Re: [DMCForum] Turbo Bosch X-Jet?

[Martin Gutkowski <martin@xxxxxxxxxxxxxx>]

They work through the control pressure regulator lowering the control 
pressure proportionally to intake manifold pressure - much the same way 
as they do anyway but ours have a "ceiling" of 1bar (atmosphere). That 
said, you can fool the stock 066 cpr into fuelling under boost, but my 
experience is it does it rather too well...

The snag for you is that they also work for a proper turbo engine where 
the air is forced through the throttles, unlike the Island setup. The 
theory is sound in that the island setup uses the K-jet metering unit as 
a MAF sensor. Unfortunately the heisenberg uncertainty applies here (ok 
not quite) in that the action of observing/measuring the air flowing 
into the intake has the effect of changing it. New MAF sensors are not 
at all restrictive whereas the k-jet system is and therefore leans out 
proportionally with RPM but which can be compensated for by steepening 
the fuelling curve. Unfortunately a turbo engine hasn't got a linear 
fuelling curve, so they use the control pressure to dynamically adjust 
the mixture. The snag here being it must be properly calibrated to the 
engine in question.

Martin

Dave Stragand wrote:

> Hi All,
>
> Does anyone know of any Bosch K-Jet components that would work with a PRV
> running 15-20 PSI of boost?  I'd like to keep things simple.  I would 
> really
> love to keep the old K-Jet for simplicities' sake on the 'FoxFire Twin
> Turbo' (or should it be the "Vixen V-Sixen"?) 400+HP project.
>
> How about any LH-Jetronic systems capable of the same?
>
> I finally located a 1987 Volvo block so things may start moving some.
>
> -Dave

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