A guy made a chart here the flow for the size on the g series is amazing they need to make a stock frame one

 

Heres the only result ive seen. If what they are saying is true then its quite promising.
I had a GTX3071R on an RB25DET on E85 and its was a killer setup!

 

Here is the link to that FB post.


https://www.facebook.com/RSTuningUK/photos/a.203761802999621.46818.202606226448512/1940390756003375/?type=3&theater
Shootout mode is estimate flywheel horsepower..

 

Sweet baby jesus! that is decent...earlier spool too! Now we just need a bolt on solution for our cars.

 

Just a reminder than they are comparing a 49lb/min turbo (G25 550) with a 56lb/min turbo (GTX3071R). The spool is roughly in the realms of what you'd expect comparing a turbo with one which flows >10% more air.

 

i wonder if the 660 is going to be a mismatched turbo like the Gen1 GTX3076R is?!? The Gen1 GTX3076R is a 5855 which means that the Compressor wheel flows more than the Turbine wheel can handle, which is why Garrett made the 3576R. Same Comp Wheel Inducer size of 58mm, but with the 35R sized Turbine wheel with a bigger Exducer of 62mm making a 5862. This is the same situation with this new G series "G25-660" It has a Comp inducer of 54mm but the Turbine Exducer is only 49mm making it a 5449 (Larger Comp wheel/Smaller Turbine wheel= Mismatch) whereas the 550 has a 48mm Comp Inducer & 49mm Turbine Exducer. It is always better to go with a turbine wheel that is closer/larger in size to the compressor wheel. Turbos work better with an oversized turbine shaft than an oversized compressor wheel. A turbo with a bigger turbine exducer measurement will help prevent surge and support the flow of the smaller compressor rather than using a smaller turbine that will choke it.
I think that the G25-550 will be impressive, but the 660 will be a disappointment. They'll need to make a G30-770 with the same 54mm Inducer but a larger Exducer, maybe 56mm.
In this format & technology, a 5456 should technically make 750-800.
With all this said, Theres just something about a GTX35R that will always be the #1 pick in my book!

 

I wouldnt even mention the GTW series in the same sentence talking about Garretts *New* and improved products. The Gen 2 GTX series is so far ahead of what anyone else offers. the 30R's and 35R's are capable of 100HP more than the 1st Gen GTX series. Gen 2 GTX3071R's now make power like a gt35r & spool like a 30R Not to mention the 3584RS thats making 900-1050whp! So idk how you can say anything negative about Honeywell/Garretts progression in late 2017-Present!

 

The numbers are not that simple if you look at the efficiency islands on the compressor map.

While I applaud you for recognizing the 3076 as a mismatched turbo, it's not as simple as comparing inducer sizes. The new Garrett turbines flow a lot more than the old turbines, and the compressors are more efficient. A more efficient compressor means the turbine doesn't have to work as hard, and a more efficient turbine is pretty self explanatory. Don't discount the 660 until we see some results. We have one going on a 2.3 4B11 now, and I believe CBRD has a turbo that he's installing on something as well.

 

What do you mean? The GTX3071R can do a max of 53lb/min at 68% efficiency, the G25-550 can do a max of 48lb/min at the same efficiency. That is >10% more flow at the equivalent efficiency. A ~400rpm improvement in boost threshold going to a new generation turbo which flows 10% less is not what I'd call jaw dropping but it's early days. The turbine is meant to suit another 20%+ more flow, though I guess the same also applies to the GT30 hotside.

 

These turbos seem to be taking a long time to get into circulation .
Assuming the suppliers have them in volume then I have to wonder if the 3" V band and T25 turbine housings are not that useful in many cases .
Also these was mention of other sizes appearing ....

 

I think people have a hard time believing the pitch with these.

The compressor map says 60lbs/min, but that's at max RPM and only 2.5:1 pressure ratio. That's only 22psi of boost at sea level. Realistically, and Evo would probably run this turbo in the 35psi range, where the map shows it probably flows ~55lbs/min. So it's probably a 550-575whp turbo on good fuel.

 

My personal view on these series is that, the only factors that do make a difference in relation to the gtx 2 series, in boost threshold, spool time, and full boost rpm point is the wheel design and weight.


For instance the g25-550 will not even do 550 crank hp much less 550 whp on pump fuel. But it might be able to do a true 500 crank hp on quality pump fuel on a low reader dyno. I will say though, that it will have a lower boost threshold than any other turbo of its size, faster spool, and lower full boost rpm point.



Also, people confuse compressor pressure ratio and boost. These may interact with one another but are two different conditions. The compressor pressure ratio is the ratio of air pressure between the inducer and the exducer of the compressor wheel, or of the inlet and exiting air pressure. Pressure ratio is solely related and connected to the mechanical efficiency of the compressor wheel, and nothing to do with an engine.



On the other hand, boost, has all to do with an engine. Boost is the inability of an engine to absorb a certain amount of flow at a given time. It has all to do with the volumetric efficiency of an engine.


For instance the above pre-mentioned example of a turbo, the g25-550, will have different boost pressures at the same flow on a 1,4L and on a 3.0L engine. Pressure ratio/flow vs boost relation will also be different even on two 2.0L engines of different volumetric and thermal efficiency.




The only occasion where a turbocharger is contributing to boost of an engine (without flow) is when the turbocharger heats the air at an excessive degree. Although hot air travels faster, when air molecules heat up they expand occupying space needed for the fresh cold air molecules, while the inducer is still trying to sqeeze in more air, thus creating a stagnant pressure situation where boost is increased but flow is not. Also, as too much air is located into the compressor housing for the compressor exducer to push out effectively many times these conditions lead to a situation called compressor surge.















Marios

 

I'm not alone in thinking that these G25s are taking a long time , nearly 6 months now , to even begin to show their worth .
AND I'm going to keep bashing the fact that mainly 3" Vband mounts are practically useless to anyone wanting to use a factory exhaust manifold on anything .
Borg does T25 T3 and T4 ...

Its all fine and well for Garrett to announce these things but if they want to be competitive in the market place - particularly with Borg Warner they have to offer a similar range and configuration of turbine housings .

Also many are wanting some data on the suggested G30 G35 and G42 sizes that are supposedly "soon" to follow .

 

Keep in mind the Aftermarket Performance division of Garrett is very small, limited resources, and bottom on the totem pole when it comes to priority. When BMW says it needs new turbos for the M5, Caterpillar needs new turbos for heavy duty off-highway diesels, Ford needs next gen for their Powerstroke diesels trucks (some 300K+ units a year), Ferrari needs additional testing and development of the Formula 1 turbos, the Aftermarket Performance team is told to wait in line. On top of that, there's a lot of quality and validation work that goes into releasing products which takes time and resources.

Remember how long it took BW to roll out the EFR series? Well, they had to fight turbine wheels breaking off in addition to turbine housing supplier issues. It really took them a good ~5 years after initial release before they were doing any real volumes.

Also, the G-series only hit the market in January. Chris Forsberg has already competed in the first Formula Drift event in Long Beach with the G25-660s. He went out of the even relatively early because his clutch master cylinder went out.

This video is of some of the testing before the event:

 

Here it is: