alistairolsen
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| posted on 19/2/10 at 09:35 PM |
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OT electronic circuitry experts
If I need to have non linear boost control on a severe budget (i.e a bleed valve or MBC wont work) can someone give me some advice on possible
circuitry?
It would need to read the rpm signal(pulse), and the throttle position sensor(potentiometer, and drive a Boost solenoid (commonly PWM)
Id want to have something like linear relationship between boost and throttle opening, but limited to 2 psi at 3kprm, 4psi at 4k, 6psi at 5k and 8 psi
at 6k or thereabouts.
I know you can buy them for a couple of hundred quid and they are nicely mappable, but Im looking for a locost way to achieve the above effect. Im not
afraid of soldering, nor is the engine particularly expensive.
Any advice?
Cheers!
My Build Thread
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tegwin
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| posted on 19/2/10 at 10:16 PM |
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If I were doing it I would build it around a PICaxe chip... Write the progtam yourself using a flow chart style programmer..
Just make sure that it will fail safe.... IE have a sepperate system that shuts the engine off if boost gets too high by accident if the pic
fails...
The datasheets for the PICaxe chips explain how the outputs/inputs work and how to wire them up...
Could take the analogue inputs and then, quite easily drive a PWM system via a transistor/triac
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MikeRJ
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| posted on 19/2/10 at 10:39 PM |
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Jaycar make a boost controller kit for ~£23.
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alistairolsen
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| posted on 19/2/10 at 10:44 PM |
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quote:
Originally posted by MikeRJ
Jaycar make a boost controller kit for ~£23.
that looks just the ticket. Shame its not laptop programmable instead of a separate £20 kit. Showing as out of stock though 
My Build Thread
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turbodisplay
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| posted on 20/2/10 at 07:44 AM |
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A boost controller can only make higher boost than what the wastegate is set at.
Normally 5 -7 psi (part throttle restriction helps to reduce this).
Saab have an apc unit that is quite advanced, adjustable internally.
Cheapest good way is a processor like a pic processsor.
I would recommend the 18f series as theyare faily logical, with no need for banking for the first 256 bytes of ram.
Darren
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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alistairolsen
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| posted on 20/2/10 at 09:42 AM |
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yeah I understand the wategate issue and Im hoping to test exactly what it can take at some point.
Whats the story with the saab unit? Is it external to the ecu? How do you adjust it? What cars was it fitted to?
is the pic processor you mention above the same as the PICaxe one mentioned earlier? How do you mean fairly logical? Im an electronics retard but as
far as I knew all chips are logical by definition?
Cheers everyone!
My Build Thread
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alistairolsen
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| posted on 23/2/10 at 10:55 AM |
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Ive done a wee bit of reading on the APC system and it looks like a good system and fairly easy to transplant into another car. From what I can see of
the internal mods you can raise the boost pressure it ultimately allows, but at the same time the lower limit is also raised (fixed range).
Has anyone on here got any experience with it? It certainly looks tempting if I can find a scrap man who doesnt know what it is!
Cheers!
My Build Thread
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