vw 1.5 diesel as genny/compressor

[adamanderr]

i have a spare engine for my daily driver 1980 vw rabbit which i plan on towing... instead of mounting my loud generator and a second gas engine to run my shop air compressor. my bus is more a rolling workshop than straight camper. my vw isnt that loud on agood day and barely works hard and isnt that heavy or big, two person lift. i was thinking a combo genny head and compressor belted off it. mounted in a vibration dampened frame behind the rear axle. same fuel as bus, run forever and can burn most anything. parts readily available? i felt smart but it may be overkill
????

[bbbrt76]

i've been thinking the same thing only the spare vw diesel I have is the 1.6. You need to keep the rpms constant under varying loads in order for the generator output to remain at the required 60hz, i have been debating several alternators and an inverter so that rpm is less critical or a generator head and an aftermarket cruise control system??

[paul iossi]

how creative do you want to get? check the industrial info, some air compressors are conventional engines with reworked cylinder heads to work as half engine and half compressor, generators/alternators are available as 2 brg belt drive or i brg direct drive,depending on what dimensions work for your applicalion, the radiator with an electric fan can be mounted anywhere, the injection pump can be setup to run constant rpm or a belt drive governor can be installed.

[adamanderr]

too heavy?
where to mount it?
i thought just a belt and pulley ratios for rpm but i didnt know the generators adjust fuel for load...
the industrial is why i even thought about this but they usually use v8+6's from what i see. i had no luck finding any info on the topic, maybe you could point me in the right direction or right keywords?

[adamanderr]

would behind rear axle be safe? and out of way. unfortunately itd be directly under my bed.
whats brg mean.
on the exhaust topic someone suggested eliminating the muffler on their bus altogether? is that acceptable as far as noise.
if i used an exhaust that big on my genny to stifle noise it would probably drown it in its own exhaust pressure??

my rabbit even when its quiet has a tone that can be felt down our long drive at the neighbors it seems, but every single cylinder ive ever heard was sharp and offensive.

i feel if i could have it1 genny 2 compressor 3 alternator/invertor 4 residual heat for wvo and house heating 5 aux water/ fluid pump in one package itd be ideal and worth the extra weight, if it would even be heavier than all those systems combined

i think the industrial compressors use a type of reed or check valve intake and exhaust valve
thanks

[paul iossi]

mercedes truck used to use a 6 cyl diesel as a 5 cyl engine with #6 as the air compresor, grimmer-schmidt used ford 302's fun on 4 compress on 4, I've also seen old flathead willy's engines run on 1&4 and pump on 2&3
it's all about reworking the valves and eliminating fuel from the pump cylinders.

set the high idle/wot setting on the pump at desired rpm and then let the internal governor adjust the throttle to the load, try to find a 1200 or 1800 rpm alternater to keep the noise down and fuel economy up, the other option is to run an electronic governor ($$) to control rpm

BRG-bearing

[paul iossi]

look at auxillary power units, APU for semi's their are now laws preventing them from idleing their main engines for heat,lights etc, consrquenly their is a whole new family of small diesel power units an the market, do msome research for info, think about using the vw to build an apu on steroids.

engines make a lot of noise from the fan, intake and valvetrain, it can be controled with insulation and proper muffeling of the intake, again look at the apu's and quietpac generators for ideas.

[lapeer20m]

Originally Posted by paul iossi

set the high idle/wot setting on the pump at desired rpm and then let the internal governor adjust the throttle to the load, try to find a 1200 or 1800 rpm alternater to keep the noise down and fuel economy up, the other option is to run an electronic governor ($$) to control rpm

BRG-bearing

I really like the idea of using the ip internal govenor to maintain proper rpm. That's genius!

vw motor as geni plus heat, plus air compressor seems like a great idea. Especially if you find an 1800 rpm generator head like iossi suggested.

[adamanderr]

thanks guys.
so is mounting there ok you as long as it doesn't hang lower than diff.
and exhaust back pressure with the bus muffler?
what era or idea of make is that mercedes. that sounds awesome.
good job bringing up the APU too, thats kinda what i was going for but forgot what to call it. so i guess it could be used for ac too.

