bad boost leak? Video attached

90tbirdsc

90tbirdsc

Registered User
ok, after swapping on a ported late model with a mp inlet and fabbing up a fmic and getting a quarterhorse chip and tune from DD and getting 2.5 mandrel bent downtubes and 3 in exhaust my car is a dog. I have sealed up all the piping and the sc hat and it didn't make a difference in boost and I cant hear where any major boost would be leaking. so im wondering if the only thing left is to pressure test the IC? or if there could be something else that could be causing this?

the car idles and runs fine as well

Video: http://www.youtube.com/watch?v=CH0PAlo7-BA&feature=share&list=UU_KBEm1RAchVUFGeEAj0i6A
 
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nmcbchief said:
You have 12 psi of boost. What size SC pulley are you running? Maf and injectors upgraded?
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LMAF calibrated for 42# injectors, I have 42# injectors and 255lph fuel pump.

running 15% OD 10% crank 5% blower with mp tensioner springs and shorter belt. I might add that during a run from 0-90MPH my IAT only went up 14 degrees. from 78-92 degrees f
 
Sounds like a leak somewhere. You should be pegging the boost gauge out. Smoke test it. Is your bypass valve working?
 
nmcbchief said:
Sounds like a leak somewhere. You should be pegging the boost gauge out. Smoke test it. Is your bypass valve working?
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I unplugged the vaccum hose that connects to the bypass valve so that the valve is closed all the time and there was no difference in boost or vaccum.
 
What could it be? Lots of stuff.

Do you know who ported the supercharger? Is it a proven job and do you have any pics of the supercharger inlet and outlets? If you do please post them or email them to me if they're top secret. It's safe with me, I rarely post on SC forums. You can over port them and loose efficiency.

Is the throttle-body at WOT when the pedal is matted?

When you pressurized the system checking for leaks did you check the intercooler and connections also? Did you hear any air escaping the intake system at 15-20 PSI? I use soapy water with lots of soap or an EVAP smoke machine.

The engine made good boost before the new blower and intercooler set-up yes or was it also low before?

So the air filter you're using isn't stock right? A stock resonater box could be stopped up with a forein object.

With the engine running at idle does the crankcase have a excess of vacuum in it? When you pull the vent tube at the valve cover does it have suction under it. If so hook up an old vacuum gauge and see what the reading is. If it builds up towards manifold vacuum you have a intake gasket leaking in the lifter valley. Or if the heads have been heavily ported it could be a crack in a intake port roof at the base of the rocker pedistal.

Vernon
 
Vernon said:
What could it be? Lots of stuff.

Do you know who ported the supercharger? Is it a proven job and do you have any pics of the supercharger inlet and outlets? If you do please post them or email them to me if they're top secret. It's safe with me, I rarely post on SC forums. You can over port them and loose efficiency.

Is the throttle-body at WOT when the pedal is matted?

When you pressurized the system checking for leaks did you check the intercooler and connections also? Did you hear any air escaping the intake system at 15-20 PSI? I use soapy water with lots of soap or an EVAP smoke machine.

The engine made good boost before the new blower and intercooler set-up yes or was it also low before?

So the air filter you're using isn't stock right? A stock resonater box could be stopped up with a forein object.

With the engine running at idle does the crankcase have a excess of vacuum in it? When you pull the vent tube at the valve cover does it have suction under it. If so hook up an old vacuum gauge and see what the reading is. If it builds up towards manifold vacuum you have a intake gasket leaking in the lifter valley. Or if the heads have been heavily ported it could be a crack in a intake port roof at the base of the rocker pedistal.

Vernon
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engine made 14-15 psi with the stock sc at 15% od and I have a aftermarket throttle body and CAI and MAF

ill check on that last stuff tommorrow
 
Where in NE are you? Have a good mechanic in Lake Manawa that could take a look at it for you. Yes, he owns SCs and works for Ford.
 
Its leaking somewhere I bet. You can rig up a tester with an air compressor, put 20lbs of pressure in the thing. Spray soapy water all over it. Any cylinder in overlap is gonna leak but youll have enough pressure to get an idea.
 
90tbirdsc said:
There is no slip, or at least a very, very, minimal amount. The belt I have is shorter than stock and I have mp tensioner springs.
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Yeah I had those too. It took me about 20 minutes to slip my belt on with my brother's help. That is how tight it was. Even so, no boost. I noticed that after just going around the block, the sc pulley was hot enough to cook meat on. On advice from David D. I filed down the ribs of the sc pulley which were worn down to the point they looked like steak knives. After I flattened them out, back to 18 lbs of boost from a low of 7.

I had a minor leak at an ic tube once and the engine started hard and barely ran. I can't see you having a leak that costs you 1/3 of your boost leaving the engine idling and running normally.
 
Flex said:
Yeah I had those too. It took me about 20 minutes to slip my belt on with my brother's help. That is how tight it was. Even so, no boost. I noticed that after just going around the block, the sc pulley was hot enough to cook meat on. On advice from David D. I filed down the ribs of the sc pulley which were worn down to the point they looked like steak knives. After I flattened them out, back to 18 lbs of boost from a low of 7.

I had a minor leak at an ic tube once and the engine started hard and barely ran. I can't see you having a leak that costs you 1/3 of your boost leaving the engine idling and running normally.
Click to expand...

Its easy enough to try also, grab a stock blower pulley and see what happens.
 
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