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making a reliable ea81t


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12 replies to this topic

#1 75subie

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Posted 23 September 2006 - 12:11 PM

hi guys,
i`m looking at an ea81t wagon, of course with an auto tranny. the guy says it needs a turbo.

i have a few questions tho. what could i do to make it reliable, and not something that will be blowing hg's, overheating or smoking?

what i am thinking is a 4speed d/r swap, some kind of intercooler (what works?) a bov (any suggestions?)

i don`t need a power house, but do these have any more guts than a n/a ea81?

#2 mikeshoup

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Posted 23 September 2006 - 12:39 PM

Most EA81s have only oil-cooled turbos. You'd be best off upgrading to a water cooled & oil cooled turbo from an EA82T/water cooled EA81T.

Definitely ditch the automagic tranny. An intercooler would be a great idea too. Look at intercooled EA82Ts for ideas. A lot use SAAB900 intercoolers.

Just don't up the boost, and you'd be fine.

#3 NorthWet

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Posted 23 September 2006 - 08:20 PM

...what i am thinking is a 4speed d/r swap...

Consider the EA82's 5-speed D/R instead of the 4-speed. Sounds like good advice on the later (and commonly available) water jacketed turbo, plus the intercooler. And more boost = more death. ;)

#4 ben--ny

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Posted 23 September 2006 - 08:38 PM

jon
dont tubrocharge it, supercharge, it think about it, when you use a tubro you just dumping hot exhaust back in the motor to get hotter!!!!!!! know wonder the heads crack??? check this out www.rotrex.com

#5 NorthWet

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Posted 23 September 2006 - 09:00 PM

jon
dont tubrocharge it, supercharge, it think about it, when you use a tubro you just dumping hot exhaust back in the motor to get hotter!!!!!!! know wonder the heads crack??? check this out www.rotrex.com

It is already turbocharged. The heat will be essentially the same for mechanical supercharging as with exhaust supercharging: The heat comes from compression (darn those Gas Laws!!!) and the efficiency of the compression (turbo-supercharging usually is better here). The head cracks due to compromised coolant flow.

#6 4x4_Welder

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Posted 23 September 2006 - 11:48 PM

Ben's avatar = :banana:


At any rate, I would definetely go with a water- cooled turbo, they last a lot longer and don't coke up so bad as air/oil cooled units. Run an intercooler for sure, and keep it around 6psi. Run Subaru head gaskets, torqued to spec (don't overtorque, that can warp the heads and cause premature failure), and run a two row radiator with a high capacity water pump. Maybe a 180ยบ t-stat, water wetter in the cooling system to help it work more effectively, and keep everything clean and in good shape. I would also run a diesel-rated oil in it, to control blow-by past the rings, provide the zinc additive that these engines need, and stand up to the heat in the turbo.
A properly set up turbo with an intercooler will provide a much cooler charge than a supercharger, plus it has the advantage of fuel economy. A supercharger is always there, always blowing the air whether boost is needed or not. The turbo, though, responds to the demand of the engine, so when you're just cruising around, it's not giving boost until needed, saving you gas.

#7 jeffast

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Posted 24 September 2006 - 12:33 AM

Ben's avatar = :banana:

i said the same thing the first time i saw that
[/hijack]
ea81t's are pretty solid they don't blow head gaskets like the ea82 but they aren't that fast eather just don't up the boost from stock and your fine. as far as turbo's there was a recall it may still be active only the early ea81t's were equipped with an oil cooled turbo these were recalled for cooling issues and replaced with the vf7 found on the ea82t's
wow that got long fast
edit intercooler is a definatly a good idea it will make the engine run consederably cooler and you may gain a little power, along with allot of longevity
jeff

#8 Caboobaroo

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Posted 24 September 2006 - 12:53 PM

and it has been proven that superchargers create a lot more heat then a turbo does. Plus, they're not as efficiant as a turbo either, granted you get the power from a supercharger off the line compared to a turbo.

#9 ben--ny

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Posted 24 September 2006 - 03:47 PM

ok maybe i'm wrong here but useing commonsense here tubro takes 1300 egt throws it down the carb, supercharger takes takes ambient air and throws it it to the carb??? whitch is hotter

#10 Caboobaroo

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Posted 24 September 2006 - 04:02 PM

you are also fogetting the intercooler, either air to air, or air to water, will help drastically reduce air temps from a turbo. You can then add an intercooler sprayer to an air to air to reduce the temps even further, and add on a fan underneath it. ANother thing to remember with superchargers, is the amount of friction within the housing from the screws inside, creating a lot of heat as well.

ok anyways, Jon, if I were you, do what a lot of the other guys recommend. water/oil cooled turbo if it didn't get the recall done to it, intercooler, and keep it at stock boost. If you want, get the turbo back exhaust reworked to have it a bit more free flowing to get better turbo spool and for that awesome turbo'd boxer sound!:headbang:

#11 mikeshoup

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Posted 24 September 2006 - 04:56 PM

ok maybe i'm wrong here but useing commonsense here tubro takes 1300 egt throws it down the carb, supercharger takes takes ambient air and throws it it to the carb??? whitch is hotter

It doesn't actually take exhaust gasses and throw it down the throttle. It uses the exhaust gasses to spin the turbine. Yes, the exhaust gasses are hotter and will make the housing hot, but the actual compression of the air is what makes it so hot.

Its from the whole equation: PV=nRT
Where P is pressure, V is volume (which is constant), R is a constant, n is how many molecules, and T is temperature.

By increasing P, you increase n and T proportionally. Which means things get hot, really quick.

Since Roots/screw type superchargers are constantly compressing, the temperature never really has a chance to cool down. With a turbo, its not always compressing, so things have a chance to cool down. Plus remember the whole friction thing that Russ mentioned about the screws.

#12 NorthWet

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Posted 24 September 2006 - 05:57 PM

ok maybe i'm wrong here but useing commonsense here tubro takes 1300 egt throws it down the carb...

This is not what happens.

*edit - took me a long time to hit ENTER... Mikeshoup got it pretty much right. No real friction between screws on the Roots, though. Efficiency of compression makes a big difference; these are not perfect compressors. Centrifigal-compressors usually have a region of compression/flow that is much more efficient than a roots-types.

#13 daeron

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Posted 25 September 2006 - 02:11 AM

ok maybe i'm wrong here but useing commonsense here tubro takes 1300 egt throws it down the carb, supercharger takes takes ambient air and throws it it to the carb??? whitch is hotter


yah, I'll say it too... the exhaust gas is used to spin the turbine, which shares an axle with the compressor impeller. the compressor takes colr air in from your air filter box, and compresses it. The mass of air flowing out of the turbo is at a higher temperature because every calorie of heat in every air molecule which got compressed, is present, and jammed in a much smaller space with more calories from other air molecules. In short, the heat from say, 10 liters of air at atmospheric pressure is all combined when that 10 liters has been pressed down into 5 liters by the turbocharger. the same amount of heat, in a denser mass, adds up to a higher temperature. Temperature is a function of heat.

besides, with either a supercharger or a turbocharger, just slap an intercooler in there and dont worry about heat.




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