So I've been driving my car for the past few months and find myself wanting more response versus big power dude to the amount of circuit tracks in my area and street driving. I just don't find myself using all 600hp very very sparing. So I'm looking to downsize my turbo. Currently running a Garrett GTW3476R .82 housing with a Ramhorn manifold. I've spoke to a slew of people and majority of the UK tuners and crowd say even though the EFR tech is over 7 years old at this point it is still top dog over Garrett's GEN2 units and G series turbos when it comes to transient response/spool etc.

I've been a loyal Garrett user for over 10 years and want to stick with them but if the quote below is true info makes me wonder why spend $2k on a GTX GEN2 or G series for it to underperformed to a older BW EFR unit.

Was looking at comparisons of the BW EFR 7670 vs the GTX3071R GEN2... I think either turbo would work a bit better and have better spool than what I currently run just wanted some opinions and insight. I know the GEN1 GTX stuff was a hit or miss on some models so would a normal GT series 3076r or 3071r suffice as well?


"It depends on the application. There are excellent models in both the Garrett and BorgWarner range. For Drift applications and street setups EFR is unbeatable in a specific HP range. For Circuit racing EFR is tops for various reasons. The Garrett Range for an all out high HP Drag application is a great choice (1500HP +) Bolt on replacements for the RB26DETT - Garrett is excellent, but MHI also has a bolt on (journal bearing) which comes into its own with bang for the buck. The VNT setups for the street cars, Garrett is tops for specific bolt on models. You need to understand that Garrett is no longer the leader in turbochargers in terms of technology nor size of the business itself -- BorgWarner has a larger range (more SKU's) than Garrett does,

MHI and IHI as well as Continental are serious contenders in this game and are up and coming in a big way. When considering a turbocharger, it's important to understand the business and the company you are purchasing from. Some interesting info for you - The Designers from Garrett in the "good old days" when Honeywell owned Garrett, was when the Garrett product was at its best in my opinion, the Honeywell aerospace engineers were responsible for the designs of the Gen1 GTX compressor, and this changed the game entirely - those days are gone, Honeywell no longer have a design "finger in the pie", and the products compressor maps and real world results reflect this.

The company is in Section11 (business rescue) because when they listed on the NY Stock exchange December 2018 - the share price was $19.00USD - and fell to under $2.00USD in a little more than a year -- ask yourself why...... Now the management team will probably try do damage control and say that it was because of an asbestos legal claim ...... At the end of the day no one has made any offers to purchase the companies Debt or rescue them as yet (you would expect one of the other turbocharger Giants like BorgWarner to opt to buy them out?) - The bankruptcy information is what is being communicated internationally by CRG financial LLC - bankruptcy Department -- so it seems that the writing is on the wall with regards to Garrett - who knows, maybe the Chinese will buy them out - something similar to Bosch/Mahle - with their turbo attempts that failed. It's really sad because the once "dream team" at Garrett is no more. The products nowadays are not what they used to be, and the pricing has increased astronomically, which brings into question the viability of the product for the price"

 

When I initially read about Garrett going **** up, I held back some tears at the news. I was STOKED when I got mine and just as excited about how it performed, then read about their claim of bankruptcy. I have looked a bit more into a few other options for replacing as well (when the time comes). Borg has been just as big a name, matter of fact, I believe they use Borgs on Porsche(?) and other euro rockets.. The Turbonetics lineup looks pretty good but, good luck finding any compressor mapping for them. I am not a fan of PTE, at least their journal turbos, strictly due to reliability concerns. Their BB units are said to be down right excellent through and through, and (both options) are actually known for SUPERB performance. If I go with another journal unit, I believe I'd look into the Turbonetics C15 line, if I go BB, I'd bite the bullet on a PTE.

 

Yeah I think BW would be my choice. I had a Precision many years ago and it took a dump 500 miles in and never again lol.

 

Whats your power target? Also when the 3476 comes alive?
7670 is most of the times meh.
7163 is a GREAT turbo. Other than that since you are in UK id do a XH40 Super 6064 14cm full divided setup.

