I could not find the post that was going earlier, But here is the link I was looking for with dyno results: http://www.carcraft.com/techarticles/116_0406_cylinder_leakdown_tester/index1.html
I have actually read that article before. It seems to be totally adverse to what rifledriver and other experts have to say about leakdown tests in that 20% is 'ok'. Leakdown tests are not considered important by some as the compression stroke is completed and over with in a fraction of a second making it irrelevant to have a test which holds and tests an engine in a way it was not designed to work. I am still undecided, but I do believe both have their merits.
It is totally dependant on the type and nature of the motor. The only people who dismiss leakdown as unimportant are those that have a severe misunderstanding of engines in general and so lack knowledge that they have no understanding that motors really are built differently and the test results need to be weighted differently for those different motors. Most motors will run quite well with 20% leakage, I don't think I have ever heard otherwise. The difference is if you have a 328 or a Daytona with 20% it will probably be 22% in 10,000 miles. Hardly makes it worthwhile to fix, or worry about depending on your standards or needs for the car. If you have a 355 or 360 with 20% it will be 40% in 5000 miles, actually that is propably understating it. That is a problem. What it speaks to is both tests are pointless to those who do not understand them. While they both produce numbers, the numbers alone are not what is important, their context is.
