Thursday, December 15, 2005

Motor Project # 3 - Waiting to Exhale

From Steve Hannes - Project # 3 is meant to inform, educate, inspire thought and Discussion. I am continuing with the disassembly of the 3.0L Jag V6 motor project, but taking a side road. I'd like to present some forensic evidence regarding the factory design of the exhaust system on the V6 transverse layout with the hopes of sparking some expert discussions and ideas. In my personal analysis of this exhaust design, there is potential for increased performance. First some commentary - I've read some about the design of Ford's duratec platform. The important design goals were to produce a very low emissions engine throughout the temperature range from warm up to operating temperature, along with low fuel consumption. With that in mind, one elemental factor in reducing emissions is heat. Thus it is part of the functioning design of a catalytic converter to operate most efficiently when hot. Now, for the Jag X-Type design influence on the 3.0L Duratec - Waiting to Exhale: The exhaust system is an asymetrical design, in the layout, in materials and in terms of flow. Here is a picture of the exhaust manifolds, catalytic converters and collector assembled as they would look on the engine. Notice the different shapes of the manifolds, and the positional layout of the Cats.

Here are some pictures of just the manifolds and cats. The one on the right coming from the outer (or left) bank is fabricated in Stainless Steel. The manifold on the left, from the inner (or right) bank is cast iron. Purely from a heat transfer and flow perspective, this must mean there is an imbalance from one bank to the other. To a performance engine designer, this looks like a golden opportunity!

And a point about the earlier reference to heat and the efficiency of cats, the jag design has these HEAT generators tucked extremely closely to the aluminum block - good for the maximum functioning of the cats, but at what expense to engine temps and premature wear of engine and extremities, I wonder. Another impact on efficiency is the different orientations of the Cats - one horizontal, one vertical. The back (right) cat takes a severe bend coming out of the cast iron manifold, where the front bank cat flows straight from the SS manifold. To protect against some of that heat, Jaguar went to extra efforts to shield the cats using several heat absorbing covers. There is one to shield the steering rack, for example, and one to shield the power steering pump. NOW FOR THE CHALLENGE - And I am inviting any expertise in engine design, engine flow, header manufacturing, materials experts, etc. I'd like to fabricate a set of tubular headers that collect at the point of this original collector, then into one (of the) catalytic converters - OR keep the headers separate, then feed each side in to its own cat. I'll use the factory Oxy sensors someplace where the headers collect on each bank, then use the Cat monitor(s) where they belong. Now is when I'd like to be a personal friend of Jesse James on Monster Garage! I invite your design and fabrication expertise to make a set of headers materialize. In some future post with a different project # I will document the entire fabrication process.


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