Return to the home page...

Go Back   Moyer Marine Atomic 4 Community - Home of the Afourians > Discussion Topics > Exhaust System

View Poll Results: What size is your exhaust system? Choose all that apply.
1 1/4" I.D. Hot section 55 58.51%
1 1/2" I.D. hot section 13 13.83%
2" I.D. hot section 5 5.32%
1 1/2" hose 12 12.77%
1 5/8" hose 26 27.66%
2" hose 10 10.64%
Don't know / other 9 9.57%
Multiple Choice Poll. Voters: 94. You may not vote on this poll

Reply
 
Thread Tools Display Modes
  #1   IP: 24.152.131.220
Old 08-17-2010, 08:29 PM
ndutton's Avatar
ndutton ndutton is offline
Afourian MVP
 
Join Date: May 2009
Location: Torrance, CA
Posts: 9,601
Thanks: 197
Thanked 2,206 Times in 1,423 Posts
Exhaust system size

We started talking about increasing the size of exhaust systems over on the troubleshooting section so I thought I'd move the discussion over here.

The more I think about larger aqualift exhaust systems on our little engines and their ability to expel water, the less I like 'em.

As an example, the difference between the cross sectional areas of 1 5/8" exhaust hose and 2" exhaust hose is about 50%. In terms of exhaust gases, going bigger reduces backpressure allowing the engine to breathe better. No quarrel from me.

In terms of expelling water though (the whole purpose of an aqualift system), it takes a greater volume of water to 'seal' off the exhaust hose so the exhaust pressure will push it along, especially push it up. Also, there's less exhaust velocity to do the job with a larger system. We need to factor in how much exhaust force we have available in the first place, most critically at idle. In sort of a twisted way, I can see where a larger exhaust line could result in more backpressure when factoring in the added volume of water in each 'batch' as the aqualift system batches out the water.

I'm sure there's a sweet spot somewhere between too small a system and one too large. We have pretty good historical data given the number of A4's with aqualift systems but I'm not sold on the 'bigger is better' strategy. The fact we're dealing with wet exhaust systems changes things.

Thoughts??
__________________
Neil
1977 Catalina 30
San Pedro, California
prior boats 1987 Westsail 32, 1970 Catalina 22
Had my hands in a few others
Reply With Quote
  #2   IP: 173.166.26.241
Old 08-17-2010, 08:53 PM
hanleyclifford's Avatar
hanleyclifford hanleyclifford is offline
Afourian MVP
 
Join Date: Mar 2010
Posts: 6,987
Thanks: 176
Thanked 285 Times in 228 Posts
Talking

Neil - I guess you knew that I would be among the first to respond to this new thread. I like the way you have framed the issue. Let me begin by saying that I have been using 2" ID pipes and hoses all the way to the transom for several years. But your discussion about "diminishing returns" is sound and should give reason for pause about going any larger. The engine must always be able to expel the water. This requirement of course is going to vary with each boat's configuration. The greater the "head" against which the engine is working, the more dangerous larger wet sections would be potentially. All this of course needs to be quantified. Just one final thought for now: the manifold exit diameter is 1 1/2" - comments on why the manufacturer would reduce immediately to 1 1/4"?
Reply With Quote
  #3   IP: 64.203.32.52
Old 08-18-2010, 12:25 AM
Dave Neptune Dave Neptune is online now
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,038
Thanks: 713
Thanked 1,298 Times in 844 Posts
Question Exhaut options

I pretty much agree with you both about the additionl preassure and or "flow" to force the water out up & over and so on. However after the water is injected the exhaust gasses will cool rapidly and require less diameter than an exhaust system without water injection and we still need to evacuate the water through the same crossection.

Perhaps the exhaust back preassure guage will give some answers as to how the A-4 responds to back preassure. Many engines due to there cam profiles require a bit of back preassuure to "breath" properly under load conditions.

I actually have two riser hoses so to speak, I take it up under the cockpit then back down to the bilge then up to the transom. Lotsa pipe and hose maybe 14~15 feet or more.

Dave Neptune
Reply With Quote
  #4   IP: 173.166.26.241
Old 08-18-2010, 12:36 AM
hanleyclifford's Avatar
hanleyclifford hanleyclifford is offline
Afourian MVP
 
Join Date: Mar 2010
Posts: 6,987
Thanks: 176
Thanked 285 Times in 228 Posts
Talking

Dave - I think as we move forward in this discussion it might be useful to post some exhaust system pictures. We have seen quite a few Catalina 30 pix. I would like to study your "twin risers". Attached is a view of my hot section. 4000 hrs on this configuration.

