new boost gauge, only 9inhg at idle

montj

New member
got a new twosrus boost gauge hooked up the back of the intake manifold.
at idle after warmed up it doesnt get any higher then 9inhg and when maintaing a speed with 10% or so throttle it reads 0 vac/pres. i hit about 5.5-6psi on first and second and 6-6.5 in 3/4/5.

after searching the forum, i read alot people get around 20ingh mostly.
does it sound like a vacuum leak? im not very good at diagnosing car problems.

thanks
-james
 

montj

New member
yeah 6psi WOT on 3rd,
the stock boost gauge sits at the - line and doesnt hit 0 until im accelerating with at least 25% throttle.
WOT on 3rd it boosts all the way to the last line on the gauge.
i know the stock boost gauge is know for being inaccurate, but it sounds more like my aftermarket gauge is off.

also the previous owner had the turbo rebuilt with a 60 trim, i havnt even heard of someone with that big of trim on stock ct26. maybe thats the problem.

and as far as i can tell the car runs fine, passed smog recently and doesnt bog down or do anything weird.

thanks alot for the help,
-james
 

db

Active member
I get between 18-20 inches of mercury at idle. Everything else you mention is hard to compare to because of the different possible situations, but you are definitely low on vacuum. Definitely sounds like the boost gauge isn't reading correctly. Is it a mechanical or electric gauge?
 

montj

New member
i fixed it, i reconnected everything and i guess some of the fittings were too tight and now it reads 18-20inhg and i hit 6.5psi, almost 7, steping on it in 3rd. sound safe to install a mbc and try some higher psi?
 

RIalltrac

Active member
montj":2gh3y5jk said:
i fixed it, i reconnected everything and i guess some of the fittings were too tight and now it reads 18-20inhg and i hit 6.5psi, almost 7, steping on it in 3rd. sound safe to install a mbc and try some higher psi?

sure, you wont be able to go past like 10 without disabling or limiting the fuel cut.
 

20incher

New member
A wee bit off topic but i had a stock ct26 with a 60 trim and a friend in austin has a ct26 with 60 trim with a 10 degree clip...so they are around. However it is a big turbo and if your running on stock internals as well as IC and Fuel...i would not suggest going above 12-13 psi. my 2 pennies
 

MetalliKAT97

New member
RIalltrac":3tnirkiu said:
montj":3tnirkiu said:
i fixed it, i reconnected everything and i guess some of the fittings were too tight and now it reads 18-20inhg and i hit 6.5psi, almost 7, steping on it in 3rd. sound safe to install a mbc and try some higher psi?

sure, you wont be able to go past like 10 without disabling or limiting the fuel cut.

Depends on how lucky you are....some of us hit higher PSI without the FCD....had 2 cars like that already
 

TomsGT4

New member
Common, just get an 3" dp & mp :D
I hit 10 sometime 11psi WOT without my boost controller, and no fuel cut.

If I remember correctly stock fuel cut is set around 12psi.
 

theUNYTEDone

Moderator
i would just be safe and get an FCD...there were a few threads saying how to make them for less than ten bucks...but congrats on fixing the problem.
 
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