

[Rae]

Installed the solas intake grate. The ride is definitely smoother, no basketball dribble bouncing anymore and managed to get another 1-2 mph out of it. Just a couple more to hit 45 mph at 4400'

 

[Joe Starbuck]

Just to be sure you are air-limited, you get a small bottle of NOS and spray it into intake at WOT, see if you get 7600.

 

[situation52021]

SO how can I build a K&N cold air intake for my friend's 2004 Sportster 4 tec? I noticed there is a sensor on the factory airbox so where would I relocate that to?

 

[Rae]

Nos? Never played with that before. Sounds scary. But I do get 7600-7700 rpms out of the water.

Mine came with a k&n already installed. I would assume there would be directions so just follow that. I do have plugs on my intake hose from the filter to the throttle body, so maybe those are the same?