When running a boost controller, how does the spring that's installed say in the Tial 35mm come into play? If I set my boost controller to say 20psi, but have a low pressure springs, does it matter?

Thanks,
-S

 

nope, you can have a 3lb spring and adjust boost to ppretty much whatever you want, but not below 3 lb. i dont exactly know how, but a boost controller just messes with the signal the wastegate gets

 

The WG spring determines the MINIMUM amount of boost you will see...the WG spring also determines the MAXIMUM boost you'll see, <u>BUT</u> a boost controller can control the the maximum boost you'll see if one is used.

EDIT: forgot to mention that it is possible to boost higher than a spring is rated at (boost spike/creep) and I think it is also possible to get a lower indicated boost pressure than your spring is rated at (pressure loss).


[Modified by BlueShadow, 7:34 AM 1/18/2003]

 

I too have been wondering about the wastgate spring. I have been working on N/A engines for years, so the turbo stuff is pretty new to me as well.
I read up on it, mostly here on H-T, and this is a general summary of what I have come up with:

*WG spring determines minimum boost capabilities.

*If you are not running an MBC or EBC you can use the spring to regulate boost. (but this is prone to erratic boost and spikes)

*If you are running higher boost it is better to get the spring thats closest to the boost you are running. (ie: if you are running 11psi, a 9.84lb spring will be better than a 6.5psi spring) This eliminates early WG blowoff as boost builds.

*On the TiAL WG, while using an MBC, it is better to use only the side port to run boost via the MBC. Using the top port will also produce boost spikes.


Am I correct? This is only info I have gathered from various other posts, because I had pretty much the same question.

 

What he said...

 

An electronic boost controller, like the Profec B, has an engine mounted box that intercepts the boost your engine creates. It does this physically with vacuum lines and electronically from the controller. The box holds the boost until it reaches the specified amount that the EBC is set to. Once the boost controller detects the specified amount of boost you have set it to, it electronically signals the box in the engine to release the boost to the wastegate and the wastegate then opens up.

 

The MBC worksl ike that too....it basically is a wastegate for boost, it will not let a signal at all go thru until it reaches the setting for the MBC (well close to it since manual boost controllers creep open), so I suppose that is why you should use a spring close to your actual boost so that when the MBC starts to creep it doesnt get the springs value before the MBCs setting

 

Thanks for the replys! It helps!

 

not true.you will never get a profec b to 25psi with a 3lb spring. it only goes 14lbs over what the spring is and it goes to a max of 28psi turned all the way up. trust me i have run a 6,10and 20 psi spring. supposedly there is a way of getting past the 28psi but you would have to call greddy for the info.

 

Is that just the GReddy unit or does it apply to all EBCs??