PCV Tubes route to the flame arrestor in a boat???

[Pete104]

Re: PCV Tubes route to the flame arrestor in a boat???

Good luck!

I'm surprised this thread has stayed so long, seeing as though nothing is broke, YET!

 

[ziggy]

Re: PCV Tubes route to the flame arrestor in a boat???

i don't get it.
what are ya trying to accomplish? what do you expect to gain from the venture?
to keep from cleaning your flame arrestor?

ya sound mechanically inclined. ya like to be around your engine. so clean the fa and leave well enough alone. i assure ya something will come along that will require mechanical expertise. specially if this statement is true.

I never did take it on the water

i bet ya take it on the water and you'll be less worrried about the crankcase ventilation. just a guess though..

fwiw. as for me cleaning my fa a few times a year. i believe it to be expected on my engine. i've never had it apart and compression is at the limits of being serviceable. i expect extra blow by. i clean my fa three to four times a season. usually it's not to bad when i clean it.

so imho. don't fix i a system that ain't broke. and do your pm.

 

[mxcobra]

Re: PCV Tubes route to the flame arrestor in a boat???

Your first boat-soon you will find out sea is differant then land in every aspect......
When you mess her all up experimenting, im sure some one on here will come allong and help you fix it!

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

Great, thanks, I will do that.

 

[Fishermark]

Re: PCV Tubes route to the flame arrestor in a boat???

I too like to think outside the box.... but another thing you will find with your boat is it takes a much bigger increase in power to notice a difference in a boat versus a car. In the grand scheme of things the amount of heated air you are adding to the intake with the vent is too small to even measure. And then the actual hp / torque difference? MAYBE a 1 horsepower if that?

If this little bit bothers you, perhaps a better solution is to add some more cooled outside air to the box. Add some vents to the doghouse.... put in another blower and run it all the time... spend some time with this instead of something that has the potential for ruining your engine with water in the oil.

(And by the way - surely you must understand there is a big difference between a dragster's exhaust DESIGNED to scavenge fumes for maximum efficiency and a boat's big restrictive water cooled log manifold? The venturi effect you mention is fine if the conditions are optimal for that).

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

I agree it may not work, the origional post was just curiosity to see if anyone else considered it, or runs it. I guess I was kind of looking for a yes or no answer and a simple definitive reason why or why not to formulate my own opinion not have people give me theirs and then assume I will ruin my boat. Hey, I had a stock Tahoe until I fabricated my own cold air intake and bought a aftermarked exhaust and reprogrammed the PCM, hell I like how it runs better now, even though there was nothing wrong with it when it was stock. Here is the link to the parts.

http://www.moroso.com/catalog/categorydisplay.asp?catcode=13023

All in all I probably wont wind up doing it, I was just asking questions first.

 

[BlueLightSpecial]

Re: PCV Tubes route to the flame arrestor in a boat???

You are talking about scavenger kits! I had them on my old bracket car! Don't know if the check valve will work in a marine app. I have come to the realization that I need to throw alot of automotive knowledge out the window. Just make sure you use marine parts instead of automotive parts on you boat, such as distributors, alternators, starters, carbs etc. Back to blowby, my pcv hoses just vent out to the engine compartment in my boat. No place on the flame arrestor to attach. So I pulled the hoses, and put in nice chrome breathers... don't know how it will work, since I haven't ran it since then, but it made sense to me. Perhaps Don will shed some light on that. Anyways, good luck!

 

[John_S]

Re: PCV Tubes route to the flame arrestor in a boat???

Interesting thread. It looks like the exhaust scavengers may function, if you wanted to go through all the trouble to fabricate, but will not provide any measurable change, outside of more water/air pollution.

Given the year and low purchase price, you will most likely find many more repair/maintenance issues that will need addressing. The bigger concern to me, would be "Does the motor have excessive blowby and why?". A leakdown test would be a good start.

 

[superbenk]

Re: PCV Tubes route to the flame arrestor in a boat???

Well you got a no answer & several reasons why not to do it so I think you had your bases covered.

 

[alamantia]

Re: PCV Tubes route to the flame arrestor in a boat???

Well you got a no answer & several reasons why not to do it so I think you had your bases covered.

I didnt get an answer because nobody was aware a crankcase evacuation system existed.

The reasons why not to do it are all opinion based on lack of knowladge, fundemental understandig of how a combustion engine operates and flow dynamics of a venturi system which pulls vapors from the crankcase rather than simply allowing them to escape on their own. Research vaccume pumps for engines and you will understand the gains associated with removing crankcase pressure.

This kit is an add on for people looking for a little extra preformance, it will adapt to the exhaust belows of a boat drawing crankcase pressure outward, not bring water the reverese direction, even if water defied the law of physics and tried to go backwards the kit provides a check valve.

