Joe and Chris Grace's seadoo spark powered Krash Footrocket

[orangefinger]

Any type of innovation for our sport is positive, even if it ends up being for a small specialized group, innovation is movement and shows that something is happening.....

"Doing the same thing over and over, yet expecting different results, is the definition of crazy."

 

[chrisgrace]

Love the activity on here, just wanted to reiterate what our goal was: Not to compete with the 2 stroke as far as performance goes, just to simply offer a cost effective/Eco friendly (lake riders) alternative stand up. If we can get the performance output near a 701cc base engine, we hope that it will have some great freeride applicability since in freeriding weight isn't so much an issue for us. We like stuff we can flip, roll, beat up, and carve a wave to pieces. If we can do all those things with the Spark Rocket it would be a great success in offering an alternative in our industry.

I am a sponsored rider for True Performance Engineering and I run a 964 in my Footrocket. I love this engine so much I wouldn't even think to switch over to a 4stroke in my personal boat. However, 4 stroke or 2 stroke we all love riding and want our sport to grow, so if we can get them near/close to a 701cc we think it will truly help make advancements in our industry and continue to expand our sport!

 

[Matt_E]

Efficiency should be getting the most power for the amount of fuel used, which is not a two stroke...

"Efficiency" is not a nebulous concept. It's defined as power out divided by power in.
'Power in' would be the chemical potential energy from the fuel.
'Power out' is the energy the engine actually puts out (at the crank).
Understand that I am being loose with power and energy here, but energy is just the time integral of power.

4-Strokes ARE more efficient.

Cool project. 2-Strokes are on the way out, it's just a matter of time. All of you know this.

 

[speedysprocket]

"Efficiency" is not a nebulous concept. It's defined as power out divided by power in.
'Power in' would be the chemical potential energy from the fuel.
'Power out' is the energy the engine actually puts out (at the crank).
Understand that I am being loose with power and energy here, but energy is just the time integral of power.

4-Strokes ARE more efficient.

Cool project. 2-Strokes are on the way out, it's just a matter of time. All of you know this.

Thanks for reiterating in a slightly more technical way!

 

[bird]

Is that why e-tec engines are comparable to 4 strokes for emissions? Read about them derp.

stop sounding like you know everything, because you don't!

"Efficiency" is not a nebulous concept. It's defined as power out divided by power in.
'Power in' would be the chemical potential energy from the fuel.
'Power out' is the energy the engine actually puts out (at the crank).
Understand that I am being loose with power and energy here, but energy is just the time integral of power.

4-Strokes ARE more efficient.

Cool project. 2-Strokes are on the way out, it's just a matter of time. All of you know this.

 

[yamanube]

"Efficiency" is not a nebulous concept. It's defined as power out divided by power in.
'Power in' would be the chemical potential energy from the fuel.
'Power out' is the energy the engine actually puts out (at the crank).
Understand that I am being loose with power and energy here, but energy is just the time integral of power.

4-Strokes ARE more efficient.

Cool project. 2-Strokes are on the way out, it's just a matter of time. All of you know this.

If it's apples to apples FI overhead cam four stroke to a FI rotary valve two stroke, do you think that line is as definite? I understand the argument that a new 450mx engine is more efficient than say a 701 but those are far from comparable tech.

 

[OCD Solutions]

You guys get so hung up on the most trivial of things.

 

[yamanube]

You guys get so hung up on the most trivial of things.

It's like we have OCD.

 

[bird]

please read up on Direct Injection vs Fuel Injection. FI is a thing of the past guys.

 

[yamanube]

Is it possible to get a build thread on this ski or would that be giving away some secrets?

 

[Matt_E]

Is that why e-tec engines are comparable to 4 strokes for emissions? Read about them derp.

stop sounding like you know everything, because you don't!

To be clear, you want me to "stop sounding like" some impression you get after you read my post? I'd say the problem is on your end.

I thought my post was simple enough, but I'll clarify:

• I was speaking of efficiency, not emissions. They both start with the letter 'e', but it ends there. And what I said is 100% true.
• I am not interested in reading about e-tec engines. I used to own one, I understand what they are.
• Sorry to upset you with my posts. I did not claim to know everything nor do I know everything. I do know this: Everything I posted is fact. If you have a problem with what I post, please refute the facts directly instead of attacking the poster. It's generally a much more acceptable way to do a debate.

That's all.
This post brought to you by the letter 'e'.


PS: Here's a challenge: Can you read my post without getting upset?

 

[Ducky]

Is it possible to get a build thread on this ski or would that be giving away some secrets?

I dont think there is any secrets really....Mr Grace took us through the build in Daytona. The fact is...he fabricated so many different parts to get this to work, it was pretty mind blowing.

