Go Back   Trawler Forum > Maintenance and Systems > Power Systems
Click Here to Login


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 06-03-2021, 10:52 AM   #1
Member
 
City: MA
Join Date: Jun 2021
Posts: 19
Injector Selection for DD4-71 ranges from N35 to N90- Anybody insight?

Hi Trawler community - new here - just bought a Gladding Hearn Pilot steel hulled lets call it trawler :-) technically would say its a DownEaster but nice displacement none the less - single engined with an awesome DD 4-71N Twindisc combo.


I try to get to know the systems and hands on spare parts - optimize what ever is possible for long range.


So here my question out to you:
the injector range that is compatible seems to go from 35 to 90 and I assume its the amount or a number correlating to that is injected into cylinder?
What are your experiences know how if I may tap into that?
Can efficiency be increased by putting smaller once in - is there associated risk to consider etc.


thank ya all in advance!!!!
Meander is offline   Reply With Quote
Old 06-03-2021, 07:03 PM   #2
Guru
 
Lepke's Avatar
 
City: Between Oregon and Alaska
Vessel Name: Charlie Harper
Vessel Model: Wheeler Shipyard 83'
Join Date: Jun 2016
Posts: 2,393
You need the correct injector for the power range you want to use. A slightly smaller injector will cause the governor to open the injector more and you won't reach full power. A larger injector will be closed more. In the end your governor has less control.

I've been burning diesel since the 1950s and the fuel we have today is crap. It has less lubrication, doesn't combust as well, and doesn't do a good job of keeping the fuel system clean. But a lot of people in the EPA that never had a real job are happy.

The best way to get economy out of a Detroit is have it in good mechanical repair. Make sure governor and valve adjustments are correct. Get a temperature gun and see what each exhaust port is registering at cruising rpm. They should be close. Very slight adjustments to the valve lash can balance the cylinders. Be careful. Also use a good diesel additive. One that improves combustion. I use Archoil 6200 and see a gain above 6% better mileage. It also improves lubrication of the fuel system, kill organisms, and cleans the tanks. Along with that I use Archoil 9100 oil additive that reduces friction. (archoil.com)
If you like to build things, make a hydrogen generator. I've been using them for years and get about a 20% improvement in gas and diesel. If you do, then you can use a 1 size smaller injector.
I have twin IL 671s naturals and at 1800 (max continuous) burn about 4.3gl/hr each with n65 injectors. Before overhaul, no additives, they burned 7+. Nice thing about Detroits, the sleeves are numbered and you can buy the same the factory used. Because of machining, each cylinder can be slightly different, but made the same with the sleeves.
Lepke is offline   Reply With Quote
Old 06-04-2021, 05:11 AM   #3
Member
 
City: MA
Join Date: Jun 2021
Posts: 19
Thanks for elaborate message!!! Really appreciated


I will look into fuel additives for sure - the dual racors need regular filter changes.
Fuel is an overloked factor in the whole power system I agree - I looked into fuel polish systems and except for all the more and better filters there was a strong magnetic component where fuel goes through and the molecules get for lack of more scientific terms - aligned for better power whila also killing algae?? Sonds esoteric but for $100 I buy in :-) why not


with sea trial we measured the cylinder temp and they were close +/- no smoke from engine whatsoever not at start not with smooth load changes so I wont rock the boat - pun intended :-)



one of the previous owners made a chart for consumption for anybody to reference:


2100rpm 7,7gph 145

2000 6,6 135

1800 4,9 130

1500 3 110

1200 1,8 (90bhp)


nice one everybody!
Meander is offline   Reply With Quote
Old 06-04-2021, 05:18 AM   #4
Member
 
City: MA
Join Date: Jun 2021
Posts: 19
Also Lepke - you mentioned a hydrogen generator - would you mind elaborating? thx!!!
Meander is offline   Reply With Quote
Old 06-04-2021, 06:17 AM   #5
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 21,964
The usual DD rule of thumb is to use 60% of available power or more to have similar economy to other engines.

If you have a log seeing where the boat was cruised would give away the power required .DD has tables for injector size and HP, at various RPM.

The CC rating used on injectors is for 1,000 strokes of the injector.
FF is offline   Reply With Quote
Old 06-04-2021, 09:13 AM   #6
Member
 
City: MA
Join Date: Jun 2021
Posts: 19
Hi FF - cool info thx - "cc" I assume is metric for cubic centimeter
Meander is offline   Reply With Quote
Old 06-06-2021, 09:41 AM   #7
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 21,964
"I looked into fuel polish systems and except for all the more and better filters there was a strong magnetic component where fuel goes through and the molecules get for lack of more scientific terms - aligned for better power whila also killing algae?? Sounds esoteric but for $100 I buy in :-) why not"


For the same reason the Brooklyn Bridge is seldom an investment.

Or the guy in Kenya needs your bank number to send a you few million bucks.

