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General => The garage => Topic started by: jamie16v on 24 May 2013, 18:35

Title: bigger turbo, need to control it! STILL OVERBOOSTING!!!
Post by: jamie16v on 24 May 2013, 18:35

hi guys, recently put my mk4 AGU back on the road with a k03s turbo which has K04 internals,forge actuator and red spring (only spring ive got).
i need some way of taming it as its boosting to more than 25+ psi and i`m sure this wont be doing the engine or turbo much good.
before i took the car off the road it was running 223bhp/244lbft on an R-tech custom map with k03s, fmic,
panel filter, forge 007p etc and boosting to about 16-17psi if memory serves me correct.
how can i tame this thing down in the meantime before i take it to be custom mapped again.  :tongue:

Title: Re: bigger turbo, need to control it! MBC?
Post by: Chris. on 24 May 2013, 22:25

Run it actuator pressure?  Connect wastegate directly to boost source.

Or stick a MBC in there and set it to its lowest.

Or just drive off boost

Title: Re: bigger turbo, need to control it! MBC?
Post by: jamie16v on 24 May 2013, 23:03

thanks for the advice chris, i may try running off actuator pressure first as you suggested. then buy a MBC if i`m not satisfied.  i will NOT drive off boost..  :grin:

Title: Re: bigger turbo, need to control it! MBC?
Post by: Chris. on 24 May 2013, 23:20

Remember, bigger turbo flows more air at lower psi, so fuelling could be off aswell.

Title: Re: bigger turbo, need to control it! MBC?
Post by: jamie16v on 25 May 2013, 10:16

i know. thats why i want to slow it down alot. not completly but down to about 12psi. ideally i think i need a weaker actuator spring..

Title: Re: bigger turbo, need to control it! MBC?
Post by: jamie16v on 25 May 2013, 15:03

just been looking at the spring rates on the forge website and red is rated to 30+ psi.. :shocked:
i`ve just ordered a yellow one. rated 17-23 psi.

Title: Re: bigger turbo, need to control it! STILL OVERBOOSTING!!!
Post by: jamie16v on 29 May 2013, 19:32

I have now moved down to a yellow spring and connected the actuator directly to boost source and overboosting to 25-30psi.
The wastegate arm moves freely when the actuator rod is loose so i can rule out seized waste gate.
the only two things i can now guess at are either a punctured actuator diaphragm or the yellow spring is too strong? but the latter doesn`t make any sense.  :tongue:

Title: Re: bigger turbo, need to control it! STILL OVERBOOSTING!!!
Post by: topher on 29 May 2013, 20:56

you need one of these dude http://www.ebay.co.uk/itm/SEALEY-VACUUM-PRESSURE-TESTER-BLEED-TOOL-KIT-/360411713118?pt=UK_Hand_Tools_Equipment&hash=item53ea364e5e

im sure there are cheaper versions that work just as well if you search. not counting a laptop or torch this is probably the tool i use most for diagnostic work! to rule out diaphragm leak though you could just suck on the pipe and seal it with your tongue to see if it holds pressure

Title: Re: bigger turbo, need to control it! STILL OVERBOOSTING!!!
Post by: jamie16v on 29 May 2013, 21:02

Ok, thanks chris.. i`ll test the diaphragm first as thats the only thing i could think of causing it to not open the wastegate when the actuator is connected directly to boost source  :drool:
Cheers!

Title: Re: bigger turbo, need to control it! STILL OVERBOOSTING!!!
Post by: jamie16v on 29 May 2013, 21:21

just went and did the sucky sucky tongue test and low and behold.. it`s losing vac.. though it doesnt seem to be at a massive rate, its probably enough to stop the actuator working.   :tongue:
cheers chris.

Title: Re: bigger turbo, need to control it! STILL OVERBOOSTING!!!
Post by: topher on 29 May 2013, 21:23

the sucky sucky tongue test is a recognised british standard :laugh: works on any engine component that needs to hold pressure. gets funny looks from customers mind..

Title: Re: bigger turbo, need to control it! STILL OVERBOOSTING!!!
Post by: jamie16v on 29 May 2013, 21:28

i`ll note that one down!  :grin: awesome  :laugh:

Title: Re: bigger turbo, need to control it! STILL OVERBOOSTING!!!
Post by: jamie16v on 30 May 2013, 16:15

just took the actuator off and stripped it down and instantly saw the problem.
the diaphragm wasn`t sitting properly around the rim.
so sat it properly and added a little gasket sealant to be 100% sure, put it back together and re-did the the sucky sucky tongue test and all was good!.
ready to re-fit to the car and see how it goes!  :smiley: