Date: Sat, 23 Oct 2004 19:03:52 -0500
Reply-To: Bruce Nadig <motorbruce@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bruce Nadig <motorbruce@HOTMAIL.COM>
Subject: Re: Project Vanagon Dyno Results & Comparison
Content-Type: text/plain; format=flowed
Jeff,
The reason that the stock rebuilt engine generated a measured 77 hp at the
rear wheels is that there is "driveline loss" between the crank and the
wheels. It takes some power to overcome the friction of turning all of the
gears in the transmission, the inner and outer CV joints, and the wheel
bearings themselves.
Manufacturers usually quote "crank horsepower" as this is the larger of the
numbers they have to work with. As a general rule, you can anticipate that
driveline losses will account for 10 to 15 percent of the crank horsepower.
Here is the math. The stock Vanagon 2.1 engine is rated at 94 horsepower (I
believe). A 15% driveline loss would account for about 14.1 horsepower. That
would mean that IF (and I did say if) the engine was producing 94 horsepower
AND there was a 15% driveline loss, then you would anticipate the wheel
horsepower to be about 79.9. This is very close to the 77 that was actually
measured (about a 3% difference).
The rebuilt Boston Bob engine was running strong. It has approximately
20,000 miles since the rebuild, and the owner is very happy with its
performance. From this dyno test, I would conclude that the Boston Bob
engine was performing very well.
As a comparison, the Porsche engine in my Vanagon is rated by Porsche as
having 217 horsepower. In addition, I have added a performance computer
chip, a test pipe (hollow replacement for the cat), and a free flowing
exhaust (good for a few hp). With these power producing upgrades, my Vanagon
produced 196.8 horsepower at the wheels. Now lets assume that there is a 15%
driveline loss for the Porsche set up (it is actually probably closer to
10%). That would mean that I am producing approximately 230 horsepower at
the crank.
I hope that this makes things more clear. I do believe that a Boston Bob
engine is probably one of the best that you can get. Not only did my
friend's engine perform well, to my knowledge, he is very happy with it and
has had no reliability issues after initial installation (there was one
small glitch then, but I don't know what it was).
Cheers,
Bruce
motorbruce
motorbruce@hotmail.com
>From: "Jeff Palmer" <icecoldvw@hotmail.com>
>To: "Bruce Nadig" <motorbruce@HOTMAIL.COM>
>Subject: Re: Project Vanagon Dyno Results & Comparison
>Date: Sat, 23 Oct 2004 00:10:46 -0500
>
>Bruce, first of all your project is sweet. But way out of my league. So
>here's my question:
>
>Why would a relatively fresh motor only produce 77hp? Why is it not closer
>to the factory original output of 94? I'm going to be looking for a new
>motor sometime soon (next spring perhaps) and I'm looking at AVP from
>busdepot, or Boston Bob, or who knows. Is this a problem with the motor is
>just the way it was tested?
>
>Thanks
>Jeff
>ps that motor would rock in my 69 type 3 notchback!!!
>
>----- Original Message -----
>From: "Bruce Nadig" <motorbruce@HOTMAIL.COM>
>To: <vanagon@GERRY.VANAGON.COM>
>Sent: Friday, October 22, 2004 4:14 PM
>Subject: Project Vanagon Dyno Results & Comparison
>
>
> > Howdy From Austin,
> >
> > For those of you that haven't been following my project, I have
>installed
>a
> > Porsche 3.2 liter engine and G50 5-speed transmission in my '87 VW
>Vanagon.
> > When I purchased my Vanagon it was completely stock with an automatic
> > transmission and a 4 -cylinder water-cooled boxer engine rated at 94
> > horsepower. It was, to say the least, rather a slug on the highway.
> >
> > I finally got my first 1,000 break-in miles completed, my valves
>adjusted,
> > and oil changed. So, that meant it was finally time for me to take a
>trip
>to
> > the dyno. For comparison purposes, I had my good friend John go along.
>He
> > has a '91 Vanagon with a 4-speed manual transmission. In addition, he
>has
>a
> > relatively fresh Boston Bob stock rebuilt engine with about 20,000 miles
>on
> > it. I felt that having his van there for comparison would be very good
>at
> > putting things in perspective.
> >
> > All testing was performed at Colvin Automotive in Austin, Texas. Project
> > Vanagon was run first, then John's stock Vanagon was run immediately
>after.
> > Weather conditions didn't have a chance to change between runs. The
> > thermometer read about 80 degrees and it was quite humid. The test was
> > performed on a DynoJet 284C dyno.
> >
> > The stock Boston Bob stock rebuild yielded a maximum 77.0 horsepower at
>the
> > wheels. Torque was very high at 93.8 foot-pounds. Most impressive was
>the
> > broad torque band. Sixty percent (56.3) of peak torque was available
>from
> > 1700 rpm to 5200 rpm. There was a real abundance of torque available
>almost
> > everywhere.
> >
> > Obviously this was not a fair fight. There is no way even the most
>pumped
>up
> > 2.1 wbx could compare to the 3.2 Porsche Carrera engine. Project Vanagon
>was
> > fitted with a test pipe and a genuine RUF 2-2 R twin tip muffler ceramic
> > coated muffler (I just got it on yesterday). Vincent showed a very
> > respectable 196.8 horsepower at the wheels. Torque was also strong at
>183.1
> > foot pounds. Sixty percent (109.86 foot pounds) of peak torque was
> > available from 3,200 rpm up to 7,000 rpm.
> >
> > So my work, and the work of some very close friends has brought about a
> > 255.8% increase in rear wheel horsepower, and a 195.2% increase in
>torque
>at
> > the wheels. Not too shabby.
> >
> > Once again, I'd like to thank all of the folks that made all of this
> > possible. It has been a long, hard road, but well worth the trip. And
>I'm
> > not done yet. There is still much more to come.
> >
> > Cheers,
> > Bruce
> > motorbruce
> > motorbruce@hotmail.com
> >
> >
>
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