Todays cars have emission systems which require crankcase pressure to be reburnt. Older cars just had breathers, you cant have breathers on a boat because of the closed compartment. So boats just route the breathers up to the carb, which I have to agree, despite not being optimal, probably doesnt hurt the performance. This kit, the one in the link, draws crankcase pressure out the engine thru the exhaust which reduces the strain on piston rings thus increasing the longevity of an angine, allows for more fresh air to enter the carb and eliminates the cleaning of the flame arrestor. All minimal gains at best, but like I previoulsy stated, I was only curiouls if there was a kit.

It all started as a simple question, thats all, some people tried to help me, some assumed I would screw up my boat, some tell me to fix other things without even seeing my boat. When I post a question looking for a direct answer, I expect a direct answer, not sarcasim, opinions, lengthly replies having nothing to do with my question and belittling. What I havent told anyone is that I spent 6 years as an engine builder by trade and have vast experiance reservicing truck gas and diesel engines. You guys may know way more about boats than me, but when it comes to engines, I'm good. I was only curious what the reason for routing the tubes to the carb were and if there was a kit to rout them thru the exhaust. 30 posts later and you know what, there is a kit to rout them thru the exhaust. Of course a majority of the people willing to offer up their stupid opinions did not know this kit even existed but were quick to type an answer. I will be sure to use this forum on a limited basis and stear clear of the engine section going forward. IF you know the answer to the OP's question, answer it, if you dont know, refrain from typing nonsence. As for the few people that truly tried to help me, I really do apreciate it.

Good day.

 

[tpenfield]

Re: PCV Tubes route to the flame arrestor in a boat???

Part of the frustration you have experienced is that your question may be more appropriate in a boat design forum. The folks on this forum are more concerned with boat operation and maintenance; most of that is focused around existing designs, which is fine and serves a large purpose. So, there is not a large member base focused on new designs or concepts.

www.boatdesign.net is probably the most popular web site for boat design activities and questions. You may want to try discussing your idea on the boatdesign.net forum.

 

[Bondo]

Re: PCV Tubes route to the flame arrestor in a boat???

It all started as a simple question, thats all, some people tried to help me, some assumed I would screw up my boat, some tell me to fix other things without even seeing my boat. When I post a question looking for a direct answer, I expect a direct answer, not sarcasim, opinions, lengthly replies having nothing to do with my question and belittling. What I havent told anyone is that I spent 6 years as an engine builder by trade and have vast experiance reservicing truck gas and diesel engines. You guys may know way more about boats than me, but when it comes to engines, I'm good. I was only curious what the reason for routing the tubes to the carb were and if there was a kit to rout them thru the exhaust. 30 posts later and you know what, there is a kit to rout them thru the exhaust. Of course a majority of the people willing to offer up their stupid opinions did not know this kit even existed but were quick to type an answer. I will be sure to use this forum on a limited basis and stear clear of the engine section going forward. IF you know the answer to the OP's question, answer it, if you dont know, refrain from typing nonsence. As for the few people that truly tried to help me, I really do apreciate it.

Good day.

Ayuh,.... This is an open forum, so you'll get all kinds of answers from all kinds of folks...
Ya just gotta skip over the answers you don't like...
It's the very nature of forums,... ALL forums...

As for this Kit,... Read the write up on it,...
It Ain't for Boats,...
It ain't even for a Street car,... It's for RACE cars...
"*NOTE: Cannot be be used on cars w/ mufflers"
If it can't be used on a car with a muffler, it sure as 'ell won't work on a choked up boat exhaust...

Nobody is belittling you, 'n yer engine knowledge should lead ya to the answers you've been given...
Yer boat, Ain't a Race car,...
'n a Boat doesn't react to Race motor mods very well...
Actually, if Race motor mods are done on Boat motors,...
Anchors are the usual results....

If ya think it's so easy to pull off,... Go for it....

We'll all be here, waitin' to hear yer results.....


Btw,... If yer boatin' in the Saltwater off Long Island,...
Yer venting is gonna cause All kinds of issues...
That kit will turn to rusty dust in no time, flat...

 

[BlueLightSpecial]

Re: PCV Tubes route to the flame arrestor in a boat???

I didnt get an answer because nobody was aware a crankcase evacuation system existed.

The reasons why not to do it are all opinion based on lack of knowladge, fundemental understandig of how a combustion engine operates and flow dynamics of a venturi system which pulls vapors from the crankcase rather than simply allowing them to escape on their own. Research vaccume pumps for engines and you will understand the gains associated with removing crankcase pressure.

This kit is an add on for people looking for a little extra preformance, it will adapt to the exhaust belows of a boat drawing crankcase pressure outward, not bring water the reverese direction, even if water defied the law of physics and tried to go backwards the kit provides a check valve.

Todays cars have emission systems which require crankcase pressure to be reburnt. Older cars just had breathers, you cant have breathers on a boat because of the closed compartment. So boats just route the breathers up to the carb, which I have to agree, despite not being optimal, probably doesnt hurt the performance. This kit, the one in the link, draws crankcase pressure out the engine thru the exhaust which reduces the strain on piston rings thus increasing the longevity of an angine, allows for more fresh air to enter the carb and eliminates the cleaning of the flame arrestor. All minimal gains at best, but like I previoulsy stated, I was only curiouls if there was a kit.