"Fuel polishing" seldom works to clean a fuel tank , it only cleans the fuel in the tank, the crud stuck to the sides and bottom is seldom removed.Till the boat is shaken.

A set of good fuel filters with a home made selecting set up will allow switching tanks underway..

Best is if they are mounted OUT of the engine space (copper tubing or fuel hose is cheap) where a filter can be changed with least effort or danger.
FF is offline   Reply With Quote
Old 06-06-2021, 09:55 AM   #8
Veteran Member
 
City: Houston / Ketchikan
Vessel Name: Backchuck
Vessel Model: 28' Crozier / Hunt
Join Date: Apr 2019
Posts: 91
Any pics of your new boat?

It must be one of GH's very early pilot boats if the hull is steel.
Jon H is offline   Reply With Quote
Old 06-06-2021, 01:32 PM   #9
Technical Guru
 
Ski in NC's Avatar
 
City: Wilmington, NC
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 6,151
Memory is foggy, but I think the 80 and 90 and bigger were generally for turbo engines. For non-turbo I think the N60 and N70 were typical.

What injectors are in it now?
Ski in NC is offline   Reply With Quote
Old 06-06-2021, 04:18 PM   #10
Guru
 
Lepke's Avatar
 
City: Between Oregon and Alaska
Vessel Name: Charlie Harper
Vessel Model: Wheeler Shipyard 83'
Join Date: Jun 2016
Posts: 2,393
Quote:
Originally Posted by Meander View Post
Also Lepke - you mentioned a hydrogen generator - would you mind elaborating? thx!!!
We ran 90s in Vietnam on natural 671s at higher than yacht rpm. Considering a bunch of kids were running the engines flat out, the DDs held up well.

You can probably get a better description online for a generator, but here's mine: Hydrogen generator is a sealed tank with positive and negative electrodes in a solution that helps the power flow. One side produces 1 oxygen and the other makes 2 hydrogen. It slightly pressurizes the tank and creates an air flow to be piped into the air intake. All it does is increase the efficiency of the fuel burn. It only works up to about a 25% increase in mileage.

Usually it's setup to use excess power from the alternator to power the two electrodes submersed in the solution. You install an amp gauge on the positive wire running to the generator and add hydrogen peroxide to water until you get the amp use you want. You need to leave enough charging amps to keep the battery up in a car. Once you know the water to HP ratio, you can have replacement mix ready to go. Or build a supply tank like I did.

I've been playing with this since the 1970s oil embargo. Originally I bought a generator from someone making them and decided I could do better. Most of the ones sold are too small. But you can see a better picture online than I can draw. What I use now are 2-4" horizontal plastic pipes about 5' long, teed together with a riser that is capped and piped to a DD intake. Each pipe has a steel electrode (1" rebar) that dissolve over time. I have one HG under the drip pan of each DD. I have a 48v system for my inverter and that supplies power.
Lepke is offline   Reply With Quote
Old 06-07-2021, 07:14 AM   #11
Member
 
City: MA
Join Date: Jun 2021
Posts: 19
Meander is offline   Reply With Quote
Old 06-07-2021, 07:31 AM   #12
Member
 
City: MA
Join Date: Jun 2021
Posts: 19
SKI_IN_NC

To answer the question I have to look next time I am on the boat - would guess N60 by previous owners max BHP statement of 140 which correlates with N60 - will let you know


Lepke
I was looking up those HHO systems over weekend - love it - was wondering since I have an air "blower" compressing air via spiral screws and an oil air filter on top - how to insert the HHO into air stream?
Meander is offline   Reply With Quote
Old 06-07-2021, 07:43 AM   #13
Member
 
City: MA
Join Date: Jun 2021
Posts: 19
Attached Picture - Engine

Hope I am not annoying forum - try to figure out how to insert pictures from my computer to posts - I tried the attachment route - hope that

works
Click image for larger version

Name:	IMG_20210406_170031974.jpg
Views:	19
Size:	156.0 KB
ID:	118333
Meander is offline   Reply With Quote
Old 06-07-2021, 12:04 PM   #14
Guru
 
Lepke's Avatar
 
City: Between Oregon and Alaska
Vessel Name: Charlie Harper
Vessel Model: Wheeler Shipyard 83'
Join Date: Jun 2016
Posts: 2,393
Quote:
Originally Posted by Meander View Post
SKI_IN_NC
Lepke
I was looking up those HHO systems over weekend - love it - was wondering since I have an air "blower" compressing air via spiral screws and an oil air filter on top - how to insert the HHO into air stream?

