Post your F355 compression test results here...

1997 spider, 27k miles, manual

1 220
2 228
3 217
4 212
5 228
6 228
7 228
8 223

 

Everybody, this is a good one. This is how it should look.

 

Rebuild? Nope, just a PPI.

 

bloody hell, that is one very tight engine!
you obviously don't KY then? LOL!

 

I don't have a printout of my resutls but a graph type thing with arcs for each cylinder so I can't tell accurately. Pistons 4 & 5 are in the 10.7s or so and the rest are in the 11.5-13 range. The car is a '99 GTB 355 with 17k miles.

 

I had two tests done ,the first one was at ppi at Ferrari of Atlanta.The second was at Boston Sports Car one year later .It is interesting to see that it got better ,as it has been said many times on this board ,compression test can give different results at different times.If looking at your numbers they don't look to good at all ,give it an Italian tune up and do it again
1,177 psi
1,167 psi
3,186 psi
4,184 psi
5,171 psi
6,186 psi
7,184 psi
8,187 psi
and at B.O.S.C
1,200 PSI
2,198 PSI
3,205 PSI
4,198 PSI
5,204 PSI
6,200 PSI
7,208 PSI
8 200 PSI
The car is a 1995 the first test the cad had 11668 miles ,and the second test the mileage was 150463.
Thats my story and I am sticking to it,DAVID

 

The 355 I had went from 180 in one cylinder to 230. What I find curious is though there is quite a spread, the readings are high compared to some. The car supposedly had 4k miles but I never felt it was right while I owned it.

 

Compression test results can vary a great deal due to the care and methodology used in the test. What you want to do is to try and get the best possible results. The motives of the person doing it can have a great deal to do with the results. One more of the many reasons I suggest finding someone you can trust, develop a relationship and deal with that person and no one else. Quit picking mechanics because they are convienent.

 

"and the second test the mileage was 150463."

I'm assuming thats a typo otherwise thats some mad mileage in a year!

 

yes 15463
ooooppppsssss
david

 

Mine was done as part of a test by the main Ferrari dealer in the uK in order to give me the extended warrantee when I bough the car. Come to think of it whe the test was done the car had 12k miles. The dealer said that the car was very good. I would also like to say that I had driven quite a few 355s before I bough the one I have now. This felt way better than all the ones I had driven before in terms of power. I cannot accept that there is so much varience between the results we are seing here and I do suspect that the diagnostic calibration or the mechanics motives may have a bearing on the results.

 

While I made the statement about differing results and the reasons for them I right now have 2 95 355s in my shop. I did compression tests on both of them for diagnostic reasons and one car has 195-215 and the other has 155-190. So yes you do see legitimate numbers all over the place.

Btw the one with good compression has had a valve job and now has 18k miles and the other with flakey compression has 27k miles and is untouched.

 

What it proves is that in very good, as new condition to someone that has tested a hell of a lot of 355's is that they should be in the 210-220 area. Any less is either an indication of faulty equipment, faulty methodology, faulty motives or a less that perfect motor. What has also been proven to many in the business that work on quite a few hard driven 355's is that they have a nasty habit of going down hill fast once compression loss starts. I have personally witnessed it several times over the course of a weekend at a track event. I have also witnessed it on street only cars over a period of a couple of weeks. You also see them go for some time.

And yes you are right if your car was brought to me for a PPI I would advise my client against buying it, thats what I'm paid for. Life ain't fair.

 

I've always wondered what those numbers mean. Anyone?

 

To confuse things more if the engine has wear in the bores and /or guides then an amount of oil will make its way into the cylinders providing an improved seal at cranking speed with no combustion hence giving a higher compression reading .
Also of note is that worn guides will not give lower readings unless they are realy bad so that the valve does not seat correctly & if that bad the engine would smoke on the over-run and of course use exssesive oil.

 

As has been said many times in this and many other threads on this same subject, equipment and methodology varies. A different gauge could easily give you 8lbs more in the test. I would consider that within the acceptable area for variation due to gauges. I have seen many 25-30k cars with perfect compression. I also did a valve job on a 98 with 5k miles. The valve was done, gone, as bad as I have ever seen. That is why a smart buyer and a smart mechanic that is doing a PPI is so particular about compression issues in 355's.

And yes, from new a 355 should have over 200 lbs and on the order of 0-2% leakage. The vast majority of 355's I have seen tested with a wide variety of gauges that have cylinder leakage below 5% have compression in the 205-210 range.

As Dave Helm and I have discussed here, due to the inconsistancy of the problem we think that there is a workmanship component at work here. At that time the majority of the cylinder head work was done by hand. I have watched some of it done and I am not surprised there were problems.