Question about my Turbo and Turbo gauge.

[JDMSupra]

Hey, I was wondering why my Supra wont show any boost from the gauge when I just rev it with the clutch pulled in, it will only boost with a load and boosts fairly late into the RPM range, should it start building boost faster? Does this happen to all supras or is it just mine, the gauge does not move at all unless hammered in gear 4000+ RPM, also hard to get boost spooling in first gear. thanks.:icon_conf

 

[Justin727]

stock boost gauge is slow

 

[MassSupra89]

It's usually harder to get boost in 1st compared to other gears, but in 2nd,3rd,etc. you should be boosting sooner than 4k. Stock I hit 6psi by 3,000 in 2nd.

 

[JDMSupra]

Im not exactly sure how to read my stock turbo gauge it goes from -2 to +4 but it never shows it going past +2. I have gotten the RPMs to redline and still not much above +2. Can someone tell me how much PSI this is?

 

[MassSupra89]

Sounds like it's time for a new boost gauge...

 

[JDMSupra]

so you guys are pretty sure its my boost gauge and not my actual turbo?

 

[MassSupra89]

Do you feel much of a pull once you hit full boost?
If the turbo feels pretty weak the gauge could be right and it could be the turbo, or a boost leak(which you would probably hear)

 

[JDMSupra]

its realy hard for me the say, i can definetely tell when the turbo kicks in but i cant say its all that hard. I have never driven another turbo supra before so its hard to say.

 

[JDMSupra]

what does a turbo leak sound like? i do hear some gurgling noises from the engine at idle or low rpm, can someone tell me what that is?

 

[robbo185]

check your ic pipes, check everything for leaks, cracks, loose clamp...whatever

 

[Justin727]

i said it once i'll say it agian STOCK boost gauge is SLOW

 

[JDMSupra]

yeah but if it was slow it the gauge would still eventually read full boost but it doesnt. thats why i dont think its just being slow.

 

[boost fiend]

i have the stock gauge and a autometer in the car. the autometer hits 10 psi before the stock one even realizes ive hit boost. spend a couple bucks and get a diffrent gauge.

 

[JDMSupra]

what kind of gauge do you recommend?

 

[Justin727]

Greddy,hks, blitz, defi, autometer

 

[Marcenator]

Turbo's build boost from energy(heat) produced by the engine under load. Just reving the engine doesn't produce much energy. The stock boost gauge reads in mmhg so +4 is equal to about 7.7 psi. Stock boost is about 4.5 to 6.5 psi. With a stock setup the gauge shoud not go all the way to the top.
Here are some conversions.
MMHG PSI BAR
0 0 0
1 1.9 0.13
2 3.9 0.27
3 5.8 0.40
4 7.7 0.53
5 9.7 0.67
6 11.6 0.80
7 13.5 0.93
7.5 14.5 1
8 15.5 1.07
9 17.4 1.20
10 19.3 1.30
11 21.3 1.50
12 23.2 1.60
A better gauge can help give you a better idea of what you are boosting at.

 

[trydrew]

Could it perhaps be a faulty bypass valve..? That would explain no 1st gear spool and low boost. This and a leak might make the problem, and a new gauge wouldnt hurt, especially something more accurate.
One more thing, you normally dont get much if any spool when not under load.