Supercharged VTEC vs. non-VTEC
Jeffrey Kwan
Their dyno plots can be found at:
http://www.jacksonracing.com/dynos/dyno.html
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Dear Jackson Racing,
There has been a discussion going on in the rec.autos.makers.honda
newsgroup about the effect of VTEC on supercharged engines. The argument
is that due to valve overlap in the VTEC engines, supercharged VTEC
engines will have the same power output as supercharged non-VTEC engines.
I have questions about some of the dyno plots. For the GSR, stock peak
horsepower is 150.6, which means 11.5% power loss through the drivetrain
from 170hp. Since the GSR and LS Integra are similar, I would expect
similar drivetrain losses from the LS, but you dyno stock horsepower for
the LS to be 106.6, which is a 23.9% loss. Where did this relatively
large loss come from?
After supercharging, what I see is a 38.2% increase in power from the GSR,
and a 50.7% increase from the LS. However, final power output is not the
same, as the GSR has 208.1hp, and the LS has 160.6hp. Corrected for
drivetrain losses (11.5% GSR, 23.9 LS), that means that flywheel
horsepower is 232.0hp in the GSR and 199.0 in the LS. I conclude from
this that supercharging has a greater effect on non-VTEC engines, but peak
horsepower is still higher on the supercharged VTEC counterpart.
We need you to settle this argument: what engine produces more power -
the supercharged VTEC engine, or the supercharged non-VTEC engine?
It seems that supercharging is most beneficial in the larger displacement
non-VTEC DOHC engines. The 2.0L CRV gets a 50.9% increase, 1.8L LS gets
50.7%, the 1.8L Miata gets 44.6%, but the smaller 1.6L SOHC CRX engine
gets 40.9%. When comparing VTEC engines, the DOHC 1.8L GSR gets 38.2% and
the SOHC 1.6L Civic gets 34.6%. So is it true that best engines to
supercharge are the large, non-VTEC engines?
More questions about the dyno plots: you dyno the '88 CRX to have
103.3hp, but the flywheel horsepower was advertised to be 105. Was the
dyno plot corrected for drivetrain losses?
Sorry for the long email. Technical replies would be greatly appreciated
and I will post it to the newsgroup.
Regards,
Jeff
Mista Bone
C. Tague aka. Mista Bone
"Baby won't you rock it tonight."
93 Honda Civic DX HB
1.5L NO VTEC! #17 DSP
15.51 @ 85 mph 1/4mile 2.02 60 ft.
THX
Supercharging. The VTEC unit has more potential at the extreme end. By that,
I mean, when boost pressure approached or exceeds 18psi, with the proper
VTEC-cam adjustment for overlap and timing, much higher output can be
realized. It really gets a whole lot complicated to get in depth...but
that's the gist of it!
THX
THX
also alters the timing at the same time...all of which can be programmed at
a desired rpm point. Little overlap is desired at low to mid rpm.
THX
Gold14K357
Clayton