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Discussion Starter #1
wastgates & boost controllers--general questions

I know there are two types--internal and external. I have heard external is the way to go due to the limitations of internal as far as boost pressure. Would someone care to explain how a boost controller interacts with the wastegate, and what the primary differences in external wastegates are among the different manufacturers?

Also, I have decided on a T3/T4 turbo, and I am wondering what the minimum PSI is that I can run with it until I get some fuel management. Is there such a thing as minimum PSI? What is the T3/T4 "default" boost pressure. Or does that depend on what wastegate I get?

Are there two versions of the T3/T4 turbo---one w/ internal wastegate, one set up for an external wastegate? If so, how does one tell between the two?
 

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Re: wastgates & boost controllers--general questions

jmcn said:
I know there are two types--internal and external. I have heard external is the way to go due to the limitations of internal as far as boost pressure. Would someone care to explain how a boost controller interacts with the wastegate, and what the primary differences in external wastegates are among the different manufacturers?

Also, I have decided on a T3/T4 turbo, and I am wondering what the minimum PSI is that I can run with it until I get some fuel management. Is there such a thing as minimum PSI? What is the T3/T4 "default" boost pressure. Or does that depend on what wastegate I get?

Are there two versions of the T3/T4 turbo---one w/ internal wastegate, one set up for an external wastegate? If so, how does one tell between the two?
You know more than you give yourself credit.

External wastegates are a much better way to go from a performance standpoint, because of the designs ability to flow 100% exhaust through the turbine to almost 100% around the turbine.

The way your basic boost controller works is it is inline between the manifold and the wastegate. (when i say inline, I literally mean, in the vacuum line between the two). Say you've got the boost controller set to 5 psi. If your pushing 4psi, it's not going to let the wastegate see any boost and it's not going to open. Then when it gets up to 6psi, then your boost controller lets the wastegate see the boost and it opens. It can limit it down by showing more boost than your pushing or push it up by not letting it see how much boost your pushing. The more complex boost controllers work a little different but it's the same principle.

About the different manufacturers of external wastegates, Tial is my favorite and everyone has their own fave.

You could theoretically push no psi, I've never tried it but with a boost controller you could possibly stick the wastegate wide open all the time and not push any boost at all. I wouldn't push 1psi without the proper fuel management though.

The t3/t4 turbo itself doesn't regulate boost at all, it pushes as much boost as it can with how much exhaust the wastegate is giving it, which is regulated by what spring the wastegate has in it.

Hope this helps, as more questions if you have any. :D
 

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Discussion Starter #3
Thanks for the help.

Here's another question then...

How does a fuel pressure regulator work? Where does it mount? Does it only prevent a momentary loss in fuel pressure, or does it act like an electronic device, increasing the fuel pressure as the air pressure (boost) increases?

I hear the term "rising rate" FPR...is there a non-rising rate kind? :confused:
 

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I may be wrong but think of an FPR as you sticking your thumb over an open faucet, thereby increasing the pressure in the line. Some mount on your fuel rail, like my AEM unit and others are placed anywhere on the fuel line
 

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jmcn said:
Thanks for the help.

Here's another question then...

How does a fuel pressure regulator work? Where does it mount? Does it only prevent a momentary loss in fuel pressure, or does it act like an electronic device, increasing the fuel pressure as the air pressure (boost) increases?

I hear the term "rising rate" FPR...is there a non-rising rate kind? :confused:
Machine head is right about how the fuel pressure regulator works. It's mounted on the fuel rail.

Fuel comes into the fuel rail from the tank and it fills up quickly, the FPR is a valve also on the fuel rail that lets fuel out and returns to the tank. By limiting how much fuel can exit it can change your fuel pressure.

All a adjustable one will do it allow you to adjust your static fuel pressure, which is where your fuel pressure is at idle. Of course, when your on the throttle, the fuel pressure goes up.

AEM's FPR is not a rising rate FPR. A rising rate FPR like Vortech's FMU will increase fuel pressure in accordance to boost.
 

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Re: wastgates & boost controllers--general questions

Also, I have decided on a T3/T4 turbo, and I am wondering what the minimum PSI is that I can run with it until I get some fuel management.

Are there two versions of the T3/T4 turbo---one w/ internal wastegate, one set up for an external wastegate? If so, how does one tell between the two? [/B]


If you run ANY boost, you have to have some sort of fuel management.

Spend a couple days reading archives on the Honda-tech FI board, you'll learn volumes.
 

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Hey jmcn,

Try doing a search on www.freshalloy.com too. go to the forums-> and do a search for "turbo" in the 240SX forum. a lot of threads came up about KA24-T times and block-buildup, I dont remember seeing any threads about fuel management though.

BTW when you do the search there are 2 search buttons.

The one right next to the "MARKETPLACE | ABOUT US | SEARCH" at the top is the wrong search button. you have to click on forums and click the search button under "FRESHALLOY.COM COMMUNITY FORUMS".
 

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With a boost controller you CANNOT set it to go lower than the spring that is in the wastegate. If you have a 6psi spring in your wastegate, that is the absolute minimum boost pressure you can run, so when you get a wastegate figure on how low you want to boost and make sure you get the appropriate spring. The lowest you can get on the Tial 35mm is .4bar (6psi).

The non-rising rate kind of fpr's have a 1:1 ratio. For every 1psi of air pressure rise in the intake manifold it changes the fuel pressure by 1 psi. It's used in order to keep the pressure in the manifold and fuel pressure at a constant deviance. The rising rate kind have a ratio of X:1 meaning that for every 1psi of air pressure change in the intake manifold, the regulator will change the fuel pressure by X amount (X being anything higher than 1).
 

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Discussion Starter #9
DirtyLude said:
With a boost controller you CANNOT set it to go lower than the spring that is in the wastegate. If you have a 6psi spring in your wastegate, that is the absolute minimum boost pressure you can run, so when you get a wastegate figure on how low you want to boost and make sure you get the appropriate spring. The lowest you can get on the Tial 35mm is .4bar (6psi).

The non-rising rate kind of fpr's have a 1:1 ratio. For every 1psi of air pressure rise in the intake manifold it changes the fuel pressure by 1 psi. It's used in order to keep the pressure in the manifold and fuel pressure at a constant deviance. The rising rate kind have a ratio of X:1 meaning that for every 1psi of air pressure change in the intake manifold, the regulator will change the fuel pressure by X amount (X being anything higher than 1).
How then does one calculate the appropriate X in the X:1 ratio of a rising rate FPR for a given amount of boost--say 6 psi? Is it a one-to-one? So I would want a 6:1 RR FPR?
 

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The higher the rise rate the richer you are going to get. There's no way to easily calculate what rise rate you want. You usually have to try a few to zero in on the right a/f ratio. That is if you are using a rising rate fuel pressure regulator. If you're getting a standalone or some other thing that controls the injectors on your engine, then you don't need to use the rrfpr.
 

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Discussion Starter #11
Do I need to get a RR FPR if I am running a (properly tuned) Apexi S-AFC?

Does it matter that the 240SX uses a MAF unit instead of a MAP unit in terms of all this fuel management talk?

edit: nevermind...got the foo's at Fresh Alloy to answer the questions :D
 
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