I have to say, that BC does have tiering in-built. Redstone engines are just wood. Stirling's are just cobble. Combustion engines are top tier, made out of iron. But as it stands, you don't really need high flow golden fluid pipes for engines. I'm envisioning a 'High-temperature Combustion Engine'. It produces 160 RF/t, but it requires two diamond gears, a standard combustion engine in place of the piston, a tank in place of the glass. A gold block in the center along the top and two Golden Kinesis pipes on the sides.
On the other hand, it gathers a lot of power per 'stroke' of the piston, and dumps it all into the system at once, but it's very slow to produce. Something along the lines of half the rate of other engines. At the same time, though, it should also require both a solid and liquid fuel to produce, as well as coolant. And it should burn an awful lot of coolant. More than double what the standard combustion engine does. If it sounds like a lot of work, that's the idea.
On the other hand, it gathers a lot of power per 'stroke' of the piston, and dumps it all into the system at once, but it's very slow to produce. Something along the lines of half the rate of other engines. At the same time, though, it should also require both a solid and liquid fuel to produce, as well as coolant. And it should burn an awful lot of coolant. More than double what the standard combustion engine does. If it sounds like a lot of work, that's the idea.