Dyno run

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Dyno run

Postby h-bot » Wed Jan 01, 2003 6:15 am

From: gentec2000_REMOVE_620300_THIS_@yahoo.com

To those interested, I posted some videos of my car on the dyno under
"Files" in the folder "Dyno Runs." This car is running a positive
displacement supercharger running 10 psi of boost. This is the same
car as posted under" Supercharged" in the "photos" section. The motor
for the most part is stock- stock cams, stock pistons and rods
(polished and shotpeened with ARP rod bolts), no sleeves. I replaced
the FI with a DFI unit and the ignition with an Electromotive
distributorless ignition. The FI was mapped out on a Dynojet under
various loads and engine speeds. Once the FI was mapped out I started
slowly bumping up the ignition advance. The car seemed to want more
advance but I stopped at approximately 26 degrees of total advance. I
could have squeezed more HP out of it but I didn't want to risk
damaging the stock pistons if the car started detonating. The car
also had a full exhaust including a catalytic convertor. For those
not wanting to download the videos, the car made approximately 180 hp
@ 7000 rpm at the rear wheels. This may not sound alot to some but
considering that this car made 98 hp stock, an 80hp gain with only 10
psi of boost is pretty decent. Since the blower makes boost
everywhere in the rpm range, the car is "very" responsive even down
low in the rpm range.

The videos don't do justice to the sound this car was making under
full load on the dyno. With the blower whine and the exhaust noise
from the motor under full load at 7000 rpm, this car sounded
incredible.

In video #3, the gold box on top of the dashboard is a Motec A/F
ratio meter using a wide band O2 sensor. This was used to tune the
FI. The boost gage is towards the very right in the center pod of the
dashboard. 10 psi is at the 30 position.

Todd




[This is message #10146 by user gentec2000 on Yahoo! Group Cosworth Vegas: http://groups.yahoo.com/group/cosworthvegas ]
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Dyno run

Postby h-bot » Wed Jan 01, 2003 6:48 am

From: doctorduke_REMOVE_551889_THIS_@yahoo.com


Sounds like you've done a good development job. As you may be aware
from previous discussions the OEM CV cam indexing has an extreme
amount of overlap to create an internal EGR system for NOx control.
This excess overlap will hurt a boosted engine even more than a
naturally aspirated engine. If you reduce the LC angle to 114 or even
116 you will likely be able to reduce the supercharger drive ratio to
achieve the same boost with less parasitic loss, which will boost the
torque curve across the entire range and probably get you to 200 HP.

With all the overlap a lot of boost pressure is leaking into the
exhaust system during the overlap period. Boosted engines need very
little overlap because the inlet side is always at positive pressure
relative to the exhaust side at WOT.

Also, a header does little good, but it doesn't hurt either. As with
a naturally aspirated CV, a key to top end power with a boosted engine
is minimum exhaust backpresssure.

Duke




[This is message #10151 by user doctorduke on Yahoo! Group Cosworth Vegas: http://groups.yahoo.com/group/cosworthvegas ]
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