Restricted Air Flow!
05-15-2013, 07:01 PM
#2
Rennlist Member
I believe you are correct, I recall reading in several threads that the AFM used in the US-spec L-Jet system is a known airflow restriction. IIRC the Euro 16v cars use a heated wire type MAF sensor which is a larger diameter (or at least the same as the inlet diameter to the lower intake "U"). I thought someone had mentioned a way to convert to a better flowing unit, but I can't imagine it would be cost effective?
05-15-2013, 11:56 PM
#4
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The 1980-84 USA spec car had a fuel injection system designed for one thing.....meet emissions NOT make power remember the speed limit was 55 MPH and the speedo on a 1980 maxed out at 85 MPH !
So yes the throttle body and airflow meter are restrictive as are the smaller intake runners, smaller ports, smaller valves , lower lift and duration camshafts, and single exhaust....
Think of it as a river with a series of dams....you can blow one up and the water just piles up on the next one down stream.
So yes the throttle body and airflow meter are restrictive as are the smaller intake runners, smaller ports, smaller valves , lower lift and duration camshafts, and single exhaust....
Think of it as a river with a series of dams....you can blow one up and the water just piles up on the next one down stream.
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05-18-2013, 06:12 PM
#8
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Sounds like some easy gains for just a bit of effort.
Too bad you weren't able to dyno before and after - would be interesting to see what actual gains are achieved by this modification.
Too bad you weren't able to dyno before and after - would be interesting to see what actual gains are achieved by this modification.
05-18-2013, 06:45 PM
#9
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Cool stuff!
Not directly related to the 928 but worth the read, I guess Alfas used Bosch L-jet too, check it out
http://www.hiperformancestore.com/Ljetronic.htm
Not directly related to the 928 but worth the read, I guess Alfas used Bosch L-jet too, check it out
http://www.hiperformancestore.com/Ljetronic.htm
05-23-2013, 09:06 PM
#12
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Awesome little mod there! Really interested in trying it out.
Out of curiosity, do you know where your idle mixture screw is currently set (how many turns CCW from fully threaded in)?
Just wondering so I have something to compare mine to.
Out of curiosity, do you know where your idle mixture screw is currently set (how many turns CCW from fully threaded in)?
Just wondering so I have something to compare mine to.
05-23-2013, 10:03 PM
#13
Captain Obvious
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You might be leaning the engine out and that's where the extra power is coming from. Since there is no dyno data its hard to tell what is happening. You could do a WOT pull and then pull the plugs right away. If they are white, its leaning out.
05-23-2013, 11:47 PM
#15
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Fantastic idea, Matt. It seems the spring pressure decrease did the most. Can you explain the spring adjustment, maybe from you picture?
Thanks,
Dave
Thanks,
Dave