[paul iossi]

I just googled 1.5 vw diesel and came up with 50hp naturally aspirated and 70 hp for the 1.6l turbo, i didn't find any hp/torque power curve data. it would be nice to see where the torque peaks and how flat the curve is to determine how big KW of a generator end to look for and at what speed, 1200 or 1800 rpm.

ok lets try to sort this out,

the first priority is probably electricity, 50 hp converts to 32 kw at peak power, so derate and figure 18 or 20 kw at 1800 rpm.
industrial generator mfg's are olympic and marathon for starters, the next choice is direct or belt drive, 110/220v or 3 ph 440v

how much compressed air in both psi and cfm do you want, you can adapt an air conditioning compressor if you don't need much air, or a belt driven bendix or borg-warner air brake compressor could be run, they are lubed with the engine's oil system and liquid cooled, available in1,2 and v4 models, another option would be a regular air compresser with an electric clutch/belt drive assembly

12 or 24v alternator for charging batteries, how much capacity is needed with a 20kw genset onboard?

heat/hot water, use either a plate or tube in shell heat exchanger, you will have to be careful with the temperature of the coach side water (to hot)

mounting, I would favor the left side forward so that it's not under my bed, look into a double isolation/mount system to minimize vibration, try to install all of the service points (filters & controls) on the outside of the unit, build a good box and use sound deadening material, make sure that you provide adequare airflow, install a properly sized muffler or 2

[gotmuddy]

What about one of those DIY generators? They use a alternator and a power inverter. If your not running AC it could work good.

I like the idea, I was thinking of doing the same thing with a 13hp honda I have in the shop.

[paul iossi]

I just ran some numbers, it would take 94 ' # of torque at 1800 rpm or 153 ' # at 1200 rpm to run a 20 kw generator

[the_experience03]

Originally Posted by gotmuddy

What about one of those DIY generators? They use a alternator and a power inverter. If your not running AC it could work good.

I like the idea, I was thinking of doing the same thing with a 13hp honda I have in the shop.

You mean one of these?

[bbbrt76]

Originally Posted by paul iossi

I just ran some numbers, it would take 94 ' # of torque at 1800 rpm or 153 ' # at 1200 rpm to run a 20 kw generator

I assume thats calculated at full rated load of 20kw, that should be a lot more juice than most should need, my house will pop the main breakers above 11kw, granted most new construction is being done with 150a or 200a service, but a household 200a service is your 20kw number, and that should be way more power than needed by your house on wheels


but those calculations do show the difficulty with electric cars, you need as much current as your house can draw at full load to get half the power of most vehicle engines

[paul iossi]

Originally Posted by bbbrt76

I assume thats calculated at full rated load of 20kw, that should be a lot more juice than most should need, my house will pop the main breakers above 11kw, granted most new construction is being done with 150a or 200a service, but a household 200a service is your 20kw number, and that should be way more power than needed by your house on wheels


yes that is calculated at rated capacity, the formulas are;
1 kw = 1.54 hp
hp =torque x rpm / 5252
it's just a matter of fill in the blanks and solve for the unknown.

and just think when mother nature comes along and takes out the grid at home you can disconnect from the grid and plug the house into the bus, just make sure that you use the appropriate wiring and disconnect switches

[bbbrt76]

Originally Posted by paul iossi

and just think when mother nature comes along and takes out the grid at home you can disconnect from the grid and plug the house into the bus, just make sure that you use the appropriate wiring and disconnect switches

yea definitely a big plus

[nearhomeless]

Just a note, that a 1.5-1.7L is going to probably use 1-2gallons of fuel per hour because it's oversized. Even a smaller powerhead wont improve things much because the gph of fuel used just to run the engine at idle is still substantial compared to a small 2.5kw diesel genset at full load.

The comment "it would take 94 ' # of torque at 1800 rpm or 153 ' # at 1200 rpm to run a 20 kw generator" is probably about right, remember you can gear it to run anything so you could run 700rpm on the engine or whatever idle is and drive any speed generator at say up to 7kw or so. It wouldn't be as efficient per kw made as a higher speed, but the dang engine would probably last near forever. Or maybe 10kw at high load at 1200rpm. Either of these options might lug the engine which it may not like, a smaller genset would stop the lugging but wouldn't improve fuel consumption much, and the lugging would only occur if youre using all that power anyways so i'd rather have the larger powerhead if available and just not tap all that power. A larger powerhead will of course cost more in most instances.

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info from random searches:

http://www.oldengine.org/members/jdunmyer/genset/ - someone else already built one like this

"The problem with the NA VW diesels is the lack of power at low RPM. Ideally you want the genset to run at 1800 RPM, less noise, hopefully less fuel consumption. The HP torque curves for the NA VW diesels of the early 80's show around 20 HP at 1800 RPM. That would run a 10KW generator. Now these little diesels were rated at 52 HP but that is much higher at around 4500 PRM. There were 2 sizes the first engines introduced in '77 were 1500 CC and produced 48 HP they grew to 1600 CC about a year or so later and bumped up to 52 HP. Around '82 they introduced a turbo version which bumped the power up to about 70 HP. These engines had aluminum heads so they did not tolerate overheating. They also used a timing belt, which should be changed every 60K miles. I've also heard of the older M-B diesels being used, those older cars rusted out before the engines wore out in northern climates."

Another post i've seen reports they last around 6000hrs even if run fairly hard (3600rpm running pumps)