Jon Moeller

Someone please help. I had a PPI done on a 951 that I'm interested in.
Compression results:
#1 = 140psi
#2 = 130psi
#3 = 130psi
#4 = 130psi

Leakdown results:
#1 = 80% into #2 + intake
#2 = 85% into #1
#3 = 80% into #4
#4 = 85% into #3

Those numbers are what I got, as in cylinder #1 lost 80% of the air in it. Can someone explain to me how this car runs? Did someone seriously screw up the leakdown test? Do these numbers make any sense?

The tech said that they could hear air escaping out the exhaust valves during the test.

-Jon(confused as hell)

david fracolli

Your leak down numbers make no sense. I cannot believe that you can have those kind of compression numbers with an 85% leak down rate.
I think the tech screwed up.

emilysgranny

Something is not adding up here.Are you saying you lost 80% of the psi reading or holding 80 % of the psi reading on the leakdown test.

Bri Bro

I vote of holding. If it were leaking compression that much, the car would not run.

Alan C.

Hold on to your hats friends.

Bodymotion's finest put together an engine with standard rings in a first over bore. That equates to 30 - 40% leakdown and compressoin numbers of 125. Can't figure out how their paperwork showed 2% on the engine. Maybe they meant the engine had a 2% life expectancy, that must be it ;-)

The thing actually ran. I did 3 DE's on that engine and then tore it down. You need to think in terms of dynamic versus static numbers. That said I'd never buy a car with 80% leakdown unless I got a good deal. Please don't ask how I ended up wih my abortion.

Jon Moeller

Guys, you're not reading the numbers wrong. I wrote them as they were reported. 80% as in 20% was remaining. That's why I am astounded that the damn car is running, if the test was performed properly.

I'm quite sure a tupperware container could exhibit similar leakdown results even using the same PSI.

Your thoughts are greatly appreciated.
-Jon

Bri Bro

There is another reason for the low leakdown numbers, they didn't have the correct valve timing when they did the tests.

Allen, did the car run a little "flat" in the DE events?

Rich Sandor

Also, I remember speaking to a Factory mechanic who said 951 compression number were supposed to be in the 140-145 range, with the last one around 138.

So it's definately leaking, but maybe they screwd up and got it backwards, looks to me like 20% of the air is escaping, not 80%.

Danno

If they got the wrong TDC, the cam won't have the valves fully closed. There are two TDC events per complete 4-stroke cycle.

The compression numbers looked decent, which leads me to surmize that the leakdown test was botched somehow... <img border="0" title="" alt="[Frown]" src="frown.gif" />