Joe Larussa Posted September 25, 2019 Report Posted September 25, 2019 So I’m upgrading from the stock manifold pressure gauge to the EI digital gauge. The piping coming from the engine looks like 1/4”, then it transitions to 1/8”, then to the gauge. The new one has a plastic hose with 1/4” fittings. Is pressure just pressure? Does it matter if the piping goes up and down in diameter? Quote
kortopates Posted September 25, 2019 Report Posted September 25, 2019 No, not an issue. Its a very good unit. I use one on my 252/Encore.Sent from my iPhone using Tapatalk 1 Quote
carusoam Posted September 25, 2019 Report Posted September 25, 2019 Interesting observation Joe... 1) the change in tubing inner diameter has no effect on the pressure, IN OUR APPLICATION.... 2) Our application has no measurable volumetric flow of any kind... 3) When tube diameter affects the pressure, is when we have a liquid or gas, flowing through it... 4) So... there could be noticeable change... if the pressure were to change quickly, on a large scale... it would take an extra microsecond to appear on the other end.... 5) The reason it is done this way...? The existing fitting on the engine is big for what is needed... thin and lighter weight is all that is required... Of course, these are only PP opinions only, not a mechanic... Best regards, -a- 1 Quote
GDGR Posted September 25, 2019 Report Posted September 25, 2019 Coming from an irrigation background, tubing diameter doesn’t change pressure. 99% of the people get it wrong when you ask them, “what is happening when you put your thumb over the end of a Garden hose?” You are not increasing pressure (the pressure of the water source, less friction, from the house is constant), you’re increasing velocity. 1 Quote
Yetti Posted September 25, 2019 Report Posted September 25, 2019 It's a sucky subject, but the comments here are correct. Quote
David_H Posted September 25, 2019 Report Posted September 25, 2019 Recall that Pressure = (Force/Area). The Manifold Pressure Gauge never "knows" what the cross-sectional area is upstream from the measurement... only the force applied to the calibrated surface area at the gauge. Diameter changes upstream from a Pressure Gauge have no effect on a static pressure source measurement. Quote
GDGR Posted September 25, 2019 Report Posted September 25, 2019 4 hours ago, Yetti said: It's a sucky subject, but the comments here are correct. "sucky" would be vacuum Quote
gsxrpilot Posted September 25, 2019 Report Posted September 25, 2019 9 minutes ago, GLJA said: "sucky" would be vacuum Yep, exactly what a manifold pressure gauge is measuring. 2 Quote
Yetti Posted September 25, 2019 Report Posted September 25, 2019 1 hour ago, gsxrpilot said: Yep, exactly what a manifold pressure gauge is measuring. Or more precisely how much suck your engine is giving. 1 Quote
David_H Posted September 25, 2019 Report Posted September 25, 2019 Perhaps this is why some have referred to their planes as being their "mistress." Just add money and presto... Stop adding money and no more suction... 1 Quote
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.