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Right seems like history is repeating it's self, been offered a home made turbo kit for my twin cam Sierra. However the kit contains no extra fuelling gubbins so I've spent the best part of the day researching cheap fuel enrichment devices....... I can't afford Megasquirt or an MF2 extra injector driver atm my funds won't allow, so I've been looking at a Hobbs switch activated extra injector. However from my limited research it seems unclear how to wire it in. Does the injector need to be fired with the other injector or can it run continuously? I've made a diagram to show what I mean....... Continuous....  Batch fired....  I understand the Sierra injection system is batch fire (i.e. it just fires all 4 injector together) so will it be a problem patching into the earth to actuate the extra injecftor? Hope this makes sence any help is much appreciated ;D |
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Sierra - here we go again! He has an illness, it's not his fault.
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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Am I right in thinking that a hobbs switch is simply an on-off pressure switch that turns on at a set threshold? If so it seems an incredibly basic method of enrichment, and I'd be tempted to look into a boost controlled fuel pressure regulator. It'd depend oh how much boost you're wanting to run, but I'd have thought that a pressure regulator will give a much nicer drive, as the additional fuel will be related to boost pressure, rather than just cutting in at a certain pressure.
If you do go down the hobbs switch then I'd have thought that wiring it to the current injector earth (ie, through the ECU) but via a transistor/relay to switch it would be the best bet, just so as not to risk damaging the ECU's internals.
How does the stock ECU meter engine load? is it using a paddle type MAF? (a VAF).
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The skogenracing guys built several sierras with 4 saab pressure switches and 4 extra injectors. Works on full throttle, driveability and engine longetivity seemed to be a problem...
Those were pintos though.
A finnish guy developed an advanced pressure switch, which could controll up to 8 (iirc) injectors, and set how much they opened from 0-100% at how many bars etc. I think it was somewhere between 2 and 300 euros. Quite cheap imho if it works.
Also 1 extra injector won't do much, 25% on top of the stock fuel capacity, so 150 horses on a GOOD day, if you go through all that trouble, make it four, that should be good for 1 bar, whatever that's in psi (i'm sorry, do the uk use bar or psi? )
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Last Edit: Jul 4, 2011 18:08:05 GMT by dude
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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If you don't mind doing the work your self you can get a reasonable (reliable but basic features) MS1 set-up sorted for about £230. That's the route I'd be looking at, but like I said, I'd favour a fuel pressure regulator over a 5th injector personally.
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I only want to run 6psi maximum, will an adjustable fuel pressure regulator be able to enrich the mixture significantly?
I think I understand about the relay, I'll do a diagram to see if we're on the same wave length.
The Twink uses a map sensor to measure engine load.
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Sierra - here we go again! He has an illness, it's not his fault.
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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Ok cool. Well at 6psi you'll have as a very rough estimate about 1.4 times the air entering the engine that it should have, so you'd need your fuel pressure to be around 1.4 times that of a standard sierra. Without knowing what the standard pressure is it's hard to say, but as long as 1.4 times the standard isn't beyond what the pump can manage then I'd say it's possible.
The issue with using the hobbs switch is even more important when the management's MAP controlled, as unless the sensor's capable of reading above atmospheric pressure, then it'll essentially flat-line the management as soon as you're reading any boost. This means that you'll have the same amount of fuel being chucked in at 1psi as you will at 6. Not cool.
Another option to get the fuelling somewhere near right would be to replace the standard map sensor with something that will read above atmospheric. As long as the resistance/voltage range of the sensor match's the standard sensor, then this will essentially re-scale your standard map, so before when 100% load was 0psi, it's now whatever the MAP sensor goes up to. This will chuck your fuelling lean across the board, but by a consistent amount, meaning you can then increase fuel pressure and/or injector size to bring the fuelling back up to where it should be. Hey presto, management now reads and understands pressures above atmospheric. It's not perfect, and would probably give a reasonably curse word idle, as well as the map not being ideal, but it'd be a damn site closer than just chucking in a set amount of extra fuel at anything above 0psi.
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get a rising rate adjustable fuel pressure regulator, up the pressure by a little bit at idle ( not alot just a tad) and have fun.
