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2005 Corolla XRS
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Discussion Starter · #1 ·
Ok,.. it says that this GT2540R turbo is "Internally Wastegated at 11psi". Ive never dealt with internal wastegates and have a few questions.

Can I chage the wastegate to say 16psi? Im assuming its a spring type system right? Can it be done, or do I need a new turbo?

Can I just bypass the internal wastegate and add an external one? Would it be worth it?

Also,... because its wastegated at 11psi,.. taht means I cant go over 11 lbs of boost right?... I would like to find an option to get at least 15psi out of this car.... which brings me to my very last question.

Is this GT2540R turbo a bigger turbo than stock? Is it more effiecient? I.E. 11psi on the GT2540R is = to 15psi on the stock CT20?? or anyone have any feedback?? Maybe I dont need more than 11psi.
 

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I would answer your questions if I could, but I don't think I know that much more about turbos than you do. I do have a suggestion for you though. You're asking some very good questions that will have a lot of bearing on how you go about upgrading your car. You might want to call whichever vendor you're considering purchasing your turbo from and ask them.

This can serve two purposes; 1 you have an opportunity to sound out the vendor and decide if they're really someone you want to do business with and 2 you get your questions answered by someone that *should* be able to explain things to your satisfaction. You might want to consider talking to a vendor represented here or on mr2oc.com as they will have more MR2 specific information.
 

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2005 Corolla XRS
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Discussion Starter · #3 ·
THanks for the reply, but Im buying the car with the Turbo already on it. This MR2 has already been modded, and Im looking ot see how hard the present owner is pushing the car.

I have a dyno test set up to see what type of power its putting down, and I have a 130point engine and car inspection set up to test things like compression, knock, a/f ratios, and eveyrthing else just to make sure im not going to blow the car up when I try to pass a truck coming home.

I am not looking to build a fully race ready track MR2, but I wouldnt mind putting down 250-275rwhp for the drag strip once a month...
 

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91 Turbo MR2
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The stock turbos, CT26 and CT20B have an internal wastegate.
I would not bother upgrading to a larger turbo if it has an internal gate ... except myabe the TD06, but I would talk to ATS Racing.net about that.

No matter if you have an internal gate or an external one, you can always run more boost than what the spring tension is set for by adding a boost controller.
 

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2005 Corolla XRS
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140 Posts
Discussion Starter · #5 ·
ok good.. the car has an electronic boost controller... greddy i think.

i just didnt want that spring to get in my way.

jekyl im glad your here to answer my questions bro.. i should have this car by this weekend and ill have a bunch of stuff to wrack your mind with...
 

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OK, the wastegate determines a "neutral value" for your car's boost situation. It's kind of a fail-safe - if my boost controller dies, the car will only bost to wastegate presure.

The boost controller is what actually limit's the car's boost. It does this by determining how much presure is dverted to the car's wastegate actuator. The boost controller does this by venting off part of the incomming boost. The remaining boost presure is then passed on to the waistgate until the allowed percentage of the intake boost exceeds the wastegate spring. At that point, exhaust some gasses are allowed to bypass the turbo to prevent overboosting the intake charge.

For refference, the bost controller reads it's boost presure from the intake tract, and then vents splits off a tiny bit of that volume for venting (usually back into the intake before the turbo) and wastegate presure. The percentage split thing is also an oversimplification. A more accurate discription would be to say that the boost controller will have a spring (MBC) or selenoid (EBC) that is designed to open at specific presure - once it hits that target value then presure from the intake tract is passed to the wastegate controller to force the wastegate open.

Hope that helps!
 

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2005 Corolla XRS
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Discussion Starter · #7 ·
great answer erioshi.. thx for the explination...

so because i have a boost contorller, i can boost 15psi...

great.. now i just need an e-manage or something to make sure im not running stupid lean.
 
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