 

[Mud-Nut]

Is it possible to get a build thread on this ski or would that be giving away some secrets?

^ I agree!

Build thread! Build thread! BUILD THREAD!

 

[glennbbautomachine]

I think its cool they tried this with a 4 stroke. Weight seems to be the name of the game today in freeride, another 30 pounds in a small hull makes a big difference!

And what about a 30lb difference in a rider?

 

[Quinc]

4-Strokes ARE more efficient.

Older article (2008) so maybe things have changed.

In the early 1990s, an Australian firm, the Orbital Engine Company, developed a two-stroke automobile engine that met then-current U.S. emissions requirements, exceeded the four-stroke fuel efficiency numbers, weighed almost 200 pounds less than a four-stroke that produced similar power, vibrated less than an equivalent four-stroke and cost from $300 to $500 less to manufacture.

The most complex and heaviest of the conceptual automotive two-strokes is Toyota’s design. The engine is basically one of the company’s dual-overhead cam, four-stroke engines converted to run a two-stroke cycle. The camshafts run at crankshaft speed and air is delivered to the intake valves through a supercharger. Fuel is added through a high-pressure, direct-injection system. An in-line, six cylinder, 244 cubic-inch version of this engine is said to produce torque equal to GM’s 454 V8.

http://www.snowgoer.com/snowmobiling-features/why-2-stroke-direct-injection-is-a-big-deal/1021/

 

[zimmy]

And what about a 30lb difference in a rider?

Rider is a separate issue.

We are talking weight of your machine as a whole : Hull and components... A fat dude on the back would do away with any weight savings even on a carbon hull with all the extra time taken to cut weight with components.

 

[OCD Solutions]

Well I don't give a poop what any of you think of this idea. I wanted to see it done and was very excited to talk to Chris about it at Daytona and am looking forward to updates as it progresses.

The install was much cleaner than I had anticipated and I thought the whole thing looked like a very natural fit. I was a bit disappointed with seeing it perform on the water on Sunday but also figured that if that was the 60HP tune then it was exactly on par with what I would expect. The 110 should certainly smarten it up some and what they can't accomplish with tunes, can be tweaked further with the pump and prop just like any other ski.

I'm also keeping in mind that they had just dropped in the motor and drive train the week prior and were finishing up some loose ends with the harness when I stopped in on Friday morning. This wasn't a project reveal with countless hours of testing and tweaking to dial it in and present the absolute best face forward but instead something that was completed and test run for the first time right in front of us. All things considering, I thought it was a great start to what should result in a great conversion package once they get a chance to dial it in.

Keep the updates coming and let me know if you need any warm weather testing done. I'm dying to drop one of these in my wife's Superjet.

 

[NVJAY775]

I can't wait to see this evolve. I'd love to get one on Tahoe on a rough day. 30 minutes away for me! High altitude will beat the crap out of the power though.

Hats off to all that got this project where it is today! Cheers fellas.

 

[bird]

bullet points don't make you look like a professional.

Efficiency is a theoretical thing(like bhp), in the real world a smaller 2 stroke will produce as much hp as a bigger 4 stroke. I'm not sure if you're talking Thermal Efficiency or Mechanical efficiency in your previous posts either.

Please give me some of the empirical evidence you have over there. A Direct Injected 2 stroke, has less moving parts, less sprung weight, and more power strokes per RPM.

not mad bro, I just enjoy the real world. 2 strokes would still be in Moto GP if it wasn't for the big 4 not wanting to spend money on two different techs.

Please submit your formulas for 4 stroke being more efficient. And while we're at it, 6 strokes are more efficient than 4 strokes because they don't need an auxiliary cooling system and they have a free power stroke due to state change(thermal expansion) not an exothermic chemical reaction.

theories work until they're proved wrong by real world results.

To be clear, you want me to "stop sounding like" some impression you get after you read my post? I'd say the problem is on your end.

I thought my post was simple enough, but I'll clarify:

• I was speaking of efficiency, not emissions. They both start with the letter 'e', but it ends there. And what I said is 100% true.
• I am not interested in reading about e-tec engines. I used to own one, I understand what they are.
• Sorry to upset you with my posts. I did not claim to know everything nor do I know everything. I do know this: Everything I posted is fact. If you have a problem with what I post, please refute the facts directly instead of attacking the poster. It's generally a much more acceptable way to do a debate.

That's all.
This post brought to you by the letter 'e'.


PS: Here's a challenge: Can you read my post without getting upset?

 

[j0hnny]

mmmmmmmm direct injected rotary valve 2 stroke..... wait a minute isnt that seapoo tech? lol