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Fuel heaters

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It's getting cold down here, the Volvo is having issues cold starting on E85. Temps are between 0c and 8c ( 32-48f).

The car will start on the third crank, but it's obviously not happy and needs the throttle nursed for about 30 seconds. Is there an inline heater I can plumb into the fuel line?

My current thought is to wrap the fuel rail with Nichrome wire and control the Nichrome element with a 30 second relay that activates with ignition on. I can't see any problems having the heater turn on for 30 seconds every start, even on hot soak, the fuel rail should cope with a little extra heat?

 

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Sounds like it might work. I do know that a little shot of ether works on my Toyota when I pull a pipe  plug and shoot a little into the intake plenum and replace the plug. If I was serious, I would rig an electric solenoid injector like diesel farm tractors have.

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Interesting you mention an injector. My car has a cold start injector. I was testing it this evening (checking for fuel, that the injector worked etc) when the idea of using it to prime the manifold came to me.

So I think I'll rig up a push button on the dash and wire a diode in the control wire from injector to button, so the ECU will still do it's thing when it wants to.

Most all fuel injectors have +12v put to one side with the ignition on and the ECU grounds the injector to pulse it. So all you need to do is ground the injector and it'll squirt. The diode prevents you confusing the ECU. You could potentially do this with a whole bank of injectors too, just hit a button and dump bucket loads of fuel into the intake. If you bought  a cold start injector from any older Bosch fuel injected engine (most 80's Toyotas run the same style injector), it would be easy to fit, they have a two bolt flange that holds them on. So, drill three holes into intake, tap two, run two wires and a switch and you'd have a priming injector. The cold start type injectors really mist the fuel up finely too, not like  a standard injector.

Mentioning ether, Detroit Diesels used to have a cold weather starting kit that used ether. You plumbed up a small pipe (brake line size) into the supercharger inlet and that pipe ran into the cabin where it had a screw socket. You had screw on ether capsules (like soda bulbs) that you screwed on whilst cranking engine, ether bulb was pierced and ether dumped into supercharger, resulting in vroom.

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My 1992 Toy 4x4 22RE has the cold start injector like you describe. It is plumbed into the fuel rail and I have thought that you could disconnect that and plumb to a little tank of gasoline that you could pressurize by hand or with a small pump.

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My 1992 Toy 4x4 22RE has the cold start injector like you describe. It is plumbed into the fuel rail and I have thought that you could disconnect that and plumb to a little tank of gasoline that you could pressurize by hand or with a small pump.

 

What you could do is use some sort of tank you could fill with fuel and pressurise with compressed air, something that is meant to store  a liquid under pressure, maybe a fire extinguisher or BBQ gas bottle? Then all you'd have to do is keep it filled with fuel and pressurise it with compressed air. You need about 30-40 psi for those injectors to work well.

Although I'm convinced that if you mist enough ethanol into the intake, it'll start well. I just don't think stock intake port fuel injectors atomise the fuel finely enough for a good cold start on ethanol, they rely on the fuel hitting the back of the intake valve as a stream, and atomising due to the impact/heat of the valve, which just won't work for a cold engine and ethanol.

 

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Without knowing the car, it's a bit hard for me to say, but a fuel heater is generally a little more complicated than 'wrap a nichrome wire around the rail'.  First, is this a 'dead head' fuel system?  That is really the only way you have a chance for success.  If you have a return line, all your heated fuel will just flush out of the rail when you hit the key. 

 

Next, you won't be able to just wrap a wire around the rail - the wire itself will have to be electrically insulated or it will just short out.  But that very insulation will prevent good thermal transfer between the wire and the rail, another layer of insulation over the wire would help.  Next comes the issue of power.  To heat the entire fuel rail and fuel in 30 seconds is going to take a moderate amount of power.  Even 1000 watts for 30 seconds is only 30kW-seconds or about 28 btu of heat.  In a 'perfect' thermal transfer, that would be enough to heat a pound of water by about 15ºC, but in the real world, you'd be lucky to get half that. (just ballpark guessing your fuel rail may have a heat capacity similar to 1 pound of water, it's likely more which means less temp rise)  1000 watts from a 12v battery is going to take over 80 amps - which is some heavy duty lines and relays.  You could heat with less power for a longer time to get a good thermal soak, though it's doubtful the average person would want to wait 3-5 minutes each time the car needs to be started.

 

The easiest thing to do would be to blend a little more gasoline into the tank for the cold times.  You might also try to richen up the fuel curve and advance the timing to deal with slower flame travel speeds in the cold.  Some other ideas kicking around  - a gasoline 'primer' system to get started, injecting flammable gas such as methane / propane from a cylinder,etc.  The pressurized gasoline tank you mention is another option, though all these things have the possibility of failure - some in more spectacular explosions...uh ways than others.  Though I think you're going to need much more than a simple switch to accurately control the fuel mix of the cold start injector through a 2-3 minute warming period...unless you can push the button really fast and modulate the frequency consistently!

