So I kinda derailed the UR Group Buy Pulley thread so I will post my pulley findings & technical info in this thread.
My apologies to Willy18 who started that thread & others. It was unintended, I just got focused on the technical discussion.
Here is a link to that thread:
http://tsxclub.com/forums/1st-gen-engine/41325-group-buy-ur-pulleys.html
Here is the Pulley/Damper Comparison I've been putting together:
(it includes further updates) I hope my info is correct.
Stock TSX steel crank damper dia------ 6.125", 4.6 lbs.
Stock K20A2/PRB steel crank damper----5.80", ___ lbs.
Stock K20Z1/PRC steel crank damper----5.40", 4.2 lbs. US$110. Actual US$160 (2005-06 RSX-S)
Fluiddamper steel crank damper-------- 5.875", 6.5 lbs, US$350.
ATI street aluminum crank damper----- 5.500", 3.6 lbs, US$330.
Alutec alum crank pulley----- 5.8", __ lbs, US$250.
UR alum crank pulley-------- 5.125", 0.75 lbs, US$___, (US$350 for the kit.)
NST alum crank pulley------- 5.2", 0.81 lbs, US$125.
T1R alum crank pulley--------5.8", 1.43 lbs, US$180.
Marcus at Heeltoe provided some valuable technical info on the Pulley Group Buy thread plus he initiated some very good discussion on K20a.org:
The whole damper vs. no damper discussion is difficult.
There is very little, if any, solid evidence to show that deleting the factory damper with a solid crank pulley will cause engine damage but WHY did Honda choose to incorporate the damper function in the 1st place if it wasn't really needed.
There is no question that an underdriven lightweight crank pulley with no damper function will provide the most HP gain but there are drawbacks & compromises to that.
This picture is totally interesting & thanks to the guy on K20a that did his research & posted it:
(note that the diameter is critical in any pulley discussion)
Thats the stock TSX crank pulley/damper on the right. The one of the left is the most interesting one though. It's from the PRC engine 2005-2006 Type S RSX.
From Acuraoemparts.com:
P/n 13810-PRC-003 PULLEY, CRANKSHAFT 2006 RSX US$109.37 (Actual US$160.)
I wish I had the weight of this pulley because this looks like a winner for my needs.
It's OEM & steel for durability. The damper functon is maintained. It likely slightly lighter than the stock TSX one, it's slightly underdriven. It's cheap!
Since it's slightly lighter & slightly underdriven it would provide a little more HP with no major drawbacks.
It looks like great value & a great compromise all around for a street car.
The K20 guys like & use this pulley also.
For reference here are some pulley links:
Pulley - Engine - 2003-2008 Acura TSX & JDM Honda Accord CL7 CL9 - Acura Parts - HeelToe Automotive
HONDA DAMPERS BY FLUIDAMPR
ATI - Super Dampers® for Honda Engines
I did mention that I totally enjoy this type of technical analysis & research didn't I?!!
My apologies to Willy18 who started that thread & others. It was unintended, I just got focused on the technical discussion.
Here is a link to that thread:
http://tsxclub.com/forums/1st-gen-engine/41325-group-buy-ur-pulleys.html
Here is the Pulley/Damper Comparison I've been putting together:
(it includes further updates) I hope my info is correct.
Stock TSX steel crank damper dia------ 6.125", 4.6 lbs.
Stock K20A2/PRB steel crank damper----5.80", ___ lbs.
Stock K20Z1/PRC steel crank damper----5.40", 4.2 lbs. US$110. Actual US$160 (2005-06 RSX-S)
Fluiddamper steel crank damper-------- 5.875", 6.5 lbs, US$350.
ATI street aluminum crank damper----- 5.500", 3.6 lbs, US$330.
Alutec alum crank pulley----- 5.8", __ lbs, US$250.
UR alum crank pulley-------- 5.125", 0.75 lbs, US$___, (US$350 for the kit.)
NST alum crank pulley------- 5.2", 0.81 lbs, US$125.
T1R alum crank pulley--------5.8", 1.43 lbs, US$180.
Marcus at Heeltoe provided some valuable technical info on the Pulley Group Buy thread plus he initiated some very good discussion on K20a.org:
The whole damper vs. no damper discussion is difficult.
There is very little, if any, solid evidence to show that deleting the factory damper with a solid crank pulley will cause engine damage but WHY did Honda choose to incorporate the damper function in the 1st place if it wasn't really needed.
There is no question that an underdriven lightweight crank pulley with no damper function will provide the most HP gain but there are drawbacks & compromises to that.
This picture is totally interesting & thanks to the guy on K20a that did his research & posted it:
(note that the diameter is critical in any pulley discussion)

Thats the stock TSX crank pulley/damper on the right. The one of the left is the most interesting one though. It's from the PRC engine 2005-2006 Type S RSX.
From Acuraoemparts.com:
P/n 13810-PRC-003 PULLEY, CRANKSHAFT 2006 RSX US$109.37 (Actual US$160.)
I wish I had the weight of this pulley because this looks like a winner for my needs.
It's OEM & steel for durability. The damper functon is maintained. It likely slightly lighter than the stock TSX one, it's slightly underdriven. It's cheap!
Since it's slightly lighter & slightly underdriven it would provide a little more HP with no major drawbacks.
It looks like great value & a great compromise all around for a street car.
The K20 guys like & use this pulley also.
For reference here are some pulley links:
Pulley - Engine - 2003-2008 Acura TSX & JDM Honda Accord CL7 CL9 - Acura Parts - HeelToe Automotive
HONDA DAMPERS BY FLUIDAMPR
ATI - Super Dampers® for Honda Engines
I did mention that I totally enjoy this type of technical analysis & research didn't I?!!