Compression tester
- Thread starter Jdc1
- Start date
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You can check any tester gauge, here's a link that describes it (Ashcroft makes some of the best industrial gauges). A similar test (the first one, using known weights) can be used for torque wrenches (how often are these checked at home?)
I'd bet that any automotive gauge would be very close to any other, although I've never actually tried to compare them. Any similar design, that is. I'm willing to bet that although very good industrial gauges are made to high standards, and have lab certs to back it up, automotive gauges are not.
More to follow on that.
For example, take a look at Snap-On's $152 push on compression test gauge and their $400 screw in gauge. They don't provide enough information to be certain, but they sure look like the same gauge to me. I can guarantee you're going to get less precise readings using the push on gauge compared to the screw in type. Same guage, though. So, which is better?
I think it depends on your use. If you have to crank an engine from the driver's seat, you're going to have to screw in a gauge. However, if you have a remote starter switch, and two hands, you can use the same gauge and spend much less, if you hold it in place while you crank. Which will give you the most accurate results?
That depends on how you use the gauge and what conditions you're testing under. For another example, say one cylinder is dry and the other is wet (for any reason). You would expect two different readings, but is the gauge designed for both situations? Again, for an automtoive gauge, I doubt the manufacturers spend a lot of time worrying about it. The difference in the gauge is more likely to be longevity than accuracy, based on what meterials they used to build it from.
Unless you're trying to machine parts for specific compression to match specific design performance characteristics, and even then it's a crap shoot, you're working too hard. For me, and full disclosure I'm not a professional engine builder, if I tested a known good engine with any given gauge, and then tested a suspected bad engine, and the gauge confirmed my suspicions, I'd be happy.
I'd bet that any automotive gauge would be very close to any other, although I've never actually tried to compare them. Any similar design, that is. I'm willing to bet that although very good industrial gauges are made to high standards, and have lab certs to back it up, automotive gauges are not.
More to follow on that.
For example, take a look at Snap-On's $152 push on compression test gauge and their $400 screw in gauge. They don't provide enough information to be certain, but they sure look like the same gauge to me. I can guarantee you're going to get less precise readings using the push on gauge compared to the screw in type. Same guage, though. So, which is better?
I think it depends on your use. If you have to crank an engine from the driver's seat, you're going to have to screw in a gauge. However, if you have a remote starter switch, and two hands, you can use the same gauge and spend much less, if you hold it in place while you crank. Which will give you the most accurate results?
That depends on how you use the gauge and what conditions you're testing under. For another example, say one cylinder is dry and the other is wet (for any reason). You would expect two different readings, but is the gauge designed for both situations? Again, for an automtoive gauge, I doubt the manufacturers spend a lot of time worrying about it. The difference in the gauge is more likely to be longevity than accuracy, based on what meterials they used to build it from.
Unless you're trying to machine parts for specific compression to match specific design performance characteristics, and even then it's a crap shoot, you're working too hard. For me, and full disclosure I'm not a professional engine builder, if I tested a known good engine with any given gauge, and then tested a suspected bad engine, and the gauge confirmed my suspicions, I'd be happy.
