PTC heater for fuel ramp with temp 70-80 C
Sida 2 av 5

Författare:  Obormot [ fre 09-10-23 16:58 ]

another installation - now posistors soldered directly to fuel rail.

waiting for results :)




Författare:  Obormot [ tis 09-10-27 21:05 ]

PTC heaters works very good.

yesterday and today was 0...+1 C.

at the morning i can start after 3-4 min. of heating, starter works 15-20 sec without any flashes and then it starts. i think fuel in injectors and near injectors not warmed up so quickly, as the rest of fuel ramp. cold fuel was injected to mainfold (with no effect) then warmed fuel come to injectors and engine starts.

when car stands 3-5 hours, it starst almost immediately, much better, then at the morning...

i do not turn off heating when driving - it consumes about 15-20 W when fuel rail is hot. acceleration of a car become noticeably better, fuel consumption decreases by 0,5...0,8 l/100 km (in city).

PS i'm driving on 92% ethanol, not E85. some people adding 10-15% of gasoline to ethanol - starting becomes MUCH better.

Författare:  aryan [ tis 09-10-27 22:16 ]

That is really cool to hear! Near 0 degrees you "should" have a serious starting problem with 92% ethanol (and 8% water??)

Have you not considered using the engine cooland to preheat the fuel once the engine getting warm (and save the extra electricity), or is the fuelrail getting warm enough anyway when the engine is warm because you have a dead and fuel rail?

greetings, Aryan

Författare:  Obormot [ tis 09-10-27 22:59 ]

i want to use ethanol fuel with minimal and easiest intrusion into engine or electric systems - for mass users.

minimal additional devices can be installed by owners or in every service workshop and can be removed without traces (it important for new cars with "factory warranty").

we decided to use only PTC heaters and maybe 10-15% additive to alcohol for better cold starting - it is a "bio-additive", not made from oil. it can be mixed with 92% ethanol without any "water problems".

any other solutions are too complicated or too expensive for mass users and for mass service workshop.

Författare:  askilje [ ons 09-10-28 19:50 ]

what do you think about put 150-300 W on a pipe before fuelrail?
my fuelrail is placed in a bad place to put the elements directly on fuelrail.

do you think you get a higher fuel comsumption when you use an additional 300W from the batteri?

Författare:  Obormot [ tor 09-10-29 10:07 ]

if you will heat up pipe before fuel rail, cold start ability will decrease.

for cold start you maybe will need to heat up a pipe, than turn ignition on and off 2-3 times (fuel pump will work 1-2 sec. every time and hot fuel will go to fuel rail) and than start the engine.

if fuel rail is dead-ended, total power consumption after engine warm-up will be only 15-25 W (with PTC or other self-regulated heaters), it will not increase fuel consumption, but you can drive almost after starting engine (less than a minute for warming).

if fuel rail is not dead ended, it will be better to use fuel heating by cooling liquid.

Författare:  askilje [ tor 09-10-29 17:44 ]

ok, but have you changed batteri to a stronger (like the diesel cars have) if you have the heaters on 3-4 min before start

Författare:  Obormot [ tor 09-10-29 17:52 ]

no, i do not change accumulator.

300 w it is ~25 A, accumulator 55-60 A/H, so it can give current 25 A about 2 hours.

Författare:  aryan [ tor 09-10-29 23:17 ]

300W each? That is quite similar to diesel plugs, but I think a diesel engine mainly needs a larger battery because of the higher compression.

The Bosch flex start system uses a special fuelrail with something that looks very much like diesel glowplugs:

Ethanol is hard to vaporize. The U.S. and Europe found a solution to this by blending gasoline with ethanol at a 15:85 ratio (hence the E85 label). But 30 years ago, the Brazilian energy authority took a different path by ruling in favor of E100 (pure ethanol) rather than E85, partly because average temperatures are higher in the Southern Hemisphere.

Above 57 degrees F, ethanol will vaporize and ignite normally. Below that, a small amount of gasoline must be injected in the intake manifold during cranking. This necessitates a rather awkward cold-start system under the hood consisting of a reservoir, an electric pump and one or two nozzles at the intake manifold level.

(57°F ≈ 14°C)

The system's main feature is the special fuel rail that heats the ethanol fuel, making it easier to vaporize. A control unit monitors temperature conditions and triggers the heating as soon as the driver's door is unlocked. Monitoring continues through the warming-up phase, thus assuring ethanol temperature high enough for good vaporization.

Författare:  Obormot [ tor 09-10-29 23:21 ]

300 W total, 100 W each.

video about this system:

Författare:  aryan [ fre 09-10-30 00:11 ]

Obormot skrev:

Yes that is where I made the screendump from ;-)

It seems that it they use 4 of these in the fuelrail



Författare:  Obormot [ fre 09-10-30 07:22 ]

i think they using not usual diesel plugs, but something self-regulated with temperature 100-120 C - i can't see thermosensors on fuelrail.

if it serial device (not prototype) it have a serial number in parts catalog and we can find it.

Författare:  aryan [ fre 09-10-30 11:45 ]

Yes it would be very interesting if we could find the bosch part numbers. It must be availabe somewhere as it is built into Polo E-Flex sold in Brasil. The good news is that we know now that in a multipoint injected engine heating the fuel should be enough for cold starting :-)

I think there probably is some kind of temperature sensing in the system. In the youtube film you can see an instrument on the dashboard at min 1:10 that -unless it is a simple timer- indicates the fuelrail temperature, and when the car is ready to start with a key symbol!


Fast heating diesel glow-plugs are also self regulating but of course set for a much higher temperature. Here are current and temperature graphs of three types of NGK diesel glow plugs:

If the current flow already changes enough between 10 and lets say 100 degrees, a controlling device maybe cold use the dieselplugs/heaterplugs primairy current for determing the fuels temperature and not need an extra temperature sensor but use the current flow as a virtual temperature sensor.

Another option is to put the temperure sensor inside or very close to the injectors I think that would be the best solution. One could use pulse with modulation and diesel plugs to quickly heat the fuelrail to the desired temperature.

The e-flex system must also know when there is gasoline in the fuel because the fuels boiling point is lower and in that case less or no heat at all is needed.

Greetings Aryan

Författare:  Obormot [ fre 09-10-30 16:00 ]
Inläggsrubrik: ... ia-em.html



looking like usual glow plug...

but here information, than this is PTC heater: ... da-a-frio/

Författare:  aryan [ fre 09-10-30 22:42 ]

Nice links! Here is anonther intresting one: ... Araujo.pdf

The temperature and pressure inside the fuelrail is in there too. The idea is to heat the fuel so that it vaporizes as soon as it leaves the injector.

Fast glowplugs use PTC material as well!
In the last '70s a new innovative technology showed up on the market and changed the diesel glow plugs forever. Untill now the internal coil was made with a single wire, also called monofilament glow plugs, made by nickel. Now Beru, the first and main glow plugs manufacturer developed a new patented concept, they put two serial resistors inside the tube, the first one, called regulation coil, made with a ptc material able to increase its own resistance wgile temperature increase, the second resistor made by an alloy able to to high temperature resistence. The new glow plugs were able of starting up a diesel engine in seven seconds and keep that temperature for longer time then the monofilament models.


Sida 2 av 5 Alla tidsangivelser är UTC + 1 timme
Powered by phpBB® Forum Software © phpBB Group