"Square" Engine Theory

[spectre6000]

From Charles Navarro:
"The Nickies, under load, were up to 150F cooler, making 15% more HP, 10% more torque, and yielding a 7% reduction in BSFC" compared to a 2110 or 2332 where the only change was the cylinders (not pistons, rings, etc.)

I would keep it to myself if I thought it was much more than marketing speak. 7% lower BSFC and 150 degrees cooler are certainly interesting numbers, but without knowing anything about the control engine it's hard to say if they really mean anything. I wish there were some actual test data available on these things with real numbers...

Does anyone have any links to information about the othe cylinder coatings that are available?

[spectre6000]

Raby is awfully excited about the dual plug heads. Higher compression and more complete burn are the benefits as I recall. From what I can tell, he's still tight lipped about the specs.

This place (http://www.greatplainsas.com/sccylheads.html) will add a second spark plug hole to your heads for a nominal fee, but I'm sure the shape of the chamber is pretty crucial to making it work in a way that's in any way beneficial. Also the location is on the underside of the cylinder which seems like it might prove problematic for the spark plug wires in terms of access and maybe the heat from the cylinders and the rubber insulation on the spark plug wires. In aircraft it's about redundancy, so I don't know that shape isn't as important for the second set of plugs. An effective ignition system would be fairly difficult as well.

Distributors would be a bit of a challenge as well. Jake has modified the usual suspects (009, 010, etc.), and someone on the Samba said something about a Nizzan Z24 cap and rotor, and I'm sure there are other solutions. Anyone?

I would like to keep as much as possible off the shelf for future parts availability and support, but some things are worth considering.

[spectre6000]

I believe someone mentioned earlier that the Nickies cylinders shed much more heat than cast iron, and the heat losses would reduce overall efficiency. I'd like to present this idea to the community of greater minds: Part of a comprehensive strategy to achieve high mpg figures is to run the engine at a lower RPM; this is clearly detrimental to an air cooled engine by virtue of lower fan speeds, rectifiable in part by manipulation of pulley ratios; loading the pulley ratios as such would add more load to the engine, and while the mechanical advantage is still in favor of this approach it's not the complete answer; another way to mitigate temperature concerns that may arise through operating at a lower RPM would be to alter the cylinder material to one that radiates heat better, ergo Nickies. I'm thinking that a combination of increased fan speed and better head shedding alloys in the cylinders combined with VW's recommended operating range of 2500-4000 RPM (re: photo below of a "NOS" Ghia tachometer) should allow for a lower "safe" RPM band. That said, I don't know that 2500 is safe to run all day long in a stock engine, but it might very well be with the above combination; I won't know until I have some test data. The Nickies piston and cylinder set is expensive, and I may be wrong about the above scenario, but if they shed heat too well I think it will be easier to raise the engine temp than to lower it via further manipulation of pulley ratios (custom pulleys aren't terribly difficult/expensive).

I would really like some input on this idea if anyone would care to give it some thought.

[Piledriver]

I thought we beat all it up pretty good already

It has merit, if you have that kind of money.

I would personally only bother with Nickies if they were 94mm or larger.
That way they have resale value if it all goes south.

[spectre6000]

There was talk of other types of cylinder coatings. What's the story on these?

[iam64185]

i like what you're going for. fuel efficiency. this thread died, or so it seems, before anything came of your motor. it's been nearly six years but surely in that time you built something. how'd it turn out. i'm about to install an 85.5x76 in to a 73 super beetle. i ran a 77x76 in the same car for many years. both the old build and the new one are mileage motors.

[Piledriver]

I can only comment on the newer cylinder coatings and so on.

Choices are pretty much still Nickasil or MMC (Metal Matrix Composite) the latter is plasma sprayed onto a slightly overbored cylinder then diamond honed to size.

MMC has most of the benefits of Nickasil, but is even tougher, and works good over iron.
I think you can do MMC over aluminum as well, and there are other similar processes being sold under a variety of brand names.

Will still cost you almost the same in the end for a tiny bit lower friction/wear.

If I was going to build a "mileage motor" I'd dig up some low drag rings and dry sump it, and run sequential EFI with dual plug heads, and as high a CR/tightest deck and thinnest oil I could get away with. Coat everything.

I'd probably go with thickwall 92s and a counterweighted stock crank, and run case vacuum of some sort.
(I don't really believe in the "magic" of the square motor setup, although it may help making tq at low revs)

Its all about combustion efficiency... but mostly the savings will be had via friction reduction... and keeping the revs down is also all about friction.
Once you get a few extra % of efficiency from good combustion and perhaps cooled EGR, the biggest losses are still friction by a huge margin.

Friction can be dealt with with high $$$ parts shaving a few% here and there, or you can cut it tremendously by dropping the revs. (friction==square law function, just like aero drag)
Water cooled heads may be a good plan, along with a 3.44 R&P and a .82 4th.(taller if available)

Stick it in something with a low frontal area/drag like a Ghia or some kit cars and you'll get great mileage, even with an otherwise mostly stock engine.

T3 fastbacks and notches aren't too horrible drag wise, ~.34Cd, about average, squares ~.37, again about average for a station wagon--- but low frontal area about the same as a Prius.