Not your typical dry pipe vs wet pipe question

[Storbeck]

Particularly interested in what @tntsuperjet has to say if he'd be kind enough to offer some insight.

But there are other very knowledgeable folks here that maybe can comment.

Fairly basic conventional wisdom is that dry pipe has higher internal gas temperature so higher speed of sound, for any given physical length the "tuned lenght" is effectively shorter so has a higher tuned rpm, wet pipe cooler, lower speed of sound, lower rpm.

It seems like it would be completely possible to have a wet pipe of very short physical length and a dry pipe of long physical length so their effective tuned rpm would be the same.

But, people still go through the difficulty, weight, expense of making dry pipes, even oem's. So there must be some inherent advantage.

Why? What is it? Something about the water damping the pressure waves so the wet pipe is less effective, or...something?

 

[DAG]

I'd be interested to know as well. Majority of the multi trick guys run a dry pipe, not sure why, maybe sponsored riders vs weekend warriors?

As you stated @Storbeck temp plays a huge roll in effective powerband. I'd be curious to know what happen to pipe temps when the ski is out of the water dry pipe vs wet pipe for you multi trick combo guys. Does one shift faster than the other? I'd assume as the pump is out of the water the wet pipe is going to heat up faster than a dry pipe that still has water in its jacket. 100% speculation though. If it does change temp is it enough to creep out of your powerband?

@Roo I believe, did a really nice write up / review on here somewhere that might have your answer

 

[Storbeck]

An interesting point, but most dry pipes, at least back in the day, were more intended for racing where the issue of leaving the water for (relatively) long lengths of time doesn't seem like it would be a major factor.

 

[Big Kahuna]

back in early freestyle days sub 800cc limit even for pro. The BPIpes worked really well. The Hit was good, throttle response was good........ For Racing, They were ok. Then the Dry Pipes came out which did not have as good of low end and throttle response down low but from Mid to Top They pulled more RPM's. Now, Mid 2000's motors started getting larger. Above 900cc the BPipes start signing off and just does not utilize the power of these 900-1200cc motors. In the past few years TNT and RRP have come out with Laydown Wetpipes that will work with these larger motors but give you the throttle response and tunability of the Wet Pipes with Power output of the Dry Pipes.

 

[Vortex]

Dry pipe has a water jacketed chamber, one additional benefit besides mid/top power was to keep under hood temps down in longer Moto's. Bpipe can get pretty hot when you ride wide open for a long time.

With electronic h20 injection you're getting the water flow inside pipe at low rpm to slow down the exhaust gasses and build torque, and then it shuts off at over 5k or so to let it rev. I imagine not many freestylers are using h20 injection, anyone know why that is? Other than it's hard to find a kit and it's more stuff to go wrong.

 

[Storbeck]

From what I've read the temperature in the pipe doesn't change quickly enough for water injection to be effective in freestyle.

 

[Storbeck]

The underhood temp thing makes sense to me. It would also explain why an oem would do it for a couch motor.

 

[Big Kahuna]

Dry pipe has a water jacketed chamber, one additional benefit besides mid/top power was to keep under hood temps down in longer Moto's. Bpipe can get pretty hot when you ride wide open for a long time.

With electronic h20 injection you're getting the water flow inside pipe at low rpm to slow down the exhaust gasses and build torque, and then it shuts off at over 5k or so to let it rev. I imagine not many freestylers are using h20 injection, anyone know why that is? Other than it's hard to find a kit and it's more stuff to go wrong.

It does not come on "Turn Off" quick enough when you let off the throttle then pin it, has a lag time. you can switch it to 3 cylinder and it will come on at a lower RPM but not enough to fool with. 1200cc motors make more than enough power!!! LOL And yes, they are a pain. I had one when I was racing with a B Pipe so I could dial in more top speed. After every moto I would have to disassemble the solenoid to clear out any sand that would get sucked in. The sand would stop the plunger from working, either clog open or closed.

 

[waxhead]

This is why you use a digital ignition and program it correctly. You can use the ignition to put the temp in the pipe instead of trying to restrict the stinger

 

[Vortex]

I need to get on the zeeltronic train. Sorry to de rail. Just had another meltdown on a fresh bore w/enhancer.

 

[waxhead]

I need to get on the zeeltronic train. Sorry to de rail. Just had another meltdown on a fresh bore w/enhancer.

Yes you do, Its such a simple thing and a lot of people have done it now. The ignition comes set up with a good curve in now as well so its a case of plugging it in and giving it a power feed. It really is harder to fit a bilge pump than it is the ignition

 

[Christian_83]

Yeah most freestylers with big engines seems to run dry pipes
Unless your name is Lee Stone or BUN - then you run wet pipe on 1200cc

 

[egbrig]

DAG, the next time we run into each other, we can have a "this is how pipes work" talk, Tim T. has done that for me and I've been modifying pipes since 90 but not at Tim's level. I let Phil C. try my last gen MSD programmable water injection modual on his boat. They worked great racing but the temp change in a freestyle pipe setup just doesn't happen fast enough. Another thing is pipe material, aluminum, ss, fiberglass/carbon. Each heat up differently so there is no "one rule". As far as engines go, the different engine designs can use injection to change the inherent design but injecting water changes the entire tuning package, ie: pump, carb and most of all rider preference. Most beginners like the power right away, while advance guys like it later but that rule isn't even a rule.

 

[CARBONX2]

In wetpipes the exhaust gas is cooler which makes the pulses/waves move slower than in a drypipe, that is why a drypipe is longer for the same rpm and exhaust timing(The drypipe pulse that is moving faster must travel further to arrive back at the exh port at the same time as a wetpipe). The drypipe is moving more gas, thus supercharging more fuel mix back into the cylinder, resulting in higher running cylinder pressures(cranking compression still remains the same). The higher supercharging effect gives more HP, as far as I remember, about 10%
I have an unfinished project of a drypipe without any water-jacket, but with a special insulation coating that keeps surface temps the same as wetpipes

 

[long beach local]

I would like to share my experience with my race buoy boat using a TNT V3 race spec pipe I purchased from Tim T. a couple years ago. It has a slightly smaller diameter at the end compared to his usual V3 and has a second water injection. I am running it in my Proforce with a Yamaha twin, 780cc ported and an enhancer 165Lb compression and have been determined to have it run reliably on pump gas . I have not had the best luck as I have melted pistons usually the rear and run my jetting as rich as possible. I hope I solved the detonation issue as I discovered when I dried the pipe out went from a 115 mainjet to a 105 my spark plugs would loosen quickly . I spoke with Tim and he told me to add more water and increase jet size slightly. I now run 1 125main in the head pipe and so far so good I can hold it wide open for long runs on 91 octane. The boat runs well all day long now and I don`t know exactly why but adding more water Works with no other changes. I was going to retard the timing but I dont think its necessary now .

 

[Vortex]

Would you guys recommend running one of the injection ports on r&d superjet pipe as a constant water port instead of just using electronic water injection on all 3 points? To help prevent melting pistons