Power problems with JWT C2s

Ari nismo87 at houston.rr.com
Fri Jun 17 21:49:06 CDT 2005


About 2 months ago I installed JWT C2s + valve springs to replace my S3s.
The reason I got C2s was because Ben at JWT told me that they didn't have a
100 shot n2o program for the S5s.  After doing the breakin and resetting my
cam gears to 0*|0* I did some baseline pulls.  Using road dyno (program I've
used for 1.5 years on the same road), I got the results and was
disappointed.

So far I've tried these combinations of cam timing +6 int/+6 exh, -6 int/-2
exh, +4 int/-4 exh, +1 int/ 0 exh, -4 int/ 0 exh, -4 int/+4 exh.  None of
these combinations made any more power than having the cam gears at 0 int/ 0
exh.  The weird thing is that when I tried -4 int/+4 exh I thought it would
have the opposite effect of +4 int/-4 exh (which made nice power from
2500-5500rpm but less toppend), however it only was able to match the topend
of the baseline pull.  I have all my pulls in a MS excel spreadsheet if
anyone wants to take a look at them.

I even did some searching and reading on degreeing camshafts and trying to
learn how lobe separation and LCA affects engine power.  So far nothing has
helped me and i'm really disappointed that I spent $1k to not gain any power
anywhere.  I see the C2 dyno on the SCC sentra se-r and decided that since I
made around 136-140whp with S3s I should see 152-160whp with C2s and
240-250whp with 100shot.  But it looks like I'm going to fall way short of
that goal :(.

The other mods to my B13 are 2.5in CAI (4.70v MAF peak), HS gen VI, 3in cat
+ midpipe with cutout, phenos, UDP, JWT ecu (C2 + n2o).  The engine has new
plugs, wires, cap/rotor, fuel filter and gets good gas mileage (26-28mpg).
Also my wideband o2 shows a 14.0-13.3 AFR from 2000-4500rpm and 12.6-12.3
AFR from 4600-8000rpm.  Leaning out the mixture didn't show an increase in
power so I reset the FP back to 43psi with the hose off.  If anyone has any
tips or critizism they are welcome.  BTW when installing the valve springs I
was able to do a leak down test.  I got 3-4% in all cylinders however I
think some pressure could've leaked out of the air hold.  Next up is a
compression test to ensure that the engine is still good. Below is a dyno of
my se-r with S3s at 0|0 vs my best C2 pull.

http://www.sr20forum.com/img/data/500/S3_vs_C2_dyno.JPG


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