Here's Steve's latest article. I hope you all find it interesting!
The future of the internal combustion engine
Whether or not you believe in global warming or the world wide shortage of oil, one thing is certain: the price of fuel is going up, and governments all over the world are putting laws into effect to improve fuel economy and curb CO2 output.
This will have profound effects on the cars we love to drive. The only way to make a high performance car engine that produces good power output on demand, low fuel consumption and CO2 output is to decrease the size of the engine and add turbocharging. The 335, 535, and 135 models are just the first few in a long line of cars BMW will likely produce. As we move forward it is likely that displacement will reduce, redlines will lower, and boost will increase. I am sure you all have heard of the new 4.4L Twin Turbo V8 coming out in the new X6. This engine will likely proliferate its way through the entire V8 product line over the next few years. Additional new engines will come out with a constant reduction of displacement and increased boost.
To get the engines to make ever-increasing power output for their size, material strength will become more important. Once BMW has had a chance to evaluate the long term wear of the new 3.0l inline six, Dinan believes BMW will upgrade the block and crankshaft rods and pistons inside the engine. They will likely increase boost as these upgrades are made, and as their confidence grows. Water jackets will be altered, and heat exchangers will get improvements to handle the extra load.
Great days ahead:
With the introduction of turbos, we can now make big power gains at low cost. The software has become incredibly complex, but even expensive software costs a lot less than making a whole turbo or supercharger kit. We are going to be making a lot of really fast cars for relatively low cost.
Turbos are like drugs. Every time you add boost the engine makes more power, and so you just want to keep adding more! The problem is that long-term durability can be compromised. Things that will not show up in the first few thousand miles, or even 10k or 20k miles, will eventually show up as the car gets old. So itís prudent even for us serious enthusiasts to add boost carefully and let the long-term ramifications of our decisions shake out before we go wild. In addition, as the factory upgrades the material strength of the engines themselves, we will be able to increase boost even more. In other words, the next generation of the 3.0L inline six will safely produce a lot more power than the current one.
Pitfalls of small turbos:
Turbos of old had a lot of lag. In an effort to reduce this, turbochargers have become very small and are now turning some incredible RPMs. It is very easy to exceed the rpm limit of the turbo, causing it to burst!! So before we can make a lot of boost at high engine RPMs, it will be necessary to increase the size of the turbos. One side affect will be increased lag.
Computer controlled boost issues:
With mechanically driven superchargers, like those in our kits for the E36 and E46, any reduction of inlet restriction or improvement to intercooler pressure drop will cause the engine to see an immediate increase in boost and power. On the other hand, with a new computer controlled waste-gate on a turbocharged engine, like that of the 335i, modifications like cold air intakes or intercoolers with improved pressure drop hardly change power output! This is because the computer will lower the turbo RPM to compensate for reduced restriction, causing the engine to continue to see the programmed boost setting and almost the same power output. A small power gain will be realized as the turbo bypasses more exhaust gasses through the waste gate and less through the turbine. Additional power can be had from a gain in intercooler thermal efficiency, but not as much as one might expect. Our testing of intercoolers and cold air intakes has yielded much less power than people are advertising. Good news though, since these modifications reduce turbo RPM, we can increase the boost at high rpm where itís falling off, increase peak power output, and extend the rev band without over-reving the turbos.
I hope you all enjoy the new direction at BMW. I know I will!