gt28r wastegate question (searched)

[sidewaysil80]

i've searched the aformentioned topic and only found personal oppinions and that the hks wastegate can supplement an electronic boost controller. with that little disclaimer outta the way...here's my query:
i have a garret gt28r turbo on my sr. currently i have the boost set to the stock 7psi. i have a greddy profect b spec II and will be raising the boost to 15psi (i have all the supporting mods including a power fc). i'm wondering if that is too much psi for the wastegate that turbo comes with or if that wastegate will cause boost spikes if the controller is set to 15psi? the greddy unit has a gain and peak feature to control spikes/drops but it said if the wastegate is maxxed out it can't control the climb in boost seen at high rpm. basically i'm trying to determine if the hks wastegate is necessary to maintain a CONSISTENT 15psi or if the greddy unit will be able to control it on its own? i know thats a fairly common setup so anyone with first hand knowledge feel free to chime in. thanks!!!!!!!!!!

[sidewaysil80]

anything? no one with any input?

[huffandpuff00]

i have the WG that came with mine on it and it holds my 16lbs fine. spikes some when i switch my boost to 18lbs, but chill around 16

[bb4_96]

Find out for yourself. Raise it in steady increments via the boost controller and see what happens. If you go slow you are not going to see it spike from 10 to 20 psi and blow your motor. You would have to be doing some additional very wrong things for that to ever happen. Isn't the HKS actuator adjustable via a nut on the rod or something? Try adjusting the wastegate to hold 10 and use the boost conroller to get you to 15.

[jspaeth]

Whether or not it spikes will be caused by

1) How large the wastegate hole is

2) If the flapper can open all the way to basically prevent any resistance to air going through the said hole


I would say for this turbo and based upon others' experience, this has NOTHING to do with which actuator or boost controller you are using....you should be fine

[bb4_96]

^^ creep, not spikes, is caused by wastegate hole being a certain(too small) size to allow enough exhaust gas to escape to effectively regulate boost.

"Typically spikes occur when the boost controller cannot keep up with the rapidly changing engine conditions" Per Garrett's website. a well designed EBC will attempt to beat the spike.

As far as the actuator is concerned, do you think it's be more precise for the Profec to up the boost pressure 8psi or 5psi from what the actuator is actually set at?

To answer the OP it isn't necessary but be wary of working the stock unit hard. HKS unit has a beefier diaphram to handle higher boost and the adjustablilty is key for helping your bc better regulate boost.

[jspaeth]

^^ creep, not spikes, is caused by wastegate hole being a certain(too small) size to allow enough exhaust gas to escape to effectively regulate boost.

"Typically spikes occur when the boost controller cannot keep up with the rapidly changing engine conditions" Per Garrett's website. a well designed EBC will attempt to beat the spike.

As far as the actuator is concerned, do you think it's be more precise for the Profec to up the boost pressure 8psi or 5psi from what the actuator is actually set at?

To answer the OP it isn't necessary but be wary of working the stock unit hard. HKS unit has a beefier diaphram to handle higher boost and the adjustablilty is key for helping your bc better regulate boost.

Yes, HKS actuator is beefier.

And yes, I apologize, you were right....I meant to say creeps but typed spikes.

Boost controller can handle spikes, but won't help you with creep.

You honestly should be fine with your setup OP, nothing crazy

[sidewaysil80]

word thanks fellas, i was worried mainly about the boost creep but we'll see what happens. if it creeps bad i'll just throw the garret upgrade one (i don't wanna have to fool with adjusting the hks one)

[Grenade180sx]

just buy a manual boost controller and set it and forget it. less headaches.

[jspaeth]

just buy a manual boost controller and set it and forget it. less headaches.


Worst idea ever, those things are pieces of shit.

You will either A) blow up your motor or B) be forced to have the car underperform.

[codyace]

just buy a manual boost controller and set it and forget it. less headaches.

Nothing like having terrible response, and having to pop your hood 100x to set it.


Find an electronic one used cheap, and never worry. Nice having 3 boost settings...gate, setting 1, and setting 2. All from in the cabin.

[Grenade180sx]

Worst idea ever, those things are pieces of shit.

You will either A) blow up your motor or B) be forced to have the car underperform.

under perform? how so? i have had electronic controllers and manual, i prefer manual i have never had any issues with spiking, i tune my car for the boost level and go. i dont need 3 maps. and incabin manual controllers works just fine.

personal preference i assume then. but ive NEVER blown a motor because a manual boost controller come on now.

[jspaeth]

under perform? how so? i have had electronic controllers and manual, i prefer manual i have never had any issues with spiking, i tune my car for the boost level and go. i dont need 3 maps. and incabin manual controllers works just fine.

personal preference i assume then. but ive NEVER blown a motor because a manual boost controller come on now.


Manual sucks.


Let's say you turn the knob so that you are hitting the maximum boost you want at like 5000 RPM or so.


Well then under those circumstances, that spring pressure is going to give you FAR less than ideal spool up as you are approaching boost, because it is not going to be bleeding off ENOUGH pressure to the wastegate.


The reason an EBC is ideal, is because you can keep the wastegate COMPLETELY shut (almost) up until just when your target boost is hit, and only THEN start letting some of the boost get to the actuator to open the wastegate.


With a MBC, by it's very nature, in the lower RPM (say 3000-5000), the wastegate is going to start opening a little bit at a time as soon as you reach the wastegate spring pressure.

So not only is an MBC worse at holding "constant boost" and preventing spikes and creeps, but it almost certainly causes the turbo to spool up more slowly.

Am i being confusing?


EDIT: I am not saying you are going to blow your motor, I meant that if you try to set up the MBC to give a fast spool up, you will inherantly overboost.


With MBC, you CANNOT decouple the spool up characteristic from the ultimate "max boost"