How far should the boost gauge show?

[Pupbelly]

1996 T5-R How far should the needle go into the white portion on full boost and when should full boost occur in the rev range?

Many thanks
Mark

[Mkengineering]

The mechanical boost gauge on the p80 is wrong and basically incorrect.

Assuming your car is running 15g or 16t turbo and has no mods, then you should be seeing roughly 15psi at the very end of the white curve. However if its on the middle then its about 5psi then 10psi inbetween.

[Pupbelly]

The car is standard. Should the needle swing right across and hold on the right half of the white portion or sit in the first third of the white?

I haven’t given the car a full test drive yet but the needle appears to go to about a third of the way into the white section so I’m wondering if that’s normal or is there a boost leak?

[andrewc1267]

You could really do with an accurate boost gauge and also as regards to lack of power it all depends on what you are comparing to. I have said before in previous posts that I find the standard T5 engine lazy especially compared to modern cars.
Once you have an accurate reading of the boost pressure firstly I would get back to basics check or better replace all the vacuum hoses and check all boost hoses intercooler ect for leaks I use a smoke Pro for this. I remember on my me7 v70r it was the wastegate control valve caused an issue where the car would be savagely quick then nearly no boost

[Pupbelly]

My daily driver is a 300 bhp Impreza Wagon so this is a different beast altogether, however the T5R just isn’t feeling swift or punchy.

I’m swapping the vacuum lines from the turbo to the turbo control valve, just got the one tucked underneath the turbo to get at next.

I gather there are conflicting reports as to which line goes to what colour on the turbo control valve but I think they look pretty much original so I’m going to assume they are routed correctly.

Is the turbo control valve a potential problem? I gather replacements are expensive or you can buy a V70 one?? Anyone got some part numbers or pointers please?

A manual boost control is seen as a no go after reading some threads. I suppose if you don’t go barmy with the boost they are ok??

Any advice welcomed as always

Cheers
Mark