Sorry to a be a bit thick but ive been looking at my boost gauge and whilst its a great toy what is it really telling me?

I reckon its measuring inlet manifold pressure. It does this in bar. but is zero bar what normally aspirated cars have? When mine spins up to 1.375bar as a peak is this ok for my engine (samco hoses, Tek2 ECU, itg filter, full decat exhaust) or am i about to see it explode? what is this in psi out of interest?

Also for info, What does a standard UK turbo put out?

also we talk of boost holding at 1.2bar but sometimes mine stays solid at that and sometimes the needle is skaking... why is that?

In the lower gears the boost seems to be lower than in the higher gers, whys that?

When the car is idling its below zero bar, so whats happening in there at this point? is my gauge reading something else mmgh - i think?

On my driveway prodding the accelerator only gets me to zero bar, why doesnt it go right up to a positive reading like it does when driving?

Sorry for all the questions but thats the problem with now seeing whats happening - i now want to understand it.... :-p

Jon.

 

Ok, first of all, think of zero as atmospheric pressure. Your manifold pressure will be less than zero (atmospheric)at idle, as there is a vacuum with air being sucked into the engine...the turbo isn't spinning at this point. As the engine revs increase and load is applied to the engine, the turbo begins to spin up and eventually, give a positive pressure. You are peaking at about 20psi, which is a bit on the high side, but will your engine blow up? well, there are many other factors to consider. Is it more likely to blow up than before the mods, there's nothing surer than that. 1.2bar is about 17.5psi, which is regarded as pretty safe, again in loose terms. I've been running 21psi peak, 20psi held for about 10k miles now with no evident ill effects. That's not to say you'll be ok, there's a much bigger picture to consider. As for the boost being higher in higher gears, this is because of the extra load applied to the engine, but your boost control should take care of that. Has the TEK3 been fitted recently? I'd talk with the guys who fitted/ mapped and get your boost control sorted out, and check your fueling.
As for the uk power figures, 208BHP for early models, 215bhp later on...98on I think.

I'm sure some of the other guys will go into more details but that's the basics of it.

Alan

 

What's the make of the turbo gauge ? Some gauges are more accurate than others. You'll find 14.5psi = 1 bar

Standard boost should be varied between 0.9 bar - 1.0 bar. Other mod's can alter settings. Having a Dawes or some sort of boost controller can also change these settings. This is all I can add to whats already above.

 

not trying to be smart but 1 bar = 14.7 psi

 

Really? And here's me thinking 1 Bar= 14.5037738psi

 

 

 

Cheers guys!

Last night i was boosting up to 1.4 peak.... hmmm...

Gauge is a Defi so I assume its pretty accurate..

I have a Tek2 not a Tek3 so I wonder why im seeing such big boost? I think the fueling is ok as the exhaust is very sooty, leading me to think its still running rich...

Anymore thoughts?

Cheers again for all your help so far... Jon

 

Not to be even smarter....
1 BAR =
1000 Millibars
401.46 Inches of water
29.52 Inches of Mercury
33.45 Feet of Water
14.50 Lb/Sq" (PSI)
2088.54 Lb/Sq' (square feet)

really confusing is that 1 BAR = 0.987 atmospheres *

oh suppose I better do the metric equivs too
100 Kpa
10197.16 mm of water
750.06 mm of Mercury
1.01 Kg/Sq cm

* note PBAR is absolute not BAR

 

And there was me thinking that 1 bar = 14.492753623188405797101449275362psi

Matt

P.S. Defi's don't actually read in Bar so your 1.3 is probably actually more like 1.2-1.25 (sorry can't remember the Defi units). What is the held figure?

 

Use this site for online pressure conversion
http://www.onlineconversion.com/pressure.htm

 

defis are kgf/cm2 but 1.4 peak on a tek2 something rong there! whats it stabalise at?

 

Hi JonW, my MY97WRX has always had a sooty exhaust, but it was only getting 4% CO on full boost!!! 8 - 9% is good, A PE Phase1 conversion sorted that out though.

 

IIRC 1 bar is 0.98 kg/cm2

 

kgf/cm2 is indeed what my Defi reads!

stabilises at 1.2-1.25 - depends on gear... is that ok? its been like this for 5k miles but ive only just fitted the gauge...

hmmm, cheers for sooty exhaust comments... worried moi????

Jon.

 

You could try one of John Banks AFR meters http://www.scoobynet.co.uk/bbs/threa...threadid=57428, which confirmed what PE said after my rolling road run.

 

Jon, all sounds pretty normal to me, but if you talk to your EcuTek supplier they will maybe say 1.4 is a tad too high. Are you getting a 1.4 spike then holding 1.2? That's a bit too big a difference. Having said that, I too have a Defi gauge and according to John Banks' it over-reads by 0.1 bar (okay I know it's not bar but it's only 2% different). This is easily rectified in two minutes with a 1.3mm restrictor. Talk to your supplier.

Good luck,

Richard.

 

As an engineering student I can honestly say that 1 BAR is not enough and we need at least 4-5 in the campus. The students drink alcohol like mad..

 

Jon

See, you'd be better off without it as you wouldn't know what was going on

You're getting exactly the same figures I was getting with my decat PPP.

BTW if you've been trying to mail me email has changed - see profile. Basically BT blow many, many goats.

 

Just thought id mention that reading the exhaust colour is apparently a waste of time when running unleaded fuel. Only works with proper leaded petrol. Same with plugs apparently. You can get SOME obvious indications still for sure, i.e. if big clounds of black smoke are eminating from your tailpipe, you can be quite sure you're overfuelling

 

Hoppy, cheers for that but i havent got a supplier as mines a second hand unit... to be honest no one like John Banks/ Bob Rawle has chimed in and said this is a worry so sounds like I should be fine....

SimonH - u have mail you goat sheppard you.... ;-p

As for bar comments well I bar is too little for workers and students and usually equates to me sliding way under teh bar by end of the evening...

Cheers again guys... Jon.

 

Jon,

Just because John B/Bob R hasn't posted doesn't mean you're ok....Who did you Tek? I'd just ask them to be on the safe side...

Matt