Brad Christy

Guys,

I've decided I need to extend the intake of the ProCharger on our boat so it will be drawing on cooler, cleaner air. I've got the ducting in hand and have a plan for the fab work. But the first hurdle is going to be rerouting the cooling plumbing, as the ProCharger install kit instructions has the water line from the heat log to the oil cooler (I think) laying right on the breather, and it will be in the way for the ducting.

First step....
THIS VIEW shows the hose I need to move, #13. The ProCharger kit instructions had us cut the bend on the bottom off and connect it to a tee, providing a tap for the intercooler. I would include a pic of it from the manual, but there really isn't a good image to share that shows what I need to show. I think I can just add a formed bend at the right spot and run it between the ducting and the stringer, with the intercooler line tee moved outside the line of the intake ducting, but as it is, this puts a kink in it. My plan is to go to AutoZone or some equivalent, root through their selection and find something I can make work. But I need some advice from someone who knows... Anybody know what size hose this is? It is tucked down there in such a way as to make it very difficult to measure. It would appear to be 1" or 1-1/4", but I can't be sure. Knowing Merc, there's a halfway decent chance it's some proprietary size and I'll have to buy the hoses from them. Hoping not.

Thanks. Brad.

articfriends

Are you concerned that its pulling air off a exhaust manifold or something to warrant the change? Keep in mind air hates to turn, especially under a vacuum (inlet side) and anything that disrupts inlet air may affect power output

Brad Christy

Smitty,

Essentially, yes. All-in-all, I'm just not fond of the idea of drawing air from under the engine, with the hot air and potential for water and/or debris (it's typically clean and dry, for the record). But more specifically, I don't like the way the cooling hoses lay right against the breather. If you look at the INSTALL MANUAL, Figure 11B, page 15, you can see how the hoses are arranged. The hoses are literally laying against the flame arrestor. This itself has to be disrupting airflow, right?

The plan was for one 90° bend just ahead of the intake snout, with the bend in the duct tilted on a 45° angle then a 45° bend, resulting in a vertical intake; the breather beside the engine, just about the level of the exhaust riser (can't go too much higher, sundeck and all). The hoses would then be routed below the duct. I was also intending to add a bung to the duct to plumb the engine oil fill tube vent to, in an attempt to mitigate some of the positive crankcase pressure present during boost condition, due to the vacuum hole in the bottom of the intake manifold.

I've seen pictures of these ducts running all around the engine well in boats and in cars, between the ProCharger and an intercooler (wherever they had room to stuff it, presumably), but I guess I never thought about the fact they've all been on the pressure side. Honestly, I didn't realize pressure/vacuum made a difference. I asked here on OSO once about it, and the responses was that it shouldn't hurt anything. Not the case?

I'm all ears....

Thanks. Brad.

Brad Christy

Smitty,


These are the duct pieces I’ve got. They would be cut to appropriate lengths, butt welded with a support ring, and a clamp ring over the ProCharger intake snout and flame arrestor flange. It would also be supported with a bracket attached to the engine in some way (I’d work all that out in due time).

Thanks. Brad.

Rookie

I'd be a little more concerned about the dipstick lifting than a system that has worked for years.

Brad Christy

Rookie,

It's worked for years, but I don't think that's to say it can't be improved. I have to think the cooling hoses lying right on the intake breather ain't doing it any favors.

I don't think the dipstick is actually "lifting", but I can say with confidence oil is being pushed up the dipstick tube. the question is how to mitigate that. The obvious answer it to pull the intake manifold and plug that weephole. This is something I think I can manage, but it will be a winter project, as will this intake duct work (assuming I move forward with it), but I'd think I still need a consistent source of vacuum to apply to the crankcase (right?). The only source for this I can see is prior to the ProCharger in the intake tract. I suppose I could just add an extension to the snout/breather to give space for a bung to plumb to, but I'd still have to do something with the cooling hoses. Either way, the cooling hoses are getting re-routed somewhere/somehow.

Thinking outside the box a bit.... Could a check valve of sorts be used to "plug" the intake manifold weephole, so that the intake can apply a vacuum while not in boot condition (90-95% of the time), but prevent a positive crankcase pressure condition during boost? I have a call in to Grant at ProCharger for advice but have not heard back. He is one of the guys there that has experience with boat engine applications. I will call again today.

Thanks. Brad.

underpsi68

I don't like such a long intake pipe. Will hurt flow.

Brad Christy

UnderPSI,

For the record, the final ducting won't be near that long. It would only be just long enough to facilitate the curves. Again.... IF.

So, which is worse? A longer than ideal intake tract or cooling hoses directly in the path of intake flow? Genuine question.

Thanks. Brad.

Rookie

I'd do a leak down and see if you having excessive blow-by on the rings and go from there. Oil dipstick lifting all of a sudden is not a sign of good things to come.

Brad Christy

Rookie,

It wasn’t “all of a sudden”. It’s been there since the day we bought the boat, and I’ve noticed some oil loss over the course of the seasons. It’s been brought to my attention there is a weephole in the bottom of the intake manifold that Merc put there to draw a vacuum in the crankcase. But ProCharger didn’t make any provisions to mitigate the effects of the positive manifold pressure condition when in boost. I’ve determined that we only get the oil on the top of the dipstick tube when we run high enough throttle to o go into boost. Not that a compression and leak down test aren’t in order, but I think we’ve established the cause of the oil.

Thanks. Brad.