Should I conduct a nitrous test???

[Z1500]

I have a very deep sickness for modifying the crap out of everything I own. It is honestly a problem. Bought a new 2019 AR240 last year and I just have it stuck in my head that I need another 10+mph on top end. I just can't get it out of my head, even though I know I should. A little critical background on me is I work at a company that builds turbo kits and turbo upgrades for crazy fast street cars and diesel trucks. I tune them, I've been tuning EFI systems for 20+yrs. I have the ability to reflash the Yamaha ECU's too. I do have the exact know how to make any HP I want out of these engines, that's pretty easy to me. But what I don't know is how the hull will react to say a 50% increase in power. What actual real world top speed gains would I get from 270hp per engine? Is their a rule of thumb to how much power% increase it takes in a boat to gain x% MPH?

So here is the test I'm thinking about conducting before I waste a bunch of my time turbocharging these engines. I could get some impellers done with much steeper pitch. Then add a nitrous kit with all the right safety timing retard, added fuel flow and high octane fuel. Jet each engine for an 80hp shot. Take the boat out and see what my new top speed is. If that confirms that adding the power is worth while I could rig the turbos up on a switch or something such, so I could make it so the boat is exactly like stock 0-40mph then the turbos only kick in then. I don't really need the boat to be chugging fuel ALL the time.

Does anyone know if this is a huge waste of time? I look at what the jet ski guys get out of these engines and it's unreal.

 

[anmut]

I mean, Yamaha straps a supercharger on these motors, not sure if the internals are any different. I would say hell yeah and go for it. You may find a diluted gain after so much HP without messing with impeller pitch. Start a build thread!

 

[zipper]

That is pretty cool, you should conduct a test. We like watching other people add power to these engines...as well as we like seeing things blow up. Just kidding. The engines can handle boost and a re-flash as they come with a factory supercharger on other models. Your limiting factor may be the jet pump moving enough water, but 10 mph+ from stock might not be too much to ask.

 

[Dave burke]

I dont know of any formula for HP vs top end but my guess is that it might be less than one might think. The only comparator I can offer is when I bought my Chaparral 1930 about 20 yrs ago and the standard engine at the time was a mercruiser 175hp 4 cylinder (going by memory). I was told by the dealer (who seemed very knowledgeable) that the top end would be around mid-40s. I bought an optional fuel injected v8 with 255hp and the top end was low to mid 50s depending on different factors.

 

[Z1500]

Oh snap!! The answer is to look at the Chaparral 243. It's almost the same boat with 200-250-300hp engines available. I almost bought one. More research!!

 

[Dave burke]

Actually thats a great point. I tested a 223 VRX when I bought my 212X. The boat I tested was 400 HP I believe. Dealer told me that the 500 HP version would do about 5-7 mph more from what I recall.

 

[Z1500]

It seems the Vortex 243 with dual 250's does about 56mph. So about a 10% speed gain over the Yami 24' boats. I can't find any stated top speed for the dual 300's Vortex. Guessing maybe 60-61?
So for my project I might need about 75% increase on my yamaha motors to hit 60-61.

 

[Dave burke]

Probably around that number. Maybe a bit less but it’s really hard to know. Is there a way to survey the 223/243 owners? Anything a dealer tells you is likely to be exaggerated.

 

[2kwik4u]

It's a waste of time. We don't have a transmission, so the only answer for more speed without repitching is more revs. You'll just find the rev limiter faster and most likely cavitate the hell out of your pump on the way to top revs.

If you repitch to a more aggressive impeller, then you'll need more HP and the N2O might help, but without it, there's a chance it won't be able to push the more aggressive pitch.

There is a reason the higher HP boats have a more aggressive pitch and 5mm more diameter on the pumps.

If you want more speed, get a tuner, raise the rev limiter. THEN repitch the impeller and tune the timing curve for max power. Lather, rinse, repeat that until you're out of octane and out of pitch......or add a full time power adder (turbo/SC) and repitch.

A "part time" power adder in a boat is a terrible idea from a usability standpoint.

 

[Z1500]

Not sure you read the first post.

 

[jsg73]

Yes... yes you should.

