JohnBoy's Turbo Build

[pnosker]

I think epoxy will handle that. I guess use JB Weld since that stuff fixes everything. I know Permatex 5-minute epoxy has a very high tensile strength and should work too.

/loves epoxy

[xxxJohnBoyxxx]

Dang not even going to mess with the A/C yet...I still hear the wastegate opening before 20psi. Looks like it needs to come back off and get stiffer springs. I'm going to buy a matched set this time. Currently I've got a 15psi spring and a .7 bar spring in it so it should be around 25psi before it opens...

Is this right cause it starts opening around 17psi and it's pissing me off. I don't get 25psi until end of 3rd gear. I want it in 1st and 2nd


It's time to take a break and take the Mirage out. Water is glass with a 1" ripple...What I call "fast water" and no one but me on the boat will be a good fast ride

[nuvolarossa]

- are you sure that wastegate open in first and second or it's simply that there isn't enough load and time to make boost?

- are you spinning tyres in those gears?
- have you tried brake-boosting in 1st-2nd to see if you can go to 25psi?

[Danny318]

I think a 7 pound spring + another spring is not just adding them together. Wont the 7psi spring be basically collapsed after 7psi, so if you have a 15psi spring after that, you would get like 15psi plus a little bit because the 7psi spring takes up a little room.

I think you need a single stiffer spring

[xxxJohnBoyxxx]

Originally Posted by nuvolarossa

- are you sure that wastegate open in first and second or it's simply that there isn't enough load and time to make boost?

- are you spinning tyres in those gears?
- have you tried brake-boosting in 1st-2nd to see if you can go to 25psi?

Positive I vent the wastegate in the engine bay it is very distinctive noise when it opens.

What do you mean brake boost?

[nuvolarossa]

1. go to the best gear for whatever mph you are gonna race from

2. while still on the gas gently press the brake pedal with the left foot, you'll want to press it hard enough that it starts slowing you down. But to keep from slowing down you apply more throttle.

3. The harder you ride your brakes the more load you put on your enigine. the more load you put on your engine the more boost you will build. (keep an eye on your gauge)

4. And as soon as you are ready to start go WOT and at the same time release the brakes, and that lovely sensation of boost is already there waiting for you rather than you waiting for it.

The key is to find just the right anount of preassure to apply on each pedal but that becomes very easy with a little pratice.

Try holding it in second at 4000rpm ( as wrote in the quote above at #2: use left foot to brake gently and the right gradually step on the gas pedal) and watch the boost gauge.

You'll see if it will it 25psi that you reach in other gears.


DISCLAIMER: Don't use it too much or you'll cook you brake pads

[xxxJohnBoyxxx]

Yes it will hit 25psi if I do that in 2nd but the wastegate is open at 17psi and the turbo still boosts up slowly to 25psi during this test. I want that waste gate to stay slamed shut until it hit's 25psi then open....

[lpcapital]

Originally Posted by xxxJohnBoyxxx

Yes it will hit 25psi if I do that in 2nd but the wastegate is open at 17psi and the turbo still boosts up slowly to 25psi during this test. I want that waste gate to stay slamed shut until it hit's 25psi then open....

You have to adjust the boost control so that no boost signal gets to the wastegate till you reach the desired boost level.

[xxxJohnBoyxxx]

On the A/C I coudn't rig it and live with myself. I took the whole thing apart last night. Intercooler, cooling system, A/c lines, etc. I'm on top of the compressor now and I'm going to install a longer bolt with a nut on the backside. This seems to be the best way, better then tapping a larger hole since there is not much metal there and I don't want to risk a striped bolt again. This will be a perma fix i hope, then 2-3 hours to put it back together

[Xenocide]

Originally Posted by lpcapital

You have to adjust the boost control so that no boost signal gets to the wastegate till you reach the desired boost level.

Maybe I don't know anything about his turbo setup, but he is using a mechanical control I think...no electronics.

[xxxJohnBoyxxx]

Originally Posted by Xenocide

Maybe I don't know anything about his turbo setup, but he is using a mechanical control I think...no electronics.

Yes I have a mechanical controller. I ported it only to the top to get maximum boost. If I port the bottom I loose boost. Tial only makes springs up to 23psi. So how are people run 30+ psi?

[Danny318]

Originally Posted by xxxJohnBoyxxx

Yes I have a mechanical controller. I ported it only to the top to get maximum boost. If I port the bottom I loose boost. Tial only makes springs up to 23psi. So how are people run 30+ psi?

non-tial springs?

[Danny318]

actually why not double up the stiff springs, instead of a stiff and a weak?

[lpcapital]

There's two way to do it: one is to use a boost control (mechanic or electronic doesn't matter) that limits the boost signal to get to the wastegate 'till you reach the desired boost level. Basically you put it on the line between the manifold and the wastegate to interrupt the boost signal untill it gets to a certain level. The second option, if the spring is not strong enough to hold the exhaust backpressure, is to use both connections on the wastegate: one will use boost to help the wastegate reamin close, while the other is the regular boost signal to open it. In this case you'll need an electornic system with a solenoid to switch from one to the other.

[Xenocide]

electronic would seem like the way to go for a system like that especially with the issues you are having, but I have never built a turbo system so take my advice with a grain of salt.