Hello, I am an engineer (trust me !). I have spent most of my career running two companies, one of which is a well-known builder of Rover V8 engines (which were originally Buick 215 c.i.). Our most common production now is a fairly sophisticated 4.8 litre (actually 4.75, 290 c.i.) with a long-runner manifold, single motorised throttle, modern injectors, and using the best of aftermarket EFI computers. This an expensive set-up but it suits certain applications.
We have recently started using Holley Snipers on some 'cheaper' engines. So where we are not aiming to produce the rather luxurious broad torque curve of the long-runner manifold, we can let the engine be more like a sports-car engine with maximum torque and power developed at higher rpm. For this the Sniper is ideal. Where we're building 4.8 or 5.0 litre engines with around 300 bhp we use the 4-barrel Sniper on an Edelbrock manifold. For smaller engines we are a bit stuck because the 4-barrel is too large, and there aren't any 2-barrel manifolds available. We have made a very good 2-barrel manifold by modifying the standard carburettor manifold for the engine, which had 2 SU or Stromberg carbs, but the modification is quite complicated and therefore expensive.
The Sniper range seems to be intended for more highly tuned engines, as even the simplest 4-barrel is said to be adequate for up to 650bhp, and the basic 2-barrel for 350 bhp. We have found that its self-learning is very good as long as the lambda sensor is in good shape (which I suppose is obvious). The tuning control allows for you to add more information and precise parameters in certain running areas. We haven't tried the ignition timing feature at all, but as that is a fairly simple output I would be surprised if it wasn't good as well.
My Bristol 409 has the original 318 in it but with a mild cam and gas-flowed heads. It currently uses an early aftermarket programmable EFI system, but it needs a thorough up-date. I am very tempted to either use the original cast iron 4-barrel manifold or find a good aluminium one, together with a 4-barrel Sniper. The original cast-iron manifold would need to have the inlet holes re-shaped and smoothed to match up with the Sniper.
The thing that would really improve the fuel-consumption, however, is a more sophisticated gearbox. We need at least 5 gears and a lock-up torque converter. I see no reason why any of the small-block Bristols should not then comfortably exceed 20 mpg. My company frequently uses the Ford 6R80 6-speed auto in other applications. The calibration is a bit time-consuming, but we can get impressive results. It might seem a bit heretical to use a Ford gearbox on a Chrysler engine but in fact nearly all of the these modern gearboxes are fundamentally ZF designs made under licence, so I feel there shouldn't be too big a culture-shock.
SO if we're using a Sniper and a Ford gearbox, you might question why you would keep that heavy iron 318 lump, especially if you have a VERY lightweight Rover V8 at 5.0 litres to hand, but there's something rather endearing about the 'Poly-sphere' 318, so I'm inclined to keep it.
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