Just insert in the intake air stream. I have the same DD roots type blower. Mine is routed to the air silencer intake and is just in front, open to the air flow. There's a Y so it goes to both ends of the old style rectangular silencer. At anchor, if I'm going to run a generator for a long time, I send the HHO to a Perkins 4108 intake. But I have to cut the amps or the addition of so much bonus fuel causes the engine to oscillate and effects the hz. All my ac goes thru my inverter and the oscillation drives it nuts.
Once the HG is off, the flow of HHO flow quickly shuts off. I don't try to store any HHO because of fire or explosion threat. I talked to someone years ago that tried compressing and storing HHO in a propane tank, but under pressure it made some water, over time rusted the tank bottom, eventually there was a large leak and a small thermobaric bomb blew the roof off and windows out of his unoccupied workshop. I never had an issue with unpressurized HHO. I never did the math, but at shutdown probably have 2-3 cu.ft. of HHO that dissipates into a 1500 cu.ft. engineroom. I usually don't run the HGs until at or near cruising speed because the 48v alternators aren't putting out extra power at idle. I turn the HGs on by a relay controlled from the lower steering station or a switch in the engineroom. When everything is right and I flip the switch, I'll see the linkage move to reduce fuel to the injectors, rpm stays the same.
Lepke is offline   Reply With Quote
Old 06-07-2021, 12:41 PM   #15
Member
 
City: MA
Join Date: Jun 2021
Posts: 19
Hi Lepke - thanks for your detailed reply - I painted a similar picture in my head - have an old but gold 8KW Westerbecke generator right after the transmission to play and experiment with - keep you appraised - might take a while the project list is long :-)


"I flip the switch, I'll see the linkage move to reduce fuel to the injectors, rpm stays the same" - that's one of a good visual aid - thx!!!
Meander is offline   Reply With Quote
Old 06-07-2021, 04:36 PM   #16
Guru
 
Lepke's Avatar
 
City: Between Oregon and Alaska
Vessel Name: Charlie Harper
Vessel Model: Wheeler Shipyard 83'
Join Date: Jun 2016
Posts: 2,393
Quote:
Originally Posted by Meander View Post
Hi Lepke - thanks for your detailed reply - I painted a similar picture in my head - have an old but gold 8KW Westerbecke generator right after the transmission to play and experiment with - keep you appraised - might take a while the project list is long :-)


"I flip the switch, I'll see the linkage move to reduce fuel to the injectors, rpm stays the same" - that's one of a good visual aid - thx!!!

With a small engine, start small. On a generator at light load, it's easy to overwhelm the governor. No harm, just shut down the HHO if it gets out of control.
Lepke is offline   Reply With Quote
Old 06-14-2021, 01:13 PM   #17
Veteran Member
 
City: New Bern
Vessel Name: Southern Lady
Vessel Model: Grand Banks 42 1971 Woodie
Join Date: Sep 2011
Posts: 36
Injector Selection

Most displacement yachts are way over-powered. Google for a formula to indicate power requirement for your boat's specs. Then call a Detroit Diesel Distributor or the factory for an injector recommendation.
__________________
Oliver Moore
Southern Lady
GB 42 Woodie
omoore is offline   Reply With Quote
Old 06-14-2021, 05:49 PM   #18
Veteran Member
 
City: San Diego
Join Date: Sep 2018
Posts: 38
More then likely N-60's for a 145hp, N-65's should be about 160hp. @2100 RPM for a 4-71NA
When you get into the 6-71NA you start looking at 2 valve vs. 4 valve heads.
Trimjb is offline   Reply With Quote
Old 06-15-2021, 06:33 AM   #19
Member
 
City: MA
Join Date: Jun 2021
Posts: 19
Hi Omoore and Trimjb - thanks for response


You mentioned boat specs - I do try to get an overall sense of where energy is used/lost - how much is needed - is prop right sized and such.
Tough part with old Detroit Diesels (DD) in term of energy input is (to mention Lepke's note on fuel quality) that the in-time fuel consumption is hard to measure with fuel circling back in high amounts to tanks - so it will take time to measure over many miles to get an "average" sense of consumption.


I did see that there are fuel consumption modules out there with 2 sensors to measure delta from flowing into engine and out of engine - unrelated to thread and don't wan't to delude the topic but anybody experience/recommendations and such? - feel free to send me private message if forum rules are to keep thread topic clear to end.


Getting my dinghy and outboard this week somewhen so will check soon for injector size but yes as Trimjb said - would think/hope its N60 don't need any larger I assume.
Meander is offline   Reply With Quote
Old 06-17-2021, 06:07 AM   #20
FF
Guru
 
FF's Avatar
 
Join Date: Oct 2007
Posts: 21,964
Beware with elderly DD engines , there are H series injectors and N series.

An engine built to operate on H injectors does not run well or start easily if newer H series are installed.

Most of the H engines were built in WWII and thru the 1950's.

A DD dealer can help if you have the engine serial number.
FF is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Trawler Port Captains
Port Captains are TF volunteers who can serve as local guides or assist with local arrangements and information. Search below to locate Port Captains near your destination. To learn more about this program read here: TF Port Captain Program





All times are GMT -5. The time now is 04:39 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012