Testing EGBP

[Andy_Mac]

By 2:1 you're meaning backpressure will be essentially half the boost pressure, or is it the other way around? This is one area i've never really put any research into in the past so pretty green on the whole idea of it

So derived from AFM readings mines getting just under 32lb/min.

Alright well in that case i might as well just take off the downpipe and headers and get a new port welded into both and go from there. Its alot easier for me to just drop parts in than taking the car in since its not driven daily.

[Guest]

Exhaust pressure always higher. Well in our realm anyway.

[lachlan]

I saw u wrote post turbo and assumed u wrote the wrong word . U wont be able to read the pressure post turbo on a boost gauge . Need a manometer or somethin .

Have u really never seen exhaust pressure lower than booat in our realm ?im not arguing I just figured it was achievable . I might check mine . Vf22 . 197kw on 11 psi boost .

[Guest]

A member once measured 3psi across a specific resonator so yep possible to measure on boost guage if it doesnt show thats mint.

Our realm being clubsub noone on here has a dedicate drag car with that bigger hot side.

Why only 11psi?

[Andy_Mac]

Yea as I said, only really even started looking into this stuff a few days ago so pretty clueless right now. I know the obvious one to do is pre turbo but with the number of people saying i've got to go for a much bigger exhaust to get more power i'm intrigued to see what results the stock one gets.

Got a couple of digital differential pressure sensors at work that'd probably do the job, apparently they're calibrated to be accurate at single digit kpa values so should pick up almost anything. Guessing just one side tucked up somewhere to get atmospheric pressure and the other in the gas flow? Thats how i'd do it atleast

Edited October 27, 2015 by Andy_Mac

[Guest]

How do they read? Link to the unit in action?

The big restriction is the cats which are no longer an issue. Even if you dont tune back to back just measuring egbp tells you a fair bit.

[Andy_Mac]

Basically a gauge with two hoses/vac hoses. One positive, one negative. Doesn't particularily matter for digital ones what direction they go but you'd usually have the positive side as the side expected to have the higher positive pressure.

We use them for checking pressure drops across filter banks and condensers/evaps for fan efficiencies

Edited October 27, 2015 by Andy_Mac

[Guest]

But what does it read? The low, high and difference? Or low and diff?

[Andy_Mac]

Measures the difference between the two sides, not sure how the digital ones calculate it though. Maybe just two highly sensitive pressure sensors.

If one has no movement, pushing/pulling, then it is essentially just measuring the pressure the one side see's and can typically be more sensitive towards small changes than other methods.

Say if you hooked both sides up to the intake manifold it would always in theory read zero since its only picking up the difference between the two, regardless of what pressure is being applied to both sides.

Thats the basic method they use to calculate the pressure difference

[Optical]

my 82 housing was around 1:1

[Guest]

 Optical said:

my 82 housing was around 1:1

Still too slack to measure the new one then. The .82 was quite soggy iirc 4k/1 bar?

[Optical]

i havent got my bits back from a friend who borrowed them.. over a year ago

that log was messing about on the motorway iirc, i should fins a log from the track, wasnt that laggy but the 63 is def much quicker to get going...

[Andy_Mac]

Thinking those two spots for getting the ports welded into. The twinscroll headers are extremely small so not sure how welding a full size bung onto one will work out. With my rather crude measurements the external diameter is about 1.5" for each on the headers just before the uppipe flange.

And short of going to the other side of the cat chamber thats seems to be the only spot it'll fit on the downpipe since the stock heatshield gets in the way of the opposite side of it. Don't think there's any chance it'd mess up the o2 sensor readings at all

[Guest]

Can weld in a smaller bung just need to get a port and plug that matches your tube fittings. Location looks fine.

[Andy_Mac]

Yea true. Well i'll see what the exhaust guys have sitting around.

None of the places i've been to have any plugs for metric size threads and claim no one else will off the shelf either so thinking about just seeing if the guys i'm taking it to have plugs and i'll just drill a hole through them and easy flow some copper to it.

[Guest]

Those capillary jobs will be imperial likely npt.

[Andy_Mac]

Yea NPT seems the more common of the options for everything else in this diameter range.

Still struggling to find any vac line kits made up for stuff like this though

[Guest]

Supercheap should have one.

[Andy_Mac]

Sweet, i'll give them a go. Could have been speaking chinese and the Repco guys would have had no less of a clue what I was on about.

Depending on how they've joined it exhaust temps could be an issue too, i'm thinking. The one you showed looks like its just copper brazed to brass. Unless they have used some strange composition silfos i haven't come across yet then the exhaust temp at full noise will surely be within the melting range of it.

Edited October 28, 2015 by Andy_Mac

[Guest]

 Andy_Mac said:

Sweet, i'll give them a go. Could have been speaking chinese and the Repco guys would have had no less of a clue what I was on about.

Depending on how they've joined it exhaust temps could be an issue to i'm thinking. The one you showed looks like its just copper brazed to brass. Unless they have used some strange composition silfos i haven't come across yet then the exhaust temp at full noise will surely be within the melting range of it.

Worked on mine for over an hour before coming apart. Didnt leak just pulled out of socket.

[Andy_Mac]

You mean the copper capillary tube pulled out of the brass fitting?

[Guest]

 Andy_Mac said:

You mean the copper capillary tube pulled out of the brass fitting?

Out of the olive

[boon]

 evowrx said:

Out of the olive

wtf do your olives properly... a properly installed olive join will handle 1000psi...

[Guest]

 boon said:

wtf do your olives properly... a properly installed olive join will handle 1000psi...

Go fck an olive. The brazed bit where the pipe goes into the flared bit thing not the join.

[Andy_Mac]

Ah so it was a brazed join that failed though? Did it look like it melted and came out or just cracked off?