09-16-2013, 07:53 AM
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#1
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Registered User
Join Date: Jul 2013
Location: Asheville, NC
Posts: 102
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Another vote for under drive pulley
Installed Pedro's 4" underdrive pulley. Wow, could definitely tell a difference! I recommend it, seems to have only benefits with no downside.
I had trouble getting pulley stud out so had mechanic use air gun, he removed it with no problem. Filling down the boss is easy and does not take away it's functionality. I will keep the original pulley in case engine ever needs to be locked TDC.
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'01 986S: LN IMS, PedroBar, PSS9 coil-overs, underdrive pulley, 997 short shift, GT3 console delete, Crios muffler mod
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09-16-2013, 11:01 AM
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#2
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Registered User
Join Date: Jul 2013
Location: Montreal QC Canada
Posts: 222
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What that do Exactly ?
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2003 Boxster S
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09-16-2013, 12:10 PM
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#3
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Registered User
Join Date: Feb 2013
Location: Land of naught
Posts: 1,302
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An underdrive pulley slows the speed that the accessories turn at therefore reducing engine rotational drag which free's up HP.
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Death is certain, life is not.
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09-16-2013, 12:57 PM
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#4
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Registered User
Join Date: Jul 2004
Location: Houston, Texas
Posts: 7,243
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I sure do like mine. The old butt dyno said, "THIS THING'S GOT MORE POWER NOW!!!"
It's a great mod.
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09-16-2013, 09:31 PM
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#5
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Registered User
Join Date: Dec 2012
Location: Colorado
Posts: 159
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+1
The UD pulley was the fix to the constant power steering issues (fluid spills) during autoX events.
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2000 Boxster S
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10-09-2013, 02:51 PM
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#6
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I am my own mechanic....
Join Date: Feb 2013
Location: Salt Lake City, UT
Posts: 3,432
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Holy crap!!!
Instant HP off the line, right where you want more.
I can't believe they don't come this way. Lots of power.
Can't wait to do cat deletes. They should be in any day!!
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'04 Boxster S 50 Jahre 550 Spyder Anniversary Special Edition, 851 of 1953, 6-sp, IMS/RMS, GT Metallic silver, cocoa brown leather SOLD to member Broken Linkage.
'08 VW Touareg T-3 wife's car
'13 F150 Super Crew long bed 4x4 w/ Ego Boost
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10-10-2013, 05:50 AM
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#7
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Registered User
Join Date: Jul 2013
Location: Maryland
Posts: 189
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How much more HP are we talking?
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2001 Boxster S - Triple Black -
Billy Boat Muffler
ROW M030 Suspension
LNE IMSB
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10-10-2013, 07:36 AM
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#8
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I am my own mechanic....
Join Date: Feb 2013
Location: Salt Lake City, UT
Posts: 3,432
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Quote:
Originally Posted by PorscheBound
How much more HP are we talking?
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Not sure, but very, very noticeable. An absolute must for a simple bolt on mod that gives so much. Can't imaging all that new power to the wheels still being absorbed by the engine components.
__________________
'04 Boxster S 50 Jahre 550 Spyder Anniversary Special Edition, 851 of 1953, 6-sp, IMS/RMS, GT Metallic silver, cocoa brown leather SOLD to member Broken Linkage.
'08 VW Touareg T-3 wife's car
'13 F150 Super Crew long bed 4x4 w/ Ego Boost
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10-10-2013, 02:42 PM
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#9
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Certified Boxster Addict
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,669
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Quote:
Originally Posted by PorscheBound
How much more HP are we talking?
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In this thread (fourth post), engine builder Jake Raby says that he has measured +5HP at the rear wheels when using a UDP.
http://986forum.com/forums/general-discussions/37563-underdrive-pulley-questions.html
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1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
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10-10-2013, 03:36 PM
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#10
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Registered User
Join Date: Nov 2004
Location: New Jersey
Posts: 8,709
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Quote:
Originally Posted by heymanwatchthis
Installed Pedro's 4" underdrive pulley. Wow, could definitely tell a difference! I recommend it, seems to have only benefits with no downside.
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none? hmm.. seems to go counter to racing logic.
How exactly is this part improved over stock?
__________________
GT3 Recaro Seats - Boxster Red
GT3 Aero / Carrera 18" 5 spoke / Potenza RE-11
Fabspeed Headers & Noise Maker
BORN: March 2000 - FINLAND
IMS#1 REPLACED: April 2010 - NEW JERSEY -- LNE DUAL ROW
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10-10-2013, 04:46 PM
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#11
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I am my own mechanic....
Join Date: Feb 2013
Location: Salt Lake City, UT
Posts: 3,432
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Quote:
Originally Posted by Perfectlap
none? hmm.. seems to go counter to racing logic.
How exactly is this part improved over stock?
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New pulley is 4". Stock is 6" diameter.
__________________
'04 Boxster S 50 Jahre 550 Spyder Anniversary Special Edition, 851 of 1953, 6-sp, IMS/RMS, GT Metallic silver, cocoa brown leather SOLD to member Broken Linkage.
