66e Billet Exhaust Manifolds

T

te4250

Location
Western NY
A couple guys asked about these after I made a one off one for myself seen here: https://www.x-h2o.com/threads/66e-conversion.198714/page-2
Planning on a run of 10 or so in the next month or two. I've changed the design somewhat with some stuff I learned on the first one:
I changed to 3 pieces after talking with @senor and @DylanS to accommodate different chambers jut by changing the "snout" piece.
Moved the chamber interface slightly forward
Added more water jacket, and moved water inlets away from motor. Original front water fitting hit starter. I plan to tap both top and bottom so water can be fed from either side.
What do you 66e guys think? What else should be changed before cutting these things?
Pics of rev 2:
66e exman rev2 half.JPG66e exman rev2 iso.JPG66e exman rev2 top.JPG
 
T

te4250

Location
Western NY
That’s one of the things I wanted to hash out, senor asked for 70mm, shown in the cad pics is 2.5” before the step and I think 2.93” after the step as measured off a pfp manifold. I’m leaning towards 2.5” before the 3rd piece and then drafting up to whatever you guys want from there with the third piece. If I remember right senor said wdk chamber was just under 70mm
 
S

Storbeck

Location
Minnesota
Does it angle downward from the exhaust port? The common PFP/RRP/TNT manifold has a pretty significant angle downward from the exhaust port, I think that is useful if there is a little bit of water in the pipe to help prevent it from going into the exhaust port, and also I think, it is good for fitting the pipe in the hull, and gives you slightly (very slightly) more room for the torturous path the front port has to take to where the two join, for what that's worth. Probably not good for manufacturability though.
 
W

waxhead

wannabe backflipper
Location
gold coast
Storbeck said:
Does it angle downward from the exhaust port? The common PFP/RRP/TNT manifold has a pretty significant angle downward from the exhaust port, I think that is useful if there is a little bit of water in the pipe to help prevent it from going into the exhaust port, and also I think, it is good for fitting the pipe in the hull, and gives you slightly (very slightly) more room for the torturous path the front port has to take to where the two join, for what that's worth. Probably not good for manufacturability though.
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What you said is perfect. The Wdk one holds water in the cylinder and stops it draining causing corrosion
 
T

te4250

Location
Western NY
I was really hoping to avoid angling it downwards, definitely complicates making it quite a bit. On my ski I left the motor at an angle so water draining back into the cylinders wasn’t as much of a concern. Idk how many others are doing it like that or using the wdk upright kit?
 
W

waxhead

wannabe backflipper
Location
gold coast
te4250 said:
I was really hoping to avoid angling it downwards, definitely complicates making it quite a bit. On my ski I left the motor at an angle so water draining back into the cylinders wasn’t as much of a concern. Idk how many others are doing it like that or using the wdk upright kit?
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The water collects in the cylinder and does not drain back to the pump. This means that the water is sitting against the billet manifold all the time and it corrodes
 
T

te4250

Location
Western NY
waxhead said:
The water collects in the cylinder and does not drain back to the pump. This means that the water is sitting against the billet manifold all the time and it corrodes
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So your concern is the water in the cooling passages not the pipe? Seems like not that big of a deal to me. Storbeck’s point seems like more of a concern, I’ve seen that point raised before about the wdk pipe. What’s weird to me though is you inject water right in the top of a bpipe with a downward path right to your exhaust port and no one seems to be concerned about it in that scenario
 
S

Storbeck

Location
Minnesota
My concern is that with a b pipe there is very little opportunity for water to get into the motor, even the little bit that might dribble from the top screw tends to drain back and down into the chamber because skis tend to sit nose up in the water. With a lay down pipe any water in the chamber drains back to the manifold. It could be water from the water injection, could be from the stinger, or biggest concern any that managed to make its way back from the waterbox, it is likely to drain back to the manifold because the chamber is generally uphill to the waterbox. Typical 62t lay down pipe manifold has a low spot so the water doesn't drain into the motor quite so easily, but if the manifold is straight it, it's a direct path to the rear cylinder exhaust port.

