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Discussion Starter · #1 ·
Is there a way to measure air/fuel mixture on a diesel? Does it matter? Just curious cause I'm gonna be making some a/f gauges for my GTI and caddy.
Tim
 

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Re: Diesel Air/Fuel mixture??? (vwrabbit)

1 wy to tell that i know of....if it smokes.....too much fuel
 

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Re: Diesel Air/Fuel mixture??? (vwrabbit)

14 parts air to 1 part fuel.

that's the ideal fuel mixture for any internal combustion engine.
diesels can run ungodly amounts of fuel though. you can actually pump up the fuel on a 1.6L natural with a Bosch VE fuel pump to produce about 90hp without breaking anything, and retaining decent fuel mileage. it's all in the fuel pump. with diesel, more fuel = more power. simple as that. valve timing is not as much of an issue as is with gasoline engines. diesel is much more forgiving. i had an 85 jetta 1.6L turbo diesel that would rip your head off your shoulders under 11psi of boost on an early t3 hybrid setup. no intercooler, no mods other than 2.5" exhaust, boost control, and fuel management. http://****************.com/smile/emthup.gif
the jett would eat 2.0L 8v's for lunch
 

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Re: Diesel Air/Fuel mixture??? (vwrabbit)

Diesel engines work differently to petrol engines, a diesel engine sucks the maximum air volume all the time there is no throttle butterfly, the engines power is totally dependant on fuel quantity, the more fuel injected into a cylinder the bigger the explosion and more power you get. When you open the throttle all your doing is increasing the pump quantity your not letting more air in, the mixture isn't measured it's imaterial as it's always changing.
Smoke isn't a result of a rich fuel mixture it's a result of the fuel not burning properly, like low compression or bad injectors.
 

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Re: Diesel Air/Fuel mixture??? (Vdubs)

Diesels run lean, probably not much *lower* than 20:1 at WOT and 100:1 or 200:1 at low power. I would imagine the excess O2 in the exhaust would swamp out most O2-sensor driven A/F gauges.
Better guage is an exhaust pyrometer. I'm working on installing an Isspro pyro in my 1.9D:
 

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Discussion Starter · #7 ·
Re: Diesel Air/Fuel mixture??? (VWCaddy)

Doh, totally forgot about the lack of a butterfly in the intake. It is straight in at all times.

What does a good pyrometer run?
Tim
 

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Re: Diesel Air/Fuel mixture??? (vwrabbit)

you should be able to find a decent pyro for under $100
but don't cheap out on it... or you'll surely get junk


DIESEL POWER!!!! (i miss my a2
)
 
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