'08 VW Touareg T-3 wife's car
'13 F150 Super Crew long bed 4x4 w/ Ego Boost
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10-10-2013, 09:23 PM
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#12
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Registered User
Join Date: Sep 2002
Location: Northern NJ
Posts: 633
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I didn't feel it did that much.
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LB/GG/MB 02 2.7 sold
MB/GG 02 996TT
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10-10-2013, 09:41 PM
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#13
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Engine Surgeon
Join Date: Aug 2008
Location: Cleveland GA USA
Posts: 2,425
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Quote:
Originally Posted by thstone
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We see this number over and over again with the 4" pulley. The UDP is THE best bolt on for net gains available.
__________________
Jake Raby/www.flat6innovations.com
IMS Solution/ Faultless Tool Inventor
US Patent 8,992,089 &
US Patent 9,416,697
Developer of The IMS Retrofit Procedure- M96/ M97 Specialist
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10-11-2013, 06:39 AM
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#14
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Registered User
Join Date: Jul 2005
Location: MA
Posts: 885
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Does it have any more/less impact on the 2.5/2.7 motors vs. the 3.2 motors, or is it a flat 5HP due the common ancillary components used on all engines?
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98 Arena Red 986
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10-11-2013, 08:05 AM
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#15
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Registered User
Join Date: Nov 2004
Location: New Jersey
Posts: 8,709
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Quote:
Originally Posted by Jake Raby
We see this number over and over again with the 4" pulley. The UDP is THE best bolt on for net gains available.
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What's the second best? 
p.s.
While you are(n't) endorsing products, do you mind sharing the make of the UDP that you use in your testing?
__________________
GT3 Recaro Seats - Boxster Red
GT3 Aero / Carrera 18" 5 spoke / Potenza RE-11
Fabspeed Headers & Noise Maker
BORN: March 2000 - FINLAND
IMS#1 REPLACED: April 2010 - NEW JERSEY -- LNE DUAL ROW
Last edited by Perfectlap; 10-11-2013 at 08:08 AM.
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10-12-2013, 03:45 PM
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#16
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Registered User
Join Date: Jul 2011
Location: Upper Marlboro, Md.
Posts: 268
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I just ordered the pulley from Pedro. He said I should get it in the next few days. I'm looking forward to a couple of more horses.
Question for the class: I the bolt reverse thread or normal thread?
__________________
'99 Boxster Artic Silver/Red
'14 Subaru Outback
'06 EG Classic
'05 Sportster
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10-12-2013, 05:16 PM
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#17
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Engine Surgeon
Join Date: Aug 2008
Location: Cleveland GA USA
Posts: 2,425
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Quote:
Originally Posted by Perfectlap
What's the second best?
p.s.
While you are(n't) endorsing products, do you mind sharing the make of the UDP that you use in your testing? |
Its not commercially available.
__________________
Jake Raby/www.flat6innovations.com
IMS Solution/ Faultless Tool Inventor
US Patent 8,992,089 &
US Patent 9,416,697
Developer of The IMS Retrofit Procedure- M96/ M97 Specialist
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10-12-2013, 10:11 PM
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#18
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I am my own mechanic....
Join Date: Feb 2013
Location: Salt Lake City, UT
Posts: 3,432
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Quote:
Originally Posted by Brockmeister
I just ordered the pulley from Pedro. He said I should get it in the next few days. I'm looking forward to a couple of more horses.
Question for the class: I the bolt reverse thread or normal thread?
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RHT. (Normal)
Should come with a new bolt. If. 4" you need a shorter belt.
__________________
'04 Boxster S 50 Jahre 550 Spyder Anniversary Special Edition, 851 of 1953, 6-sp, IMS/RMS, GT Metallic silver, cocoa brown leather SOLD to member Broken Linkage.
'08 VW Touareg T-3 wife's car
'13 F150 Super Crew long bed 4x4 w/ Ego Boost
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10-12-2013, 11:41 PM
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#19
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Registered User
Join Date: Apr 2011
Location: DFW
Posts: 713
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Okay I'm sold on the Udp. But whats this about shaving down the boss? Can someone explain? This sounds like a must do for my Fall projects.
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10-13-2013, 04:08 AM
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#20
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I am my own mechanic....
Join Date: Feb 2013
Location: Salt Lake City, UT
Posts: 3,432
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Quote:
Originally Posted by rp17
Okay I'm sold on the Udp. But whats this about shaving down the boss? Can someone explain? This sounds like a must do for my Fall projects.
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The boss sticks out far enough to almost touch the back side of the pulley. The belt surface just wraps around it on orig pulley.
The UD pulley will rub into the boss. It's belt surface is dead even with the boss. So I used a sawzall and cut mine off. It would take a while to file down. Cut off flush or slightly proud.
I do not suggest you use a sawzall unless you are skilled with one. I've been using them for many years.
__________________
'04 Boxster S 50 Jahre 550 Spyder Anniversary Special Edition, 851 of 1953, 6-sp, IMS/RMS, GT Metallic silver, cocoa brown leather SOLD to member Broken Linkage.
'08 VW Touareg T-3 wife's car
'13 F150 Super Crew long bed 4x4 w/ Ego Boost
Last edited by Timco; 10-13-2013 at 07:03 AM.
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