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oh and as a rule of thumb, retard ignition by 1 degree for every psi of boost
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The fifth injector run off a hobbs switch really came from the Skogen racing guys, however I do realise it would probably be difficult to get right. The issue with using the hobbs switch is even more important when the management's MAP controlled, as unless the sensor's capable of reading above atmospheric pressure, then it'll essentially flat-line the management as soon as you're reading any boost. This means that you'll have the same amount of fuel being chucked in at 1psi as you will at 6. Not cool. Another option to get the fuelling somewhere near right would be to replace the standard map sensor with something that will read above atmospheric. As long as the resistance/voltage range of the sensor match's the standard sensor, then this will essentially re-scale your standard map, so before when 100% load was 0psi, it's now whatever the MAP sensor goes up to. This will chuck your fuelling lean across the board, but by a consistent amount, meaning you can then increase fuel pressure and/or injector size to bring the fuelling back up to where it should be. Hey presto, management now reads and understands pressures above atmospheric. It's not perfect, and would probably give a reasonably rubbish idle, as well as the map not being ideal, but it'd be a damn site closer than just chucking in a set amount of extra fuel at anything above 0psi. Yeah I remember when a mate of mine turbocharged his Sierra he had a pre-set MF2 5th injector driver which had come off another car, before he fitted that the car would come on boost and it would splutter and die (no surprise!) once we fitted the MF2 it went like stink. I understand what you mean regarding tricking the ECU into reading boost, but I would imagine you'd need a couple of sets of injectors to get the right combination. Lots of trial and error. oh and as a rule of thumb, retard ignition by 1 degree for every psi of boost I've read this several times although my mates twink Sierra ran 9 psi without any sign of pinking or det, I don't plan to run anywhere near that so I'm hoping it will be fine. TBH I only want to run 6psi so given that the standard Sierra ignition map will be fairly conservative and I'm planning to run it on super............. I'm hoping it should good lol! So adjustable fuel pressure regulator it is, well until I can get my hands on a cheap MF2 or do megasquirt. Thanks for the help guys really appreciate it ;D |
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Sierra - here we go again! He has an illness, it's not his fault.
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Something like this.......  Use the gauge to check what the standard pressure is then adjust but 1.4 standard pressure for 0.5 bar of boost? |
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Sierra - here we go again! He has an illness, it's not his fault.
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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The 1.4 times was simply a very rough guess. What you basically want is a pressure regulator that increases the fuel pressure in proportion to the boost pressure. So at anything under 0psi the pressure wants to be standard, then gradually increasing up to something like 1.4 times standard at 6psi. The exact amount under boost would want to be checked and adjusted to suit though.
What I was meaning was to check that your pump would manage about 1.4 times standard pressure, because if it wont, then this method isn't going to work for you.
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How do I test if my pump can handle it?
I know the intank Ford pumps (used on the twink) are considerably weaker than the earlier external pumps (used on the pintos, colognes and YBs)
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Sierra - here we go again! He has an illness, it's not his fault.
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fiesta RS turbo uses same map sensor as far as i know, i've a bini supercharger on a sierra twink but its on hold at mo,was very rich with gm V6 injectors & wouldn't idle below 2000rpm witm map connected, thinking of refitting std injectors.
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theres more to life than mpg & to much power is just enough.
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Colonelk
Posted a lot
Posts: 3,742
Club RR Member Number: 83
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Dude you sorted for injectors? Just trying to remember if I've got 4 kicking around.... can have a look.
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the ignition is mainly if your not running an intercooler, if you sort the charge air cooling its less of an issue, fit a decent cooler anyway, they can be had for pennies from scrap yards
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ive fitted a 306 Dturbo intercooler.
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theres more to life than mpg & to much power is just enough.
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rysz
Club Retro Rides Member
Posts: 2,558
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Does this have to work off boost? Would an acceptable trigger be the number of revs that the engine has reached? If so, it is the work of a few small bits of electrickery with a total cost of £10-£15 to have a small circuit board to do the job...
Rysz.
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yeah it needs to work off boost, boost changes with load on the engine so going off the revs would have the AFR all over the shop
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stefan
Posted a lot
If it isn't broken fix it till it is
Posts: 1,598
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I have plans to do somethink like this with the adjustable fuel pressure regulater on my E23 bmw but had not thought to much about weather the pump could make the extra pressure, still most people seem to do this on the M30 so it should be ok.
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POWER IS EVERYTHING WITHOUT CONTROL
1985 Honda jazz
1997 Saab 93 convertible
2010 transit 280
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Tim
Posted a lot
Posts: 3,340
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How are you planning to seal the intake into the throttle body?
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