


Toyota's mainstream Camry lineup also looks reinvigorated


I. The New Camry

i.  Built in America with Non-Union Labor






ii. Tech Specs on New Camry




iii. Sales and Marketing





II. Twins Are Born

i.  The Hybrid Specs





ii. Sizing Up The Competition







Comments     Threshold


By lagomorpha on 8/24/2011 8:06:16 AM , Rating: 2
I can almost guarantee you that a 2.5L V4 with the sort of power curve needed for an Accord would vibrate itself apart. That's why you don't typically see them outside motorcycles these days.

By YashBudini on 8/24/2011 2:01:05 PM , Rating: 2
If the V is the proper angle (90 degrees for 8 cylinders and probably 4's, 60 degrees for V6s) what you say would hard to believe.

V twins should and do shake far worse than V4s. Yet the market is filled with Harley clones.

By lagomorpha on 8/24/2011 7:19:56 PM , Rating: 3
The real difference is the type of vibration. Four-stroke V-twins (except Harleys, long story...) have pistons that move together (both up, both down). This gives them vertical vibration which is easily solved with a pair of contra-rotating balance shafts. They even cancel out the horizontal part of their vibration in a function of the angle between them (even firing parallel twin like old BSAs get no cancelled vibration and throb noticeably, 90 degree V-twin gets 50% cancelled, 180 degree boxer-twin has almost no vibration). V4s produce twisting vibration which is harder to deal with.

And as far as Harley V-twins and some clones go (with both pistons sharing a crank-pin), Harley had to go so far as to add an option to mount them on big soft rubber engine mounts just to try to isolate most of the vibration. Harleys vibrate. To many Harley owners it's endearing, but no one wants it in a Toyota.

If it's cheaper to build an I4 and you end up with a quieter, smoother engine why bother with a V4? The Ford Taunus V4 only existed because they found a way to cut down a V6 and share parts which is why it's at 60 degrees instead of 90 degrees and has splayed crankpins.

Now if you need to fit a powerful engine between someone's legs and the more narrow you can make it the more lean angle it can get in corners a V4 makes perfect sense. V4 sportbikes like the Honda Interceptor, Aprilia RSV4, and Ducati Desmosedici have very short strokes in order to reach high-rpm. Short stroke = less piston travel = less vibration, unfortunately it also means less torque. Something tells me if Toyota put an engine in a Camry that needed to rev out to 12,000rpm to make its advertised power some people would swoon, but most would complain.

Are there 2.5L V-twins? Yes, Viper Motorcycle makes one. Does it have a car-like bore/stroke ratio? Nope, short stroke.

By Dorkyman on 8/25/2011 1:48:18 PM , Rating: 2
I enjoyed your comments about engine layouts, but have one minor quibble.

From what I recall, going with a short stroke (and larger bore) means lowered peak ring velocity, giving the ability to rev higher. Also the larger bore allows for better breathing via 4 or more valves. The more air moved through the engine, the more fuel, and the more work performed.

Nowhere do I recall a loss of torque inherent in a short-stroke design. Yeah, in a long-stroke engine the crank throw is greater, but the piston area is correspondingly smaller, canceling any theoretical benefit.

