Garrett G-Series turbos
 

Here's an analysis of the new turbos, lots of improvements from the GT/GTX turbos:
http://www.motoiq.com/MagazineArticl...ochargers.aspx

I was just looking at this, kinda happy I am still running the stock turbo as the larger G series may be very interesting

We will have to see. Those are some optimistic numbers for those tiny wheels.

What numbers are optimistic? The maps are the maps. Data doesn't lie.

real-world > text book

I would argue that the real-world doesn't match text book when text book (i.e. science) wasn't understood in the first place.

Wut?

Oh come on, you have never seen something that all the data on paper said would perform a certain way and when it's in the real-world, it under performs?

They're claiming power figures that everyone else's need an approximately 8-10mm larger compressor to hit. So, we'll see.

Garrett has always been a bit optimistic with their numbers. They're claiming 550hp with a 50lb/min turbo and 660hp with a 60lb/min turbo. I think people will be pretty hard pressed to hit those numbers without killing the turbos off pretty quickly.

For the ~$2100 price tag these had better be able to compete with the EFR stuff. Even with all of the graphs and everything they're pitching I'd still take an EFR over it, and the EFR stuff is starting to get older now, in a few years BW should be coming out with their new cutting edge stuff and hopefully the EFR stuff becomes a bit more bread and butter affordable. The only thing Garrett has had going for them lately is their GTW line and that they started offering reverse rotation options for some of their turbos about a year ago.

What they claim for potential power figures is irrelevant because it's completely dependent on the engine, fuel (diesel, 87oct, 110oct, e85), etc. Those numbers are really just to give a ballpark reference for people who don't know anything technical. Kinda like the broad generalization of 4 cylinder vs V6 vs V8. Go talk to your grandma and she can tell you that generally a V6 is more powerful than a 4-banger.

But what is indisputable is the compressor map. What an engine can do with the airflow provided by the compressor is dependent on the engine. To make an analogy, the VW Golf GTI and Audi A5 use pretty much the same 2.0L gas engine rated at 220hp (i.e. compressor map). The Golf does 0-60 in 5.9s (i.e. claimed power potential) and A5 in 5.0s. Golf is 500lbs lighter but FWD whereas the A5 is AWD.

Now, where there has always been a big chunk of missing data is the turbine efficiency map. Garrett only shows the flow, but not the efficiency curves. This is the whole reason why the GTX3576R spools up essentially the same as the GTX3076R in the same A/R turbine housing while also making 50whp more on kill mode. The 3576 has way better turbine efficiency due to a better blade speed ratio due to better wheel size matching. But Garrett doesn't show that turbine efficiency info.

So yeah, there is half of the equation missing being the turbine efficiency data. But if you want some unsubstantiated numbers at this point, a little birdy told me the GT25-660 (2567)made about 630whp on an Evo, pure test/max flow setup (straight pipe exhaust, no mufflers/cats) on E98. Which blows my mind, so I'm awaiting the presentation of the data myself before I say it's concrete.

Figure you put the turbo in a more realistic setup with exhaust, E85, etc. 500-550whp seems more reasonable. The compressor map showing 60lbs min, and the turbine flow in the 0.72 A/R housing being a little less than the GTX30 turbine in the 0.83 A/R, stated turbine peak efficiency of the G-series at 74% which is higher than GT/GTX, seems reasonable as the GTX3071R Gen2 is ~525-550whp turbo.

Did you read the article? You do understand these G-Series turbos come with a higher temp capable turbine wheel right?

With the ballpark calculations for inertia in the article, I do think the EFR7163 will have a slight inertia advantage on the turbine side vs. the G25-660, power will be in the same ballpark. The G-series will have less inertia on the compressor side, so maybe overall inertia will be about the same. But the G-series will have greater durability (mar-m vs. TiAl) and smaller package size. In comparing the G25-550 (2560), it will make way more power than the EFR6258 but have more inertia, and make similar power to the 6758 and maybe similar inertia; G25-550 compressor wheel has much less inertia, but the turbine makes up a much greater % of the overall inertia and I think the G25-550 will have greater turbine inertia vs the EFR 6758.

I sure appreciate you talking to us like we are fifth graders.

They won't publish any sort of turbine efficiency maps, no ones does. It's one of the most closely guarded secrets in the turbo industry and there's only a handful of test stands in existence that can accurately measure that.

As to having a higher temp turbine, I don't think it's doing as much as you think it is. Being able to withstand higher temps means it can be run at a higher speed without damage and this higher speed allows a higher pressure ratio on the compressor side. But if you look at the compressor maps vs the old GT stuff you'll see that peak pressure ratio curve is hardly any higher, which tells you that higher wheel speeds is a moot point.

As for inertia, weight is the name of the game (your article even stresses this) and no one has made a lighter weight commercially available wheel combo than the EFR stuff. Durability is relative to the setup on whatever car the turbo is on so that's kind of moot (if the EFR stuff wasn't durable then it wouldn't have been used in some of the highest forms of motorsport for the past 5 years). As for how it will stack up against other turbos that can really only be proven after people have started using it.

The biggest turn off for me is the lack of turbine housing options. I'm absolutely not a fan of v band flanges whatsoever and I'm a large advocate of twin scroll turbos.

I'm just trying to be thorough in making my points so as to not leave too much room for misinterpretation. And while you are tech savy and able to do logical deduction, let's face it, many people reading this may not have enough tech background to do that. For example, I was at PRI one year and a guy was like, the wheel is billet so it'll flow more right?

Higher temp limit does allow for higher performance in addition to greater durability. Mustang Ecoboost 4-banger uses lower grade materials compared to the Focus RS Ecoboost. The head on the Focus RS has higher grade materials to handle higher heat. I'm 75% sure the Focus RS turbo uses Mar-M turbine wheel whereas the Mustang uses Inconel. The higher temp capable materials allows Ford to run a more aggressive calibration with higher EGTs and make more power in the Focus RS.

A T4 twin-scroll internally wastegated housing will be available next year.

Random tidbit, the Ferrari 488 has TiAl turbine wheels along with abradable coatings on the compressor side and a ball bearing design. Turbo is from IHI.