It all started as a simple question, thats all, some people tried to help me, some assumed I would screw up my boat, some tell me to fix other things without even seeing my boat. When I post a question looking for a direct answer, I expect a direct answer, not sarcasim, opinions, lengthly replies having nothing to do with my question and belittling. What I havent told anyone is that I spent 6 years as an engine builder by trade and have vast experiance reservicing truck gas and diesel engines. You guys may know way more about boats than me, but when it comes to engines, I'm good. I was only curious what the reason for routing the tubes to the carb were and if there was a kit to rout them thru the exhaust. 30 posts later and you know what, there is a kit to rout them thru the exhaust. Of course a majority of the people willing to offer up their stupid opinions did not know this kit even existed but were quick to type an answer. I will be sure to use this forum on a limited basis and stear clear of the engine section going forward. IF you know the answer to the OP's question, answer it, if you dont know, refrain from typing nonsence. As for the few people that truly tried to help me, I really do apreciate it.

Good day.

I, for one, never belittled you. I am well aware as to how the scavengers work, knew they exist, etc. I think it is something that may not work in a marine application, however, i may be wrong. As long as there is enough exhaust flow, by all theory they should work. But my concern would be water backing up the exhaust. Now, i know you are thinking that what i say will "defy the laws of physics", but keep in mind there are flaps in most inboard and I/O exhaust that keep water from getting in to the engine via the exhaust, in cases of a sudden slow down, such as backing out of the throttle. When you do this, there is a surge of water coming up from behind the boat, that eventually hits the boat. Sometimes these flaps fail, and let water enter the exhaust, the wrong way. My concern would be the check valve. Does it have a good water tight seal, to keep the water from possibly entering the crankcase. Listen, I got pist last week on these forums. Then I realized, no one on here knows me personally, until you are known well on the forums, its human nature for the veteran forum members to write the things they do, since they dont know what your skill level is, your knowledge etc. They are trying to help you, or trying to give you advice on what to do. I would have to agree to one of the earlier posts. You havent had the boat in the water yet. There may be underlying problems that wont show up until its in the water, that would take priority to venting blowby through the exhaust. I know you are asking "why do they do it that way", and "why dont they do it this way". You just want the answers. But some people are smart *****es, and you just have to overlook those answers. If you try the scavengers, let the forum know, and if it works, then you can say " I told ya so". I am a mechanic myself, working for a school bus company. I would have to say that I have learned that some things that almost always apply to anything automotive, do not apply to marine applications. An engine is an engine, however, the application of the engine determins a lot of things. Good luck, and let us know what you come up with, I, for one, am interested.

 

[CharlieB]

Re: PCV Tubes route to the flame arrestor in a boat???

The 'inductor' effect of merging a PCV into the exhaust stream 'may' be beneficial at 'some' RPM ranges, however, at idle to low throttle ranges it 'could' very well pose a problem.

There are yards and yards of postings explaining 'reversion' in the exhaust, 'sucking' water back upstream at low throttle, wetting exhaust valves causing damage.

Reversion can be caused not just by installation of a non-marine cam but by simple rusting, aging of exhaust risers. The design of the risers incorporates a 'lip' cast into the lower side of the risers arced passage to act much like a 'dam', to stop the reverberating stream of water.

Experimentation with a 'wet' exhaust may be undertaken only with the knowledge that very often, experiments fail, sometimes with expensive consequences.

Proceed at your own risk.

 

[Silvertip]

Re: PCV Tubes route to the flame arrestor in a boat???

I dont own a car with a PCV system, I have a newer Tahoe. The camaro is carberated and does not require emissions like a boat and I was using tha analogy as a basis for my question.

If you have a Tahoe it has a PCV system. Engines need either a draft tube or a pcv system. Without one or the other the engine would blow oil out every seam due to the pressure build up in the crankcase. PCV systems don't normally dump fumes above the throttle plates on a carbureted or throttle body EFI engine -- they dump into the base plate of the carb or into the intake manifold. Port fuel injected engines typically dump PCV fumes into the intake manifold.

What's being missed in this thread is that there is generally no direct connection to the intake air stream using the vent tube feeding the flame arrestor. At the air gap a great deal of fresh air is collected along with the fumes so the engine simply doesn't know any fumes are there. These are also 4500 - 5000 rpm engines as well with pretty "lazy" camshaft profiles so they will hardly be bothered by a few blow-by vapors. If there was a better way to do this, the engineers at Merc and Volvo Penta would have done it long ago. An automotive PCV system does dilute the fuel mixture but the ECU and related sensors can compensate for that. Besides -- when is the last time the average grocery getter saw 5000 RPM? Bets it was just after the 16 year old left the driveway on his first outing alone.