09-23-2014, 08:13 PM
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#1
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Certified Boxster Addict
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,669
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Old vs New Engine Power Difference
Ever wonder what the power difference might be between an original high mileage Boxster engine and a high-end full rebuild?
Shown below is a dyno plot of hp and torque for the old engine (Green) vs the rebuilt engine (Red).
Net result: +17hp at 5900 rpm (max).
This data is from the same car, same ECU, same exhaust, same intake, same dyno, same operator, and same air temp. Its as close to an apples-to-apples comparison as I could create.
Old Engine: Original '99 stock 2.5L engine with 136,000 miles along with 89 track days.
Rebuilt Engine: Complete full rebuild professionally done by Hergesheimer Motorsports. Almost every friction surface new. Completely stock. 500 miles and one race day.
Sorry for hiding the absolute hp and torque scales but racing is competitive. I hope you understand. 
__________________
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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09-23-2014, 08:24 PM
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#2
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Registered User
Join Date: Jul 2008
Location: austin
Posts: 824
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Quote:
Originally Posted by thstone
Ever wonder what the power difference might be between an original high mileage Boxster engine and a high-end full rebuild?
Shown below is a dyno plot of hp and torque for the old engine (Green) vs the rebuilt engine (Red).
Net result: +17hp at 5900 rpm (max).
This data is from the same car, same ECU, same exhaust, same intake, same dyno, same operator, and same air temp. Its as close to an apples-to-apples comparison as I could create.
Old Engine: Original '99 stock 2.5L engine with 136,000 miles along with 89 track days.
Rebuilt Engine: Complete full rebuild professionally done by Hergesheimer Motorsports. Almost every friction surface new. Completely stock. 500 miles and one race day.
Sorry for hiding the absolute hp and torque scales but racing is competitive. I hope you understand.
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Yeah, but what does the butt dyno say :-)
I've got a 2.7 here that we just rebuilt and it feels stronger than my 100k mike 3.2!
Mike
__________________
Drivers: '15 Panamera Hybrid (wife's), ' 01 996 GT2, 00 Boxster S, '96 993 Çab/Tip (wife's)
Race Cars: '75 911 RSR Replica & '99 Spec Boxster
mike@lonestarrpm.com
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09-24-2014, 11:40 AM
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#3
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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 seningen
Yeah, but what does the butt dyno say :-)
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My butt dyno says that its definitely more power! However, I never trust a butt dyno, too subjective.
More conclusively, I set a personal best in the second session out with the new motor.
Between the dyno data and the improved lap times, I'm convinced the rebuilt motor has more power.
I'll be racing again this weekend and looking for my first win! 
__________________
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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09-24-2014, 03:20 PM
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#4
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Registered User
Join Date: Dec 2012
Location: FL
Posts: 4,144
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Quote:
Originally Posted by thstone
My butt dyno says that its definitely more power! However, I never trust a butt dyno, too subjective.
More conclusively, I set a personal best in the second session out with the new motor.
Between the dyno data and the improved lap times, I'm convinced the rebuilt motor has more power.
I'll be racing again this weekend and looking for my first win! |
More videos please! Especially with the annotations and commentary. It is very helpful and entertaining.
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09-24-2014, 06:54 PM
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#5
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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 steved0x
More videos please! Especially with the annotations and commentary. It is very helpful and entertaining.
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Sure! I'll be sure to turn on the camera this weekend! 
__________________
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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09-24-2014, 07:10 PM
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#6
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Registered User
Join Date: Sep 2013
Location: Chandler, AZ
Posts: 1,796
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Good luck with the race!
__________________
03 Carrera
02 Boxster S Guards Red, black interior with matching hardtop
89 Carrera 4
89 944 S2
78 911SC
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09-24-2014, 08:08 PM
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#7
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Track rat
Join Date: Nov 2006
Location: Southern ID
Posts: 3,701
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Nice! 17hp is a big difference in Spec racing. I wish I could be out there with you guys this weekend but family stuff got in the way. Hope to catch you at the NorCal vs SoCal BW race in Nov.
Have a great weekend and keep the shiny side up!
__________________
2009 Cayman 2.9L PDK (with a few tweaks)
PCA-GPX Chief Driving Instructor-Ret.
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09-25-2014, 09:13 AM
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#8
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Registered User
Join Date: Nov 2004
Location: New Jersey
Posts: 8,709
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Mind sharing what a typical rebuild for this BSR racing typically runs?
As in you don't need to tell us what HRG charged you.
Whatever it is, I'm sure this is the most cost-effective (if such a term can be used in racing) series of racing any Porsche.
p.s.
My butt dyno, mostly on the low end, has always told me that that I've lost 10-20 hp over the years.
So it was interesting that your telemetry here show something similar'ish.
Makes me feel better about the expense of lighter wheels and seats and some aftermarket headers/exhaust. well maybe just a little bit.
__________________
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; 09-25-2014 at 09:16 AM.
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09-25-2014, 10:09 AM
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#9
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On the slippery slope
Join Date: Mar 2014
Location: Austin and Palm Springs
Posts: 3,797
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Quote:
Originally Posted by thstone
My butt dyno says that its definitely more power! However, I never trust a butt dyno, too subjective.
More conclusively, I set a personal best in the second session out with the new motor.
Between the dyno data and the improved lap times, I'm convinced the rebuilt motor has more power.
I'll be racing again this weekend and looking for my first win! |
best of luck to ya
say hi to Dave T for me
__________________
2004 Boxster S 6 speed - DRL relay hack, Polaris AutoTop DIY
2004 996 Targa Tip
Instructor - San Diego region
2014 Porsche Performance Driving School
2020 BMW X3, 2013 Ram 1500, 2016 Cmax, 2004 F-150 "Big Red"
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09-25-2014, 10:39 AM
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#10
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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 Topless
Nice! 17hp is a big difference in Spec racing. I wish I could be out there with you guys this weekend but family stuff got in the way. Hope to catch you at the NorCal vs SoCal BW race in Nov.
Have a great weekend and keep the shiny side up!
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Yes, I noticed that you weren't signed up!  Have a good weekend with the family and we'll catch up in November.
__________________
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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09-25-2014, 10:52 AM
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#11
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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 Perfectlap
Mind sharing what a typical rebuild for this BSR racing typically runs?
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$15K+ depending on the shop and how many engine parts were damaged when it stopped running.
This is the high-end approach with everything new. There is no reason why a low mileage replacement engine couldn't be sourced and installed at a cost of $8K or so.
In terms of durability, remember that my old engine lasted 89 track days or 3+ years of hard use track time.
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
Last edited by thstone; 09-25-2014 at 10:55 AM.
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Lil Red
2009 Porsche Cayman 2.9L
2004 Porsche Boxster S
2004 Porsche 996 Targa
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