Date: Mon, 3 Jan 2000 20:33:42 EST
Reply-To: FrankGRUN@AOL.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Frank Grunthaner <FrankGRUN@AOL.COM>
Subject: Re: Some Comments on Engine Conversion Eurospec vs. non -
Content-Type: text/plain; charset="us-ascii"
Sorry, apparently too confusing. Some more details on the air filter setup
and rear ducting.
The '90 GTi engine throttle body faces the rear of the engine compartment. I
cut a rubber air hose (connecting the AFM to the throttle body) from a Fox.
The cross section of the center of the hose is the same as the throttle body.
I cut the hose using the round (65 mm diameter) hole to point vertically. In
other words I made a short 90 degree interface to the throttle body that ends
in the same diameter as the AFM mounting port. I then used a 2.5 inch PVC
pipe elbow (same ID as the port coming from the AFM) and coupled them with a
short rubber hose. This second right angle points into the open area -
drivers side, leading to the air intake on the side of the vanagon. This is
the area where the original diesel brought air in through a phase separator.
I then mounted the AFM so that the entrance to the AFM is right at the
entrance to this open area. I then mounted a p-flow K&N air filter (round
conical design) to the front of the AFM. The air filter is taking in air
introduced from outside via the side scoop/intake. When moving the pressure
generated in the engine compartment is such that the air temperature in this
area runs more than 30 C (range is 30 to 60 C) above the outside air
temperature. (Yes, I actually ran with a thermocouple bonded to a 10 cm. by
10 cm. copper foil to measure air temperature.) Remember that this is also
the side of the exhaust manifold. Finally, I took a strip of neoprene
(available at diving shops) and cut it so it had a circular hole to slip over
the round mount of p-flow to AFM. A slit is provided to slip over the p-flow
and the rubber is bolted in place at the top of this air intake area and
along the fenderwall side of the engine compartment to close off this area
from the hot air generated around the engine. No screws for the bottom or the
taillight side. I then took a piece of rectangular cross section dryer vent
pipe (meant for mounting a clothes dryer close to a wall) and fabricated an
air channel which goes from the air intake area to the rear louvers at the
exit of the engine compartment. Not hard to do. The Al cuts nicely and I just
pop-riveted the assembly together. To remove it though, one has to
disassemble the whole AFM intake package.
The modified Fox air intake to PVC system was designed to minimize the intake
air length. BTW, I added a port to the PVC tube for the inlet to the idle
stabilizer. My previous design actually starved the engine for air at high
rpm. It was 4 X as long as the stock digifant air intake hose and included a
180 degree bend together with some 30 and 60 degree turns. The new part
(Fox/PVC) has the same flow at 1 Bar pressure differential as the stock part
despite the two 90 degree bends.
Current temperature stays at ambient regardless of velocity, sometimes it
goes as much as 5 C below ambient, but under these conditions wind chill is a
factor in the ambient measurements. System works just fine. Picked up 1 to 2
inches of vacuum at cruise and the engine doesn't run out of air at
ridiculous rpm's. (I often run this thing at 6000 to 6500.
Hope this clarifies,
Frank Grunthaner
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