The Shelby block is stronger in nearly every aspect. It has solid main webbing with caps that are machine fit the full length vertically with dual side bolts, thicker decks than any other block with head studs that go the full distance and tie into the main bulkheads. They also have full support for the dry installed cylinder liners. But the majority of strength comes from the very thick bulkheads at the main supports. The block is just stronger in every single area.

And Ken, it surprises me that anyone would invest in another block design specifically for the cammer. I'd almost have to assume it would be a low volume deal. Sounds interesting though.

Mark,
What would you charge to build a set of headers for this combo?  Looks like you use Stainless? Do you wrap them to reduce engine compartment heat? What do you wrap them with?
Thanks, josh

On "optimal" headers, I'll go out on a limb here. If our poster (or anyone for that matter) runs a full length exhaust with mufflers, I don't believe one set of headers makes a big difference, minimal at best. That assumes a fairy well-designed yet off-the-shelf header with appropriate sized primary, collector, exhaust pipe and free flowing mufflers.

Are those xfi cam lobes?  If so, I would take a long hard look at your valvetrain setup and to be honest, I've picked up 25 hp by using milder lobes.

Quote from: Barry_R on February 24, 2015, 09:01:59 PM

My thoughts on headers is approaching the ones I have on cams.  The more experience I get the more likely I am to just try stuff & see what happens.  So far I can say that something of at least a short straight run out of the port definitely helps - and is nigh unto impossible in a shock tower car.

My stuff has proven to be MUCH more sensitive to collector length and design than it is to primary features - as long you are in the general rational realm of sizing.  I am also pretty well convinced that some characteristics that show up good on the dyno are not going to be optimal in a car.  The difference is one of running against a load that controls acceleration rate (dyno) compared to running against a variable load while trying to maximize acceleration (car).  Blair has more experience than I do in race car optimization and I would tend to follow his lead there - I've seen some stunningly small choke diameters in use.

Your comments on primary and collector length pretty much repeat what is in David Vizards book; he says on a normal V8 engine (one with a standard crank, not a flat plane crank), the exhaust pulses on the primary are a little fuzzy because of the two cylinders on each bank that fire in succession (4-2 on the right bank, 7-8 on the left).  His claim is that this tends to defeat the purpose of sizing the primary pipe length, and the result is that if all the primaries are in the 30-40 inch range, they will work just as well as if they are all the same length.  On the other hand, he says that normal V8 engines are very sensitive to collector lengths, and that people should spend a fair amount of time and effort playing with those, because there is significant power to be gained there.  Of course, if you attach an exhaust system there is less sensitivity to the collector length.

I'm considering making two new sets of headers for my engine, one where the bends are minimized and the lengths are all in the 30-40 inch range, and one where I keep all the primary lengths at about 33 inches (which will require more and tighter bends), and test them out to see which works better.  I'm also looking forward to trying a "collector comparo" at the track...