Alfa Romeo Giulia Forum banner
861 - 880 of 926 Posts

·
Premium Member
2018 TI Sport Q4
Joined
·
315 Posts
Why not use the compressor housing from the GTX2867R? Too many modifications to fit the stock wastegate actuator? Or the intake and outlet piping?
The wategate actuator, charge pipe, and inlet piping would all have to be modified. If its absolutely necessary, its something that can be done, but retaining the oem turbine and compressor housing keeps it slightly more plug and play.

Its also nice that our housing is a .56ar This will help keep the nice and quick spool dynamic, while at the same time making much more power with the larger wheels.
 

·
Registered
Joined
·
13 Posts
[QUOTE="Tekgnome, post: 922778, member: 34475"
Its also nice that our housing is a .56ar This will help keep the nice and quick spool dynamic, while at the same time making much more power with the larger wheels.
[/QUOTE]

Compressor A/R has very little affect on spool. Normally they are sized by the compressor wheel so dumping a large compressor wheel in a small housing isn't the best for performance.
 

·
Premium Member
2018 TI Sport Q4
Joined
·
315 Posts
[QUOTE="Tekgnome, post: 922778, member: 34475"
Its also nice that our housing is a .56ar This will help keep the nice and quick spool dynamic, while at the same time making much more power with the larger wheels.
Compressor A/R has very little affect on spool. Normally they are sized by the compressor wheel so dumping a large compressor wheel in a small housing isn't the best for performance.
[/QUOTE]
In this case its a GTX28 chra it's far from a large compressor wheel. I trust the shop building the hybrid, if it was going to be enough of a restriction to noticably effect power he would have had me just use GTX housings.

Generally speaking, the turbine housing size and design plays a big part in where power will come in at. With a .56ar power will come in a significantly lower rpm range vs a 1.06 but won't peak as high.
 

·
Registered
Joined
·
985 Posts
You will need roughly at least 40% more exhaust flow to drive the GTX28 compressor. My guess is if you can actually fit the correct turbine wheel it may be able to deliver 30 psi by around 3k or 3.5k rpms best case.
 

·
Premium Member
2018 TI Sport Q4
Joined
·
315 Posts
You will need roughly at least 40% more exhaust flow to drive the GTX28 compressor. My guess is if you can actually fit the correct turbine wheel it may be able to deliver 30 psi by around 3k or 3.5k rpms best case.
I'd be more than happy with 30psi @ 3,500 rpm

30psi with a .86ar gtx2867 is like 460hp (obviously that's best case scenario and ignores potential multiair, and fuel problems.)

Our engines have a pretty high compression ratio for a turbo engine, I'm expecting to be able to make some decent power with a bigger turbine and compressor wheel. Again though that's best case scenario there's still so many unknowns on what could be a limiting factor.

I'm still not sure of the exact turbine wheel I'll end up using. The turbo shop thinks we can cut the OEM housing to fit the GTX28 turbine wheel but I won't know for certain until it's in my hand finished.
 

·
Registered
Joined
·
13 Posts
If you were talking turbine AR I would agree but not compressor housing AR. It may affect surge and overall airflow but not so much spool.

Generally speaking, compressor housing size and design plays a big part in where power will come in at. With a .56ar power will come in a significantly lower rpm range vs a 1.06 but won't peak as high.
 

·
Premium Member
2018 TI Sport Q4
Joined
·
315 Posts
If you were talking turbine AR I would agree but not compressor housing AR. It may affect surge and overall airflow but not so much spool.
Ar is measured by the compressor/turbine housing.
From my understanding wheel size isn't directly linked to the internal housing area.


It stands for Area over Radius. It's the cross-sectional area divided by the radius from the turbo centerline to the centroid of that area.

A GTX28 compressor wheel isn't going to be massive enough to have a noticable negative impact from a .56 compressor ar.

I'm only aiming to flow 400whp worth of air, not 4000
 

·
Registered
Joined
·
13 Posts
Turbine and compressor housing AR's are specific to the individual housing. Most turbos you will find one compressor housing but multiple turbine housings due to the effect on spool/power. Compressor housing AR has very little effect on spool.

 

·
Registered
2019 Giulia Ti Q2, Performance Pack
Joined
·
2,255 Posts
Correct, for compressor housing most turbo companies i know of do not even let you have choices because it really doesn't matter much. Turbine ar matters alot for high/low end flow
 

·
Registered
Joined
·
13 Posts
I took your original reply to mine as meaning the compressor AR had a lot to do with spool which it does not. If you are talking our exhaust housing has a .56 AR that's different.

A GTX28 compressor wheel isn't going to be massive enough to have a noticable negative impact from a .56 compressor ar.
 

·
Premium Member
2018 TI Sport Q4
Joined
·
315 Posts
I took your original reply to mine as meaning the compressor AR had a lot to do with spool which it does not. If you are talking our exhaust housing has a .56 AR that's different.
Ahh no I was initially talking about the turbine housing
In this case its a GTX28 chra it's far from a large compressor wheel. I trust the shop building the hybrid, if it was going to be enough of a restriction to noticably effect power he would have had me just use GTX housings.

Generally speaking, the turbine housing size and design plays a big part in where power will come in at. With a .56ar power will come in a significantly lower rpm range vs a 1.06 but won't peak as high.
I thought you were trying to say the a .56ar was going to be so small that it would restrict the compressor side.

Looks to be just a misunderstanding.
 

·
Premium Member
2018 TI Sport Q4
Joined
·
315 Posts
So far they have completed the compressor side and are working the turbine side next week. Supposedly may ship by Thursday.

I was impressed they are using a brand new OEM Garret turbo for the project. No used core.

View attachment 116035


View attachment 116036


View attachment 116037
That's promising, I'm excited to see they changed their minds on the no picture policy. I reached out a couple of weeks ago and they said that they don't send pictures of there products, which is a huge red flag.

They originally made it seem like they had hybrid turbo's ready to go and I could buy now but when I asked about pictures they quickly back tracked lol

My shop checked with over a dozen suppliers and couldn't find rebuild kits for the OEM CHRA, I'm guessing GotTuned found they weren't easily rebuild-able as well and decided to just replace the entire chra with a new one.

This is huge progress for those who want a journal bearing completely drop in setup.🥳

I'm still curious how they will handle the turbine side of things, they told me that they are going to use a "47/54, like GT28" turbine wheel
 

·
Premium Member
Joined
·
772 Posts
Any expected after market enhancements to support the hybrid? Spark plugs/cable, coolest, etc. Sorry for my lack of knowledge.

On the flip side, anything expected to give because of the extra power besides tires/breaks?
 

·
Registered
2019 Giulia Ti Q2, Performance Pack
Joined
·
2,255 Posts
Ultimately we're talking 50 hp over tuned cars so im not worried about needing a big brake kit. Goid pads and good fluid and we'll see.

For charge cooling kozak had good intake temps so we'll just have to see. Mine are fine with maxed stock turbo but ill have to test this one going slow at 22psi then 24, then 26 to see how it looks.

I have drained my lt coolant loop and a running 95 percent water with super coolant to reduce temps a bit. In south Florida we can do that all year round.

If i need more i can always pop in an additional heat exchanger. Thats easy enough but we'll see. I dont like to add shit just to add shit.

Ill use stock plugs and log. Doubt they need a change but we'll see. Ive added 200 to 300hp to most audis ive owned and stock plugs always gave me best results but still you never know.
 
861 - 880 of 926 Posts
Top