Well I had a disappointing day at the dyno today. Only gained 1.4RWHP and
5RWTQ, this is after the HO cams. This brings me to 225.4RWHP and 283.5RWTQ.
My guess is that 3.5 degrees of timing out of the PCM is making a big
difference! Also, you can see a steady decline after 4400 RPM of the of the
TQ/HP curve.
Changes between this run and last run:
- HO cams
- 21# FMS injectors
- (-3.5) degrees timing on the PCM
Other things that may make a difference between this run and last run:
- I have a bolt in cat for the third cat now. There is a minor leak around
where the cat bolts to the exhaust. I can tell this because water leaks out
from where you bolt the cat in (I got ripped on the install job I had this
crappy shop do)
- I'm running a Robertshaw 330-180 thermostat. The problem is it's such a
HIGH FLOW tstat, the truck doesn't warm up a lot of the times, and trips a
check engine light. I'm thinking I should change it to a GT755-180
thermostat? Could this be affecting HP/TQ?
Here are my questions:
1) I think I need to get that timing put back in! 3.5 degrees must make a
big difference
2) HO intake?
3) I'm going to remove third cat, and weld in some pipe between the Y pipe
and muffler. My question is, should I go 3" between Y pipe and muffler, or
go 2.5" to like halfway to the muffler. I DO NOT want to loose any more
power, and I know our engines aren't that large, so we need to be
conservative on pipe size. Is this even worth doing?
4) Anything else you can suggest based on my mods. Do I need to change my
exhaust?
Again, my mods are as follows:
- Mike Leach PCM (With 25 degrees of timing instead of 28)
- FMS 21# injectors
- HO Cams
- 4" Z-tube
- Magnaflow 3" IN 2x2.25" OUT exhaust
- F&B Throttle body
- Robertshaw 330-180 Tstat (180 degrees)
Sorry for the long post, this whole thing was kind of frustrating.
This archive was generated by hypermail 2b29 : Fri Feb 06 2004 - 11:47:26 EST