RiverRat's 927cc WDK ENVY

[AlbanyMotorsports]

Hunter, I cant wait to see some more pictures.

I have also got an Envy on the way . The interchangeable pump is going to be amazing to see. I cant wait.

I ended up finding a motor in pieces and I got the bottom end put together last night. I boughta pair of PowerBombs becasue I pussed out on full specs so hopefully im not in the dark with these things. I am waiting for the rest of the parts from Jeff to come with the hull so for now everything is on hold. Jeff has been a great help with getting me throught this motor on my own and I cant wait to hear how yours runs.

Thanks again for the help and I will get some pictures up here of my build soon.

Mike

 

[freestylegeek]

...Since the new dry pipe responds well to water injection ...

Can you explain how that works?

 

[RiverRat]

Can you explain how that works?

From MSD's website:

"Exhaust systems cause racers to compromise their engine’s power. Exhaust systems are designed to be tuned to deliver maximum power within a specific rpm range. Performance can be gained by using the exhaust pulse waves to create pressure variations which have an effect on the rate as the exhaust gases exit the combustion chamber. The problem is that you are limited to that one power band which compromises your power!

Fortunately, MSD offers the Pulse Width Modulated Water Injection Control Kit that allows you to modify the exhaust at programmable rpm points by injecting water into the pipe. Introducing water to the exhaust alters the exhaust pulses thereby modifying the back pressure! With this technology you can “tune” your exhaust system throughout the rpm range of your engine.

For example, by injecting water into the exhaust chamber at lower rpm, the density of the exhaust pulse is increased which slows it down. This has the same affect as lengthening the chamber to increase low to mid range torque and power!

The MSD PWM Kit takes the engine rpm signal and processes it through a digital controller which pulses a solenoid to allow water to enter the exhaust chamber. The system can be installed on virtually any watercraft and features dip switches for easy adjustment of the rpm activation points. There are also bright LEDs that alert you as to when a solenoid is pulsing water into the system and to confirm a solid trigger signal from the ignition."

 

[RiverRat]

Hunter, I cant wait to see some more pictures.

I have also got an Envy on the way . The interchangeable pump is going to be amazing to see. I cant wait.

I ended up finding a motor in pieces and I got the bottom end put together last night. I boughta pair of PowerBombs becasue I pussed out on full specs so hopefully im not in the dark with these things. I am waiting for the rest of the parts from Jeff to come with the hull so for now everything is on hold. Jeff has been a great help with getting me throught this motor on my own and I cant wait to hear how yours runs.

Thanks again for the help and I will get some pictures up here of my build soon.

Mike

Nice!! Hopefully, I will have mine on the water for testing soon and can give you some more specifics when I start getting it dialed in.

 

[freestylegeek]

From MSD's website:

"bunch of stuff that only applies to 'b' pipes"

So, how will you be injecting water into your dry pipe? Or will you be converting it to a wet pipe?

I know some racers used to use valves on their dry pipes so that they could slow the flow of water in the jacket and allow the pipes to run hotter at higher RPMs. As the RPS dropped down, the valve would open up again and let more cold water run through the jacket. This helped them gain more top speed with higher RPMs, but the reaction time of the pipe was a few seconds.

I didn't know if you were doing that, or drilling through the jackets and spraying water into the exhaust stream of the pipe.

 

[waxhead]

Are you talking about the jetwerks valve that opened with higher rpm and created stronger wave in the pipe by increasing back pressure

 

[Matt_E]

Eh....water injection for dry pipes has been around for quite a long time now.
Fittings are drilled into the manifold, and water is injected directly into the exhaust stream there.

Have you seriously never heard of this?

 

[freestylegeek]

Eh....water injection for dry pipes has been around for quite a long time now.
Fittings are drilled into the manifold, and water is injected directly into the exhaust stream there.

Have you seriously never heard of this?

So, it's no longer a dry pipe then, right?
Maybe I should post this as a new topic so we don't detract from RiverRat's build thread - sorry Hunter. :cool2:

 

[RiverRat]

So, how will you be injecting water into your dry pipe? Or will you be converting it to a wet pipe?

I know some racers used to use valves on their dry pipes so that they could slow the flow of water in the jacket and allow the pipes to run hotter at higher RPMs. As the RPS dropped down, the valve would open up again and let more cold water run through the jacket. This helped them gain more top speed with higher RPMs, but the reaction time of the pipe was a few seconds.

I didn't know if you were doing that, or drilling through the jackets and spraying water into the exhaust stream of the pipe.

