PPI - compression/leakdown results

[VroomGrrl]

Got a 2 page fax from the mechanic doing a PPI for me on the 88 911 I'm considering for purchase. He'll go thru the fax with me tomorrow. In the meantime, here are the results of the compression & leakdown testing:



Leakdown
#1 78/80
#2 76/80
#3 73/80
#4 74/80
#5 78/80
#6 79/80

It's all Greek to me!

Well not totally. I did read up some on this, and to my noobie eyes, the compression looks to be in normal range (160ish) & range of values appears within 7 of each other (relying on Bruce Anderson's Porsche 911 Performance Handbook which says values should be 130-170psi and within 15 of each other).

Leakdown - . In reading up on this I saw values in 100% format (100psi, 97 left, 3% leakdown value). Do I convert the above numbers to 100% scale & do the calculations from there? If so, I get 3, 5, 9, 8, 3, and 2%. If not - help?

Tomorrow I'll talk with the mechanic & go thru the 2 page laundry list of items he noted in the PPI. It looks daunting, but most of it is cosmetic stuff that does not really concern me (I'm not looking for concours quality & am willing to compromise those finer points for $ value if the important things are solid). But there are some bigger items that I'll have to know more about, particularly how soon they must be repaired & estimated cost to repair.

More tomorrow after I talk to the shop.

[samsnead]

If i was to take a guess the mechanic put 80 psi and recorded the numbers, meaning 1-7% leak.

[Greek55]

Greek to me too and I would agree with samsnead.

[Nine9six]

Originally Posted by samsnead

If i was to take a guess the mechanic put 80 psi and recorded the numbers, meaning 1-7% leak.

I humbly disagree, as the numbers posted above do not represent percentages.
Here are the percentage leakdown numbers based upon the figurs posted. Oh, and Kathy is correct in her reading of the information.

1. 97.5%
2. 95%
3. 9125%
4. 92.5%
5. 95%
6. .9875%

Some say rule of thumb is to look for leakdown less than 10% across all cylinders. As we can see, this car meets that criteria.
Kathycha, based upon what you posted, and without knowledge of the particulars of how the tests were conducted (hot / cold engine) I personally think you have some good numbers there. Still I would wait for the mechanic to fill you in on the details.

P.S. What's the mileage on the car? These leakdown and compression #'s would be very good on 100K+ motor
HTH

[VroomGrrl]

Originally Posted by Nine9six

P.S. What's the mileage on the car? These leakdown and compression #'s would be very good on 100K+ motor
HTH

Thanks for your take on the numbers! The car has 148K miles on it.

Will report back on the rest when I've talked with the mechanic (fingers crossed!)

[VroomGrrl]

Well I've gone and done it. I pick up the car next weekend. There is not enough room here for the number of !!!s I'm feeling at the moment.

Goofy video with a good dose of Porsche garage porn, and some pics of the car at the end HERE.

Thanks to yall for entertaining my noobie questions and helping me work thru the process of buying at a distance.

[samsnead]

Originally Posted by Nine9six

I humbly disagree, as the numbers posted above do not represent percentages.
Here are the percentage leakdown numbers based upon the figurs posted. Oh, and Kathy is correct in her reading of the information.

1. 97.5%
2. 95%
3. 9125%
4. 92.5%
5. 95%
6. .9875%

Some say rule of thumb is to look for leakdown less than 10% across all cylinders. As we can see, this car meets that criteria.
Kathycha, based upon what you posted, and without knowledge of the particulars of how the tests were conducted (hot / cold engine) I personally think you have some good numbers there. Still I would wait for the mechanic to fill you in on the details.

P.S. What's the mileage on the car? These leakdown and compression #'s would be very good on 100K+ motor
HTH

OK I humbly agree with you, my bad

[janz]

Sure are quite a few Porsches there. Love the music, put together a great video. Car looks good. The mystery color of the car in question is Cosmic Cranberry. Welcome to the sickness.

[Pazuzu]

Originally Posted by kathycha

Well I've gone and done it. I pick up the car next weekend. There is not enough room here for the number of !!!s I'm feeling at the moment.

Tell us when you're gonna be here, some of us could probably meet you for lunch or coffee, and you can show off the new car

[VroomGrrl]

Originally Posted by Pazuzu

Tell us when you're gonna be here, some of us could probably meet you for lunch or coffee, and you can show off the new car

Don't have the logistics worked out yet, but looks like we'll fly in early Sat AM, pick up the car, and start the drive back. I'll give a shout-out when we have more precise timing. I'd love to meet you guys & see your cars - who knows when I'll be in Houston again!

[Super_Dave_D]

Congrats!!!! 88 is the best year!!!!

[VroomGrrl]

Originally Posted by Super_Dave_D

Congrats!!!! 88 is the best year!!!!

Ha! Thanks! And that's what I hear about 88! (well, and to be honest, about 89, too.....)