Boost leak testing
 

I am at my wits end with this car. I have boost leak tested from the intake and I have made an adapter to pressurize the intercooler horn going into the intake manifold. Testing from both location yields the same result.

At first when testing from the intake I could hear a hiss from under the intercooler which is what lead me to make the intercooler horn adapter. I still hear the leak but I cannot confirm where it is coming from. No bubbles anywhere. The injector o rings are brand new, the intake manifold gasket is new, I have the diverter valve ziptied shut but the loss of pressure is so rapid that there is obviously a leak somewhere. Compression test for all cylinders is in the 160's

I recently installed the rebuilt supercharger and it hit 15.7psi at 6600rpm with a 2% crank and a 17% supercharger pulley. Now its 12psi if I am lucky. I have changed the K060535 belt twice and have the manual Alta tensioner. Last night I wen't so far as to remove the spring from the stock tensioner and install a shorter K060532 belt. The alta pulley was installed with loctite on the snout shaft as well as the clamping bolts.

Any insight is appreciated

I had a leak which I was able to track back to the vaccum line under the passenger side SC horn. Super hard to see but you can check without removing the intercooler. If that's not it maybe a smoke test would help. Good luck!

Speaking of that fuel regulator vacuum line, besides being connected well, make sure it's in good condition, they've been known to dry out and crack from heat, but not show outward signs.

Heya,

I replaced my SC a few years back, and had the same problem. Hissing, loss of boost, and often times an irregular idle. Turns out that there was a small hole in the intercooler bellows causing my issues. The local shop had one sitting on a bench and replaced my old one. No more hissing, and boost was back where it ought to be. Don't know if you've tested yours, but this could be a possible culprit.

Best of luck!

Try a homemade stethoscope. Just stick one end of a piece of small diameter tubing in your ear and put the other end in various places until you hear the hissing loudest. Another way is to spray small bursts of starting fluid in suspected areas. A rise in rpm will give you an indication of the source.

I've replaced all the vacuum hoses to no avail. I am guessing that the leaking I am hearing is air moving past the valves since this car is ****ing retarded and has no timing marks for the crank there is no way to determine if I am at 30* ATDC to properly conduct the boost leak test.

The intercooler boots are relatively new ALTA pieces but they have been removed and reinstalled so many times they may have a hole. I will order up another pair.

thanks again for the pointers guys

​​​​​​ALTA silicone boots?
Do yourself a favor and get some factory boots, while they may not look as nice, they fit and seal much better than any silicone boots.
This may actually be the issue, sometimes the silicone boots are just too rigid and can't conform properly to the horns. Plus some have been known to be slightly too thin, causing the clamps to bottom out before they are actually tight against the boot.

https://cimg6.ibsrv.net/gimg/www.nor...9333b02bfe.png
Ok will see about the OEM one's then. Also just to show some data, for some reason the AFR's are much leaner even though the boost is down. PCV valve?

Also leans toward a boost/vacuum leak since the fuel regulator is boost/vacuum based.

So after removing the intercooler and going over the vacuum hoses again I start the car up and walk around for a listen. Low and behold the ****ing supercharger pulley is moving in a direction it should not be, perpendicular to the shaft.

The reason why it was always an issue with boost but vacuum was fine was because.........

https://cimg9.ibsrv.net/gimg/www.nor...9bf8ac5d4.jpeg
All 3 bolts sheered off the Alta supercharger pulley and as luck would have it i got 1 out clean and an easy out broken off in the 2nd one. The only thing spinning the supercharger was friction between the outer pulley and the hub. Ordered a cravenspeed 15% pulley which has 4 bolts.

Wow! That's a first. Maybe they were over torqued? Not that I've seen a whole ton of examples, but I never expected that would be a common point of failure. Glad I got a 4 bolt pulley from the start.

At least you found the primary driver of the issue. Sorry you had to go through troubleshooting hell to get there! Let us know how the replacement works out.

After l comparing the Alta with my Way pulley, it looks like the collar is tightened down to the SC shaft with 2 bolts. The Way is a squeeze fit that tightens as you torque the pulley onto the collar. I wonder if the shock from abrupt acceleration/deceleration on the Alta can stress the bolts more because of this design. Sorry, just thinking out loud here.

To add further insult to all these injuries I believe I have a bad map sensor since my innovate reads 17-17.5psi peak and the logs from the factory ecu are showing 14.5-15psi. This would explain why the car is running almost 2 points leaner than it should be (the fuel pressure regulator has proper vacuum signal).

I hate chasing down issues like this. It's like for every problem you find, it only leads you to another. It happens more and more as our cars age.

Hopefully your saga will be at an end soon. Keep at it, we're rooting for ya!

I had the innovate sourcing pressure from the intercooler outlet horn thing that goes into the intake manifold. It appears that it was reading spikes in pressure. I relocated the source to the fuel pressure regulator source and boost is reading inline with the factory map sensor. I also borrowed a known good autometer boost gauge and the needle will barely touch 15psi further verifying the factory map sensor readings.

At this point consider the towel thrown in. No idea why a 2% crank pulley and a 17% supercharger pulley, MILDLY ported head, 264/272 cam, intake, header and exhaust with no boost leak that I can locate is only netting 14-15psi. Time to go turbo

Your motor is a lot more efficient than a stock engine with the same pulley sizes. You could be making more power than someone making 19lbs of boost with a stock motor. You really need to get it dyno tested to see if you're making power in line with your modifications.

Far be it from me to dissuade anyone from doing a turbo conversion, esp as much as I like mine, but... Those boost numbers don't seem that far off.
Remember, boost is basically a measurement of back pressure, a 19% should realistically get you 17 "ish" psi at sea level with a stock motor, everything you've done to your motor is designed to let it breathe better, esp the cam & header.
Don't confuse boost with power, without some before and after dyno or track info of some kind, you'll never know for sure what the end result has been.

When I was still using the Sprintex I lost about 1.5 psi of boost simply swapping From stock to mild cam alone. But I gained power.