Mr. Vizard, this is the discussion I've been looking for. I will notify all the gear-heads at
Ford Six Performance: The Web's Leading Resource for Ford Inline Six-Cylinder Engines and Cars!, many of whom have a keen interest in building street engines for maximum fuel efficiency. We have our own discussions including setting a good tight squish-height for detonation-resistance so we can add a bit of compression. Some of us want to really squeeze down on the heads, while using water-injection so that we can still burn the low octane gas. Of course, a lot of our discussions are specific to our engines, concerning camming and rocker ratio, the well-worn rod-length:stroke arguements, and so forth. If you get a chance, pay us a visit. I think a couple of the posters were students of yours. (I just typed a web address up there; why did it turn into an advertising slogan? But it's a great site).
I have a project you'll like. Ford 300 inline six for a van. Stock cam, stock valves, the standard 1.6 rocker ratio for the intake but maybe 1.7 rockers on the exhaust. Squish at .036-.039" using either the early 240 closed-chamber head or the recent swirl-head. I have two compression ratio targets, one for use with water injection, one without, but I'll ask you about that some other time. I'll fabricate an exhaust system per Philip H. Smith's design.
Here's the interesting part. If I wanted to spend a lot of time and cash, I'd carburate with three sidedraft Webers, OR use the late factory fuel injection hardware for this engine combined with the do-it-yourself Mega-Squirt programmable controller and its various sensors. But first I want to try what I have now, which is a Clifford single 4bbl manifold and a Holly Pro-Jection 2bbl 670cfm throttle-body injector with oxygen sensor.
Now this Clifford manifold is supposed to be a performance item, with nicely-radiused runners . . . BIG runners, and a BIG plenum. And that 670cfm injection unit seems pretty BIG, too, for an engine that will never see the far side of 4500rpm. The Sixers typically like the Holley 390cfm 4bbl for this kind of work. Well, the Smitty plan is this: since the engine is basically two triples set end-to-end, I have fabricated a divider in the center of the plenum o this Clifford manifold, so that any cylinder will draw a vacuum on just half of the manifold volume, and draw from only one side of whatever injection unit or carburetor I use. In other words, like virtually every factory V-8, my I-6 will have a dual-plane manifold!
Before I obtained the Pro-Jection unit, I had thought to try a Quadrajet o my split manifold. A Quadrajet would normally be far too big for a six like mine, but by effectively splitting it into two 2bbl carbs on a dual plane manifold, it could work. My only reservation is that since I'd have to mount the carb sideways to it's preferred orientation, the float-height and metering might fluctuate a lot under routine acceleration and braking. The Pro-jection won't be bothered by this at all.
But now think about this one. A third possibility might be the Street Predator. A normal orientation of this carb (float-bowl AFT on a street machine, says the manufacturer) is perfect for an inline six, whereas on a dual-plane V-8 manifold the spraybars of the Predator are funneling its charge right at the manifold divider, which seems less than ideal. Of course, the Predator is huge, 1050cfm or some-such. But what if I could fabricate a divider, say 3/8" wide, inside the middle of that carburetor, matching the divider in my split manifold? If I could be sure that the spraybars would meter evenly on either side of the divider, that might be a very functional, easy-to-tune, altitude-compensating carb for my purposes.
What do you think of that last idea (before I call Predator and see what THEY think of it)?