lost boost

ThePikey

Registered User
I recently put a new supercharger on my bird... i stayd with the same 90 eaton m90. after we got it all back together i noticed a loss of boost. instand of the 11-12 i had been getting i am not getting 6-7. all the vaccume lines are attached and cant hear or feel any leaks there. i was wondering if anyone could give me any imput as to why the loss of boost.
 
darkstar_one said:
exhaust? did u open up the exhaust?

still 6-7psi is tooo low , you must have a huge boost leak maybe in the ic tubes or the SC top,
how much vaccum are you pulling at idle
at what altitude ?
auto or 5speed ?
list all your mods.
 
turbospeed said:
still 6-7psi is tooo low , you must have a huge boost leak maybe in the ic tubes or the SC top,
how much vaccum are you pulling at idle
at what altitude ?
auto or 5speed ?
list all your mods.


Idle Vaccum is about 15-16in/hg
Altitude is 650 (approx) st.louis
auto
no mods. all ive done to the car is the tranny (with shift kit) still had good boost (this was back in feb). the starter (memorial day) and the waterpump (where ALL my supercharger problems began, and why i put a new one on. see "is my supercharger toast?" thread for details there

i know there is a boost leak. i can hear the hissing as the engine reves up.. but cant find it at an idle. how would i go about testing the joints and what not to find the leak. i reved the engine up and didnt feel anything
 
I used a brake bleed style tube (about 2 feet long), and put one end in my ear, and the other end around the intercooler connections. The air loss was extreemely noticeable at idle. besides, 15-16 inches of Hg for vacuum is quite low. Does it have a rough idle?

Do a search for tbird88 (Texas Thunderbirds) and his reuseable gaskets for the intercooler. I'm about to order a couple sets having seen them on someone else's car. The looked very solid. And it sure beats squeezing a truck load of blue rtv around the connections.
 
i discovered those gaskets last night while surfing the net. gonna get me a set of them... im thinking its the IC tubes thats leaking.

it doesnt idle rought at all... quite smoothe actually, not much different than before the SC swap.

i noticed the problem when one morning as i was leaving work i jumped on it.. and i used to be able to light the tires up for about a city block and a half... and when they didnt even chirp i noticed somethign was wrong...
then a few mins later when i got on the highway i jumped on it and could hear the hissing sound while i was in boost... but when im idling theres hardly any difference and no hiss.

the gaskets sound like a good deal to go.. just gotta wait til pay day
 
Your local auto parts store can hold you over until you get the parts from Texas T-birds. Permatex Copper high temp RTV works well as a sealant. About $6.00 a tube.

I would start with making sure the big nut on the SC top is tight.

I found a leak once by working with someone. More often than not, when shutting off the engine there is some latent pressure in the intake system. With my head under the hood I had my son shut off the engine and then listened for a hiss of releasing pressure. It took a few tries but I tracked it down to the big nut being loose. Mine worked it's way loose over time after an accident with a deer.

Since your's is recently assembled it might be leaking from somewhere else.
 
its the lower IC tube where it bolts up to the intake... you can actually see the gapping there..
im gonna get a set of the gaskets and then reset the tube back on there
 
just in case, I've always found it beneficial to have the intake system just barely held together by the bolts (but have every piece in it's place) before I start to torq down the bolts. that way, I get better alignment of the tubes and intercooler.
 
thats where i goofed when putting the new SC on... i tightened the bolts... then went to the other end not thinking about the alignment...

this who SC induciton is new to me and a learning process along the way. luckily through here and a couple other sites ive found ALOT of good info on what work i have had to do to the car in the few months ive owned it.. (yea almost $2000 in 4 months... but what do you expect when you buy a 14yr old car) The way i looked at it is the parts that i have replaced ie tranny, starter, water pump, plugs, wires, washer fluid bottle,(which was non exhistant when i bought the car) are old parts and are bound to go out at one point...

hopefully tomorrow i can get that ic tube realligned and stop leaking. couldnt do it today due to rain.
 
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