Homemade pressure transducer

Just made my own transducer today. Will test it out in a day or two.

Are there any "rules" to using these homemade ones?
Does it matter what hose I use?

I saw Jarhead diagnostics boasted that their could handle 3000psi, and that it was important for the hose to be of good quality to get the right measurement.

In my case I was thinking of just using a couple hose clamps directly to a leak down test kit. At least temporarily to check out how it works.

To get really accurate pressure readings you would have to account for the extra volume the hose adds to the combustión chamber. While a stiff hose is somehow "measurable" a soft hose isn't so much.

To put this into perspective: on a 2 liter 4 cylinder engine with a 10 to 1 compression ratio a hose with 5ml volume would add an extra 10% of volume to the combustión chamber and lower pressure accordingly.
This will be more critical with CR diesel engines where 'combustion chambers' have migrated into the pistons and are of really small volumes.

While you may not get an 100% correct absolute reading with your rig I'd say it's good enough to get you started/going with in-cylinder diagnostics. If you feel like you later can shell out 1500 to 2000 $ to get the real McCoy .

Try to use a compression tester hose. A vacuum leak hose is designed for 100 psi test pressure at best, most of them work with ~ 30 psi only.

juergen.scholl wrote:

To get really accurate pressure readings you would have to account for the extra volume the hose adds to the combustión chamber. While a stiff hose is somehow "measurable" a soft hose isn't so much.

To put this into perspective: on a 2 liter 4 cylinder engine with a 10 to 1 compression ratio a hose with 5ml volume would add an extra 10% of volume to the combustión chamber and lower pressure accordingly.
This will be more critical with CR diesel engines where 'combustion chambers' have migrated into the pistons and are of really small volumes.

While you may not get an 100% correct absolute reading with your rig I'd say it's good enough to get you started/going with in-cylinder diagnostics. If you feel like you later can shell out 1500 to 2000 $ to get the real McCoy .

Try to use a compression tester hose. A vacuum leak hose is designed for 100 psi test pressure at best, most of them work with ~ 30 psi only.

Thank you so much for your input!

Yeah i was planning on using a compression tester hose. I didnt know that it would be more critical on diesels, thats some good info.