What caused my power loss?
12-10-2008, 01:46 PM
#1
What caused my power loss? Two years ago I had a lifter tray break and I thought I'd dump the plastic trays and go with a rev kit. Rev kit worked for about a year and then it cracked, either due to poor directions, poor installation, and/or poor quality, so I went back to the plastic trays due to cost.
I finally dyno'ed the rebuilt motor last weekend. Between the motor with the revkit and the current motor with the plastic tray, I lost 10-15rwhp across the entire RPM band, with basically an identical AFR. We dropped the AFR a full point and it changed +/- 3rwhp across the entire power band.
Old:
Piston rings gapped by me
Rev-kit
Comp LSK 227/235 .645/.650 110+2
Cadillac lifters
German Castrol 0W30
Bearing clearances may have been a little looser
Now:
New rings, identical part number, gapped by locally renowned LS1 speed shop
OEM lifter guides
Comp XFI 226/232 .604/.609 110+2
Catch can
LS7 lifters
Redline 10W40
Re-used previous PRC Platinum springs after all were tested and were still like new
Bearing clearance may be a bit tighter
Obviously I'm irked. Could the LSK cam really be that big of a difference? I still have that LSK cam in a box but it has a little bit of wear on one lobe. I considered sending it back to Comp but convinced myself nothing would come of it so I didn't.
I finally dyno'ed the rebuilt motor last weekend. Between the motor with the revkit and the current motor with the plastic tray, I lost 10-15rwhp across the entire RPM band, with basically an identical AFR. We dropped the AFR a full point and it changed +/- 3rwhp across the entire power band.
Old:
Piston rings gapped by me
Rev-kit
Comp LSK 227/235 .645/.650 110+2
Cadillac lifters
German Castrol 0W30
Bearing clearances may have been a little looser
Now:
New rings, identical part number, gapped by locally renowned LS1 speed shop
OEM lifter guides
Comp XFI 226/232 .604/.609 110+2
Catch can
LS7 lifters
Redline 10W40
Re-used previous PRC Platinum springs after all were tested and were still like new
Bearing clearance may be a bit tighter
Obviously I'm irked. Could the LSK cam really be that big of a difference? I still have that LSK cam in a box but it has a little bit of wear on one lobe. I considered sending it back to Comp but convinced myself nothing would come of it so I didn't.
12-10-2008, 06:50 PM
#2
The cam differance will be a factor. Also out side temperature can come in to play, like you said tighter bearing, dyno, ect ect... I wouldn't get to cought up with a 2 year old dyno sheet with a differance of 10 hp. Big thing is how does the car feel.
12-10-2008, 08:59 PM
#4
I wouldn't care as much if it was just on the top end, but I want torque throughout the whole powerband for autox and roadracing. 410rwhp/378rwtq (SAE) or 420rwhp/389rwtq(STD) is phuckin weak for the money I've dumped in this motor. Used the same dyno. Maybe I need to start fresh with a complete new longblock instead of repairing the current block as things break.
