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Anyone Had Stalling Issues Running A 3" Intake On A 4" Turbo?

Harey

By Harey,
in Engines & Forced Induction

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Harey Veteran

Harey

Posted
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Hi all,

I went to see a reputable performance joint yesterday about installing a HKS 2835 Pro S kit I have got my hands on. I already have a 3" metal intake to the Z32 afm and then pod.

However, the new turbo has a 4" intake and the tuner is strongly recommending I move the afm to the cooler piping and run a 4" intake due to reversion and potential stalling issues arising when transitioning on/off boost. He said this seems to occur frequently with the larger compressor covers.

I want to keep my 3" metal intake and leave the afm in the factory location. Even though the turbo has a 4" intake its not designed for huge power (280rwkw max) and from what I can see all the other guys running this turbo dont run 4" intakes.

Has anyone had this issue? Or is it minor, the extra price of this work is scaring me off changing to this turbo.

Harey Veteran

Harey

Posted
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just run a 4"-3" reducer, install the kit and be happy :)

That was my original plan, I hadnt even heard of anyone else doing that on this turbo. Do you have experience with this configuration or just everyone else's results?

Harey Veteran

Harey

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not a problem even with an atmo bov fitted, but my HKS2835pros has a 3" intake and surge slots

oh wow yours has a 3" intake as well!! Mine has surge slots too but is definitely 4".

Joeyjoe's turbo has a 3" intake as well. I wonder why mine is 4"??

Harey Veteran

Harey

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Think about how much air is going through the turbo on idle...... Next to none. 3" pipe will be fine. They supply a 3 inch pipe and reducer for a reason. Never heard of any issues

What size intake does yours have? Yours is the KAI version right?

femno Grand Master

femno

Posted
Posted

Put the turbo in and see if you have any dramas before deciding to do the extra work?

We always do the 3076s with 3" hard piping and 3-4" reducer at the turbo and never have any problems. The factory arrangement should provide enough air mass not to disturb the AFM if/when the compressor surges.

Different turbos have different flow characteristics though. I say just give it a shot first then tackle the problem IF it arises.

discopotato03 Grand Master

discopotato03

Posted
Posted

From memory there are two versions of the GT Pro S compressor housing and both are port shrouded . The main difference is that one has a 100mm inlet snout and the other is 90mm with a separate machined boss fitted .

If you have the 100mm version I'd say the way to go would be a reasonable section of 100mm bore hose to let the PS'd comp housing do its thing then reduce to 80mm to suit the Z32 meter .

If tuning isn't a problem you could consider fitting the element and electronics into a 90mm AFM body making the difference only 10mm . 90mm is 3.543 inches and I reckon at 1mm over 3.5" you could stretch something to fit .

A .

Harey Veteran

Harey

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reducer on the turbo will be fine. just make sure theres a bend and as much length as possible between the afm and turbo

I have just finished a custom 3" intake (90 deg bend) with the bov return and breather hose fittings for the current turbo and I do get the issue on my current turbo so I am thinking it might get worse.

Harey Veteran

Harey

Posted
  • Author
Posted

Put the turbo in and see if you have any dramas before deciding to do the extra work?

We always do the 3076s with 3" hard piping and 3-4" reducer at the turbo and never have any problems. The factory arrangement should provide enough air mass not to disturb the AFM if/when the compressor surges.

Different turbos have different flow characteristics though. I say just give it a shot first then tackle the problem IF it arises.

Great to hear with your personal experience with the 3076s, thats great info.

That was my third option, 1. keep current turbo, 2. install new turbo and relocate afm, 3. install current turbo with reducer and see how it is

The only cost that I would double up on would be the tuning.

Harey Veteran

Harey

Posted
  • Author
Posted

From memory there are two versions of the GT Pro S compressor housing and both are port shrouded . The main difference is that one has a 100mm inlet snout and the other is 90mm with a separate machined boss fitted .

If you have the 100mm version I'd say the way to go would be a reasonable section of 100mm bore hose to let the PS'd comp housing do its thing then reduce to 80mm to suit the Z32 meter .

If tuning isn't a problem you could consider fitting the element and electronics into a 90mm AFM body making the difference only 10mm . 90mm is 3.543 inches and I reckon at 1mm over 3.5" you could stretch something to fit .

A .

Bugger I have just finished a custom 3" 90 degree bend with the bov return and the breather fitting. Ended up being a fair bit of work.

Interesting idea with the larger AFM body. I was trying to stay on the beaten path though :)

Nengun says the two sizes are 80mm and 100mm:

http://www.nengun.com/hks/turbine-gt2835-pro-s

Although I trust you disco more than nengun!

Do you know the reasoning behind the larger intake? It seems funny for a turbo designed for a standard engine to require such modifications.

Harey Veteran

Harey

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Mine is the KAI yes and has a 3" inlet on the turbo. Not the 4" like the pro s

The pro s kits come with a 4" to 3" reducer and a 3" hard intake pipe

See thats the thing all the people on here that I have spoken to with the Pro S (joeyjoejoe, 75coupe and others) all have the 3" intake.

Are you sure the Pro S kits came with a 4" to 3" reducer at the turbo? As far as I know the Pro S kits have been discontinued and only the KAI is still made.

89CAL Grand Master

89CAL

Posted
Posted

Pro s kits came with a 3" to 4" reducer. The one I saw this reducer was black unlike the rest of the hoses which are purple.

They have a 3" hard pipe which is identical to the one supplie with the KAI kit. No need for the reducer with the KAI as it's 3" turbo housing to 3" pipe

Harey Veteran

Harey

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Dave I will post the id number up when I get home.

89CAL, that is promising! Although I am just trying to point out that not all Pro S turbos have a 4" intake. There are two versions, 80mm and 100mm.

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