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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,289
The smooh finished cast aluminum lambda USA fuel head is alot more versatile then the rough finish painted black cast iron rest of world or euro fuel head.

The USA head can be adjusted to flow up to 20-25% over stock while keeping good low speed manners which is 10% -15% more fuel than the euro head is capable of because it has a more flexable synthetic diaphram that does the final fuel metering individually for each injector.
It is also quite a bit lighter and won't rust internally if water accumulates and sits in the lower chambers because it's cast aluminum rather than cast iron, and it can be used with the lambda controller to give better gas milage and pass emissions with air injection installed and working in some states if thats required.

There is nothing better about the euro fuel head. It got that reputation years ago because if you compare it to a stock USA fuel head a stock Euro head flows around 10% more fuel under boost.

But because the euro head has a stiff stainless steel metering diaphram/gasket between the upper and lower chambers where the USA head has a flexible synthetic metering diaphram/gasket with 6 individual stainless steel metering discs attached to it - one for each injector under each of the 6 upper chambers and injector line metering orifices, the USA head can be adjusted to flow alot more fuel under boost than the euro head.
If you tried to adjust the euro fuel head for much more fuel the one piece stainless metering diaphram will be dimpled downwards under each of the 6 upper chamber metering orifice's and ruined.

Taking all this in consideration the slightly newer USA lambda fuel head is better.
I know from experience because I have owned both and tried them on my car and kept the 20% over CIS Flowtech modified fuel head.
In my opinion the USA head modified to flow 20% over stock with lambda removed and a Brian Leask adjustable WUR to fine tune AFR's is the best CIS fuel head for performance.

The aluminum fuel heads for big Mercedes and Bentley V8's are also interesting because they are the same size as a 930 head and have 2 more fuel injector outlets machined in the top that can be plugged or used for an extra injector(s) with an electronic injector controller on a 6 cylinder motor.
Old 07-16-2011, 10:04 AM
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