Stuck in the projects
I am a new subscriber and just got my first issue in the mail. Gave it a quick scan-where is the "Project Cars" section that's on the website? I came across the website and really enjoyed reading about the project cars, enough that I decided to get a print subscription. Things like that will set this magazine apart. Hope it's just missing from this issue and is normally part of the magazine.
We publish project updates when we can, but given the legwork, labor and testing involved they are some of the more complicated features in the magazine. Having said that, check out the back of the mag for an update on Project Z4 M, and an intro to a new project spearheaded by Mr. Neilson wherein he and a few other crazy Canadians begin their build-up of a 911-beating Cayman. Also, stay tuned for updates on Project 997TT and Project R32, along with a few other new series we've got in the queue.
Cars as art
I just wanted to say that I enjoy the magazine. I like the editor's column, Parts & Labor (Flying Hammer, yeah!), and Sport-it's about time! However, I do miss the Imagineering section. I like to draw cars myself, so I can appreciate someone that does it well.
We're currently searching for talented illustrators to take the Imagineering section to the next level. Anybody out there wield a mean Adobe Illustrator?
Not to complicate the issue...
I'd like a little more explanation from someone in regards to the letter from Brandon Grantham of Kleemann USA (Incoming, February '09). His argument that it's incorrect to assume a certain percentage of driveline loss regardless of power input seems correct to me. What doesn't seem correct is the argument that the driveline loss is a "fairly fixed and finite number." His example is a car with a 63hp driveline loss regardless of power input, which would seem to imply that it takes 63 hp from the engine to see any output at all at the driven wheels, but I don't think that's what he meant.
It seems logical to me that the loss through the gearbox itself (not the whole drivetrain) is pretty close to a fixed percentage since I would suspect that the viscous drag in the bearings and the power to overcome the inertia of the gears are both small compared to the friction between the meshing gear teeth. A quick scan of my mechanical engineering textbooks has uncovered talk about a fixed gear-train efficiency factor, not a finite number. The friction force is proportional to the coefficient of friction multiplied by the normal force and the normal force on a gear tooth face would increase as a result from an increase in input torque. So for the just the gearbox itself, I suspect it's probably pretty accurate to assume the power loss is a fairly fixed percentage of input power.
I guess it seems that Mr. Grantham is being conservative (which I appreciate), while other tuners who assume a constant powertrain efficiency are overestimating the power output at the engine. Can someone help clear up the entire picture? Maybe european car could run some experiments and give us readers all the data in a tech article or something?
This particular subject is way over my head, but given the feedback we receive on dyno tests and the debate over dyno testing in general, it seems a primer on the ins and outs of dynos, engine output, and drivetrain loss is in order.--KF
Readers On Other Readers
For Teddy N. (Incoming, February '09): The reason you see so many BMWs on your commute is because they are reliable. I've owned a Volvo, two Audis, and a Fiat (Fix It Again Tony), and all they did was put my mechanic's kid through college. I can remember my dad cringing when I shellacked his Volvo on Father's Day (thinking it was wax). So I've known Euros. Nothing is like my Bimmer.
By the way, if anyone did make German Car the magazine, I'd subscribe to that too.