Thread: About to finish a writeup - 1 question

I'm about to finish a writeup on testing intake manifold pressure for a leak. I have the equipment setup, but I need to know how many psi I can apply to a STOCK sr20de non det engine without accidentally blow seals or rings

I've searched and it seems most are the det at 15psi, doesn't say for regular de's tho.

Think about how much pressure the piston sees during combustion, way over 15 or 30 psi lol, it's over 150psi with no ignition. I usually pressure test at 30 though, I dont think the intake mani would like full shop air.

I wouldn't be worried about a measly 30 psi.
Crank it up!

hey now! he might blow the welds on his intake manifold!

lol, I think i've seen someone do 50psi before... I think the rubber injector plugs started to leak then...

lol 30 psi it is - anything more and I'm afraid of wrecking something, just want enough to hear a hissing from wherever my gigantic leak is, not to test anything more

I thought you were asking for more general advice... Usually the advice is to test at twice your expected pressure (so if you're going to run 15 psi, you test at 30 psi). I always thought this was way over kill. I'd take the pressure I plan on running and add 5 psi, maybe 10 if I want to be super duper cool.

hmm. what is stock sr20de engine vacuum pressure?

I've seen as low as 20 kPa engine braking down steep hills... But now you have me intrigued. What exactly are you trying to accomplish here? =]

Did you mean highest pressure? Just use 100 kPa (atmospheric / 14.7 psi above true vacuum / 0 psi to most people) as the max for any N/A engine.
You plan on keeping it N/A?
I assume you're going to run some boost?
Why would you need to pressure test the manifold otherwise?
You think you're sucking in air through a hole during idle? If so, I guess 14 psi would be a good pressure to use to test for that.

I have a vacuum leak the size of kentucky somewhere - to the point where i can unplug my idle air control valve and it runs the same

So I've made a intake leak tester and need to know how many psi the manifold can take before blowing seals or whatever - with the car not running obviously, to the point where i can take a spray bottle of soapy water and spray a couple sections and see the bubbles forming from the leak. I will post how to and pictures immediatly after it either works - or no pictures if it doesnt.

the problem is though the air is going to be pressurized INSIDE the manifold, pushing out, not vacuum the other way around - So whatever psi proshops use with their smoke machine ($3000 is too much for a backyard mechanic like me!) is roughly the pressure I need to put on the valve to pressure up the system.