Date:         Wed, 26 Aug 2009 14:28:18 -0700
Reply-To:     Robert Fisher <refisher@MCHSI.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Robert Fisher <refisher@MCHSI.COM>
Subject:      Re: Drafting (was Re: Engine to auto-tranny match and the Indy 500
In-Reply-To:  <c2c43a7e0908261317l6a3ad02fgb50224df8d65ecaf@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

I experimented with this on my recent trip out to Laughlin, initially by
accident (meaning I first just happened to notice the effect, and then I
began to try to duplicate it). If you approach a semi from the rear (paying
attention to your distance) I could actually feel the sweet spot when I
entered and left it, at least on the standard 'big box' trailer (tank
trailers, for instance, apparently bend the air differently, as you would
expect). There was an area in which the feel of wind resistance lessened
considerably and the noise also dropped noticeably (we had the windows
down). That's how I knew I was in the zone, when I had both of those things
at the same time. It was kind of weird to have the noise go away like that. 
I certainly wasn't drafting, but it was a little closer than I think I'd
normally want to follow anything, mostly because I hate not being able to
see the road ahead. I noticed that if I closed up on the truck I lost the
low-noise effect for some reason. I followed one truck in this 'zone' for
quite a while on one stretch and it had no noticeable effect on my temp
gauge.

My tranny shifts out of first at around 18 mph and out of second at around
28, both of those between about 2300 and 2800 rpms, depending on conditions.
I'm sure the idea was to balance fuel efficiency, emissions, performance and
so on, but those both seem ridiculously low to me. I've never taken 2nd to
more than about 48/4K; it feels pretty wound out above that, and I remember
Dennis warning that the oil temps jump considerably with long pulls over 4K.

As to the 55 mph 'limit', remember that at the time these vans were built
and sold, the US speed limit anyway was 55 nationally. I have this same
thing in one of my 80s Chevy vans that has a 4-speed/overdrive auto. If you
try to exceed 55 in a lower gear in auto mode it won't let you. I don't know
that they actually picked that number for a limit, but from an engineering
standpoint I'm sure they were trying to build vehicles to the known existing
conditions. There are sections of I-40 that have a 75 limit now, and on
those I just stayed over with the trucks and kept it to about 65, trying not
to get killed by the a-holes in SUVs that were clocking 80-85.

I wasn't going to mention it because somebody alluded to it several weeks
ago and made it sound like some sort of secret (I wasn't give any reason to
think it was, however), but then somebody addressed it in this thread, so if
the cat was supposed to be in the bag it's out now. Akiba told me some time
ago that they're working on a way to get the entire Zetec drive train into a
Vanagon. Considering his frustrations in being cut off from what is probably
the majority of his potential market, I'd think that solving the Cali smog
issue is essential to the long-term survival of Bostig. I've given a lot of
thought to what he told me, trying to work it out in my head. It's a very
interesting idea. If anybody could pull it off I think he'd be the guy, and
it'd be a great thing for Vanagons.

Cya,
Robert

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Marc Perdue
Sent: Wednesday, August 26, 2009 1:18 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Drafting (was Re: Engine to auto-tranny match and the Indy 500

Given that drafting is dangerous, given that Mike S. probably wasn't
implying drafting, the question remains, does drafting affect the
cooling system significantly on a water-cooled vehicle?  Additional
question, assuming you are not drafting but following at a safe
distance (3 second rule), would you be outside of the lower pressure
zone behind the truck in front of you?  Just curious...

Marc


On Wed, Aug 26, 2009 at 3:50 PM, Dave Mcneely<mcneely4@cox.net> wrote:
> On Wed, Aug 26, 2009 at 1:59 PM , Greg Potts wrote:
>
>> Hi Marc,
>>
>> The benefit of "drafting" is the reduction in relative wind speed
>> lessens the load on the engine.
>>
> Surely the poster who said he just settled in behind a semi on hills
> wasn't talking about the practice of "drafting" (following very closely
> behind another vehicle so as to avoid air resistance).  Of course,
> because the vehicle ahead might make unexpected maneuvers, this is
> extremely dangerous.  I think the poster simply meant that he follows
> behind the semi at whatever the semi is running and at a prudent
> distance.
>