I couldn't tell you I'd it really is a problem but it would concern me. I think you want either a high spot or a low spot, just don't want a gradual downhill slope all the way from stinger to exhaust port.
 
DylanS

DylanS

Gorilla Smasher
Location
Lebanon Pa
We’ve been running the non-angled manifolds, both old and new gen, for more years than I can recall. As far as corrosion goes I’ve had zero issues on either billet or cast manifold, but I’ve never opened the billet one to check the water jacket to be honest. IMO for how many of these are likely to sell, as of now, it doesn’t seem like it would be worth the price and headache to manufacture them at an angle even though it would be beneficial as far as water ingestion goes. I only ever had water come back into my cyls once with the older style cast manis In my EME when I was trying to make my own water trap. Other than that I’ve had no issues when using a directional spray bar on either ski, one with Powerfactor water box and one with no box at all. But I always routed my lines so that there was minimal leakage into the manifold after the motor was killed.
i know the 927’s and up run very well with the 70mm DIA WDK manifold but I’ve never ridden one with a different DIA so there very well could be room for improvement. As far as changing the end snout to run different chambers my biggest concern would be the snout pieces having a inwards funnel type shape to help the exhaust gasses transition smoothly into the chamber. I’m by no means a machinist so I have no clue the cost or ammount of work that would go into something like that. What is the measurement from side to side (ex port face to bend)? I can get you measurements of the other manis to verify fitment too if you’d like.
 
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T

te4250

Location
Western NY
I think it’s around 5.8” overall width, don’t have the cad in front of me right now. Yeah I was thinking the manifold before the snout would end at the smallest size someone was likely to run then taper out to whatever size so it’s a smooth transition, that makes the manifold like your lead in length and then the tapered snout is the start of your expansion chamber.
I think like you’re saying there’s not gonna be a huge demand for these and angling it wouldn’t be worth the hassle. I’m still on the fence about it that it even matters. I for sure see the theoretical concern but what happens when you land upside down with a pfp, does the water just drain out of the waterbox into the chamber which is now lower than the outlet, and now your angled manifold is directing water right into the ports? Does everyone install their chamber so it makes enough of a bump to keep it from getting to the manifold when upside down? What happens when you roll your ski over then now the whole chamber goes though a phase of draining back to the manifold. Seems like with all the scenarios a ski can be in, the 2-3” elevation in a pfp manifold when it’s level becomes negligible. Not trying to sound like a flat earther here lol
 
DylanS

DylanS

Gorilla Smasher
Location
Lebanon Pa
te4250 said:
I think it’s around 5.8” overall width, don’t have the cad in front of me right now. Yeah I was thinking the manifold before the snout would end at the smallest size someone was likely to run then taper out to whatever size so it’s a smooth transition, that makes the manifold like your lead in length and then the tapered snout is the start of your expansion chamber.
I think like you’re saying there’s not gonna be a huge demand for these and angling it wouldn’t be worth the hassle. I’m still on the fence about it that it even matters. I for sure see the theoretical concern but what happens when you land upside down with a pfp, does the water just drain out of the waterbox into the chamber which is now lower than the outlet, and now your angled manifold is directing water right into the ports? Does everyone install their chamber so it makes enough of a bump to keep it from getting to the manifold when upside down? What happens when you roll your ski over then now the whole chamber goes though a phase of draining back to the manifold. Seems like with all the scenarios a ski can be in, the 2-3” elevation in a pfp manifold when it’s level becomes negligible. Not trying to sound like a flat earther here lol
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Real men simply combust the water anyways, simple as that’
Only chicks worry about bending rods :cool:
 
DylanS

DylanS

Gorilla Smasher
Location
Lebanon Pa
te4250 said:
Just finished a job on the machine I want to run these on so should be able to throw some on there, would you be interested in test fitting a 3D printed one to make sure we’re not overlooking anything?
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Absolutely man
I can test Fit in a few different hulls with wdk conversion plates etc if you’d like
 
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