Last edited by hanleyclifford; 07-13-2016 at 08:36 PM.
Reply With Quote
  #5   IP: 142.68.253.241
Old 08-18-2010, 05:19 AM
rigspelt's Avatar
rigspelt rigspelt is offline
Afourian MVP
 
Join Date: May 2008
Posts: 1,186
Thanks: 0
Thanked 19 Times in 17 Posts
I like Hanley's two 90s and one 45, but can't arrange that in our boat. Ended up going with the design it had when I bought the boat, after much head-scratching and research, except for more height in the dry stack, adding height to the red coolant line (added antisiphon valve in the red hose later -- this photo was taken during dry-fitting) and shortening the exhaust hose run to the transom. Haven't measured the back pressure, but seems to run just fine, with no seawater backup threat. After running the engine, there is about an inch of water in the muffler. Boat's level waterline is just below the top of the muffler.
Attached Images
 
__________________
1974 C&C 27

Last edited by rigspelt; 08-18-2010 at 05:23 AM.
Reply With Quote
The Following User Says Thank You to rigspelt For This Useful Post:
Brent W (07-03-2017)
  #6   IP: 173.166.26.241
Old 08-18-2010, 09:26 AM
hanleyclifford's Avatar
hanleyclifford hanleyclifford is offline
Afourian MVP
 
Join Date: Mar 2010
Posts: 6,987
Thanks: 176
Thanked 285 Times in 228 Posts
Talking

Rigspelt - Nice neat set up. Are we looking at the MM aqualift unit? I like the fact that you appear to have your injection point about a foot above the water line. One of the weaknesses of my system is that I inject just about at the line. For this reason I am obsessive compulsive about shutting off the thru hull every time I shut down the engine - even at a refueling stop! Regards, Hanley
Reply With Quote
  #7   IP: 64.203.32.52
Old 08-18-2010, 11:03 AM
Dave Neptune Dave Neptune is online now
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,038
Thanks: 713
Thanked 1,298 Times in 844 Posts
Lightbulb Headers?????

Guys, I think this may work out to gather some useful information albeit that there are so many ways to get it to the transom or out the side.

I'll try to give a better description of mine then I'll borrow a camera. I don't think I can get pics of some sections. My engine sits amidship and is entirely below the water line. From my exhaust flange 1 1/4' it's straight out back and facing down hill slightly, then a 90 down (my water injection is here well bellow the water line) to the bilge and another 90 and about 2 1/2 feet to the water trap muffler beneath the floor (I made it of F/glass ). Out of the muffler it goes up about 4 feet under the front of the cockpit then two 90's and right back down to the bilge, then uphill to the top of the transom another 90 down to the exit under the transom. I have an old Ericson 35 with an overhanging transom and while motoring the exhaust stays out of the water in most conditions. I'm quessing that I have a run of about 18~20 feet. My hot section is less than a foot long and I made the mistake of using galvanized pipe as I had it in stock at work. The engine box is under the settee and the settee bunks are below the water line. I have had many an issue with salt water getting back into the engine and have since gone to a manual syphon break. And 3 times I have forgot to open the valve and filled the beastie at anchor. It's about an hour to get the water out from under the oil and I'm running easy until I get the oil changed a couple of times.

I'll try to get some details with photos soon.

Dave Neptune
Reply With Quote
  #8   IP: 173.166.26.241
Old 08-18-2010, 12:42 PM
hanleyclifford's Avatar
hanleyclifford hanleyclifford is offline
Afourian MVP
 
Join Date: Mar 2010
Posts: 6,987
Thanks: 176
Thanked 285 Times in 228 Posts
Thumbs up

Dave - Yeah, headers! I remember that dollar for dollar they were the best thing you could do for a street racing machine. But we didn't have to worry about water backing in on us. Sounds like you do (me too). Also, remember why Neil started this thread - we are going to try and figure out just how big one can go with an A4 system before the danger of being unable to "batch" the water out sets in. I'm hoping some of our young college members (Trumps, where are you?) will step in and correct me if needed. I think we need to look at how much work has to be done by the exhaust gases to lift the water up and out. Work=force x distance. Force=mass x acceleration. Ok, all you engineering students, take it away! Regards, Hanley
Reply With Quote
  #9   IP: 71.118.13.238
Old 08-18-2010, 03:56 PM
Dave Neptune Dave Neptune is online now
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,038
Thanks: 713
Thanked 1,298 Times in 844 Posts
Red face Wow!

Guys, I stopped by the boat this morning on my way to work and checked a few things including my compression for the first time in probably 8~10 years. I was a bit surprised as the numbers are now better than they ever were.

