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Author Topic: Keeping the BOOST up  (Read 13767 times)

Offline Gofra

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Re: Keeping the BOOST up
« Reply #15 on: November 05, 2009, 07:39:15 pm »
Guys, so far thanx for your inputs - I got one more "beginner" question...

I can't seem to understand it - if the wastgate valve is opened or closed mechanically with the spring (when there is enough pressure), what is the ECUs "mission" here then? How can you change the performance via remap if the spring will let go everytime the pressure reaches certain level? I know these questions sound kind of silly, but hey, we learn :)

Thanx!

BW

Frane

AbarthForum.co.uk

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    Offline matthew9712

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    Re: Keeping the BOOST up
    « Reply #16 on: January 17, 2010, 06:11:39 pm »
    Has any one had a boost gauge on their Abarth Grande Punto 155 as the most I could reach on overboost was 1.1bar but the car had little mileage and the ecu may still not have run a calibration.

    Offline Gofra

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    Re: Keeping the BOOST up
    « Reply #17 on: January 26, 2010, 11:00:33 am »
    Should be 1.3 bar if you ask me - could it be that the gauge is faulty? Does the car behave normally?


    Offline matthew9712

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    Re: Keeping the BOOST up
    « Reply #18 on: January 26, 2010, 05:30:47 pm »
    Hi, message to Gofra, did you have an actual boost gauge bridged between your fuel pressure regulator and your inlet manifold and achieve 1.3bar. I am going to be going on a rolling road again soon so will be trying again now it has got some miliage on it so will let you know the results. And to answer the question about the wastegate and how a remap can increase boost it is that on a modern car i.e grande abarth you have a boost control solenoid which is what allows your boost pressure to enter the wastegate hose so it isn't actually the wastegate controlling the boost pressure it is a solenoid controling when to let the wastegate open, you would find that the wastegate spring is only set at around 1bar if not less as the solenoid holds the pressure. So by remapping you change the parameters to tell the solenoid to open at say 1.5bar instead of 1.3bar ect. Hope this makes sense for you.

    Offline matthew9712

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    Re: Keeping the BOOST up
    « Reply #19 on: February 01, 2010, 12:57:45 am »
    Hi, i've put my own boost gauge in and i'm getting the correct overboost. What is your running boost figure Gofra? i.e 0.8bar ect

    Offline Gofra

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    Re: Keeping the BOOST up
    « Reply #20 on: February 01, 2010, 12:40:38 pm »
    Hey,

    I'm not using the gauge but my car's been remaped so the figures I might have are not comparable to yours. I'm about to redo the remap as I'm not quite happy with it and will measure all the pressures then...The 1.1 on normal and 1.3 in overboost are stated form the side of factory though...

    F

    GTT

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    Re: Keeping the BOOST up
    « Reply #21 on: January 30, 2011, 12:26:42 am »
    Hi guys, did you know the stock IHI turbo has a wastegate with an actuator that has an opening pressure of a very weedy  0.25 bar !   :o

    Regarding boost pressures generally you must at the very least use a guage coming off the inlet manifold . The factory guage is reading turbo pressure after the intercoolers but upstream of the throttle body.. very misleading for most purposes. eg If the throttle is half closed you could easily see say 1.3 bar 'turbo output' but only 0.8 bar at the inlet manifold!
     Idealy you need 3 guages. 1) Mounted between compressor output and intercoolers 2) Mounted after intercoolers but before throttle body  3) Inlet maniold.
    Oh Put a vacuum guage on the clean side of air filter too, and if you realy want to see whats going on on the hot end you want 3 more boost guaes .. 1) On the exhaust manifold ...2) After turbine housing but before cat ...3) After cat but before backbox.
    Thats 7 guages + your original 500 pod guage.
    Then you realy can see whats going ......Weve done all of this on the Abarth 500....Some VERY interesting results!
    One final thing if you have Darrens TMS box your factory guage reads typically 20% low, so you you have to add 25% ( not misprint) to the guage readings to achieve actual turbo output pressure . ..Regards Roland GTT

    Offline nardoo

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    Re: Keeping the BOOST up
    « Reply #22 on: January 30, 2011, 05:34:15 pm »
    hi guys,
    I am living near Munich in germany and i have been talking to g-tech alot (60km away) and other abarth drivers there. if you get your car remapped you need a stronger wastegate. this is the answer i got from the boss of g-tech persoally when i was there to see my mates car being done to 240 hp. the standard wastegate is to "weak". the new stronger one has a much stronger spring. it is not really hard to remove and put in a new one apart from the A500.  ;D
    with a stronger wastegate the car can hold the boost longer and more of it. the people i have spoken to had g-tech s kits (boxes) and their opinion was that the remap plus the wastegate is perfect. more power at low revs. hope that helps you guys. ;)

    leo

    GTT

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    Re: Keeping the BOOST up
    « Reply #23 on: January 30, 2011, 08:07:30 pm »
     This is true, I discovered the stock actuator was hopeless  about 30 minutes after buying the car.
    All the forthcoming GTT conversions will use stronger actuator, also they will include stronger more rigid  GTT bracket, interchangable spring , but above all they will be T3 size.
     Why T3? 
     Isn't an uprated  15psi actuator just a 15psi actuator regardless of whether its T2 or T3 size?
      The reason we uprate the actuator is because what is happening is the EXHAUST gas is overcoming the spring pressure and pushing the flapper valve in the turbine housing open all by itself. This  occurs at high rpm BEFORE the actuator is opened as it is designed to be . (ie from pressure through the small rubber pipe that comes off turbo compressor outlet.) The reason T3 is better is  because  the diaphragm has twice the surface area , therefore to pull the rod out will require twice the force of a 'same psi' rated T2 actuator. That means there is twice the force holding the wastegate flapper shut giving further resistance to premature opening of the wastegate by the exhaust gas pressure.
    In summary a stronger T2 actuator is better than stock but stronger AND larger ( ie T3) even better still.
    All this when used in the right context will result in much flatter boost curve, and as mentioned will hold onto it longer giving higher peak power. Quite how people can make power claims of 180-190bhp on   A500 running stock IHI turbo and actuator is beyond me. Max power comes at around 5,500rpm ....by this time boost ( at manifold) is just 12.5 psi )0.8 baR  and even less at redline. No remapping can change this.   

