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Discussion Starter #1
New to the group. I own an '85 300sd turbo diesel. My question is what size is the turbo and can you go slightly larger w/o damage to the engine? Also, I saw the post from the guy who did the intake mod "cold" air. Does all air go through the turbo?
 

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If your turbo works fine, there is absolutely no point in getting a larger unit, unless you are looking to create another "super diesel" Our turbos can handle twice as much boost than they come with from the factory.
 

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You can easily adjust the boost pressure. You would have to connect a boost gauge to the ALDA tube and then turn the screw or nut on the wastegate. I've been told that 15psi is the safe limit for the engine.
 

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Discussion Starter #4
Thanks guys. My second question was the "cold air" that someone posted. Does all the air go through the turbo. Even if the turbo isn't spooling up? Is there a carb? Or does all go throught the turbo. Newbie...so cut me some slack.
 

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All the air goes into the turbocharger but some of it is pushed past the wastegate directly into the exhaust stream. There is no carburator since diesels are fuel injected, nor is there a throttle body or any type of butterfly valve. The engine takes in all the air it possibly can but limits the power by limiting fuel.
I personally don't believe a turbocharged engine can benifit much (if at all) from a cold air intake, because the air is heated by being pressurized through the turbo, but that opinion has been argued by others in here. I believe the only way to gain power from cool air is to incorporate an intercooler into the system, which is not the easiest thing to do. Hope this answers all your questions.
 

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Stevenpfaff - 5/19/2005 6:31 PM
I personally don't believe a turbocharged engine can benifit much (if at all) from a cold air intake, because the air is heated by being pressurized through the turbo
I'm with you on this. I don't believe there is a significant enough difference between the air temp coming from the stock system and a "cold air" intake. As a matter of fact, I tend to believe the taken from under the hood is probably slightly warmer than that taken from the stock inlet at the front.

The only real way to cool the air into the engine enough to make a significant difference is to cool it AFTER it leaves the turbo.
 

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jrehm - 5/19/2005 10:37 PM

Stevenpfaff - 5/19/2005 6:31 PM
I personally don't believe a turbocharged engine can benifit much (if at all) from a cold air intake, because the air is heated by being pressurized through the turbo
I'm with you on this. I don't believe there is a significant enough difference between the air temp coming from the stock system and a "cold air" intake. As a matter of fact, I tend to believe the taken from under the hood is probably slightly warmer than that taken from the stock inlet at the front.

The only real way to cool the air into the engine enough to make a significant difference is to cool it AFTER it leaves the turbo.
You hit the nail right on the head, and the only way to cool the air after it leaves the turbo is to run it through an intercooler.
 
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