Its GT28 time!

[Pasteurised]

Hey guys ive decided to take the plunge and go for a GT28 setup, ive looked at different variations and have settled on this:

Compressor
Trim 48
Inducer Diameter 49.20 mm
Exducer Diameter 71 mm
A/R 0.60

Turbine
Trim 76
Inducer Diameter 53.8mm
Exducer Diameter 47 mm
A/R 0.64

Apparently this should flow up to 400bhp but im not chasing numbers.

Only parts i still need to find are silicone joiners to connect the compressor inlet to the tip and outlet to the charge pipe, and a EGT probe boss.
Could someone plz confirm the charge pipe diameter for me, and if you know what thread and pitch boss i need that would be awesome.

Cheers

 

[Tj 0785]

What Inlet manifold and exhaust manifold have you gone for? I'm still weighing up to go Aet 380 hybrid or gt30 or precision 6262just getting prices together at min for all the other bits and bobs needed.

 

[Pasteurised]

Exhaust manifold is going to be custom, and my plan was to see how much the stock intake can handle and then go from there. Is there a definitive limit on the stock inlet?

 

[Tj 0785]

Couldn't tell ya every gt build I've seen always has a bigger inlet so I always thought it was required just like bigger injectors are. More fuel more air

 

[Pasteurised]

Ah ok, I'm not going huge power, probably on par with hybrid k04, but gt works out cheaper for me and gives potential for future.

 

[Pasteurised]

Realistically it should make 300bhp on 21psi at 6500rpm.

 

[Gops]

you're better off going for a GT30

 

[<tuffty/>]

but gt works out cheaper for me and gives potential for future

Only if you go v-band and external gate from the start else you will need to replace it all to go bigger..

Most GT28 based turbos are T25 internal gate... its a fairly p*ss poor at flow tbh (having been there myself) so if you are looking for a setup thats got some future proofing then you need v-band and external gate...

<tuffty/>

 

[Pasteurised]

Thanks ill go for vBand GT2871R.
As the internals are standard for the moment, if i keep the torque flat at 242 lbft, This should roughly give 300 bhp on 21 psi at 6500rpm with the turbo at around 76% efficiency, hitting 21psi at 4000rpm.
Once forged if i keep the torque flat at 304 lbft, This should roughly give 375 bhp on 30 psi at 6500rpm with the turbo at around 74% efficiency, hitting 30psi at 5000rpm.

 

[Pasteurised]

I miscalculated slightly, the power would be achieved at 6000rpm.

 

[Stuart B]

I am no expert but would you be better off doing the engine internals before fitting essentially a bomb to your car?
Just in case ?

 

[Pasteurised]

Dont have the funds to do it all at once.
Surely 300/240 will be fine on stock internals, Im already no 265/265 with a Stage 1 map.
And the bigger turbo will be much more efficient and generate less heat.

 

[Tj 0785]

Personally I'd do the internals 1st then more power don't see why you would fork out for bigger turbo and not make the most of it.

 

[Stuart B]

As I said I am no expert. To be fair I have a stage 2 ecu with no FMIC at the moment so no better myself. I will follow your progress with interest as with virtually everyone with S3's if there is not a modification in progress it's very easy to get bored.

 

[Pasteurised]

Means i can enjoy 300bhp till i can afford to fully build the engine.

 

[superkarl]

Mine makes 300 at 0.9 bar.
A turbo so big tuned down to that level just feels so lame. No torque, something like 250lbs. Just revs out till you fall asleep.

Would suck to be a vtec owner

 

[Pasteurised]

Only thing i still need to find out is the egt boss thread and pitch, anyone any ideas?

 

[superkarl]

Only thing i still need to find out is the egt boss thread and pitch, anyone any ideas?

M12 X1.0

 

[Pasteurised]

thanks man!

 

[badger5]

What Inlet manifold and exhaust manifold have you gone for? I'm still weighing up to go Aet 380 hybrid or gt30 or precision 6262just getting prices together at min for all the other bits and bobs needed.

you could'nt go more an extreme choice if you tried between those, lol

Not looking for a desired power then!

 

[Pasteurised]

What size injectors would you guys recommend to support up to 400bhp

 

[superkarl]

What size injectors would you guys recommend to support up to 400bhp

depends on fuel pressure, but 630cc at 3 bar. Minimum

 

[Pasteurised]

sweet, thanks

do you mind if i ask at what rpm your car is making 300bhp at 0.9bar

Been learning more about Compressor maps and Volumetric efficiency, calculated my cars VE by logging RPM, boost and Airflow.
Based on my airflow calculations my engine would make 268.6bhp at 6500rpm on 0.9bar boost, but im guessing that Timing Advanced would be what pushes it up to 300bhp.

 

[superkarl]

sweet, thanks

do you mind if i ask at what rpm your car is making 300bhp at 0.9bar

Been learning more about Compressor maps and Volumetric efficiency, calculated my cars VE by logging RPM, boost and Airflow.
Based on my airflow calculations my engine would make 268.6bhp at 6500rpm on 0.9bar boost, but im guessing that Timing Advanced would be what pushes it up to 300bhp.

7000rpm.

Compressor maps and VE only tell you a small part of the story. Good to get an idea yes. Dont get blinded by them

As an example, my turbo is ~1.7bar at 7000rpm. Now look at the compressor map for the 67mm billet wheel, and it theoretically should be flowing 45lbs/min. Yeh, quite a discrepancy

 

[Tj 0785]

you could'nt go more an extreme choice if you tried between those, lol

Not looking for a desired power then!

Ha not really ideally I'd like to big turbo 500bhp route but I would be happy with 350+ it's all down to funds car needs new engine so would want that done 1st just don't want it sat on drive for years

 

[Stuart B]

Wait and copy Andrew ALD no lag electric spin up F1 style turbo <-- or perhaps not - just speculation really - but I can read people

It is what I assumed everyone meant when I first joined the forum and they were talking about hybrid turbo's <-- I think "Frankenstein" is more accurate for the commonly used hybrid turbos