 

[tdonoughue]

In theory, there may come a point where the inability to tune the pitch of the jets causes the boat to become unstable at higher speeds. There is a hull speed, but that is for displacement hulls, not planing hulls. Ours are planing hulls, so there should be a much higher top speed. But at a certain point either a) the lift on the bow will be too much and it will start bouncing or b) the thrust will be too much and create too much torque to lift the bow. Either way, I opine those will cause a loss of control. That might be able to be addressed to a certain point with trim tabs, but I am not sure extra drag is what you are going for...

That said, certainly there has to be more speed in these before you hit that point. Would be interesting to find where that is. Theoretically there should be a limit of the amount of water that can fit through the pumps (same as a pipe capacity limit). Should probably check that as well.

 

[Neutron]

These engines are well known to be safe under 8500rpms above that you will need new valve springs, locks, etc or you will grenade the engine. So tread carefully my friend.
The pump is another limiting factor. Twin 160mm pumps with reworked tunnels to match will help.
This is all where it gets costly. Is it really worth it

 

[jgourlie]

I have a very deep sickness for modifying the crap out of everything I own. It is honestly a problem. Bought a new 2019 AR240 last year and I just have it stuck in my head that I need another 10+mph on top end. I just can't get it out of my head, even though I know I should. A little critical background on me is I work at a company that builds turbo kits and turbo upgrades for crazy fast street cars and diesel trucks. I tune them, I've been tuning EFI systems for 20+yrs. I have the ability to reflash the Yamaha ECU's too. I do have the exact know how to make any HP I want out of these engines, that's pretty easy to me. But what I don't know is how the hull will react to say a 50% increase in power. What actual real world top speed gains would I get from 270hp per engine? Is their a rule of thumb to how much power% increase it takes in a boat to gain x% MPH?

So here is the test I'm thinking about conducting before I waste a bunch of my time turbocharging these engines. I could get some impellers done with much steeper pitch. Then add a nitrous kit with all the right safety timing retard, added fuel flow and high octane fuel. Jet each engine for an 80hp shot. Take the boat out and see what my new top speed is. If that confirms that adding the power is worth while I could rig the turbos up on a switch or something such, so I could make it so the boat is exactly like stock 0-40mph then the turbos only kick in then. I don't really need the boat to be chugging fuel ALL the time.

Does anyone know if this is a huge waste of time? I look at what the jet ski guys get out of these engines and it's unreal.

The answer to Nitrous is always yes...of course that is because I remember my college years when I had a 125 shot on my truck...good times indeed

 

[zipper]

In theory, there may come a point where the inability to tune the pitch of the jets causes the boat to become unstable at higher speeds. There is a hull speed, but that is for displacement hulls, not planing hulls. Ours are planing hulls, so there should be a much higher top speed. But at a certain point either a) the lift on the bow will be too much and it will start bouncing or b) the thrust will be too much and create too much torque to lift the bow. Either way, I opine those will cause a loss of control. That might be able to be addressed to a certain point with trim tabs, but I am not sure extra drag is what you are going for...

That said, certainly there has to be more speed in these before you hit that point. Would be interesting to find where that is. Theoretically there should be a limit of the amount of water that can fit through the pumps (same as a pipe capacity limit). Should probably check that as well.

Whoever said displacement hulls are not planing hulls... drain the water ballast from a Macgregor and she will get up there and go.

https://m.facebook.com/home.php?ref...2869,"role":1,"share_id":0}]}}&__tn__=*s*sH-R

 

[the MfM]

I dont know of any formula for HP vs top end

Go-Fast.com > Knowledge base > Boat Speed calculator

 

[Weeb]

I would love to see you achieve this, it would be great to follow your progress. But it might be cheaper to buy a WaveRunner if you want to go 60 mph on the water lol.

 

[djetok]

I would love to see you achieve this, it would be great to follow your progress. But it might be cheaper to buy a WaveRunner if you want to go 60 mph on the water lol.

@SamCF should interject being the Yamaha speed king.

 

[NorfolkJames]

1. How do you intend to add more fuel to compensate for the air you just added to the mix?

2. Do you have the coin to rebuild the motor(s) after you either melt a piston or grenade the top end.

If you can answer the first question and say "yes" to the second question, go for it.

 

[anmut]

1. How do you intend to add more fuel to compensate for the air you just added to the mix?

2. Do you have the coin to rebuild the motor(s) after you either melt a piston or grenade the top end.

If you can answer the first question and say "yes" to the second question, go for it.

No no, we're talking about spray here. The only question with spray is "how much."