but how did your gauge read boost when the throttle is closed??? and your saying you had to pressurise your intake system to 100PSI?!?!?!

 

It read it, I don't know how, it just does. I tried to pump (with a bike pump) up to 23 psi, on the bike pump gauge. that wasn't pressure enough to get the air in the system, and "charged". I needed 100psi in the can, and started to pump the air in the system, and someone was in the car, as to NOT over fill the system with any more boost than the turbo could handle, or you could blow out seals etc.... It took a minute of pumping the air in from the "air can" to get to the desired pressure on my cars boost gauge (23psi) once we got there, we stopped filling the 'system' with air. the air tank gauge read 10psi when we got done charging the system.


100psi in the air tank: (usually seen at autox's) a can, a gauge, and a stem to fill up car tires. Purchaced at Walmart for 25 bucks, filled up at a gas-station. you want to keep a watchful eye on the boost gauge. It might depend on where you have the boost gauge tapped in. I will go see where mine is tapped into. Maybe for the purpose of this test, you would have to "re-T" the line further down the line. Anyone have input on this? Be back later, when I find out where I am "T"ed in.

 

How does a your car idle when the "throttle is closed" ?

b/c the throttle body is never 100% sealled when the throttle is closed if is was no air could enter the motor and it would not run....

edited

 

Thanks Matt, that was the answer I was trying to explain.

 

Anyone else having problems holding pressure while testing due to air seemingly blowing by through the crank case? I have heard that you should bump the starter to get all valves where they need to be in order to hold pressure. 13-0 and I could both hear pressure blowby when we put our ears to the oil fill hole on the valve cover.

 

I was thinking the same thing.

 

Great info mitsu, I didn't hear any extra blow-by, so my valves must have been in the "proper" position.

 

There will always be some leakage into the crank case, especially if you are doing the test cold. In my experience, even with a very good motor, you can get a lot of leakage out the valve cover due to the PCV valve. I've always eliminated that POS, but I've yet to do it on this car.

The throttle is actually 100% closed. The air is bypassed via the ISC, FIAV, and BISS.

 

Yeah, my next little project too

 

Exactly....this one one of the first things I learned when dealing with a forced inducted car (DSMs to start).

 

Well I was fixing the boost leak around my BOV and tore the darn gasket. I tried to pit back on with some RTV and get a nasty whistle at High boost. Anyone know if the roll-o-gasket material at Advance auto and such will work? Either that or black RTV is going to have to do!!

 

Both Andrew at Dyno4mance, and AMS told me up front "is the car "sorted" out?" meaning ready to go with NO issues before tuning. I replied "yes" it is. when in fact it wasn't. So I take blame for that. it was a dumb mistake on my part, but that said, I assumed there was NO leak, because I didn't hear anything. the boost gauge was reading "low" at high RPM, but I didn't know what to expect boost-wise with a stroker motor. easy fix was to do this test!! would have saved me money, time, and I would have a KILLER tune by now!!

 

I am not sure. I got some "red" gasket maker for my Saab back in the day, for the same reason, and it worked awesome!! I believe it would work, but not 100% sure.

 

I find it interesting that the owner is willing to take responsibility for his actions and words, which is a rare thing these days, and everyone still wants to hang the shop by its *****. I mean, you can pay the shop at thier standard labor rate to do a boost leak test, but it is certainly not thier responsibility.

 

do you have the car on or off when you do the leak down test.