On planet Pathak, peak torque is closer to 6000 rpm. That's one revolution every 10 milliseconds. A modern automotive fuel injection system is sequential, meaning it fires each injector in sync with that cylinder's intake stroke. That means the injector has two revolutions, or 20 milliseconds to do its cycle. The limit of 0.8 milliseconds is only 4 percent of that 20-millisecond window, so the duty cycle can be 96 percent before the injector goes static.
Now, before someone tries to fact check me again, realize that the 0.8 millisecond limit is a pretty rough number. The actual minimum closed time depends on the injector, the fuel pressure, the voltage used, the phase of the moon, and the type of injector driver in the ECU.
Big Motor, Small BMWI was looking into purchasing an older BMW and came up with an idea and wondered if it was stupid or not. I was thinking, why not take the 318 Ti, because of its size and weight, and put in a good old 2.8/3.0L I-6? Both of these motors would be pretty easy to find at a junk lot and be a lot cheaper than, say the M3's 3.2L motor. With the small size of this car and the higher output I-6 motor I could easily make into a strong track/autocross vehicle. Would it be possible? And if it was, would it be worth the time?David HummelAngier, NC
Back in 1999 Subaru was known only as the slow but reliable way to dig out of a snowy driveway, and the WRX was a mythical beast known only to a privileged few. Josh Jacquot and I were two of those few and we made a regular habit of borrowing the keys to one 1997 STi RA. The RA was the lightest and most powerful WRX you could get at the time. Lacking bumpers, air conditioning, or even a radio, the RA weighed about as much as a Miata with a fat guy in it. It also happened to have the biggest turbo Subaru had ever used to date, matched with ultra-short rally gear ratios. It was the best car I had ever driven at the time, and remains in my top ten even today.
What this has to do with your BMW is this: Thinking we had found the unbeatable sleeper, we entered the tame-looking sedan (16-inch wheels, no wing, rental-white paint) in the Mid-Priced Sedan class at One Lap of America. Strutting around the parking lot at the start of the race, Josh and I had that confident air of someone packing a suitcase nuke at a knife-fighting tournament. Not only were we virtually guaranteed to clean up Mid-Priced Sedan, our dopey looking Subaru would guarantee that the ass whooping we were about to hand out would be as shameful as having your leg bitten off by a puppy.
Then we noticed a gentleman by the name of Catesby Jones. Standing next to his innocuous looking BMW 318 Ti, Mr. Jones looked somehow familiar. You meet a lot of car dorks in this line of work, but neither Josh nor I could place this guy. Then we realized it wasn't his face that was familiar, it was his air of confidence. His puppy was itching to bite someone's leg off too.
Catesby Jones had a turbocharged M3 engine tucked away under his mid-priced hood, and as it turned out, it was our asses that got the whooping.
So yes, the big BMW engine in the small BMW chassis is a good idea, but only if you sleep on a mattress full of cash every night. BMW engines, even in junkyards, are expensive, and making power with them is even more expensive.