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Genset 100kw ENBA NG to Propane Questions


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  #41  
Old 12-13-2017, 06:45:36 PM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Quote:
Originally Posted by PopsGarage View Post
the adjustment in the photo is a butterfly valve 1/4 turn from wide open to shut off there might be a R and L on the casting for rich and lean settings..


Ok, it DOES have a R/L setting and when viewed from the bottom looks like the 'propane adjustment valve' as shown in this screenshot of the Onan ENBA manual (its also a manual for about 4 other generators that have different fuel options; Ill bet this same mixer is the same on the propane models)..The only difference is it does NOT have the graduation ticks and the R/L is on the side and not the face. It COULD be that they just painted over the markings or there was a sticker placed on the face for the models that use propane.


*NOTE:
The factory setting was dead on at the 50% mark between R and L. It was my intent to put the mix level at the tick at the first mark counterclockwise from the 'L'. Meaning if R is 100% and L is 0% it would be at the 25% mark vs the 50% mark as factory set for NG. Does this sound like a reasonable area of adjustment for an initial setup for propane use? Should I take it a little further to the lean side?


~JH

---------- Post added at 05:45:36 PM ---------- Previous post was at 05:44:31 PM ----------

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  #42  
Old 12-14-2017, 01:17:18 PM
Mac Sine Mac Sine is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

You need to do more than just make a carburetor adjustment to switch between natural gas an propane gas. An Impco carburetor is designed to work with a propane inlet pressure of negative 1.5 inches water column. Natural gas, in contrast is fed to the carburetor at in inlet pressure of 5 inches positive water column. This is done to compensate for the difference in heat content (BTU) between these two gas fuels.

There was discussion in an early post about installing a vaporizer-regulator. This needs to be an Impco "EB". The B designates a blue spring in the demand regulator that sets the negative 1.5 inch water column outlet pressure. By feeding propane to the carburetor at the negative 1.5 inch water column (a vacuum), the load adjuster on the carburetor will have the same range of adjustment as it does when operating on natural gas. Accordingly, you can keep the nominal adjustment at the center of the range until you can run the engine at full load and make a precise adjustment based on exhaust gas O2 content.
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  #43  
Old 12-14-2017, 07:53:58 PM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

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Originally Posted by Mac Sine View Post
You need to do more than just make a carburetor adjustment to switch between natural gas an propane gas. An Impco carburetor is designed to work with a propane inlet pressure of negative 1.5 inches water column. Natural gas, in contrast is fed to the carburetor at in inlet pressure of 5 inches positive water column. This is done to compensate for the difference in heat content (BTU) between these two gas fuels.

There was discussion in an early post about installing a vaporizer-regulator. This needs to be an Impco "EB". The B designates a blue spring in the demand regulator that sets the negative 1.5 inch water column outlet pressure. By feeding propane to the carburetor at the negative 1.5 inch water column (a vacuum), the load adjuster on the carburetor will have the same range of adjustment as it does when operating on natural gas. Accordingly, you can keep the nominal adjustment at the center of the range until you can run the engine at full load and make a precise adjustment based on exhaust gas O2 content.

The Impco I got was the Model EB.



This was purely by accident that I did the the EB version. Thankfully amazon didnt have the model 'e' version just the eb! Got lucky that I didnt get the wrong one.

After a little reading it does confirm that the EB will run a little leaner than the E variant. Ill keep the mixer flow control at 50% unless someone recommends a different setting using the blue spring Impco vaporizer.

-After a little more reading Impco recommends the vapor outlet is pointed down so I am going to have to do a little re-configuring to get it where it needs to be. Currently its mounted so the vapor outlet is chassis parallel.

~JH
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  #44  
Old 12-15-2017, 07:40:02 PM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Two easy and fun questions, just slightly unrealted to the propane conversion.


1. Does anyone have an 'Onan Green' factory paint code? I would like to shoot the housing before its moved into location.

2. Some confusion about the manual:

Before Stopping

Run generator set at no load for 3 to 5 minutes before stopping. This allows the lubricating oil and engine coolant to carry heat away from the combustion chamber.


NO-LOAD OPERATION

Periods of no load operation should be held to a minimum. If it is necessary to keep the engine running for long periods of time when no electric output is required, best engine performance will be obtained by connecting a dummy electrical load.



So in the manual (*same page even) it says run the engine with no load 5 minutes before each shutdown and a few paragraphs away, 'keep no load running to a minimum'.

