Dry vs. Wet

[Mobile Chernobyl]

So I'm in the process of a build and came across two good deals on used pipes.

A Riva Red pipe and a Riva Freeride Dry pipe (some say it's a Factory Pipe Dry Pipe / Type 4)

What I'm trying to accomplish is a ski that has great all around power, not all bottom and not all top. Sofar I've got a JM 718 engine on the way and I'll be going with a solas 12-vane mag pump stator and hooker 9/15 in the rear.

Just looking for opinions and experience - I might keep both pipes but if there's over whelming support one way or the other I'll sell the other one.

Right now I'm slightly biased towards the dry - I've heard great about it when it's tuned well, i.e. hitting like bricks (not quite B-Pipe bricks tho) and pulling to the moon and I'm a pretty patient fellow in that regard with getting my dirtbikes running mint. I'd like to strip the half assed paintjob off the dry pipe and powdercoat it - but just want to see if it's worth it or not.

I've also noticed that theres some 1/8 NPT and some 1/4 NPT holes for water routing in these pipes. I'm thinking of boring all the 1/8 to 1/4 for clean threads (1/8 NPT + vibration usually isn't a great combo) - I imagine there's no issue here? I just want to clean whichever pipe I'm using to give it a fighting chance.

Despite their differences in physical size and the fact that one is made of cast aluminum and the other of seemingly lighter weight aluminum sheet metal - the chambers weight the same exact amount - 13 pounds! This through me off - but the first time I pulled the red out of the box it was a lot lighter than I thought it would be.

The way both castings have touch up welds in the same spot almost makes me think this was a post-process done right after casting?




And just a funny size comparison of the Freeride Dry vs. stock bread box. Could smuggle a little more bread in the dry pipe.

 

[Big Kahuna]

The Freeride pipe actually makes a little more bottom end power than regular type 4 drypipe. The red pipe is close to a BPipe. The manifold design was the basis for the Dry Pipe manifold. The runners were the same length vs the protec pipe at the time and a long leg and a short leg. (Remember article in Splash talking about the design differences between the Protec and Riva ).

 

[Quinc]

I think the riva will give you less of a headache and blown couplers. To make up for the bottom end you can lighten the flywheel and run the Zeeltronics or msd enhancer.

Edit: also run a girdled head to save your cylinder from cracking.

 

[waxhead]

I would go for the dry with the silicone adapter. It will give you a flexible join of sorts the red made great power but unless ll the planets aligned they used to blow that gasket a lot. you could make them reliable but you need the patience of a monk to align them correctly

 

[Mobile Chernobyl]

Yea I'm probably going with the Dry setup.

There's a few interesting observations on this pipe.

1. Factory Pipe calls for a #337 o-ring in the slip joint between the header section and the expansion chamber - this seems way too big.
   1. The chamber slip-fit portion has an OD of 2.6" and the header slip-fit socket has a ID of 2.935" - for comparison a #337 o-ring is 3" ID and 3.375" OD. It would get squished into place vs a slight stretch like you should have with a proper o-ring fit. I would think that would just blow out over time and do a poopty job overall.
   2. I ordered a #333 o-ring - this has a 2.5" ID and 2.875" OD - so a slight stretch fit and it will squish from it's static width of .21" thickness to the .167" gap (the gap between the chamber male and header female socket once slid together) nicely - this is within the allowable tolerance of a normal static o-ring fit.
   3. I'm not an o-ring expert - but I am an engineer who has spec'd a lot of o-rings. I'm also a dirtbiker who replaces essentially this same o-ring on my pipe and we use brown viton o-rings there too. This specific o-ring is serving the same purpose as a dirtbike header o-ring essentially.
2. I ordered some 3.5" silicone hose that's typically used to join pressurized intake systems on turbo'd cars. I use this because the same material works great on my dirtbike for the chamber to silencer junction - where there is no fancy water jacket cooling of the exhaust.
   1. I ordered the matching T-Bolt clamps for this silicone hose. A normal hose clamp will shred silicone multi-ply hosing so that's why they make the smooth surface t-bolt clamps.
3. I ended up drilling all 1/8" NPT fitting holes out with a 7/16" bit and a stopper so I didn't blow through the double wall. I then tapped em for 1/4" NPT. I chased the existing 1/4" NPT holes with a single turn of the tap just to clean them. She's all ready now for new fittings!
4. My pipe and header currently still have their ridges where the silicone coupler slides on - I'll end up filing down the header to just a slight bump and possibly the ridge on the chamber side too - this is as per the recommendations here. I know that link says to file down the header side completely - but a good rolled joint for silicone couplers is typically a smooth bump - not the barb the header currently has. The bump on the chamber side is a little too pronounced as well in my opinion - but probably fine.

Currently stripping the paint off the chamber and header and hopefully I'll find a local powdercoat shop in denver to pimp it out.

 

[Harbor]

You may have already Pressure tested the water jacket, but if not, now would be a good time, before the powder coat.

That oring sites flush up against a grove in the chamber face, not around the inlet OD.. at least that’s how I remember it..