I checked my exhaust so we know what I am dealing with. I have a hot section that the total length is 8" (3 straight out of the manifold and 5" straight down) and another foot to the bilge, then 4' to the muffler. from the muffler straight back 1' and then up 4' 90 straight 90 back down 4' then up hill 9' to the top of the transom and back down 15" to the atmosphere under the transom. Approximately 25' and it's all 1 1/2" hose and 1 1/4" pipe fittings and a shut off 1 1/4" ball valve at the transom. I WAS SURPRISED AT THE LENGTH~~ WoW. That'll make some back preassure I would think.
Last weekend I was cruising at 2100 rpm's @ 7 1/2" of vac with my Indigo.

Dave Neptune
Reply With Quote
  #10   IP: 64.231.85.178
Old 08-18-2010, 04:29 PM
67c&ccorv's Avatar
67c&ccorv 67c&ccorv is offline
Afourian MVP
 
Join Date: Dec 2008
Location: London, ON
Posts: 1,559
Thanks: 4
Thanked 9 Times in 9 Posts
Here is mine - original copper jacketed exhaust installation on 1967 C&C Corvette:

(I have not measured but am pretty sure the exhaust is 1&1/4" from the exhaust flange to the muffler.)
Attached Images
 

Last edited by 67c&ccorv; 08-19-2010 at 01:01 AM.
Reply With Quote
  #11   IP: 142.68.255.162
Old 08-18-2010, 07:25 PM
rigspelt's Avatar
rigspelt rigspelt is offline
Afourian MVP
 
Join Date: May 2008
Posts: 1,186
Thanks: 0
Thanked 19 Times in 17 Posts
Quote:
Originally Posted by 67c&ccorv View Post
Here is mine - opriginal copper jacketed exhaust installation on 1967 C&C Corvette
Nice engine room! I continue to be mightily impressed by the seamanship displayed by the owners of so many of these old A4s, chugging away and well cared for. I can see why Don got hooked on them. Must be gratifying for him to see them carry on this way.
__________________
1974 C&C 27
Reply With Quote
  #12   IP: 173.166.26.241
Old 08-20-2010, 04:38 PM
hanleyclifford's Avatar
hanleyclifford hanleyclifford is offline
Afourian MVP
 
Join Date: Mar 2010
Posts: 6,987
Thanks: 176
Thanked 285 Times in 228 Posts
Lightbulb practical exercise

While still mulling over how to come up with some formulas (formulae?) that will predict exhaust performance of various pipe sizes, I decided to run the back pressure test on the hot section according to the instructions from Don Moyer. My system consists of hot section 2" ID with two 90 degree turns and one 45 degree turn, thence to Vetus waterlock (2"), out to transom via 2"ID wet hose. The rise from bottom of waterlock to maximum hose height is about two feet. The pressure gauge oscillated with the "batching" cycle between 0 and slightly less than 1 psi. I had never paid much attention to this matter until this issue came up in this thread. I recommend that any owner with a long or otherwise suspect exhaust system consider ordering the pressure test kit from the MM on line catalogue.
Reply With Quote
  #13   IP: 142.68.245.21
Old 08-20-2010, 06:57 PM
rigspelt's Avatar
rigspelt rigspelt is offline
Afourian MVP
 
Join Date: May 2008
Posts: 1,186
Thanks: 0
Thanked 19 Times in 17 Posts
Quote:
Originally Posted by hanleyclifford View Post
Rigspelt - Are we looking at the MM aqualift unit?
Hanley, yes, that's the stainless MMI waterlift muffler.
__________________
1974 C&C 27
Reply With Quote
  #14   IP: 173.166.26.241
Old 08-23-2010, 08:58 PM
hanleyclifford's Avatar
hanleyclifford hanleyclifford is offline
Afourian MVP
 
Join Date: Mar 2010
Posts: 6,987
Thanks: 176
Thanked 285 Times in 228 Posts
Question Copper jacketed system

67 - That exhaust system you have could very well be the least restrictive of all. It appears to eliminate the need for a riser and all the 90 degree bends associated with most systems. Can you give us the ID numbers from engine to transom? Also, do you have any sort of muffler or waterlock anywhere in the system? Regards, Hanley
Reply With Quote
  #15   IP: 216.115.121.253
Old 08-24-2010, 01:06 AM
lat 64's Avatar
lat 64 lat 64 is offline
Afourian MVP
 
Join Date: Oct 2008
Location: Fairbanks, Alaska
Posts: 1,964
Thanks: 39
Thanked 240 Times in 157 Posts
I think I have nearly the same as 67'.
Here' some "before" shots from '08 that might give a clue. I don't think it gets any smallr than the fitting at the flange.

