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Also, I am looking forward to purists biting through their steering wheel when they realise I'm doing all this to a cab.
Vide:
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The 3.7 litre upgrade route has been extensively tested by Hartech, it's a development of their existing rebuild - the difference being 100mm diameter liners instead of the 96mm stock, and new pistons. They keep everything else the same as the rebuild, but that includes closing the deck as part of the rebuild due to the new liners.
What we're adding to that proven recipe is new cams, possibly some head work (although from stock the heads seem to flow exceptionally well) maybe a compression bump.
Port velocities on the stock head at stock capacity are actually very low for a modern engine - the increase in capacity both unshrouds the valves and increases pumping efficiency which brings the port velocities much closer to what we'd expect to see - but the cams are, as previously stated, a compromise for the 3.4, let alone the 3.7.
I don't think we're doing much that is totally new, hopefully what we're doing is, via testing and calculation, adding to and refining an existing recipe.
Fitting a Mezger might be cheaper, it is true - but I enjoy the project, the research, design, finding the parts etc. Also, it's fun to make the (very much unloved) M96 into the engine it might have been - an extension of the X51 program, if you will.
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I suspect I've been well and truly out-done, turning up in a Volvo estate is not going to cut it when the other visitors are turning up in V12 Ferrari's.
With regards to my engine there are a lot of unknowns - but that's why the heads have spent eight hours on a flow bench, and why the designer has both a full intake and a pair of tubular exhaust manifolds, so he can calculate exactly what cam profiles we need.
The camshafts in the 3.4 (which I have) are shared with the 2.5 - and if we kept them unchanged when we go to 3.7 litres then we'd be using camshafts that were designed to operate an engine almost a litre smaller in size, which would not be using the new capacity to its best advantage.
Unknowns currently concern the throttle body to use, I think that the exhaust side of things would be tubular (FVD style) tubular manifolds, 200 cell cats and the current Cargraphic sports exhaust. I'll need to check that we have enough injector to give us safe headroom, the goal is to achieve both a strong, linear delivery of power from idle and (in have your cake and eat it style) hit a volumetric efficiency figure of 100 bhp/litre.
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I find the Apple photo application a huge irritant, but it is what it is.
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The 250? I believe it's real, the chap was dropping off four V12 Ferrari heads.
I may however be wrong - I know little enough about these.
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The engine designer sent me the below picture of a vehicle that one of his clients was using as a delivery hack:
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A little more than that, we're upping the capacity to 3.7 litres, so the existing cylinder liners need to be machined out and new (Capricorn) liners installed - a nice consequence of this is that it closes the deck. There's some other stuff also.
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He's had no money so far, but this will not be without cost ultimately.
I wanted to rebuild it to engineer out the weaknesses that Porsche left - the IMS, the bore ovality, the unsupported crank and associated RMS issues, the heating and oiling (under severe load).
Doing this involves (amongst other things) the new cylinders - at which point it's the cost of new pistons to get the capacity increase.
But - the issue with upping capacity and changing nothing else is that whilst you move the entire power band up you also move it left, so peak power rises to (say) 340 bhp, but it also moves to 6,000 rpm rather than 6,500.
I started thinking about what we could do to keep the engine revving out to it's previous peak, which lead to the discussion with the engine designer, his flow bench, new cam profiles being created and so forth.
I'm also going to use the oiling and cooling upgrades from the X51 Power Kit, including the new sump, scavenge pumps, and additional centre radiator.