EA82T boost pressure ?

steptoe · Post by **steptoe** » Sun Jul 22, 2007 9:32 pm

figuring std boost pressure is about six psi, does waste gate begin to open just above like at 7psi or does it wait until 8 or 9?

another LPG conversion calculation 'ere

Gannon · Post by **Gannon** » Sun Jul 22, 2007 9:56 pm

Standard boost pressure is 6.5psi

I assume that the wastegate would start to open before 6psi and would be fully open at 6.5, depending of course on engine rpm and load

steptoe · Post by **steptoe** » Mon Jul 23, 2007 11:20 am

the factory manual says to use a vacuum pressure tool to give 9 to 10 psi to the rubber checking hose to ensure wastegate opens . Caused me some confusion, thats all, ta.

SubaRute · Post by **SubaRute** » Mon Jul 23, 2007 12:13 pm

im sure the waste gate will open when boost has reached the std psi or if you have increased the boost to ?.... it would open once it has reached that psi

correct me if im wrong ....

BlackMale · Post by **BlackMale** » Mon Jul 23, 2007 12:55 pm

You should also be aware of waste gate leakage… a dirty word I know however something to be aware of, as it unfortunately happens.

Subafury · Post by **Subafury** » Mon Jul 23, 2007 9:01 pm

run it on standard first, then crank it up to like 10psi max like i have- works a treat and isnt too much for the ol ea82

steptoe · Post by **steptoe** » Tue Jul 24, 2007 11:36 am

was thinking 10psi max and that equates to 320CFM at 6000rpm

discopotato03 · Post by **discopotato03** » Tue Jul 24, 2007 7:05 pm

Jono turbocharger waste gate diaphrams are designed to crack the gate open a little before the desired boost pressure is reached . This way the vent path swing valve has a chance to regulate the turbine speed and hence compressor revs , boost pressure is merely a measure of resistance to airflow . Manufactures in the 80's liked it this way because rapid boost rise often means rapid torque rise (well designed turbo engines can easily double their torque outputs in 500 RPM) , ok for petrol heads but not at times smooth or easy to control on a tight bend especially in the wet . Modern turbo engines have much more linear power delivery and more sophisticated engine management and turbos make a big difference .
Many turbo cars nowdays use electronic control of the wastegates pressure signal and this is mainly about keeping the gate shut until the regulated pressure is reached . In other words it gets around the mechanical limitations of the spring/diaphram waste gate actuator . I believe this is what the 4 plug RX turbo cars have so very likely they'd be a little more responsive than the 3 plug cars .

Jaycar make a very interesting kit that controlls a boost solenoid but its signal is supplied from an injectors duty cycle . It is far and away a MUCH faster and more accurate means of boost control signal than a MAP sensor based one . I intend to build one along with their Digital Fuel Adjuster so that I can have some say over injector size/AFM size and retain a std Subie ECU . Thank god for basic engine control systems from the 80's .

Cheers A .

Gannon · Post by **Gannon** » Tue Jul 24, 2007 8:20 pm

I noticed while driving since i hooked up the WGDS, (i previously had it bypassed)...
The WGDS operates at partial throttle, you can hear it clicking, and full throttle until about 2400rpm, then it stops clicking.

This is exactly what you just described, it ensures that the wastegate stays fully closed until full boost is reached.

Although i noticed apon accelerating that boost spikes to about 8psi and then settles to 6.5 once 2400rpm is reached. Im guessing that this is because i have a free flowing exhaust and i reach full boost (6.5psi) at about 2200rpm

steptoe · Post by **steptoe** » Tue Jul 24, 2007 10:51 pm

It'll be trial and error and fiddling for me, and more questions posted as I learn or discover more.Noticed green boost light during free revving in neutral or park does not glow until about 4500 rpm

!! . BUT took it for a few laps up the road to clean the rust off the discs and notice boost light at about 2500rpm

. Know someone with a boost gauge not in use, so off to knick that soon I'd say ...

Yeah 80's and 90's turbos were a bit umm harsh, TX5 and oh the Cordia just got rated as worst performing car safety wise. NSW coppers used to torque steer themselves off the tarmac with these !!

D3V1L · Post by **D3V1L** » Tue Jul 24, 2007 10:59 pm

while free revving the turbo does not boost up, engine needs pressure to wind up the turbo..hence y the bost light does not go on till late in the rev when free revving...when driving there is pressure on the engine hence the boost rising when and how it should b

dave

discopotato03 · Post by **discopotato03** » Wed Jul 25, 2007 9:46 pm

Yes the cops got into hot water with the Cordias and VLT's . People who aren't used to turbo torque tend to stand on the go pedal and wonder why the cars spins wheels or torque steers at not terribly high revs . Its suddenly a whole new world of how to balance throttle inputs and adhesion levels .

I haven't looked into how the 4P RX does its solenoid regulation as there's a few ways to go about it ie restricton and signal bleeed or the total block method . Either way the Jaycar system is fast/modern/cheap and makes you learn how to identify/solder/test circuits . They supply very easy and simple to use instructions in all their kits . I'll find out tomorrow .

Cheers A .