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Tips om extra bensintank till kallstart?
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Författare:  Dr. Mabuse [ mån 10-01-11 17:01 ]
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Tänk på att så fort bensinbränslepumpen startar så kommer den pumpa bränsle genom fuel rail, via reduceringsventilen till ordinarie etanol-tank.

Givet bensinbränslepumpens flöde, hur lång tid tar det att fylla hela fuel rail med bensin innan bensinen når reduceringsventilen och börjar flöda in bensin i bränslereturen?

Edit:
Kanske vore det lämpligast att bensinpumpen enbart fick ström när startmotorn går.

Författare:  aryan [ mån 10-01-11 17:06 ]
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Good you could translate my posting :-)

Obormot skrev:
but:

1. high-pressure fuel pump costs about $30-40.

2. you have to add gasoline before cranking - and wait some time after adding - ethanol and gasoline has to mix up.

3. better point for connection is a middle of the fuelrail - to obtain same % of gasoline in whole fuelrail. if you will add gasoline to only one end of fuelrail, you have to wait while ethanol and gasoline mixing up, or concentration of gasoline near 3 and 4 injectors will be very small and engine will work on 1-2 cylinders first 5-10 seconds (if it will start).

4. i can't find a way to quick and reliable connection to different fuelrails...


1. Stämmer, men du sparar en bensin avslutare som kan kosta lika mkt som en halv pump.

2. Det kommer bensin in fuelrail innan starten, eftersom att (bensin) pumpen då går i 0,5-1s när man slår på tändningen. Då fylls fuelrailen med bensin innan starten samtidigt som etanol trycks tillbaka till bränsle/etanol tanken genom bränsletrycksregulatorn.

3. Jag vet inte, om pumpningen innan/under starten räcker för att fylla hela FR med bensin är det bäst att ta det längs bort från den normala ingången. Annars har man altid en "ficka" längs ut i fuel railen där etanolen är kvar.

4. Hmm ja det kan vara ett problem, bilar som är ombyggda för dead end fuel rail har redan en utgång där tryckregulatorn fanns men andra bilar har väl ofta en luftningsnippel som kanske skulle kunna användas?


/Aryan

Författare:  aryan [ mån 10-01-11 17:19 ]
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Dr. Mabuse skrev:
Tänk på att så fort bensinbränslepumpen startar så kommer den pumpa bränsle genom fuel rail, via reduceringsventilen till ordinarie etanol-tank.

Givet bensinbränslepumpens flöde, hur lång tid tar det att fylla hela fuel rail med bensin innan bensinen når reduceringsventilen och börjar flöda in bensin i bränslereturen?


Det är tidsbegränsad, så det kan vara precis lagom, beroende på fuelrail etc volym och flödet genom tryckregulatorn.

Det kan man kanske med testa en bit genomskinligt tryckslang och färgad bensin?

Jag tror denna lösning skulle kunna ge helt automatiska kallstarter och dessutom mindre risk att sura ner motorn som man annars har när man bara häller i skvätt bensin + etanol och det borde ge lägre utsläpp av kolväten vid start.

/Aryan

Författare:  Dr. Mabuse [ mån 10-01-11 17:28 ]
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Jag gjorde en edit, du kanske missade den...?

Författare:  aryan [ mån 10-01-11 17:41 ]
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Nej jag såg det, men tror själv att det bara är en fördel om extra bensinpumpe går lite innan för att fylla fuelrailen med bensin.

Men det kanske räcker bra om pumpen endast går samtidigt som startmotorn går.

/Aryan

Författare:  aryan [ tis 10-01-12 14:39 ]
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Jag blir allt mera entusiastisk över detta, jag tror att det borde ju funka hur bra som helst med

tank => pump => filter => tryckregulator (med retur till tank) => (eventuell värmeväxlare/etanolvärmare =>) FR med injektorer <= exra bensinfilter <= extra bensinpump <= extra bensintank

/Aryan

Författare:  Obormot [ tis 10-01-12 17:51 ]
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and another moment.

for cold start you need to increase concentration of gasoline in whole fuelrail, up to 50-60% - it is about 100 ml of fuel from little second tank. usually it contains about 1 l of fuel - so you have to add it very often.

for start with direct injection into mainfold we need less fuel.

Författare:  aryan [ tis 10-01-12 18:45 ]
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Yes maybe it uses more petrol each cold start, but if that is the case it will also make the engine run smoother right after it has started and still is to0 cold to run as well on ethanol.

Suppose you have 200 cc E50 in the fuelrail when the engine starts, that should be enough to drive a few hunderd meters - 1 km while the engine is warming up and not yet running in closed loop.

/Aryan

Författare:  Obormot [ tis 10-01-12 18:54 ]
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as i know, 200 ml of E50 or 500 m is not enough for heating up engine, working on ethanol when -10...-15 C outside.

Författare:  Dr. Mabuse [ tis 10-01-12 23:15 ]
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Obormot skrev:
as i know, 200 ml of E50 or 500 m is not enough for heating up engine, working on ethanol when -10...-15 C outside.
True, but I don't think it's desireable to have any gasoline left in the fuel rail when engine temp rises above... say 30°C.

When engine gets warm enough to enter closed-loop, any gasoline left in FR will upset the Short Term Fuel Trim, and probably also Long Term Fuel Trim if you make a few cold starts without driving very far in between.

Drivability while the engine is warming up can be accomplished with the NTC-in-series-with-Temp Sensor sollution.

Författare:  matsuda [ ons 10-01-13 00:07 ]
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My engine has cold starting issues. I might need to crank 3 - 4 times before it starts running. But once I've driven ~500 meters it runs much better, but I'm heating fuel rail. Temperature is usually below -10 degrees. So I think that any kind of warm up fuel would be nice for the cold start. If possible, I think it would be better with propane/DEE but gasoline is also better than E85.

Författare:  aryan [ ons 10-01-13 01:06 ]
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Obormot skrev:
as i know, 200 ml of E50 or 500 m is not enough for heating up engine, working on ethanol when -10...-15 C outside.


Can't really follow you this time ;-),

First you say that 100 ml petrol / start is too much because you'd have to fill the petrol tank too often but now you say it is not enough?

Författare:  aryan [ ons 10-01-13 01:19 ]
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Dr. Mabuse skrev:
Kanske vore det lämpligast att bensinpumpen enbart fick ström när startmotorn går.


Eller temperatur beroende:
motortemp <T> T °C : vanliga (etanol)pump bygger upp tryck innan start men bensinpump när startmotorn går.

T kan då vara 0 - 10°

Författare:  Obormot [ ons 10-01-13 08:49 ]
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i mean that additional fuel tank is not better solution for improoving of driveability.

for improoving of driveability much better using heated fuel or air - no extra fuel will be use for it, i think such systems is "must have" for ethanol engines.

for good starting we have to obtain high concentration of gasoline into fuel rail - at least 50% of it's volume. if we have small fuelrail, it will be 20-30 ml, if we have big fuelrail - it will be 100-120 ml, but in any case it will be 50% or more.

for cold start we will burn 10-30 ml of this mixture, after this engine can idling on pure ethanol. the rest of gasoline in fuelrail is not necessary - yes, it can give some improvement while running on cold engine, but for cold start enough only 10-20 ml of gasoline.

such situation with heated fuelrail - actually we don't need to heat up whole fuelrail, only little portion of fuel for starting and first 1-5 seconds of idling. when we heat up whole fuelrail, we spend extra energy from accumulator and it taken much more time - in this situation heated injectors is much better solution - it heat up only little portion of fuel, which will be burned right now - and using less power and time for it.

direct injection of pure gasoline as solution very similar to heated injector - we deliver to mainfold very small quantity of fuel, which will be burned right now.

or we can use ether instead gasoline - quantity of fuel, needed for 1 cold start will be even smaller. gasoline is easy-to-get, ether is "greener", can be made from ethanol and using in "absolutely no-gasoline car" :)

Författare:  aryan [ ons 10-01-13 11:20 ]
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Obormot skrev:
i mean that additional fuel tank is not better solution for improoving of driveability.

for improoving of driveability much better using heated fuel or air - no extra fuel will be use for it, i think such systems is "must have" for ethanol engines.


Ok, I understand what you mean. Of course the idea of pumping some gasoline into the fuelrail prior and during cranking does not mean that fuel or air (pre)heating is not longer possible. For example this might be a solution:

tank => pump => filter => pressure regulator (& return line to tank) => new water/fuel heat exchanger to preheat fuel => Fuel Rail w injector <= filter <= pump <extra> pump => filter => pressure regulator (& return line to tank) => new water/fuel heat exchanger to preheat fuel => Fuel Rail w injector <= filter <= pump <= extra petroltank

Obormot skrev:
for good starting we have to obtain high concentration of gasoline into fuel rail - at least 50% of it's volume. if we have small fuelrail, it will be 20-30 ml, if we have big fuelrail - it will be 100-120 ml, but in any case it will be 50% or more.


In Sweden we have 23% petrol in E85 during the winter, this has been tested to be enough to start FFV cars down to -30°C.

A nice feature of the "fuelrail" solution is that it would automatic adapt / increase the petrol concentration in the fuel depending on the time it takes (how difficult it is) to start the car. So the petrol concentration will vary, depending on the engines abillity to start on ethanol which in turn will be dependent on, weather, engine and fuel temperature, ignition spark heat, crank speed, how much cold start enrichement it has etc, etc.

Obormot skrev:
for cold start we will burn 10-30 ml of this mixture, after this engine can idling on pure ethanol. the rest of gasoline in fuelrail is not necessary - yes, it can give some improvement while running on cold engine, but for cold start enough only 10-20 ml of gasoline.


The advantage to be able drive away right away without major hickups should not be underestimated. Leaving the car on idle for more than 1 min (to heat the engine) is not even allowed here in many cities.

Obormot skrev:
such situation with heated fuelrail - actually we don't need to heat up whole fuelrail, only little portion of fuel for starting and first 1-5 seconds of idling. when we heat up whole fuelrail, we spend extra energy from accumulator and it taken much more time - in this situation heated injectors is much better solution - it heat up only little portion of fuel, which will be burned right now - and using less power and time for it.


Of course I like the heated injectors too, but that is another thread :-)

Obormot skrev:
or we can use ether instead gasoline - quantity of fuel, needed for 1 cold start will be even smaller. gasoline is easy-to-get, ether is "greener", can be made from ethanol and using in "absolutely no-gasoline car" :)


Yes an onboard ether generator would be nice!

/Aryan

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