Russ
Attached Images
   
__________________
Whiskeyjack a '68 Columbia 36 rebuilt A-4 with 2:1

"Since when is napping doing nothing?"
Reply With Quote
  #16   IP: 193.253.220.149
Old 08-24-2010, 04:40 AM
Kelly's Avatar
Kelly Kelly is offline
Afourian MVP
 
Join Date: Oct 2004
Location: Brest, France
Posts: 662
Thanks: 0
Thanked 9 Times in 7 Posts
Older exhaust systems

Russ and 67-

Do you have some sort of mixing chamber after the copper jacketed section? You can see in my set-up that the gases are mixed with the cooling water in what I call the mixer (for lack of a better term) which is tucked up under the deck as high as possible above the water line. From there, it's a straight shot out the transom after about 4-5 feet.

I like this system as apart from the iron hot section, it's all copper. And, it seems highly unlikely that water could ever "back up" with this design.
Attached Images
 
__________________
Kelly

1964 Cheoy Lee Bermuda Ketch, Wind and Atomic powered

Reply With Quote
  #17   IP: 173.166.26.241
Old 08-24-2010, 11:02 AM
hanleyclifford's Avatar
hanleyclifford hanleyclifford is offline
Afourian MVP
 
Join Date: Mar 2010
Posts: 6,987
Thanks: 176
Thanked 285 Times in 228 Posts
Lightbulb

Kelly - That is quite an elegant looking jacketed pipe (exchanger?) set up. Can you say what the ID of the inside and ouside components are? I like the early smooth 90 degreee turn and the next smooth 45. The mixer itself seems to be the last "turn" in the system. Since we have such similar boats you can see why I am particularly interested in your system. Regards, Hanley
Reply With Quote
  #18   IP: 216.115.121.253
Old 08-24-2010, 11:38 AM
lat 64's Avatar
lat 64 lat 64 is offline
Afourian MVP
 
Join Date: Oct 2008
Location: Fairbanks, Alaska
Posts: 1,964
Thanks: 39
Thanked 240 Times in 157 Posts
Kelly,
I don't have an extra water lift, just the jacketed pipe.
Here's a link to the thread in '08 where I posted a crude drawing and explanation.

http://www.moyermarine.com/forums/sh...1145#post11145

Mine works good. It is copper color but I don't know if that is real copper or not. I never investigated it. It must be a kings ransom to replace.

r.
__________________
Whiskeyjack a '68 Columbia 36 rebuilt A-4 with 2:1

"Since when is napping doing nothing?"
Reply With Quote
  #19   IP: 173.166.26.241
Old 08-24-2010, 12:10 PM
hanleyclifford's Avatar
hanleyclifford hanleyclifford is offline
Afourian MVP
 
Join Date: Mar 2010
Posts: 6,987
Thanks: 176
Thanked 285 Times in 228 Posts
Question

Russ - I count 4(each) 90 degree bends at the end of your system. Can you say what material is used after the jacketed section and are the bends as harsh as they appear in the schematic? Regards, Hanley
Reply With Quote
  #20   IP: 64.231.81.231
Old 08-24-2010, 12:44 PM
67c&ccorv's Avatar
67c&ccorv 67c&ccorv is offline
Afourian MVP
 
Join Date: Dec 2008
Location: London, ON
Posts: 1,559
Thanks: 4
Thanked 9 Times in 9 Posts
Hi guys - here is a blueprint of mine from C&C. It shows a waterlift of some kind at the transom end but to tell the truth I have not found it on mine and my copper jacket exhaust is much longer than the one shown in the blueprint.
Attached Images
File Type: pdf Corv trad cabin plan.pdf (756.6 KB, 1565 views)
Reply With Quote
  #21   IP: 216.115.121.253
Old 08-24-2010, 02:48 PM
lat 64's Avatar
lat 64 lat 64 is offline
Afourian MVP
 
Join Date: Oct 2008
Location: Fairbanks, Alaska
Posts: 1,964
Thanks: 39
Thanked 240 Times in 157 Posts
Quote:
Originally Posted by hanleyclifford View Post
Russ - I count 4(each) 90 degree bends at the end of your system. Can you say what material is used after the jacketed section and are the bends as harsh as they appear in the schematic? Regards, Hanley
I don't have a picture and I'm 700 miles away right now.
That last piece is a big cast bend that is not painted and not rusty at all. I think it is bronze. It's not standard stuff at all. I'm sure it would cost like hell nowadays. It just a high loop to keep the sea from getting in the boat.(water is bad for boats ya know)
I'll get a photo when I go down next month.
R.
__________________
Whiskeyjack a '68 Columbia 36 rebuilt A-4 with 2:1

"Since when is napping doing nothing?"
Reply With Quote
  #22   IP: 71.118.13.238
Old 08-24-2010, 05:49 PM
Dave Neptune Dave Neptune is online now
Afourian MVP, Professor Emeritus
 
Join Date: Jan 2007
Location: Grove, Oklahoma
Posts: 5,038
Thanks: 713
Thanked 1,298 Times in 844 Posts
Red face Volador's exhaust.