    Offline nardoo

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    Re: Keeping the BOOST up
    « Reply #24 on: January 30, 2011, 08:20:35 pm »
    from GTT: "Quite how people can make power claims of 180-190bhp on   A500 running stock IHI turbo and actuator is beyond me."
    it depends if it is "stock". for example g-tech changes your turbo for the rs kit. only the more powerful kits get new turbos. so a modified IHI turbo with the right remap and few other minor changes could produce that power but is running very close to its boarders. any more and it will break. ;D

    GTT

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    Re: Keeping the BOOST up
    « Reply #25 on: January 30, 2011, 09:37:00 pm »
    hi, I think you may have misunderstood me. What Im refering to is a Stock Abarth 500 ( 135bhp, small IHI turbo, weedy stock 0.25 Bar actuator). What im saying is that by just adding a remap to this ( any remap) it is not IMO  possible to achieve 180-190bhp.  The main reason being that the wastegate will simply push open under the force of the exhaust gasses at high rpm where peak power is achieved ( Typically 5,500rpm ). Power and torque can be much improved at lower and mid  rpm because boost can sucessfully be increased in this zone without the exhaust gas blowing the wastegate open prematurely. As the ultimate test,  if one were to pull the pipe off the actuator ( dont try it folks !!), the turbo  would put out around 1.8 Bar at 3,000 but it would still drop progressivly  to a puny 0.8 bar at 5.500-6,000rpm.  No remap can prevent it.
    I agree with you/ G tech that stronger actuator is the way to go. Or even better still stronger T3 actuator AND bigger turbo.  :)
    « Last Edit: January 30, 2011, 09:45:07 pm by GTT »

    Offline nardoo

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    Re: Keeping the BOOST up
    « Reply #26 on: January 30, 2011, 11:42:20 pm »
    yes you are completely right. no way you can achieve that power just from a remap. impossible. the thing with the small boost at the top is just because the turbo is to small. but thats why the abarths are so nippy in corners. good boost at mid range rpm. take a bigger turbo and you have more oomph at the top and higher speeds. but alot of turbolack at low revs.  ;)
    but the thing with bigger turbos is that you have to change alot to make it last. we got a few guys driving around at about 300hp and there alot of problems at this level of power with the 1.4 l engine. especially the second cylinder always gets cooked. apparently it is a thermic problem. they also have a diesel GP with 256hp and 506nm! ;D mad thing. but they have been through a few engines so far. :)
    what do you mean by T3 actuator?? got a link or pic? i am not sure what you mean with that!! ??? ;D

    GTT

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    Re: Keeping the BOOST up
    « Reply #27 on: January 31, 2011, 08:06:22 am »
    Hi , yes in general terms if the turbo is small relative to the engine the turbo fails first, but if the turbo is big relative to engine size its the engine that fails first. Similar thing on the Cooper S Minis but is piston No 1 that fails mostly due to excess inlet charge temp combined with using 95 octane instead of 99. Forged pistons and or water/mehanol injetion would be sensible above circa 230bhp.
     T3 refers (originally) to the old Garrett T3 turbos, these had a larger diameter can being 3" dia compared to 2" diameter for the T2 type ( dimension excludes the pressed flange lip). The size/name just sort of stuck T3 is 'the big one' T2 is 'the small one'.
    The art with turbo selection is A) choosing a range of turbos that are efficient in the first place ( eg Garrett GT over Garrett T), then choosing a compressor thats graphs peak efficiency at the flow rate v pressure ratio the unit will be operating at, then selecting the optimum AR turbine housing to give good spool up without the exhaust valves meeting too much backpressure at the turbine inlet.
    Everything is a careful balancing act ...get it right and the results shold be awesome.  :)

    Offline nardoo

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    Re: Keeping the BOOST up
    « Reply #28 on: January 31, 2011, 09:48:13 am »
    alright now it makes sense. just didn't know exactly what you ment! ;)
    it is, as you said, a careful balancing act. and you have to decide what you want to do with your car. it is a slightly different story in the UK (i think) because of the smaller roads and speed limit. i would only go for a good nippy car. so not a big turbo and more power at low and mid range revs. and obviously one major issue is the heat. the GPA/evo are still better off then the 500 but for me the exhaustsytem and intercooler are the first steps i would take before putting in a larger turbo. some guys here have got the big turbos and a long fifth gear (A500) and they say it makes it even more comfortabel on the autobahn and more efficient. and if they want to drive fast the little pocketrocket goes like .....!! ;D :thumb:
    i think we are slightly moving to an off topic talk but i hope that helped you Gofra?? :)

     

    Offline cb500t

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    Re: Keeping the BOOST up
    « Reply #29 on: January 31, 2011, 10:09:12 am »
    So would it be worthwhile to change the actuator for say a slightly uprated one on a standard AGP without it going bang?

     

    hungry