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Old 06-03-2019, 10:27 PM
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mark boschert
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Default motor rebuilds

I have 3.5 seasons with 8-9 weekends/season on current motor with ~70k miles and am a little down on power but otherwise runs great.
Questions:
1. what is an average output for one of these motors? 195 HP?
2. when do most of you rebuild/replace motor?
3. replace or rebuild?
4. if rebuild, who do people recommend?
5. anything I should try before considering rebuild?

Thanks!
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Old 06-03-2019, 10:46 PM
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audipwr1
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Mark - ask this on our west coast Slack

I'll tell you neither Heath or I make that much power (195)
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Old 06-03-2019, 10:50 PM
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Originally Posted by mark boschert View Post
I have 3.5 seasons with 8-9 weekends/season on current motor with ~70k miles and am a little down on power but otherwise runs great.
Questions:
1. what is an average output for one of these motors? 195 HP?
2. when do most of you rebuild/replace motor?
3. replace or rebuild?
4. if rebuild, who do people recommend?
5. anything I should try before considering rebuild?

Thanks!
2. When they blow up.
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Old 06-03-2019, 11:09 PM
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Power is a moving target. It really depends on the dyno. There are significant variations. I say this so that when you do a refresh or rebuild you dyno on the same machine before and after. Otherwise dyno results are useless.

I have three rebuilt motors in my garage that I rotate throughout the season.

That's a lie. I lie sometimes. Most of the time actually.

I had my engine rebuilt probably 4 years ago ish and I'm not thinking of doing it again anytime soon.
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Old 06-04-2019, 11:30 AM
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3.5 seasons - it's likely time to freshen the engine.

We would typically do a leakdown/compression check first as well as a baseline dyno pull to verify engine health.

Dyno numbers are relative so giving numbers is meaningless.

For rebuilds/replacements you have several options. You can have the entire engine rebuilt and that will cost $$$$. We (Atlanta Speedwerks) generally don't touch the bottom end as it gets too expensive. Instead we swap in a low mileage street bottom end and rebuild the heads (as well as replace other internals and bolt ons as needed). That's the best performance to cost ratio.

The cheapest option is to just replace the engine with a known good street engine, but you're leaving some performance on the table.


Originally Posted by mark boschert
I have 3.5 seasons with 8-9 weekends/season on current motor with ~70k miles and am a little down on power but otherwise runs great.
Questions:
1. what is an average output for one of these motors? 195 HP?
2. when do most of you rebuild/replace motor?
3. replace or rebuild?
4. if rebuild, who do people recommend?
5. anything I should try before considering rebuild?

Thanks!
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Old 06-04-2019, 11:53 AM
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Originally Posted by toddlamb View Post
3.5 seasons - it's likely time to freshen the engine.

We would typically do a leakdown/compression check first as well as a baseline dyno pull to verify engine health.

Dyno numbers are relative so giving numbers is meaningless.

For rebuilds/replacements you have several options. You can have the entire engine rebuilt and that will cost $$$$. We (Atlanta Speedwerks) generally don't touch the bottom end as it gets too expensive. Instead we swap in a low mileage street bottom end and rebuild the heads (as well as replace other internals and bolt ons as needed). That's the best performance to cost ratio.

The cheapest option is to just replace the engine with a known good street engine, but you're leaving some performance on the table.
I know you guys are stand up, but the last guys out here "rebuilding the top ends" were touching valve ports amongst other things which is a major no no in the rule book. We subsequently got that engine removed from PCA racing, some still floating around in the POC which monster dyno which arent my problem.

My motor has 4 seasons on it for example, and I have no idea on street miles before that.

These arent miatas where the last 2 hp is a world of difference, you need to make 10-15 to pull on people and you cant do that legally. Pretty easy to tell and we protest them to keep west coast clean.
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Old 06-04-2019, 12:00 PM
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Let me be more specific: torque as well as "area under the curve", makes a HUGE difference in these cars. Quoting peak numbers is irrelevant. You can most definitely see big gains LEGALLY over a 3 season race engine. Factor in a few overrevs and peak HP can easily be down 10-15hp over a fresh LEGAL engine.
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Old 06-04-2019, 12:27 PM
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Maybe we are talking shades of grey here.

1. Personal experience with a top built east coast super fancy car and my current middle of the road car is no difference in lap times or acceleration.

2. I totally agree at some point from racing a motor gets tired, I haven’t found its as fast as three moderate seasons (4-7 weekends a year), I dont over rev, I change the oil every other weekend, and generally take good care of the motor as I dont want the time or expense of swapping it, others may differ, but that is the general consensus amongst most of the SPB folks I know and talk to

3. So long as the rebuild doesnt make a ounce more power than a crate motor would, people can have at it with rebuilds, if they are even gently more then it is exactly what I dont personally want in this series personally which is checkbook racing. Plenty and plenty of racing out there for those folks

4. Even the ultra built out motors, in these cars if you arent fast in it doesnt matter, the delta in fast out wont do the trick which thankfully has kept most of this at bay

Totally my own opinions, but when I start hearing special rebuilt motors it drives me nuts
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Old 06-04-2019, 06:38 PM
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Like Hunt, I’ve got a few fresh motors in the garage to swap out through the season...
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Old 06-04-2019, 06:40 PM
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I put a full rebuild motor in my car in its 3rd season. I just wanted to know I had all I could. The motor I started with was from a crashed SPB. It had non-OEM coated pistons in it, so somebody had been in there before. Whole motor was disassembled and rebuilt using all components purchased from a Porsche dealer to be absolutely sure it was as OEM as when it went down the line originally. It made exactly 2hp more than the 45k mile motor that was pulled from the car. (same dyno, same day)

I always changed to oil after every event, did 5-6 races a year and maybe another 3-4 practice events a year. My notes show the motor had around 50 race hours on it and 4 years when I sold the car. The buyer did a leak down on it and it had perfect numbers. That was after sitting, un started for a year. The stock motor in the car did not have perfect numbers when it came out, but I have no idea what its early life was like.

So my experience was a fresh rebuilt motor, treated as intended and maintained exceptionally well, kept all its performance after 50 hours of podium finishing racing. For me, that was worth the price of admission.
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Old 06-05-2019, 01:17 AM
  #11  
mark boschert
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Thanks for all the thoughts which pretty much validate what I had surmised or heard before from SPB racers in Colorado and CA. I had it dynoed in the paddock at Sonoma last fall where it did ok (189 hp). I am sure the car just needs a driver "rebuild"
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Old 06-05-2019, 04:15 AM
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Originally Posted by Streak View Post
Power is a moving target. It really depends on the dyno. There are significant variations. I say this so that when you do a refresh or rebuild you dyno on the same machine before and after. Otherwise dyno results are useless.

I have three rebuilt motors in my garage that I rotate throughout the season.

That's a lie. I lie sometimes. Most of the time actually.

I had my engine rebuilt probably 4 years ago ish and I'm not thinking of doing it again anytime soon.
You better grab one of those other cheater motors as you only limped along at a 2:13 vs. 2:11 last year...
Nice job out there Hunt!!
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Old 06-06-2019, 11:13 PM
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mark boschert
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anyone use rebuilt motors like from Vertex? any good?
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Old 06-07-2019, 10:46 AM
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Question: Is there any way to guesstimate engine hours from track miles covered? If all of a car's engine miles are track miles...and the average lap speed at most tracks is somewhere around 70 mph... would it be fair to divide the total miles by 70 and come up with a rough "hours" figure?
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Old 06-07-2019, 11:09 AM
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That’s what I do, yes. I’ll use an hour meter when I rebuild or replace my current motor
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