It will be injected into the exhaust stream at the manifold. You can achually inject water at 3 different locations if you buy the multi-channel unit. But that is really only if you want to tinker with water inection points at the manifold, chamber and stinger locations. Single channel is fine b/c all I am doing is fiddling with the EGT before it enters the chamber...........which makes the motor perform better down low. It is still a DRY pipe b/c it was developed on the dyno as a DRY pipe. The water injection just makes it less RPM specific as far as powerband. The water being injected is not that much and is only on within certain parameters.

http://www.msdpowersports.com/pwc_waterinjection.html

 

[Matt_E]

So, it's no longer a dry pipe then, right?
Maybe I should post this as a new topic so we don't detract from RiverRat's build thread - sorry Hunter. :cool2:

Well...true. :biggthumpup:

It's a drypipe with water injection.

 

[SuperJETT]

Well designed dry pipes don't need no stinking water injection to get bottom end, like Speedwerx pipes. Darren Hedlund :notworthy:

 

[RiverRat]

Well designed dry pipes don't need no stinking water injection to get bottom end, like Speedwerx pipes. Darren Hedlund :notworthy:

OMG you are such a tool!!! This new system is being designed by one of the best 2 stroke pipe companies in the business. :tapedshut:

 

[SuperJETT]

OMG you are such a tool!!! This new system is being designed by one of the best 2 stroke pipe companies in the business. :tapedshut:

It's a joke sorta. Darren Hedlund though, when he was at Speedwerx, that was the stuff man.

BTW, if they're so good, then why is it going to need water injection to get bottom end?

 

[Matt_E]

It's a joke sorta. Darren Hedlund though, when he was at Speedwerx, that was the stuff man.

BTW, if they're so good, then why is it going to need water injection to get bottom end?

Because they're designed for higher powerband delivery.
You add water injection to widen that powerband a bit.

Run a B-Pipe without water and see if it does as well as a drypipe without water.

Then try the B-Pipe with water and the drypipe with water.
I guarantee the drypipe will win both times.

 

[RiverRat]

It's a joke sorta. Darren Hedlund though, when he was at Speedwerx, that was the stuff man.

BTW, if they're so good, then why is it going to need water injection to get bottom end?

Didn't mean to jump your sh**. You just came across as a D*** in that last post.

To anwser your question, the new pipe is being developed on the WDK 1200cc motor. It will still work really well on the 927 and 800 but IMO it would be benificial to have the ablity to adjust the backpressure in the system. The system does not NEED water injection just like a factory b-pipe or any other pipe does not need a Flow Control Valve. But it is a accessory that will not hurt you to have.

 

[SuperJETT]

Backpressure is adjusted at the stinger then, not via water injection. That's what a flow control valve does, dries out the box at low rpms plus puts water back in for upper rpm power.

 

[RiverRat]

Backpressure is adjusted at the stinger then, not via water injection. That's what a flow control valve does, dries out the box at low rpms plus puts water back in for upper rpm power.

MSD's webiste:

"Introducing water to the exhaust alters the exhaust pulses thereby modifying the back pressure!"

 

[SuperJETT]

MSD's webiste:

"Introducing water to the exhaust alters the exhaust pulses thereby modifying the back pressure!"

Based on my knowledge, I'd say that statement is wrong. MSD doesn't build exhausts either.

Factory Pipe: http://www.factorypipe.com/a_ecwi.php
injects water at lower RPM to cool the exhaust and produce a slower sonic wave for greater torque. At high RPM, the water is gradually shut off to allow the exhaust to heat up and make the sonic wave travel faster for more speed and top end horsepower.


The triple point system you mentioned is for headpipe/stinger/waterbox setups to control sonic wave/backpressure/sound level separately.

 

[RiverRat]

Based on my knowledge, I'd say that statement is wrong. MSD doesn't build exhausts either.

Factory Pipe: http://www.factorypipe.com/a_ecwi.php
injects water at lower RPM to cool the exhaust and produce a slower sonic wave for greater torque. At high RPM, the water is gradually shut off to allow the exhaust to heat up and make the sonic wave travel faster for more speed and top end horsepower.


The triple point system you mentioned is for headpipe/stinger/waterbox setups to control sonic wave/backpressure/sound level separately.

Cooler gas is denser. Denser air travels slower than warmer air (which is why they taper off the water injection in the upper RPM's). Air density (or air temp depending on how you look at it) and air speed effects backpressure in the system. Injecting water effects air density which inturn effects air speed therby effecting backpressure.

 

[upstand2]

Water injection delays the soundwaves back to the exaust port. Like a longer chamber would.
Water at the stinger takes up space in the outlet. It has the same effect as a smaller exaust outlet , it increases rpm and head tempeture.