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Old 09-23-2014, 08:13 PM   #1
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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.





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Old 09-23-2014, 08:24 PM   #2
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Quote:
Originally Posted by thstone View Post
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.



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
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Old 09-24-2014, 11:40 AM   #3
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Yeah, but what does the butt dyno say :-)

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!
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Old 09-24-2014, 03:20 PM   #4
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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!
More videos please! Especially with the annotations and commentary. It is very helpful and entertaining.
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Old 09-24-2014, 06:54 PM   #5
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More videos please! Especially with the annotations and commentary. It is very helpful and entertaining.
Sure! I'll be sure to turn on the camera this weekend!
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Old 09-24-2014, 07:10 PM   #6
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Good luck with the race!
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Old 09-24-2014, 08:08 PM   #7
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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!
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Old 09-25-2014, 09:13 AM   #8
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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.
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Last edited by Perfectlap; 09-25-2014 at 09:16 AM.
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Old 09-25-2014, 10:09 AM   #9
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Quote:
Originally Posted by thstone View Post
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
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Old 09-25-2014, 10:39 AM   #10
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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!
Yes, I noticed that you weren't signed up! Have a good weekend with the family and we'll catch up in November.
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Old 09-25-2014, 10:52 AM   #11
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Mind sharing what a typical rebuild for this BSR racing typically runs?
$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.

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Last edited by thstone; 09-25-2014 at 10:55 AM.
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