Date:         Wed, 26 Aug 2009 18:15:45 -0400
Reply-To:     rolftruck@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Rolf Lockwood <rolftruck@AOL.COM>
Subject:      Re: Engine to auto-tranny match and the Indy 500
In-Reply-To:  <200908261349.8b94a9575a134a@rly-ma07.mx.aol.com>
Content-Type: text/plain; charset="us-ascii"

 Mike S. wrote in response to Marc Perdue...



Date:    Wed, 26 Aug 2009 13:28:30 -0400
From:    Mike S <mikes@FLATSURFACE.COM>
Subject: Re: Engine to auto-tranny match and the Indy 500

At 12:27 PM 8/26/2009, Marc Perdue wrote...
>Is there any kind of automatic transmission alternative that could
>take advantage of the torquey (technical term again) Vanagon engine

Acceleration and holding speed up a hill are all about horsepower. An
engine's torque numbers are only useful as a rough indication of how
wide it's (horse)powerband is, and even then, only when considered in
relation to it's HP numbers.

A transmission can be made to give as much output torque as you want,
it's just a matter of gear ratios - but more torque = lower speed. HP
remains constant through a transmission (neglecting frictional loss).
More gears in a transmission allows one to keep the engine running
closer to it's maximum HP output, for better performance.

The comment you responded to was in relation to the scarcity of
transmissions to handle more powerful engines which have been adapted
to the Vanagon.

For the stock engines, VW engineers designed the gear ratios (and shift
points) for the best all-around performance and reliability, given the
available engine power. The stock 90 HP simply won't push a Vanagon
through mountains at 65 MPH, no matter what you might change in a
transmission.

When going uphill, I just get behind a semi going 45, and enjoy the
journey. If you're in a hurry, a Vanagon with a stock engine isn't a
good choice.




 Hello all. I'm both a Vanagon newbie and a virgin poster on this great list, from which I've already learned a ton in just a week or two. Thanks to all of you.

Lord knows my first post shouldn't be combative, and I don't mean it that way, but I think I need to say something about torque and horsepower. I'm a some-time truck driver (big rigs, that is) and 30-year trucking journalist, so I know torque pretty well.

Mike, you said acceleration and holding speed up a hill are all about horsepower, but I think that's only half right. Torque is defined as an engine's ability to do work, characterized by the twisting motion off the end of the crankshaft. Horsepower is a purely calculated value that measures only the speed at which the work is done. So the ONLY thing that gets you over the crest of a hill is torque, while horsepower determines how fast you do it. Torque is an absolutely 'tangible' value, horsepower a mere calculation.

Not sure what you mean when you say "...torque numbers are only useful as a rough indication of how wide it's (horse)powerband is, and even then, only when considered in relation to it's HP numbers."

Torque values are actually far more useful than horsepower numbers.

Truckers plan their shifts and their highway cruising speed based on where their engine produces peak torque, so when they hit a hill they fall into peak torque range -- usually around 1200 rpm -- and thus might be able to avoid a downshift. Torque alone carries them up the hill. If they have to drop a gear, they do it so that they fall into a spot above peak torque in the next gear so that they'll catch the torque curve and not have to downshift again. Driving truck is all about managing rpm in relation to torque, and horsepower isn't even a consideration.

I used this thinking on my inaugural trip in my weak-kneed but very fun 1990 Westfalia last week (4-spd manual box). I drove a 4300-km rounder from Toronto to Cape Breton and back, meeting some mighty hills in New Brunswick and Nova Scotia in the process. I learned quickly that if I cruised at a point just above where torque has its finest moment in a 2.1 Wasserboxer (3200 rpm with all of 117.3 lb ft), I could make a lot of hills without a shift. I cruised at 3300-3400 rpm, which looked to be about 96 km/h or about 58 mph, though the speedometer disagreed with my GPS thingy -- when the speedo said 95, my GPS said 91. I'll believe the GPS, but I'm only interested in the tach anyway. The hills would steal both engine and road speed but most of the time I fell into good torque and had no problem. It's actually a sweet sound to hear that little engine digging in to do some work at peak torque.

Anyway, on some roads and in some traffic conditions (I drove mostly at night partly to avoid those traffic conditions) I couldn't run at 3300 rpm, rather had to loaf along at 3000 or even less. That's when the hills gave me a problem and I frequently had to find 3rd gear in those situations while watching road speed drop sharply -- because I had less torque to fall back on. I haven't seen power maps for the 2.1 engine (anybody have such a thing?) but I'd guess that torque falls away pretty rapidly below 3200 and that the torque band is pretty narrow.

So that's my advice, FWIW: keep your engine turning just a couple of hundred rpm above peak torque and all but the worst grades should be manageable, with a manual or an automatic transmission. But you can't drive any vehicle well if you don't know where its engine develops power.

Mike's approach of tucking in behind a semi is on the money, I think. I did it more than once, though a couple of times I actually had to pull out to pass them on serious grades. They weren't pleased, I'm sure!

Hope this helps.

By the way, I have to praise Vanagon guru Frank Condelli before I go. I spent a day with him before I ventured east while he sorted my Westy, installing real headlamps, new shocks, and a few other bits and pieces. I learned a lot that day, so a public thanks, Frank.

Rolf in Toronto
3 weeks into 1990 Westfalia ownership