Guys, I've been trying to attach a drawing of my exhaust and when I check the "prieview" it is huge! How do I reduce the image so I don't screw it up?

Anyone?

Dave Neptune
Reply With Quote
  #23   IP: 216.115.121.253
Old 08-24-2010, 06:59 PM
lat 64's Avatar
lat 64 lat 64 is offline
Afourian MVP
 
Join Date: Oct 2008
Location: Fairbanks, Alaska
Posts: 1,964
Thanks: 39
Thanked 240 Times in 157 Posts
I don't know what you have for software.
If you have a camera then you probably have a disc with some limited photo editing software. Fire it up and look for settings that are good for resizing for e-mail., that's what you want.
You could e-mail it and I'll copy it and resize it for you for now 'til you learn how.


Update: Right on Shawn
__________________
Whiskeyjack a '68 Columbia 36 rebuilt A-4 with 2:1

"Since when is napping doing nothing?"

Last edited by lat 64; 04-04-2015 at 09:38 PM. Reason: shawn suggestion
Reply With Quote
  #24   IP: 138.88.73.244
Old 08-24-2010, 09:53 PM
sastanley's Avatar
sastanley sastanley is offline
Afourian MVP
 
Join Date: Sep 2008
Location: Solomons, MD
Posts: 6,986
Thanks: 1,133
Thanked 603 Times in 443 Posts
quick & dirty!

lat64 - great idea creating an e-mail address with L/L coordinates! Be careful leaving that link active for too long though, as I think the Google bots search this forum and cache that stuff and then spammers can get it...may want to change it to all text similar to this: 64n147w at gmail dot com.

Dave, Another quick & Dirty answer - If you are using MS Windows, open it in "Paint" and choose Image>>Stretch/skew and then set both vertical & horizontal to some percentage (make them the same number!!) that makes it reasonable..(try 50%???) - Then save the file with a new name.

Eventually, you'll find a size that works.

I personally have a Microsoft Powertoy called "Image resizer" installed which allows me to right click on the file directly (right from the camera card) and re-size it to 1024 x 768 (or smaller).

Alternatively, I also have installed a free program called Paint.NET which is much more powerful than MS Paint, and has a resizing option built right in from the menu.
__________________
-Shawn
"Holiday" - '89 Alura 35 #109
"Twice Around" - '77 C-30, #511 with original A-4 & MMI manifold - SOLD! (no longer a two boat owner!!)
http://www.moyermarine.com/forums/signaturepics/sigpic3231_6.gif

Last edited by sastanley; 08-24-2010 at 09:55 PM.
Reply With Quote
  #25   IP: 193.253.220.149
Old 08-25-2010, 03:54 AM
Kelly's Avatar
Kelly Kelly is offline
Afourian MVP
 
Join Date: Oct 2004
Location: Brest, France
Posts: 662
Thanks: 0
Thanked 9 Times in 7 Posts
jacketed pipe dimensions

Hanley,

I'll have to measure when I get back down to the boat. If I were to guess at the inner pipe diameter (hot section), I would say 1 1/4". I'll get back to you...

67,

As drawn in your schematic, our exhaust systems are nearly identical, with only small differences in the angled connections. It would be interesting to know if someone removed the mixer (riser?) from your setup. This would, I assume, as in Russ' example, eliminate almost all back pressure.
__________________
Kelly

1964 Cheoy Lee Bermuda Ketch, Wind and Atomic powered

Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
A few critical suggestions Don Moyer General Interest 20 02-10-2014 01:45 PM
New exhaust system jsedivy Exhaust System 11 08-01-2011 07:50 PM
Tartan 30 exhaust system rebuild jacques debauche Tartan 2 05-22-2010 06:48 AM
Exhaust system elements Kelly Exhaust System 4 06-18-2007 10:47 AM
Check valve in exhaust system BBH Exhaust System 3 11-16-2006 06:03 AM


All times are GMT -4. The time now is 07:19 PM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2024, vBulletin Solutions, Inc.


Universal® is a registered trademark of Westerbeke Corporation

Copyright © 2004-2024 Moyer Marine Inc.

All Rights Reserved