This is sort of contradictory. Is it bad for the alternator or other components to run the generator with no loads? At the radio station I worked at we had a really big generator that would automatically start and run once a month for 30 minutes just to keep the generator on its toes. It never was loaded to my knowledge during these runs.

I would like to do testing and maintenance running with no load and wondering if its safe to no load run.

Tks!

---------- Post added at 06:40:02 PM ---------- Previous post was at 06:31:53 PM ----------

Quote:
Originally Posted by AngrySailor View Post
Love the trucks! Yours looks a like '69-71 c-10... attached is my '68 910 which is now my fathers summer ride. It was my daily until it was rear ended by a drunk and needed a box and frame The '67 biscayne is now my summer car. It sat since '81 when the original owner stopped driving it at about 47,000 miles. He logged every fill up, last was 119th tank of gas is '81 then it sat till this spring when I finally plated it again. It's first trip was 1200 miles to my new place. Made it with no issues
Those ^^^ are awesome.

Funny my grandfather bought the 70 new and got the fewest options that could be. The SPID is almost a blank sheet. The thing that drives me nuts is the 67-72 C10 Short/Wide have a cult following and is actually more valuable than the 1938....even though its got the baby 250ci and no factory options.

~JH
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  #45  
Old 12-15-2017, 08:03:51 PM
dracer dracer is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Quote:
Originally Posted by Jonny Hotnuts View Post
The Impco I got was the Model EB.



This was purely by accident that I did the the EB version. Thankfully amazon didnt have the model 'e' version just the eb! Got lucky that I didnt get the wrong one.

After a little reading it does confirm that the EB will run a little leaner than the E variant. Ill keep the mixer flow control at 50% unless someone recommends a different setting using the blue spring Impco vaporizer.

-After a little more reading Impco recommends the vapor outlet is pointed down so I am going to have to do a little re-configuring to get it where it needs to be. Currently its mounted so the vapor outlet is chassis parallel.

~JH
can't help on gen , but you sure take nice clear pic's you must have a good cam
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  #46  
Old 12-15-2017, 08:57:50 PM
nothingbutdarts nothingbutdarts is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Hotnuts,

The reason for running 5 minutes before shutting down is to cool off both the engine and generator section. They are thinking you have had the set running with a substantial load on it creating heat on both so they are suggesting to run it unloaded to cool down. Especially since it's turbo charged. This is always suggested on turbo charged diesel engines to cool off the turbo so as not to have coking of the oil within the turbo from a hot shut down. And the no load running for extended periods is to keep engune wear down from not having the engine up to full operating temperature.

Yes, it's safe to run no load, just for one it's not practical with the big 460 fuel comsumption. It never hurts to get some load on that baby if you can.
Test away and do your maintenance.
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  #47  
Old 12-16-2017, 09:16:14 AM
sprkplug sprkplug is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

Quote:
Originally Posted by len k View Post
Maybe one can't , but the gas company can.....

Bit like driving cross country at 8 mpg in a 1969 Camaro Z-28 with 327 , high lift cams, Holley duel pumpers, headers, chambered exhaust, class winner at the dragway, ( only got to drive it 1 weekend, car sold in 4 days).





.
What happened to the 302 engine that was original to that 69’ Z28? They would eat a 327’s lunch.
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  #48  
Old 12-16-2017, 02:33:50 PM
len k len k is offline
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Default Re: Genset 100kw ENBA NG to propane questions.

Been a long time since high school. I forget the exact number, the numbers run together. Maybe 302, 307, 327, 325 ....

What ever it was window was plastered with class winner stickers from local dragway. A hot car and a real looker, dark green with wide white panels and stripping running from hood, to roof , to trunk lid. Corvette hat and ring hubcaps. Car was only ~ 3 years old, bought Friday afternoon, sold Monday noon. And on tuesday someone came in waving fist load of cash saying he WANTED it, said it was hottest car in NH,....... we gave him the new owner's phone #.

Last edited by len k; 12-16-2017 at 03:12:15 PM.
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  #49  
Old 12-17-2017, 11:22:46 PM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions





I am planning on using this coolant hose (*the one removed from the return stack) to go to the vaporizer and back to the coolant return stack.

