WRX Intercoolers and Turbos
Posted: Sat Jul 07, 2001 1:35 pm
I have a 92 USA turbo sedan. A few years ago I got an early (black angled air-air model) WRX intercooler from Oz.
The inlet pipe turbo end was bigger than my turbo and the complex, problematic inlet pipe was designed for a much different turbo outlet angle than my application. I had to fashion my own pipe, move the AC line to under the "dogbone" engine locator and drop the igniter down from the firewall. None of the mounting ears line up to anything. I screwed up and overlooked the fact that the clutch arm would abrade my AC hose, which failed about two months later at a cost of about $300 US. The car ran better with the intercooler, but it gave me a bit more lag. The intercooler also drops your actual manifold pressure, so it is a good time to increase boost a bit. Incidentally, my intercooler covers my clutch reservior cap. The stock air scoop was totally inadequate for an air-air intercooler, so I hand-built one that resembles an Impreza RS scoop, but is somewhat smaller. I ducted my intercooler by making a black rubber "bib" out of a piece of white water raft floor and the foam gasket that is used on overhead garage door bottoms. The "bib" compensates for the differences in the angles and locations of my hood (bonnet) scoop opening and my intercooler core. Most applications place the intercooler ducting on the underside of the hood, but I found it easier to place mine directly on the intercooler. I also put diamond expanded aluminim grate on the top and bottom of my intercooler. The fins are unbelievably delicate and there are lots of ways they can get bent in that application.
I subsequently replaced my turbo with a Mitsubishi unit off a Japan market Legacy EJ20G engine. As near as I can tell, its angles were comparable to what the stock WRX intercooler pipe was intended for. While the stock USA "tinyturbo" angles up at about a 45 degree slope, the EJ20G turbos (I have another EJ20G with am IHI and it is very similar to the Mits turbo) come off at the horizontal, aiming straight under and perpendicular to the throttle body. The turbo outlet is bigger than stock. 1 7/8" as I recall. and the damn thing aims straight at some cooling hose fittings. If the intercooler pipe is included, use it. Mine came torn and I finished trashing it to make it fit my stock turbo. All that's left of my intake pipe is about a 4" stub that includes the triangular flange. I affix silicone hose to that tapered stub with siliigigcone sealer and after it has cured for a week, I put in two worm drive hose clamps. Whereas the stub is tapered, the hose will climb right off if you tighten the clamps before the silicone sealer has cured. If you use the "stub" technique, your first piece of equipment will be an abrupt 90 degree silicone elbow, followed by a 45 degree elbow to aim the flow toward the rear corner of the intercooler. I am furtunate enough to live within walking distance of the world's premier manufacturer of silicone turbo hoses which happens to be next doo to an aluminum supply store, so I just get my hoses and elbows then walk next door to buy thinwall pipe to fit it perfectly. I have had whistling problems with tapping the compressor bypass valve from the intercooler pipe, so I had an industrial hose supplier weld a bung onto the corner of my front end tank on the intercooler. That is more sanitary.
Oh, to answer tour last question, the WRX turbo is bigger, so it spools up more slowly, but it has more top-end. If you could get an intercooler, intake pipe and turbo that all match, I think it would make a big improvement, assuming that you also put on a bigger scoop, wrap the turbo with insulation, put in a bigger fuel pump and a 4/1 rising rate fuel pressure regulator.
Bill Robinson
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The inlet pipe turbo end was bigger than my turbo and the complex, problematic inlet pipe was designed for a much different turbo outlet angle than my application. I had to fashion my own pipe, move the AC line to under the "dogbone" engine locator and drop the igniter down from the firewall. None of the mounting ears line up to anything. I screwed up and overlooked the fact that the clutch arm would abrade my AC hose, which failed about two months later at a cost of about $300 US. The car ran better with the intercooler, but it gave me a bit more lag. The intercooler also drops your actual manifold pressure, so it is a good time to increase boost a bit. Incidentally, my intercooler covers my clutch reservior cap. The stock air scoop was totally inadequate for an air-air intercooler, so I hand-built one that resembles an Impreza RS scoop, but is somewhat smaller. I ducted my intercooler by making a black rubber "bib" out of a piece of white water raft floor and the foam gasket that is used on overhead garage door bottoms. The "bib" compensates for the differences in the angles and locations of my hood (bonnet) scoop opening and my intercooler core. Most applications place the intercooler ducting on the underside of the hood, but I found it easier to place mine directly on the intercooler. I also put diamond expanded aluminim grate on the top and bottom of my intercooler. The fins are unbelievably delicate and there are lots of ways they can get bent in that application.
I subsequently replaced my turbo with a Mitsubishi unit off a Japan market Legacy EJ20G engine. As near as I can tell, its angles were comparable to what the stock WRX intercooler pipe was intended for. While the stock USA "tinyturbo" angles up at about a 45 degree slope, the EJ20G turbos (I have another EJ20G with am IHI and it is very similar to the Mits turbo) come off at the horizontal, aiming straight under and perpendicular to the throttle body. The turbo outlet is bigger than stock. 1 7/8" as I recall. and the damn thing aims straight at some cooling hose fittings. If the intercooler pipe is included, use it. Mine came torn and I finished trashing it to make it fit my stock turbo. All that's left of my intake pipe is about a 4" stub that includes the triangular flange. I affix silicone hose to that tapered stub with siliigigcone sealer and after it has cured for a week, I put in two worm drive hose clamps. Whereas the stub is tapered, the hose will climb right off if you tighten the clamps before the silicone sealer has cured. If you use the "stub" technique, your first piece of equipment will be an abrupt 90 degree silicone elbow, followed by a 45 degree elbow to aim the flow toward the rear corner of the intercooler. I am furtunate enough to live within walking distance of the world's premier manufacturer of silicone turbo hoses which happens to be next doo to an aluminum supply store, so I just get my hoses and elbows then walk next door to buy thinwall pipe to fit it perfectly. I have had whistling problems with tapping the compressor bypass valve from the intercooler pipe, so I had an industrial hose supplier weld a bung onto the corner of my front end tank on the intercooler. That is more sanitary.
Oh, to answer tour last question, the WRX turbo is bigger, so it spools up more slowly, but it has more top-end. If you could get an intercooler, intake pipe and turbo that all match, I think it would make a big improvement, assuming that you also put on a bigger scoop, wrap the turbo with insulation, put in a bigger fuel pump and a 4/1 rising rate fuel pressure regulator.
Bill Robinson
To unsubscribe from this group, please send an email to:
BC-BFLegacyWorks-unsubscribe@egroups.com
zZz <http://docs.yahoo.com/info/terms/> .