Fuel heater

[Apache]

For my next little lathe project I'm thinking of making a fuel heater of the glow-plug variety in series with a coolant heated one before it. Then once the coolant is up to temp, I can switch off the glowplug one.

So the unit wont be too big, I was looking at using one or two glowplugs directly into the fuel passage of the unit I'll make rather than heating the housing. I would like to use fairly short glowplugs so the unit isn't too deep. Can anyone recommend a likely type before I go Halfrauds and open every box on the shelf?

Also, I was planning on making the housing from ally bar as I have a load. Is brass OK for the fuel in / out connectors - I was thinking of barbed fittings much like I used on the ATF temp sender unit I built.

[POPEYE]

You'll need to run the glow plugs via a temp switch so they dont burn the oil,
i was gonna fit plugs in tha swirl tank and that heated tape stuff on the injector lines but the price went up so it's a bit pointless especially as i aint got a regular wvo supply

brass is ok

[Apache]

Any recommendations for the switch Ian?

[RodLeach]

I'd look at some early pug's.

a 105(6? ) had a 1.5 N/A diesel engine. I think the glow plugs on that would be pretty small.

[Apache]

I found some pics of Pug plugs on eBay and they do look smaller than Surf ones.

[POPEYE]

Not sure if the CPC (farnell) type thermo switches would do, their a bit lacking in exactness for want of a better word, i used em on the intercooler fan and elect water pump but i guess you'd need summat a bit precise for heated plugs, perhaps Matt has some ideas
If you can manage to plow through this guys achievements it may give you some pointers, he made a glow plug heater for his wvo set up, looked a bit heath robinson to me and i'm sure you can make summat better engineered

http://www.bjblaster.com/
http://cpc.farnell.com/jsp/search/br...at+switch&Ntx=

[That Ruddy Squirrel]

Andy,

http://cgi.ebay.de/SVO-WVO-Heater-Ex...QQcmdZViewItem - This is what I had on hippo, any use for ideas ?


Trev

[MattF]

You're better off heating the housing rather than the fuel directly. The rate the oil is moving, it'll be like a chocolate fireguard trying to heat the flow itself, I would assume. Temp switch wise, just use those that Ian suggested. The thermal cutouts that you find on washing machines, steamers and such. They are perfectly designed for bolting to a flat block of aluminium.

[POPEYE]

Thats mainly why i was going to use glow plugs in the swirl tank as opposed to a small alloy type block like the link trev's added, the oil will be going so slow through there there's a good chance of burning, was'nt sure if those thermo switches were sensitive enough, although looks like one on the link,
with the swirl tank your heating approx 1/2 to 1 lt of ready use oil where burning would be less likly to happen, my main prob at the time was controlling the flow to the swirl tank (via an extra electric pump) oil level etc, bought some reed switches and haveing learnt about the diods (one way current flow thought perhaps summat could be worked out useing them,
you need to switch on the pump via a low level reed and switch off via a high level reed, reeds opperated bu a magnetic type float like break master cylinders, hope this is makeing sense

[Apache]

I would have thought heating the flow is better for the following argument.

You have (say) 100W of heat. You use it to heat the aluminium over a space of 30 second. You use the same amount of heat to heat the flow directly. Which gets the fuel the hottest? The flow rate is the same. One puts all the heat into the fuel, the other puts a small part of the heat into the aluminium block.

<edit> or are you saying you'd heat the fuel too quickly with the plug in direct contact? Hmmm... maybe worth thinking about...

As for the switch, what about this tapped directly into the ally block so its in contact with the fuel?

[POPEYE]

Personally i'd prefer to "warm up" the oil directly till the engine water starts to warm the oil via exchangers etc, i had big plans for mine till the price shot up, i liked the small tank idea that aussy guy did, but i planned to fit two glow plugs for quick warm up and a coil heated by the coolant for when the engine was up to temp, ya'd need your batterys in tip top shape tho for the winter, i'd imageing glow plugs take a fair bit of current and if your useing heated tape for the lines even more current,
the temp range on that switch looks a bit high, you only need to warm the oil to about 50-60 deg,
you doing two tanks?

[MattF]

I would have thought heating the flow is better for the following argument.

You have (say) 100W of heat. You use it to heat the aluminium over a space of 30 second. You use the same amount of heat to heat the flow directly. Which gets the fuel the hottest? The flow rate is the same. One puts all the heat into the fuel, the other puts a small part of the heat into the aluminium block.

<edit> or are you saying you'd heat the fuel too quickly with the plug in direct contact? Hmmm... maybe worth thinking about...

As for the switch, what about this tapped directly into the ally block so its in contact with the fuel?

Truth be told, either way could be best. Personally however, I would think that heating the flow directly with tip inline would lead to either scorching the fuel OR the cold ally block dissipating most of your heat initially anyhow, if the fuel has to carry on through what is essentially a cold heatsink. Stability would be best when both the block and fuel are upto temp. Possibly a two glowplug approach? One inline and the other in the block itself? Myself, however, I'd be more inclined towards heating the block rather than the fuel.

Again, I'd agree with Ian on that temp switch. 98 degrees seems a tad excessive. I believe the minimum optimal temp is around 80+, so a scrapyard session on Corolla's, (or whatever they are called now), would be on my books. I believe that switch that both myself and Ian have used is 82 degrees.

[POPEYE]

Suppose the question here is how fast does the fuel flow through the lines? i thought it were pretty slow but i'm useually wrong, that aus bloke had a pic showing the swirl tank with the lid off and engine running, bearing in mind he plumbed the return from the IP back into it and it was just a dribble comeing out the return, also that way of doing it returned warmed oil back to the swirl tank,
might just finish mine one day just for the f##k of it