-The issue I have is the coolant hose is 5/8" and the in-out to the vaporizer are 3/8". The smaller diameter of the fittings and increased resistance through the vaporizer will restrict coolant flow through the engine. I was considering putting a 'T' at the hose and at the coolant return stack, having a 3/8" line going to the vaporizer and a 1/2" line (bypassing the vaporizer) and going straight to the return stack.

Any comments on what I am suggesting? I am concerned that the combo of 2 different sized lines and restrictions of the vaporizer (path of least resistance) will not have enough flow through the vaporizer.



~JH
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  #50  
Old 12-18-2017, 12:15:39 AM
AngrySailor AngrySailor is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

That hose just circulates a little water through the block while the thermostat is closed to prevent hot spots. I would just run it through the vapourizer and be done with it.
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  #51  
Old 12-18-2017, 01:14:43 AM
Birken Vogt Birken Vogt is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Agreed.

The cylinder heads are where all the heat is made and the thermostat is right next to them so as long as a little water is making it past the thermostat element, i.e. the stat is the same temperature as the heads, it will be all right.

Very little heat by comparison is generated in the cylinder walls.
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  #52  
Old 12-18-2017, 08:37:41 PM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

THanks for the info guys. I coundnt find any info on the 429/460 water circuit. A back feed to the thermostat is ideal (most applications use this hose for the heater core and 'thought' it would be OK). Just didnt want to starve and heat up a head!


~JH
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  #53  
Old 12-19-2017, 01:05:20 PM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Something I am confused about.....


Onan made 5 versions of this generator:

ENA, ENB, ENC, ENDA, ENBA.

They range from 60kw (ENA) to 100kw (ENBA). The only differences I can see are that the first 3 are normally aspirated and were for NG, Propane, gasoline (very similar outputs) and the last two being turbocharged and for NG/Propane. The last 2 may have a different alternator.

The ENDA and ENBA (80kw and 100kw) are turbocharged and from what I can see in the parts manual the only mechanical difference was the ENBA used a larger turbocharger.


With all this being said.....
The Ford 460 can easily make 350hp normally aspirated. From what I read it requires around 130hp to produce 100kw. Even in its most restricted versions the 460 for automotive use makes 250hp.

So if 130hp is needed to make 100kw and a NA 460 can make significantly more HP than needed to make the 100kw what is the point in having the engine turbocharged?

~JH
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  #54  
Old 12-19-2017, 01:25:57 PM
Mac Sine Mac Sine is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

JH,
100 kW equates to 134 horsepower. For an engine-driven generator there is a kW-electrical value, that is slightly different from the mechanical conversion, as related to the generator efficiency.

The key to your horsepower query is the difference in rated speed between the a 460 engine used in generator service compared to a 460 engine in automotive service. The automotive engine is rated at a speed in the 4400 rpm range. The generator engine is rated at a much lower speed. Engine speed influences the horsepower the engine develops, therefore, in generator service the engine develops lower horsepower, compared to the automotive engine and the turbocharger is used to achieve the required engine horsepower at the rated generator speed.
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  #55  
Old 12-19-2017, 02:02:55 PM
len k len k is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Also NG has less energy than propane, so need high compression engine to let NG make normal power. Turbo might do same, I don't know.

Also engines want some extra reserve power to take on sudden heavy loads dropped on gen. Rule of thumb I've heard is 2hp of engine for every 1kw output.
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Old 12-20-2017, 12:17:28 AM
Jonny Hotnuts Jonny Hotnuts is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Thanks for the hp explanation. The engineer in me (well....I dropped out of high school so I am not an official engineer; I just play one at work) says "IMO it would be better to use a smaller displacement engine running closer to its designed HP peak and compensate the higher rpm with a form of reduction to the alternator"....but Ill just leave that alone.





Here is a pic of my hear complete LPG conversion on Big Pig. I will need to fabricate a bracket to the chassis with some form of vibration isolation. The gassifier and assembly are pretty heavy and being cantilevered from a ridged structure will cause fatigue at the joint where the pipes meet at the 'T' from vibration. Last thing I need is a cracked propane pipe! I may also use a couple of 90s on each one of the coolant in-out barbs going on the gassifier/reg. just to help keep the hoses straight.


~JH
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Old 12-20-2017, 01:02:58 AM
Birken Vogt Birken Vogt is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Don't use that yellow dryer connector to feed liquid. Use a proper braided high pressure propane liquid hose.
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Old 12-20-2017, 01:17:15 PM
Mac Sine Mac Sine is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

I offer the suggestion to not run the engine with the set-up shown in the picture.

