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Maximum safe psi to EGR diaphragm?

Does anyone know the maximum psi to which an EGR valve diaphragm should be subjected?

This particular EGR valve is on an 87 Dodge 3.9L engine. It opens at about 5-6 psi. I hooked up a vacuum gauge to it and found out, while driving on the freeway, that the vacuum can reach a sustained 12 psi. I'm asking because I modified the carb where it supplies the vacuum port for the EGR to work in this application. Basically it looks like a transfer slot, but does not extend quite as high. I made it to look like it does on the stock carb. It seems to work fine. It doesn't kick in too soon, smooth and powerful acceleration from a dead stop. I just don't want to have to worry about blowing the diaphragm and overheating the rings, pistons, etc. Thanks

Reply to
Jack
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Your EGR does not operate on pressure as measure in PSI. The measurement is in inches of mercury column. It will not be damage by any level of vacuum that can be generated by your engine under any conditions. It is not likely that your engine would be damaged in any way if the EGR were to be disabled unless it began severe detonation which is one of the jobs of the EGR system. Your vehicle vintage may use exhaust system pressure for timing and control of the EGR. Again, there would not be sufficient pressure to cause damage. If it generates that much pressure in the exhaust system, you will note a serious loss in performance and fuel mileage. I don't believe there is much way your engine could produce enough vaccum or pressure to damage the EGR valve.

Lugnut

Reply to
lugnut

Thanks, Lugnut. I will drive without worry.

And thanks for the heads up about vacuum being measured in inches of mercury, not psi.

Jack

Reply to
Jack

lugnut wrote in news: snipped-for-privacy@4ax.com:

I think it might be more accurate to say that the engine management system has been designed around the presence of EGR.

Detonation is easily controlled in the absence of EGR, but if the engine's management system is expecting that combustion temperatures are being reduced by the use of EGR, it will adjust timing and mixture with the expectation that EGR will do its job.

Reply to
Tegger

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