Its to do with emmisions and exhaust gas recirculation. leaving it off wont hurt unless you have to pass a major emmisions inspection. Mine has siezed in the open position and been like that for a long time.
I would keep it connected unless you take it off. disconnecting it drops power on miine.
1993 MU 2.8L TD - Boosted, Fueled, 'Cooled, Lifted and Locked! 2.5" mandrel bent exhaust with custom dump, EGRs removed, Snorkle and Uni Filter, Intercooled, Inline boost controller @ 17PSI, 2" Body Lift, 3" Suspension Lift, 33" Mudders, Custom LSD rear and Lokka Front with 100HP 880lb-ft (4th) where it counts.
This is actually to do with the warm-up system on your vechile. there is a button just below the steering wheel with a glow plug symbol on it. When you push the button and the engine sensor says the motor is cold it will activate this valve and another 2, one on your exhaust and one on the fuel pump somewhere. they restrict the amount of air that can enter and exit your motor plus increase the reves a bit. I have had mine removed for 2 years now and i live in southland and never miss it. take it to bits and take the flap out of the casting and you will get a slight power gain!!
"there is nothing wrong with getting a mu airborne, bad things only happen when you land"!!
I'm using a complete water to air system from a Subaru Liberty RS Turbo. Its perfect for 4WDing as it doesn't require lots of airflow to do its job... so ploughing through soft sand at 15kmh in low range isn't going to effect it like an air-to-air intercooler is affected.
I picked it up for $160 complete with intercooler, heat exchanger, pump and water lines. The heat exchanger will be mounted in the front grill area and the pump close by. The intercooler itself will be mounted where the original air filter sits. I'm doing a mod to the air intake where a snorkel fits on the driver's side. This makes a lot shorter inlet tract for quicker spool of the turbo.
From the outlet of the turbo the air travels across the engine to the intercooler. After being cooled the air then travels back to the plenum (I'll remove that entire casting that houses the actuator that this thread is about).
I'll do a full writeup in the engine mods section when its finished. I've taken lots of progress pics so far.
I do believe the actuator/butterfly valve is an over boost valve. If the boost or turbo gets out of control it will try an shut down the inlet or limit the inlet manifold boost pressure
How does the water system offer you an advantage, surley the water system cooling will also be poor at low speeds unless you add a fan? Otherwise it's just a thermal mass that will delay the warming up of the intercooler, but not prevent it. So it will offer a warm up delay and then when warm offer cooling only equal to the heat loss out of the water system. Unless it too can get get rid of heat out of the water system? Does it have a fan? In which case why is it an advantage?
Last Edit: Nov 12, 2005 11:38:30 GMT 11 by James W
Well I guess that depends on exactly how long you will be on boost at low speeds. Typically a water to air intercooler can absorb 4 times as much heat as an air-to-air 'cooler.
However this does have its disadvantages, as it takes longer to cool down if it does get hot.
I choose water to air because it is easier to plumb in the Mu's engine bay. The air-to-air when front mounted is difficult to pass the 2.5" (or whatever) pipework through the radiator support panel and surrounding areas. The water to air one only needs 1/2" heater hose plumbed through this tightly packed area.
I did consider the top mount Isuzu intercooler, but I personally just do not like it there. It suffers from heatsoak and even a fan doesn't prevent it. Why you'd stick an inter"warmer" (sic) above the hottest part of the engine bay is beyond me. Plus I don't want to cut a hole in my bonnet.
I recently did a front mount conversion on my old Celica GT4, as it had the intercooler topmounted. I used the existing core and mounted it in front of the radiator. My intake temps dropped markedly, especially in heavy traffic. This gave me better power, as the ECU was not constantly pulling timing from the engine to prevent pinging.
So yeah, I do think that front mount air-to-air is the best, but its not quite as practical in the Mu engine bay. Water-to-air was the next best choice in my personal opinion. Depending on results, it may have a fan attached to the heat exchanger.
Besides, its different from the rest of the Isuzu top mount intercooler installations you see, so thats always a good reason to do a mod
Oh, back on topic: Its a mystery if that butterfly is a boost control device... why would you have two devices doing exactly the same thing ? The wastegate is much better way of restricting boost because it stops the turbo spinning up further, whereas putting a butterfly in the inlet tract just makes the turbo push hard against it causing compressor surge and stalling of the turbo.
Very strange indeed. I can't find a mention of it in the 4JB1T manuals that were (helpfully! ) linked from this site.
Last Edit: Nov 12, 2005 12:24:30 GMT 11 by spectral
Local wreckers dismantal lots of Subarus especialy turbo ones although lots of these have nothing left in front of the windscreen. Liberty in Aus = LegacyGT here. The bighorns got an intercooler but the Subaru way has got to be the easy way to do a front mount due to the smaller pipework etc
yeah I was going to ditch that whole cast piece that crosses the valve cover (and that actuator/butterly with it). Mainly because the Subaru inlet is 2" which almost matches the turbo outlet on the 4JB1T... and the outlet is 3", which is conveniently similar to the plenum intake size.
I didn't see the point in then reducing it back down to 2" to enter that cross-piece and *then* get pushed back to 3" or so.
That PWR barrel is the smallest one they make I believe. The manufacturers site is www.pwr.com.au (they are actually made 30mins drive south from here).
That ebay link is pretty high priced.. $345 USD... The item is available directly from PWR for $396 AUD. The radiator to suit is around $300 and the pump another $270. And thats the cheapest/smallest one It all adds up
I've love a PWR setup, but my pockets are somewhat empty so my crusty old Subaru core will have to do me.