The vaporizer-regulator should be supported using the ears that are a part of its body and install a flexible connection between the vaporizer-regulator and the carburetor gas inlet. The carburetor gas inlet boss is not designed to support the weight of the piping and equipment upstream in the fuel system. There will be vibration that can result in breaking the carburetor gas inlet boss.

Also, the Maxitrol ("IMP) regulator needs to be removed from the system. It is replaced by the EB vaporizer-regulator. The EB has a demand (negative-feed) regulator built into it.

The only reason you would need the IMP regulator now is to run natural gas in a dual-fuel configuration but it is not installed correctly to do that in the picture of the current system. Consult the Impco Service manual for a schematic of how the dual-fuel system will be configured.
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  #59  
Old 12-22-2017, 12:43:11 PM
PupTentacle PupTentacle is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Hi,
I live off grid up in Northern MN, and rely on my Onans.
Both the 6.5NHEFA26100D and the 30EC-4R8/14M are propane fired.
Initially, I tried the 30EC on a 20lb'er in the hot summer. The OPD cylinder won't supply the gas demand. A non-OPD 20lb'er "iced up" in a manner of minutes.

What feeds both my Onans are 2x 1,000 gallon tanks.
One tank regulator drops tank pressure to 10.5 psi the other tank regulator drops tank pressure to 9.5 psi.
The output of both those "first stage" regulators is manifolded together so one tank gets drawn down first.
That ~10psi is then feed to each of my Onans.
At each generator the is another regulator that reduces pressure to ~.5psi which is then feed to the demand regulators.

Buying propane in bulk is WAY CHEAPER than and infinitely more convenient that filling 20's or 100's. Besides most propane companies, in our area, will set and then rent you the tank for $1/year. And for ~$100 will run all the lines, supply the regulators, and isolation valves. Having them do the plumbing avoids home owners insurance issues if something goes horribly wrong.

The 6.5 consumes ~.8 GPH @ 2/3 'rds load (~4KW). The 30EC, built in an era when fuel was cheap, consumes ~.8 - 1.0 GPH NO LOAD. @ 15KW load she's eating 1.5+ GPH. Soooooo, 3-6 GPH sounds like a good ball park @ 20-25 KW loading.

A word of warning, don't run a vapor or liquid line @ tank pressure into a structure. Leaks will turn that structure in a very large bomb waiting for a spark.

Hitch up those vaporizer coolant lines ASAP. As it will likely "ice up" the first time you put any kind of a load on it.

I would also consider installing a block heater, if nothing else, as an insurance policy to make sure it kicks off when needed. Power it off the grid to keep your unit nice and snuggly warm so it starts quickly when the grid goes away. This also saves the wear and tear on the engine from abruptly loading up a cold/cooler unit. Then you can run the nice thick synthetic 20W-50 oil these Onans like. I prefer the Valvoline 20W-50 because it has higher concentrations of zinc (a lubricant) cuz' both my units have mechanical lifters. YMMV.

You can buy Lambda/AFR kits with the sensor, gauge, wiring, and bung on the internet for ~$180. Some of them have data logging built in so you can get a runtime history.

Inline flowrate meters calibrated for propane/butane which read out in GPH can also be had after a google search.

Hope this helps and stay warm.
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Old 12-22-2017, 02:13:29 PM
len k len k is offline
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Default Re: Genset 100kw ENBA NG to Propane Questions

Quote:
Originally Posted by PupTentacle View Post
One tank regulator drops tank pressure to 10.5 psi the other tank regulator drops tank pressure to 9.5 psi.
The output of both those "first stage" regulators is manifolded together so one tank gets drawn down first....
nice idea I was wondering how to do that on 20# tanks ganged together.

The 6.5NHE consumes ~.8 GPH @ 2/3 'rds load (~4KW).
Should be propane .5 GPH no-load, 1.0 half load, 1.6 full load, so ~ .83 at 1/3 load, ~1.19 at 2/3load.

The 30EC, built in an era when fuel was cheap, consumes ~.8 - 1.0 GPH NO LOAD. @ 15KW load she's eating 1.5+ GPH.
Sounds low. 15JC is gasoline ~1.0 GPH noload, 2.4 full load. Would rough estimate double that for 30kw, Then add 15-20 % for propane

Propane has ~100k BTU/gal, gasoline ~ 128k


...........

Last edited by len k; 12-22-2017 at 02:31:20 PM.
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