I didn’t have much luck with silicone couplers, I ended up switching to boat out drive exhaust Hose. I cut a section from an old hose, it’s Thick rubber and never had another failure..

I think I have a photo I’ll look

 

[Mobile Chernobyl]

You may have already Pressure tested the water jacket, but if not, now would be a good time, before the powder coat.

That oring sites flush up against a grove in the chamber face, not around the inlet OD.. at least that’s how I remember it..

I didn’t have much luck with silicone couplers, I ended up switching to boat out drive exhaust Hose. I cut a section from an old hose, it’s Thick rubber and never had another failure..

I think I have a photo I’ll look

Seller said it pressure tested fine, I will definitely do that though after the paint is stripped off. That would be a nut puncher if it leaks.

I think with the oring I'm imagining it is intended to be placed like the speedwerx pipe but without the Machined grooves that fail on them. In an ideal scenario thats the best place to have an oring on a 2 stroke header to expansion chamber joint.

 

[Harbor]

The #337 oring goes here, but I read your going a different route....

 

[Mobile Chernobyl]

@Harbor - thanks that should've been obvious to me haha. I'll throw a 337 on there along with the 333's in the slip joint. The 337 should help metal to metal impact and the 333s will center it up nice and do all the sealing work.

Well paint stripped and cooling jacket pressure tested. A small crack on the stinger end shows some bubbles and thats it. I let the water settle in that crack then listened inside the chamber and no noise so thats a relief.

i'll probably find someone local to lay down a nice wide bead there and re pressure test it to be sure. As-is it leaks from 20psi to 0 in about 30 minutes so its minor.

Found some powder coaters locally that I'll give a ring tomorrow.

 

[Quinc]

20psi is pretty damn high. Probably only sees 5-10psi.

 

[MTRHEAD]

Be careful with too much pressure you can collapse the inner chamber!

 

[Mobile Chernobyl]

Yea I only tested up to 20psi - collapsing the inner chamber was definitely a concern so I didn't push it - not intending to turn this thing into a potato gun! Honestly wasn't sure what psi the cooling system would reach under normal operating conditions.

Found my leaks so after welding I'll test around 10psi with soapy water again and then off to powdercoat if it passes!

 

[hornedogg79]

A section of 2.5" silicone hose fits perfectly in the void. Keeps it aligned too. I also put a bead of high temp rtv around it when I install it.

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[Mobile Chernobyl]

Well with the pedal literally to the metal, I dumped all 160 Amps that my tig welder had into this pipe. I'm not proud of it but the last time I welded aluminum it was with a bad ass liquid cooled Miller dynasty.

Hopefully the stinger doesn't crack off before I can find a B pipe for under $1000 haha.

The little bubbles are just from the spray bottle - no new bubbles propagated and she's holding 10psi like its the last 10psi on earth.



Off to powdercoat tomorrow hopefully!

 

[Carrera911]

Welds look good all things considered. The nice thing about the powder coat is it will seal possible small pinhole leaks. A lot of shops don’t use or stock it, but ask them about using epoxy primer first. I’d also ask if they’ll sand blast it to texture the surface. I’ve been surprised at the amount of stuff I’ve seen powdered that wasn’t even textured before powder coat. It really does make a big difference in adhesion.


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[Quinc]

Anyone can have pretty welds. All it takes is

 

[Storbeck]

As the wise AVE says: "A GRINDER AND PAINT MAKES ME THE WELDER I AINT"

 

[Mobile Chernobyl]

Alright this question was bound to come about. I've looked into a bunch of posts about dual cooling strategies and dry pipe cooling strategies. Seems there's two schools of thought when you combine dual cooling and a billet head:

A) Keep all flow going into the engine via the two taps on the header
B) Provide dedicated flows for the engine and the pipe for better tune-ability

So here's my two ideas for cooling with this dry pipe:



I'm also not 100% sure about how to provide the water to the stinger - I've seen some suggest a Tee before the stinger is a good thing - then route 1/2 of that flow to a pisser and the other 1/2 to the stinger though a restriction of some sort (valve, jet jammed in there, jetworks flow control deal, etc). I've also seen people avoid this all together and just run a tap from the pipe to the stinger and skip the Tee altogether in favor of letting the flow restrictor do all the work (in this case I imagine the pisser would be pissin hard coming outta the pipe.

So just putting out my ideas and seeing if either are good to go. I'm personally thinking the separate cooling is the way to go but the elegance of running all the water to the engine first makes sense too - plus it provides warmer water to the pipe which may not be a good thing...

 

[fastgtfairlane]

i run separate cooling on all of my skis even with wetpipes.

 

[Storbeck]

I don't know how racers do it, and I have zero personal experience with dry pipes.

I can tell you though, that if you look at countless examples of freestyle skis on this site running powerfactor pipes dry, universally they all run two lines into the manifold and split one to go to the chamber water jacket, with a single pisser coming out of the jacket.

The only exception is xscream uses a far more elaborate cooling system that separates motor and exhaust manifold with two cooling lines each (so four total lines from the pump) and a zillion pissers, and even then they don't have a dedicate line for the exhaust and they only have one pisser from the exhaust jacket.