Jafro

One vital area of turbo performance that's frequently overlooked is BOOST LEAKS. So you've got all the bells and whistles installed on your engine that push higher-than-atmospheric pressure into the combustion chamber... How do you know that ALL the compressed air from the turbo is actually making it to where the fuel is? How do you know your turbo's not being overworked getting it there? Air is invisible. You can feel it escape from large leaks, you can hear it escape from most others, but you don't see it escape so discovering or pinpointing leaks can be difficult.

Your wastegate regulates boost pressure. Most turbos don't have a problem creating enough boost to open the wastegate even when air escapes the intake system, but what happens as a result of the escaping air... is that your turbo has to spin faster to create the pressure needed to force the wastegate spring open. This causes more heat which counteracts the efficiency of your intercooler, increasing the possibility of detonation, and causing your engine to produce less hp at any given pressure than it would if the turbo didn't have to work as hard. Another thing that it can do is wear out your turbo's bearing cartridge. If the air is escaping after the systems that meter air to determine how much fuel to inject... then your fuel tuning can be affected, too. All of this is bad.

If this all doesn't make sense, try crushing a soda bottle and poke a hole in it. Now put your lips on the bottle and try to blow the bottle back up. Tough isn't it? If you do manage to re-inflate that soda bottle, then have I got a job for you .

With issues like these looming over the turbo community... and with so many people concerned about 1 or 2 hp here and there... and the price and value of indexed plugs, synthetic oil, location of their intake temp sensors and all the other little tricks needed to get every drop of power out of your investment, why not spend the effort to get rid of all the boost leaks so that nothing is in question, and none of that other power-gaining effort and time you spent is wasted.

Lets start with the tools needed.
1. Air compressor
2. home-made Boost Leak Tester
3. Turbo car.
4. SoftSoap hand soap. The clear kind. Not the milky kind with lotion.
5. spray bottle
6. random bolts to fit vacuum lines.
7. light

Some other good things to have around are:
vacuum plugs, zip ties, teflon tape, RTV, make-a-gasket material that you can cut gaskets out of, and a friend.

Item #2 in the list above is something that you can't easily buy. Some people have tried to build and market boost leak testers, but it's a miserably stupid idea to try that. No matter how well it's engineered, DIY'ers will continue to make their own because it's cheaper, and the first part of this DIY will show you how to make a tester of your own. Turbos come in all shapes and sizes so the part needed to plug the compressor housing can vary drastically from 1.75" to 4", so you need to make one that fits your turbo. Here's one I made for my Big16g.


1. Get a ruler and measure your turbo inlet.
2. Buy a rubber coupler from the plumbing department of your local hardware store that fits over your turbo inlet.
3. Find a PVC end cap that fits snugly inside the coupler you selected.
4. Get a worm-gear clamp that fits around both parts that can clamp them FIRMLY in place. But don't do that yet.
5. Go to an auto-parts store. NAPA is everywhere, and they have everything needed as far as the remaining parts go.
6. Get two clamp-style valve stems. Get long ones if you can. These are used on 18 wheelers and some racing wheels. Un-screw and remove the guts out of one valve stem so that air passes freely through it.
7. Get a dial-type tire pressure gauge. I use the tire gauge for 2 reasons. One is the fact that you can't find a higher quality gauge that reads less than 180PSI for a decent price, and the other is that you need to have a fairly small range of pressure on the dial so that the needle moves farther under pressure. Gauges for air compressors might only move about 2mm if they display 200 or so PSI, so they're much harder to read at say... 10 PSI... and they're about $40. Tire gauges are usually around $2-3, and accuracy isn't really much of a problem. Before you make the purchase, make sure the fitting for the tire's valve stem unscrews from the bottom of the gauge. If it does, you'll probably find a standard NPT threaded male fitting.
8. Get a section of fuel line that fits snugly over the gutted valve stem.
9. Get a few brass fittings that fit the gauge's threads, and that will snugly fit inside the other end of the fuel hose. Teflon tape them before screwing them together. About 2 layers is fine. If you're lucky, you'll find one in the bin with a hose barb on one end.
10. get 2 small hose clamps that fit snugly over the fuel line.

Assembly:

1. Drill 2 holes in the PVC end cap that are just large enough for the clamp-style valve stems to fit through. Make sure they're far enough apart that the bottom flanges don't touch, but not so far that the flanges hit the sides of the cap. Either one of those problems can cause your tool to leak, and the cap will be basically ruined. Clamp the valve stems down tight with the lock nuts.


2. Squish the end cap down into the coupler, then use the big worm-gear clamp to honk it down tight. You don't want this thing blowing out under pressure.

