flat lining HP....question is why?
11-08-2007, 01:41 PM
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flat lining HP....question is why? Got a head scratcher here, need some more input.
I have done two different dyno sessions last month, here is a brief overview.
1st Round:
put down 612hp/650TQ. Max HP was at 5500ish and flat lined to 6500. Max TQ was just south of 4500 rpm. My meth blew a fuse, wound up with IAT's at 150* and only 7.5* timing.
2nd round:
667HP /700TQ...pretty much same RPMs as first pull
with low ambient temps and my Meth working I was getting 22* timing, hit a little rough spot with KR, but at WOT no KR and full timing. LC-1 reported 10.9 AFR. The curves look the same between the two pulls, although I picked up 50/50 I would have thought 15* of timing to be worth more?
I have been calling the "experts" but have yet to find a concensus. Some believe its the exhaust, some think tuning more tuning...
I find it interesting that despite AFR and timing adjustments the HP / TQ curves look the same albeit slightly higher. It is just weird how 5500 rpm seems to be the max power setting.....whether it was 612 hp or 667 still flatlines at the same point?
could this be valve float?
Rhoads lifter issue?
Need inputs....Thanks Guys.
I have done two different dyno sessions last month, here is a brief overview.
1st Round:
put down 612hp/650TQ. Max HP was at 5500ish and flat lined to 6500. Max TQ was just south of 4500 rpm. My meth blew a fuse, wound up with IAT's at 150* and only 7.5* timing.
2nd round:
667HP /700TQ...pretty much same RPMs as first pull
with low ambient temps and my Meth working I was getting 22* timing, hit a little rough spot with KR, but at WOT no KR and full timing. LC-1 reported 10.9 AFR. The curves look the same between the two pulls, although I picked up 50/50 I would have thought 15* of timing to be worth more?
I have been calling the "experts" but have yet to find a concensus. Some believe its the exhaust, some think tuning more tuning...
I find it interesting that despite AFR and timing adjustments the HP / TQ curves look the same albeit slightly higher. It is just weird how 5500 rpm seems to be the max power setting.....whether it was 612 hp or 667 still flatlines at the same point?
could this be valve float?
Rhoads lifter issue?
Need inputs....Thanks Guys.
11-08-2007, 04:18 PM
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Valve float will cause more than a flatline, especially under positive manifold pressure. What are the iats at with the 22* timing? What intake are you running and is the afr doing anything weird after 5500?
11-08-2007, 09:21 PM
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Starting @ 5500RPM IAT 65* timing 22*
@ 6200 RPM, IAT increase to 81* timing decrease to 20.5*
Running an OEM LS6 intake
AFR with the tail pipe sniffer, was steady @ 11.7
my LC-1 showed a little richer, by half a point roughly.
11-08-2007, 09:25 PM
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Now that I am starting to rethink the whole build, what would the indications be of a timing chain being off by one tooth?
This was not my first dance so to speak, and although I was careful it doesn't mean a mistake was made and I just did not notice it. Gonna have to look through my assembly pics, pretty sure I documented that part of the install...just thought I would throw that out for comment....anyone had that happen? what were the results?
This was not my first dance so to speak, and although I was careful it doesn't mean a mistake was made and I just did not notice it. Gonna have to look through my assembly pics, pretty sure I documented that part of the install...just thought I would throw that out for comment....anyone had that happen? what were the results?
