-
This is cool stuff. What was the motivation? Just to get more contemporary performance or just because you can't help hot rodding? Both reasons equally valid.
TRA-
This is cool stuff. What was the motivation? Just to get more contemporary performance or just because you can't help hot rodding? Both reasons equally valid.
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.
Dammit
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.