boost operated switch

[sam80quattro]

wonder if any1 can help me. i am after a switch that will close when my car reaches a certain level of boost say 7psi. do any cars have these as standard? its for a 5th injector cheers

[S2central.net]

Dude - we all have five injectors already Give us some more info on your application. Dare say there are some funky pneumatic devices that can do this.

[Billman]

Exactly. Look at pneumatic devices. You want a sixth injector on the 5 Cylinder Turbo? Dude it is not a Punto GT or a Uno Turbo. Pay the money for a proper ECU remap or for a chip.

[dest]

Extra injectors are a can of worms that I wouldnt want to open!

[kwlw]

wonder if any1 can help me. i am after a switch that will close when my car reaches a certain level of boost say 7psi. do any cars have these as standard? its for a 5th injector cheers

You can find oil pressure switch which does that. There are ones rated at 0.3, 0.7, 1.3, etc. bar.

Sau

[DJones]

I to would not bother. However a water injection pressure switch will do the job and is completely adjustable, try ERL.

[Acidburn]

I've seen a switch like this on my mates car he is using it to up the boost but its got a mind of its own, sometimes its up to 22psi other times off the scale... not recommended.

[sam80quattro]

unfortunately its for a 205 1.9gti home brew turbo conversion, just need a cheap effective way to add more feul. and im not wasting my emerald ecu on the dam thing lol

[TEKNOPUG]

Aha! Welcome to my world. I ran a 205 Turbo Technics for about 3 years before recently selling it. What you need is a 5th injector plumbed into the throttle body. Take a seperate fuel line from the fuel filter. Then you need a 5th injector controller. Turbo Technics had them custom made and you may be able to find one secondhand. A better solution is to use an Aquamist water injection system (but obvioulsy use it to inject fuel). It'll have an input control (boost) and an output control (fuel). Very basic but it does the job. However, what you'll also need is some way to retard the iginition when on boost. My TT had a boost retard capsule fitted in the dizzy.

If you are using a later DFZ (CAT) engine then your world just got a whole lot eaaier. This uses a coil pack which means that you can just fit bigger injectors and then have the ECU remapped to suit.

I suggest that you look here first http//forum.205gtidrivers.com should be able to answer all your questions in depth.

Feel free to ask me if you have any specific queries.

[Jeffer]

Aquamist uses a nice switch.

[sam80quattro]

ive used the cold start injector of an audi 80 in the inlet pipe, its all plumbed in just i need the switch now. ill have a look about, cheers

[kwlw]

ive used the cold start injector of an audi 80 in the inlet pipe, its all plumbed in just i need the switch now. ill have a look about, cheers

It seems, that you don't get it. What you need is additional injector, which is regulated somehow. If you put it switch way, you will end with very rich mixture when the switch enables aditional injector, and very lean condition at some rpm's after.

In short - static injection should be adjusted, and works well only in very narrow rpm range.

What you need, is some basic fuel controller, like some boost sensor (~30eur mpx for example) + simple 555 based pwm controller, and mosfet with big radiator . PWM control of the injector is needed, because it is like digital device, which has two stages - on and off. You cannot regulate how much fuel it gives you.

That cheap fc/piggyback lacks rpm input. With RPM input and trivial map (let's say 10 values), you could be even more on safe side .

I have seen even more interesting controll of additional injector - if you have distributor with hall sensor and four windows on it, you can take simple mosfet, and drive injector from hall sensor signal. And the pressure switch enables or disables whole thing. It worked amazingly well on some old turbo fiat. If your engine uses distributorless ignition - then you can use rpm signal from ecu, one of injectors (if it's non sequential injection system), etc. .

Sau

[dubmeister]

Aha! Welcome to my world. I ran a 205 Turbo Technics for about 3 years before recently selling it. What you need is a 5th injector plumbed into the throttle body. Take a seperate fuel line from the fuel filter. Then you need a 5th injector controller. Turbo Technics had them custom made and you may be able to find one secondhand. A better solution is to use an Aquamist water injection system (but obvioulsy use it to inject fuel). It'll have an input control (boost) and an output control (fuel). Very basic but it does the job. However, what you'll also need is some way to retard the iginition when on boost. My TT had a boost retard capsule fitted in the dizzy.

You need to talk to Teknopug- I rebuilt and tuned one of these TT 205s years ago- the system it ran for the extra fuelling was very crude by todays standards but worked ok (with 4 star- optimax wasn't around then!) as long as the boost was not too stupid-but the owner decided to unscrew the bleed valve and turned the engine into a hand grenade (or Renault5 GTT as i like to call them)
The fuelling needs to be controlled so it doesn't run too lean and melt the engine or too rich that it just burns fuel for no increase in power.
You are better off in the long run using a standalone system with larger injectors- it will be cheaper and less costly than a lump of melted aluminium under the bonnet

[TEKNOPUG]

I agree with Dubmeister. Running a 5th injector without a properly programmable ecu will lead to problems as it'll be very hit & miss whether it is set-up properly - you'll need to put it on a rolling road for sure either way. Without being able to retard the ignition, the engine start to pre-detonate as the engine revs increase an it'll cost you power and run ****.