 

One idea we've kicked around, though never tested, is an air heater like the ones used for diesel engines.  This is a nichrome resistance grid which would be put into the air inlet to heat the incoming air.  It has some advantages of not being explosive, not requiring a second fuel tank to be monitored and maintained, avoiding the cost of extra fuel usage, etc.  But the current draw could be quite high - possibly even requiring a second battery for extended / very cold use.  There are also allegedly heated fuel injectors available from Delphi.  These heat the fuel right at the tip, so would work with any type of fuel system.  Plus, only the injected fuel is heated, so the overall power needed is relatively small.  Downside is probably cost and availability - don't know if they are out on the market yet or not - and in a form/capacity which is compatible with your car.  The ultimate solution to cold starting seems to be higher compression.  CR's of 12, 13, 14:1 give enough heat to help vaporize the ethanol, though an engine rebuild / piston replacement is usually not an option for a lot of people.

 

What type of 'absolute low temperatures' do you expect to see?  That would help dictate what overall type of actions you need to take.  Either way, good luck and stay safe when playing with pressurized flammable substances!

 

 

 

 

 

 

 

 

 

 

 

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Thanks for the reply. Yes, fuel heating would be difficult but it is an option. Even picking up 10-15 degrees would help. I agree with all your comments about Nichrome wire, insulation etc, I knew it would not be that simple. It's not a dead head system, However, it only flows fuel for two seconds pre start, so you would still have a fair to good chance of getting some warmed fuel into the combustion chambers. Also, a fuel rail is relatively small in thermal mass, I reckon it would heat fairly well, but I do agree, it would take a lot of heat. I have dismissed heating intake air as being too heavy on electrical consumption, although it would be effective.

I'm against blending as it's too much work and a compromise for 15-30 seconds of cold start.

I want to devise a system that approaches the convenience of electronic fuel injection, something simple and that anyone can do if they borrow my car. One of my goals when modifying my vehicles is to ensure that anyone can use the vehicle, I strive for total automation if at all possible.

The maximum cold temperatures I would be up against would be -8/10c ( 17/14f) and that would only be two to three months of the year however 0c(32f) will be likely around another three months of the year.

I'm behind the 8 ball with compression as well, I have a factory turbocharged car with 8.8 to 1 compression.

I've researched my cold start injector and discovered it will only be operated when temperatures are below -15c (5f) so I intend to initially run a manual push button to fog the intake with extra ethanol and see how that works. It should work well enough. If it does, I will set up a timer so it does this automatically every cold start. I saw a cool stand alone glow plug timer/relay setup that measured engine temp and vaired on time accordingly, I think that controlling the cold start injector would work well.

 

Without knowing the car, it's a bit hard for me to say, but a fuel heater is generally a little more complicated than 'wrap a nichrome wire around the rail'.  First, is this a 'dead head' fuel system?  That is really the only way you have a chance for success.  If you have a return line, all your heated fuel will just flush out of the rail when you hit the key. 

 

Next, you won't be able to just wrap a wire around the rail - the wire itself will have to be electrically insulated or it will just short out.  But that very insulation will prevent good thermal transfer between the wire and the rail, another layer of insulation over the wire would help.  Next comes the issue of power.  To heat the entire fuel rail and fuel in 30 seconds is going to take a moderate amount of power.  Even 1000 watts for 30 seconds is only 30kW-seconds or about 28 btu of heat.  In a 'perfect' thermal transfer, that would be enough to heat a pound of water by about 15ºC, but in the real world, you'd be lucky to get half that. (just ballpark guessing your fuel rail may have a heat capacity similar to 1 pound of water, it's likely more which means less temp rise)  1000 watts from a 12v battery is going to take over 80 amps - which is some heavy duty lines and relays.  You could heat with less power for a longer time to get a good thermal soak, though it's doubtful the average person would want to wait 3-5 minutes each time the car needs to be started.

 

The easiest thing to do would be to blend a little more gasoline into the tank for the cold times.  You might also try to richen up the fuel curve and advance the timing to deal with slower flame travel speeds in the cold.  Some other ideas kicking around  - a gasoline 'primer' system to get started, injecting flammable gas such as methane / propane from a cylinder,etc.  The pressurized gasoline tank you mention is another option, though all these things have the possibility of failure - some in more spectacular explosions...uh ways than others.  Though I think you're going to need much more than a simple switch to accurately control the fuel mix of the cold start injector through a 2-3 minute warming period...unless you can push the button really fast and modulate the frequency consistently!

 

One idea we've kicked around, though never tested, is an air heater like the ones used for diesel engines.  This is a nichrome resistance grid which would be put into the air inlet to heat the incoming air.  It has some advantages of not being explosive, not requiring a second fuel tank to be monitored and maintained, avoiding the cost of extra fuel usage, etc.  But the current draw could be quite high - possibly even requiring a second battery for extended / very cold use.  There are also allegedly heated fuel injectors available from Delphi.  These heat the fuel right at the tip, so would work with any type of fuel system.  Plus, only the injected fuel is heated, so the overall power needed is relatively small.  Downside is probably cost and availability - don't know if they are out on the market yet or not - and in a form/capacity which is compatible with your car.  The ultimate solution to cold starting seems to be higher compression.  CR's of 12, 13, 14:1 give enough heat to help vaporize the ethanol, though an engine rebuild / piston replacement is usually not an option for a lot of people.

 

What type of 'absolute low temperatures' do you expect to see?  That would help dictate what overall type of actions you need to take.  Either way, good luck and stay safe when playing with pressurized flammable substances!

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The two ideas that I found the most interesting were heated injectors and the 12v disks attached to the bottom of the fuel rail to heat it.

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