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Discussion Starter #1
Hi, so I have a tune in just 2 weeks. I made the last minute switch too boost by gear and was wondering what springs to use? My tuner suggested to get 10psi but i dont know what spring/s to get and if I need more than one? Im running a VS Racing MVR 44mm wastegate. I was told to get red and black from go-autoworks.

My next question is how to rewire my fuel pump. He suggested this since i guess the stock wiring isnt as efficient. Do i just use the wiring that came with the kit and just redo the plug or, do I actually redo the entire harness?
 

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93 Civic HB SI
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What are your power goals? What kind of fuel pump do you have installed? What is your current wastegate spring rated at now?

These answers are important to know to determine if its worth it to do either change in your case.

If you're going to enable boost by gear, then you no doubt have an electronic boost control method that controls wastegate diaphragm operation.

If you have at least a 6-10psi spring now, which is pretty common, coupled with a functional electronic boost control method, then you won't need a spring upgrade as long as you don't plan on having more than 20-25PSI max boost pressure. I comfortably control 20PSI overall boost using electronic boost control, and I have a 7psi spring installed in the gate.

Beyond 25PSI boost, the actual exhaust gas pressure in the manifold between the exhaust valves and the turbine wheel are roughly equal to your intake manifold pressure, +/- a couple PSI. So if you're running 25PSI boost, you'll have between 23-27PSI of exhaust gas pressure pre-turbine. That kind of exhaust pressure level is about enough to force a 44mm wastegate valve to open against a low pressure spring, bleeding off boost when it may not be desired.

If you don't plan on shooting for the moon, and won't see more than 20PSI, then I'm sure your current spring will work just fine. Your tuner will just need to sort out the boost control settings if you want to go higher.

If you don't know what your current spring is, you'll find out on dyno day :) The tuner will baseline the car using the installed spring, incrementally upping a boost cut until you find the spring rating.

Honestly, I'm a big fan of using the lowest possible rated WG spring pressure needed for an application, especially since electronic boost control is magic and lets you add more without changing springs :)

When using electronic boost control, having the lowest possible spring installed can prove to be a piece of insurance in its own way. If there is a solenoid malfunction, the solenoid is supposed to mechanically return to its default position and allow air to no longer bleed, and the WG diaphragm will see straight intake manifold pressure. At this point, you'll only ever see WG mechanical rated boost pressure, which could allow you to notice a problem with boost control sooner rather than later if you take boost higher than spring rating.

Of course, the ultimate failsafe is a good boost cut :), especially if bugs decide to nest in the guts of your solenoid, rendering the mechanical return failsafe useless haha.

But a low pressure spring will also allow the tuner to ease the engine to higher boost levels. He'll hit the gate rating, smooth some things and feel the engine out from there, then start playing with boost control to add more when ready.

You'd be surprised at what 6PSI does to wake these engines up, going with a high spring baseline off the bat might not be ideal. You might hear/see a problem starting to happen at lower power levels, whereas a 10PSI spring might skip the friendly "somethings wrong" sound and proceed to throw a rod out the block, or blow the upper rad tank due to HG failure.

My $0.02. Have fun and good luck!
 

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Discussion Starter #3
What are your power goals? What kind of fuel pump do you have installed? What is your current wastegate spring rated at now?

These answers are important to know to determine if its worth it to do either change in your case.

If you're going to enable boost by gear, then you no doubt have an electronic boost control method that controls wastegate diaphragm operation.

If you have at least a 6-10psi spring now, which is pretty common, coupled with a functional electronic boost control method, then you won't need a spring upgrade as long as you don't plan on having more than 20-25PSI max boost pressure. I comfortably control 20PSI overall boost using electronic boost control, and I have a 7psi spring installed in the gate.

Beyond 25PSI boost, the actual exhaust gas pressure in the manifold between the exhaust valves and the turbine wheel are roughly equal to your intake manifold pressure, +/- a couple PSI. So if you're running 25PSI boost, you'll have between 23-27PSI of exhaust gas pressure pre-turbine. That kind of exhaust pressure level is about enough to force a 44mm wastegate valve to open against a low pressure spring, bleeding off boost when it may not be desired.

If you don't plan on shooting for the moon, and won't see more than 20PSI, then I'm sure your current spring will work just fine. Your tuner will just need to sort out the boost control settings if you want to go higher.

If you don't know what your current spring is, you'll find out on dyno day :) The tuner will baseline the car using the installed spring, incrementally upping a boost cut until you find the spring rating.

Honestly, I'm a big fan of using the lowest possible rated WG spring pressure needed for an application, especially since electronic boost control is magic and lets you add more without changing springs :)

When using electronic boost control, having the lowest possible spring installed can prove to be a piece of insurance in its own way. If there is a solenoid malfunction, the solenoid is supposed to mechanically return to its default position and allow air to no longer bleed, and the WG diaphragm will see straight intake manifold pressure. At this point, you'll only ever see WG mechanical rated boost pressure, which could allow you to notice a problem with boost control sooner rather than later if you take boost higher than spring rating.

Of course, the ultimate failsafe is a good boost cut :), especially if bugs decide to nest in the guts of your solenoid, rendering the mechanical return failsafe useless haha.

But a low pressure spring will also allow the tuner to ease the engine to higher boost levels. He'll hit the gate rating, smooth some things and feel the engine out from there, then start playing with boost control to add more when ready.

You'd be surprised at what 6PSI does to wake these engines up, going with a high spring baseline off the bat might not be ideal. You might hear/see a problem starting to happen at lower power levels, whereas a 10PSI spring might skip the friendly "somethings wrong" sound and proceed to throw a rod out the block, or blow the upper rad tank due to HG failure.

My $0.02. Have fun and good luck!
My goal is around 400hp and the spring currently in the car pretty sure is a 7.5lb spring just in the middle there. The car currently has a aem 340lph non e85 on stock wiring. If you say that spring is fine thats all i need to hear for that then. Very informative above, I appreciate that.
 
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