Turbo Boost readings... -18psi on idle.

PobodY

PobodY

Moderators
Staff member
That's about -1.2bar yes? - That can't be right; it should definitely be negative at idle because the turbo isn't spinning so you've just got vacuum, but I would have thought -1.8psi was more realistic.

Where is the boost gauge T-d in; maybe that has something to do with it?
 
John

John

New Member
Should be around the negative 0.5-0.6 bar from my own experience, so something definately not right there.
 
PobodY

PobodY

Moderators
Staff member
I'm surprised the gauge even has markings that low; are you sure there's not a small dot between the numbers? - It doesn't look like it in the video admittedly.
 
Braveheart

Braveheart

New Member
Gauge is T'd into the boost sensor input pipe at near side inner wing. Was using that source before with a different gauge which would read around -8 to -9 psi (-0.55 to -0.6 bar) I also have a 3 bar boost sensor for emu T'd off from that source now and can connect the other psi gauge to that and see what reading I get. The new autometer gauge has a step down connection provided and uses a micro stiff plastic vacuum pipe from source to back of gauge. Car's getting transported to Irvine today for it's rear quarter transplant operation so I will have another quick look but will leave vacuum lines intact until I get it back.
 
Braveheart

Braveheart

New Member
PobodY said:
I'm surprised the gauge even has markings that low; are you sure there's not a small dot between the numbers? - It doesn't look like it in the video admittedly.
Click to expand...
The scale is in full units.... +/- 0 to 30psi.... good old yanks.
My second gauge is not in my box of tricks... I've left in my garage at home... :doh: I'll get this rear quarter done.... maybe get it painted then take the car back home where I can work on it... most of my tools are there and the garage here is like a cave and very small.

 
Braveheart

Braveheart

New Member
Been looking into this further on the www. Wanted to check if you could calibrate the gauge.
Found a thread that said -18psi is good, ... it also went on to say that -13psi and you have an air leak... maybe I'm chasing a red herring.... the gauge series is "phantom"... go figure.... :lol:

"Hehehe... His is better then yours. If you are running 13-14 you ###### have a leak. Its suppose to be like 17~18ish.. 21 is ok though. When mine dropped to 14 I tested and found some leaks."

"Right around 18-19 is normal. 13-14 is really low and if you gauge is accurate means you have a problem. If it's low and steady your ignition timing might be retarded or cam off a tooth"

http://www.dsmtuners.com/forums/app...-merged-8-9-adjust-adjusting-calibrating.html
 
B

boost

Member
mines atleast - 18psi which is absolulty fine mate, if you didnt have neg vac i would be concerned.
 
Braveheart

Braveheart

New Member
boost said:
mines atleast - 18psi which is absolulty fine mate, if you didnt have neg vac i would be concerned.
Click to expand...
Good stuff.... It used to sit about -10psi on idle. Now I have changed turbo, intercooler, boost gauge and fitted 3bar boost sensor it has gone to -18psi. Must be my quality plumbing and parts that's caused the gain... ;-) I'll move onto other tasks and get this car finished! :thumbsup:
 
Davie Houston

Davie Houston

Member
Mines is down at -12 but theirs deffo no air leak, as have pressuriessed the system and it doesnt leak anywhere and reading stays the same.
I just put it down to the 264 cams that are fitted to the engine.
 
Trip

Trip

New Member
I suggest you get a second rading from another boost guage. I have my boost gauge which reads -18 but my PLX datalogger reads -10psi
 
Davie Houston

Davie Houston

Member
I have my AVCR aswell, and thats the same.
Used to be down at 500, but since cams have been fitted its dropped to 330 ish.
So thats what my reason was for the low reading.
 
Braveheart

Braveheart

New Member
I will try another gauge ... have an other gauge at home and one in the post to me here... whichever comes first. Car's away now to get rear quarter replaced and maybe paint. When I get it back, I will fit 660cc injectors and my ECM... that should be able to give me some data via the boost sensor. I also have a greddy profec spec II that I could fit. I just wanted to take small steps and add mods when I was happy with the last mod. Sure it will all come out in the wash...
 
B

boost

Member
all the cars ive owed mate, eben a 5 tubby, was around the same.. depends on how well your engines breathing etc
 
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