Infinity

I know its been asked thousands of times before but...

I have just installed a mechanical Blitz boost gauge and was wondering what pressure I should see on full bost.

At Idle it pulls a vacuum (I know this bit is normal)

I am seeing a constant 0.9 bar (13.2psi) and an over boost at 1.1 bar (16.1 psi) in fifth gear

Mods to date are a scoobysport back box and an ITG panel filter. ECU reset with optimax.

Is this normal?

Thanks in advance.

Martin.

IanW

That sounds about right to me.

ScoobySnack

When I had my MY00 with just the exhaust system replaced I had a pressure of between 13.5 to 13.9PSI. This was confirmed using some software and a few runs at different times.

If you have just reset the ECU then it will take a period of driving to learn, say about approx 300miles. During this time I would hope the overboost should disaappear.

If it doesn't then there are ways to fix it.

Do you also have a decatted downpipe fitted?

J

Infinity

Thanks for the info lads

No the only exhaust mod is the back box, for the minute

Overboost only last for about 2 to 3 seconds.

I am quite happy with it..more boost = more bhp

Thanks again

Martin

kevin stanton

with you running 13.2 constant your over boost seems slightly high for just a back box and filter.

buy a dawes to smooth it out and run 16 psi at constant.

john banks

16.1 PSI is a bit high for an overboost spike. The ECU has uses a boost target of 13.7 PSI and adjusts the solenoid duty cycle according to an error table of +-0.3, +-0.8, +-1.7 and +-3.0 PSI subject to the maximum and minimum (0%) duty cycle tables.

Infinity

Thanks again for the info

John Banks, do you think I should have the car checked out by T&C subaru?

Are the waste gate solenoids prone to clogging up, or becoming weak over a period of time?

Should I get the ecu reset again?

Thanks in advance

Martin

john banks

16 is just a bit high not dangerous. If it was clogging you would probably overboost in the other gears as well. I cannot explain why you only overboost in 5th and not in the others - you would expect a little bit in the other gears. Just see what it does as the weather gets colder - not long to wait now

Infinity

Me again John

I have been out playing in the colder weather today and have the following results

1st gear at approx 5K revs peak of o.6 bar (8.8 psi)

2nd gear at approx 5.5k revs peak of approx 1.08 bar (15.8 psi)and constant at .97 bar (14.25 psi)

3rd gear at approx 6k revs peak of 1.1 bar (16.1 psi) and constant at .97 bar (14.25 psi)

4th gear at approx 6k revs peak of 1.1 bar (16.1 psi) and constant at .95 bar (13.9psi)

5th gear at approx 6k revs peak of 1.1 bar (16.1 psi) and constant at .97 bar (14.25 psi)

Do you think I may have a problem after seeing this?

The car has had one previous owner, but he said the only thing he did to it was a filter and a back box and centre section. But no rechip. The take off for the sender line is on top of the plenum chamber, would this make any difference?

Thanks again for the advice

Martin

Infinity

Forgot to add, me being the engineering type (ha ha ha )
and spending 4 years studing marine engineering at college, I am using 1 bar = 14.7 psi atmospheric
so 1.1 bar = 1.1 x 14.7 = 16.17 psi
I have heard of people using 14.4 up to 14.8 before. Hope this helps calrify things.

Martin

john banks

Your boost peaks sound too high and it probably flutuating a bit and will worsen in cold weather.

WUZ

iTrader: (14)

Martin, Boost stays lower on the first two gears due to the ecu having a function in it to prevent excess power going through the gearbox in 1st and 2nd.

If you want to see Angie, she'll show you the flow regulator (originally JB's idea-thanks JB!) - this can slow down spool up very slightly and allow the ecu to control spool-up with the Boost Control Solenoid better.

You thinks its bad now - wait till you go full decat NIGHTMARE!

See ya in 2 weeks.

Russell

RT

Don't confuse "bar" with "atmosphere".
1 atmosphere = 1.013bar.

Therefore:

1 bar EQUALS 14.503773773 lbf/in² (psi)
and
1 atm EQUALS 14.695948776 lbf/in² (psi)

Infinity

Thanks for that Wuz

Drop me a line when you are home and we'll meet up and discuss cars over a pint or 8 at the four mile

RT. I was told 14.7 psi in air = 1 bar at sea level
Thought the S.I index was supposed to sort these descrepencies out Oh well

Thanks again

Martin