GT2554R Turbo - Map Opinions
Turbo Mini Forums

Here is the development of the GT2056 turbine map for a 998 running a GT2056.



At least 4500rpm before full boost.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

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Edited by fab on 6th Nov, 2010.

paul - whats that telling me?

Chris

The thick blue line is the turbine performance from Garrett. This is turbine flow corrected to "normal" pressure and temperature.

If you apply the pressure ratio and the expected exhaust temperature to the garret data you get the pink and peach coloured lines representing 750 and 850 degress C respectively.

The four light blue lines represent the calculated air flow of the engine based on the pressure ratio.

Now, if you compare where the lines cross you will get an idea of at what speed the pressure ratio will be achieved.

Based on the above, you would expect to see the pressure ratio of 2:1 i.e 15psig boost at around 4500 rpm.

Now, one fundemental assumption to the above is that the turbine inlet pressure is equal to boost pressure during the spool up. Hence this is only an approximation. However, it does seem to give the right sort of numbers when compared against actual rolling road results.

My own experience has shown that there is far more to this with both load and time being a major factor. The 998Ti will only reach full boost at 5000rpm in first gear on the road or in third gear on a low inertia rolling road. However, foot to the floor on a steep hill in 4th and I see full boost by 3000rpm.

So, you can apply +/- 1000rpm to the above.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Ok cool,

I understand much better cheers. So full boost at 4500

So in your opinion which turbo should I go for? GT17 or GT20?

Chris

I think for your projected power output the GT17 would be best.

If something is worth doing, it's worth doing half of.

Yes, what he ^^^^^^ said.

Anything up to 200hp, I would recommend the Gt17 although we still do not have a compressor map. Above 200hp there are better turbo selections IMO.

You may also wish to consider the Mitsubishi TD04-13G or the BW KO4-0025.

However, word of caution. Mak sure you get a turbo with a decent A/R and wheel size on the turbine side. A lot of the newer turbos seem to offer higher efficiencies on the compressor side but restrictive turbines which will effect VE at high power outputs.

An A/R of 0.5 on a 50mm turbine wheel will need more pressure to drive than an A/R of 0.5 on a 60mm wheel. So it's not just a matter of comparing A/R. You need the turbine performance curve as well.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Turbo Harry uses the Gt2056 on his 16 valver. 225hp at 15psi.

why do you need anything bigger?

Why indeed sprock, why indeed

I have been using this turbo on my 1152cc 5port and its unreal. The 0.64 turbine was a little big so i have a 0.49 from a CA18det T25 that has been modded to fit.

Full boost (15psi) is all in by 4400rpm going off the data log from the megajolt.

I reckon it would only take a few hundred rpm to get to 20psi as it rockets up once it hits about 7psi

but theres probably a big dfference to a 1L

But you really need a big rev limit to make full use of the turbo power doesn't drop off till 8000rpm ish

Edited by benjamin on 6th Jan, 2011.

1152cc turboed mini clubman, most powerful 1.1L a-series?

http://boostmini.justboard.net/

Is the gt2554r just a full t25 with a roller bearing core?

If something is worth doing, it's worth doing half of.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I could make boost by using the two maps on Megajolt. In the second map on the button set a low rev limit and bang the engine on the hardcut. It would make about 5PSI. Like has been said above though boost is instant as the clutch is lifted. With good grip it smashed my CWP. Ron