3. Slip the fuel hose over the gutted valve stem, clamp it down tight.


4. Press the gauge/fitting assembly into the fuel hose, and clamp it down tight.


You're done building the tool, read on to learn about the test.

With this style of boost leak tester (with the gauge attached to it), you can easily perform boost leak tests without anyone's help. The gauge will give you instant feedback concerning your intake system's general health. If you choose not to install a gauge on your tester, it will cost you about $7-$10 less to make, but you'll need someone to help you test the car... to sit inside the car and watch your boost gauge and shout-out what it's doing. My advice: Spend the $7-$10 and add the gauge. It's not always easy to convince your average video-gaming buddies to leave the keyboard and spend a hot sweaty day in a garage.

Now for the testing procedure...

The reason my recipe only calls for one clamp is because your turbo intake pipe already has the right size clamp on it. Also, if you purchase a second clamp for the BLT you made, it usually falls off of it in your toolbox and gets lost, or your friend borrows it and loses it, so why bother. Save your dollar. Anyway. Remove your intake pipe and filter. Use the clamp from your intake...


...and clamp the boost leak tester tightly onto your compressor inlet.


Cram bolts firmly into your vacuum lines if any of them had to be removed from the intake pipe. Different cars are set up different ways. I'm not even sure if pressure will even vent from these vacuum lines, but since we're trying to eliminate all the leaks, you're better off doing it anyway. Air leaking from these would not be a problem when the car is assembled, but will make testing more difficult.



Now that everything's sealed up tight, apply air pressure to the valve stem on your tool, and watch the gauge. Did it move? If it did, you're one of the rare lucky ones. Usually it won't on a car that's never been tested unless it's bone stock, and still then, many don't. At this stage, you should be able to listen and feel for leaks.


If you have that friend handy that was listed in the stuff that's nice to have around section, have that person apply the air pressure while you poke around. Feel all the couplers, throttle body, BOV, J-pipe if installed, intercooler core and end tanks, and vacuum lines. Big leaks are easy to hear and feel. Once you've found and fixed all the big leaks, you should be able to build pressure on the tool's gauge.


It's the small leaks that can be a problem. This is where the fine tuning begins, and the soapy water comes in to play. I like the SoftSoap variety of soaps. They smell good, rinse clean, and you can find it anywhere. Dish soap works, but doesn't seem to bubble as well. Mix a tablespoon or two to a quart of water. Things you should liberally soak are:

Boost controllers
BOV(s)
all intercooler pipes and couplers (bad welds are known to happen, too)
Intercooler(s)
throttle body(s)
intake manifold(s)
vacuum lines
PCV system
injector seals

Spray everything intake or vacuum related down with soapy water.


Apply pressure again, and you'll see bubbles forming on parts anywhere where air is leaking.





Fixing all the leaks you find will take as much time as the number of leaks you find. Usually, the leaks are a result of something not fitting right or a part that's gone bad. RTV is okay in some instances, but you don't want that stuff getting inside your IC pipes. If flanges leak, you may need to block-sand them flat again with 80 or 120 grit sandpaper, and then make new gaskets for them because the old gaskets are probably damaged. When I make gaskets for IC pipe flanges, I like to put a THIN coat of RTV on them to guarantee they'll seal.

Before block sanding...


After block sanding...


Anywhere you find a threaded part leaking, a few layers of teflon tape on the threads will seal it up well. Zip-ties on all of your vacuum lines ends should keep the hoses sealed tightly to the barbs.

There are plenty of other ways to diagnose intake leaks, but this one has always worked the best for me. Some people just plug the turbo compressor, and blow air pressure into a vacuum hose that's connected to the intake. That's fine, but requires 2 people. Some people like to use fuel sources like carb cleaner or other flamable gasses to see if the car's idle raises when they're sprayed on suspecting areas. That's an old trick that came from the NA crowd. Turbo intake systems are usually too large for that to be practical, and on a turbo car, some leaks don't occur under vacuum. Some leaks don't start until X or Y pressure is achieved. It's better to use pressure to determine whether or not your intake system is healthy on a turbo car.

That's it for the most part. Be patient, and persistent, you'll get all your leaks sorted out. Some may cost money to fix, but fortunately 99 times out of 100, the parts are cheap for this kind of thing. It's the perfect hacker/tweeker thing to spend time on when the weather's nice, and when the track ain't open. And you'll feel better about your car when you know it holds air.

Jafro

There. Restored. This thread dates back to 2004, but I thought I'd fix it rather than let it die forever. I included the links to this same DIY on my YouTube channel below to bring it into a modern era.