 

Target power is 600hp but majority of the time I plan on using only 400-500whp for circuit racing. So I want something very responsive. After looking through a few threads the GTX3071R Gen2 seems to be a perfect fit!

My engine is a 84.5mm gsr with a stock stroke 87.2
10.7:1 compression, Tuner1 cams, GoAutoworks ramhorn manifold etc.

GTW3476R doesn't come in till 4,700 rpms this is the dyno

 

That's a Chapter 11 Bankruptcy that was filed on March 11,. I received a press release on it on March 9th about it. Chapter 11 simply means a re-organization of the company, and not Chapter 7, which is about "closing doors".
You guys are fine. plenty to choose from including those that use Garrett parts, but aren't exactly.. "GTX"... ;-)

Companies in bad times do Chapter 11 all the time. Chrysler did it a few times with Daimler (which was bought and sold by Cerebus Investments and resold to Fiat), GReddy did it in 2007. Precision never went into bankruptcy, but was bought by Wabtec (a locomotive conglomerate) a few years back , and is now being sold again, to an undisclosed buyer for about 40 million. Jaguar is now owned by Tata Investments in India. I mean, these brands are still around, just under new management/ownership. It happens much more than you realize

 

In short i'm willing to sacrifice big power to have faster spool... so the turbo can max out at 550hp in all honesty. Although i'm thinking of taking a cheaper route in hopes of it helping versus an entire new turbo for $2k
You guys think downsizing to a .63 housing and putting the GSC T1's cams in would make it spool roughly 1,000rpms sooner or nah?

 

I'd be using EFR on my street EG were it not for the fact that their housings make A/C fitment impossible (to my knowledge. If someone wanted to go super-custom, something could work I guess).

As you said, EFR has better transient boost response than their Garrett counterparts. You can see with Garrett's "G" series that they tried to take a leaf from Borg's books in terms of turbo profiles and wheel/housing sizes, or at least that's what it looked like to me.

 

Keeping the GTW3476R and going with a .63 exhaust housing? Yes! You were almost exactly 1k rpm over where I started seeing positive boost; 4.7k vs 3.5k on the Z6. It would be a less expensive route for you as well with just swapping that housing. You have my vote for this idea!

 

Circuit racing requires gradual boost build up and this rings once again the didivded/twin scroll bell. It gives you a gradual 1 to 20 psi. Much better on .82 a/r anything when youll loose grip from the torque punch.
If you are most of the times on 400-500whp id say get a T4 0.8 divided 7163.A stock fn2 had this setup at Greece and it was REALLY spool happy. Plus 7163 was/(is still?) used on indy racing.
It has all the war medals


Yeah that will help too.

 

I've explained in a PM about this idea of the housing swap. It'll help, but not the same way that it would help a Z6. Completely different behaviour.

I think Balor_GR is a bit more on point, but I'd still keep the .63A/R if going overall smaller in size like the BW7163 ( A bit smaller than what the GTW3476R is on both ends of the table), but that's mainly due to your displacement, and driving ability. Balor_GR is right, however, in that power delivery needs to be more gradual, and that's where your foot and brain need to take over and feel out for the proper balance. But I concur with him on a smaller unit overall.

 

Thinking on your opening statement here for a moment, the reasoning why it would differ better for the Z6 be the same reason it would behave entirely different on a GSR; better flowing B-series? For instance, the .63 housing being a bit of a bottleneck on the GSR due to more exhaust flow?

 

Better flowing, meaning improved combustion resulting in better exhaust energy volume. The .63A/R is not nearly as much of a "bottle neck" as the rest of the system of exhaust energy. (For example, exhaust back-pressure is not as much of an issue between the two sizes of volutes for either D-series or B-series.) However, the combustion efficiency of the D-series is much more sensitive to changes in turbine volute size due to its use of a single camshaft, smaller valves, and fewer number of them when compared to their DOHC cousins. The Y6 and Y8s were mainly designed for efficiency as their primary role, (From what I remember, the Y8 head has one of the intake ports on each cylinder partially obstructed to aim the output towards the center of the cylinder which was designed to create a bit of a stronger swirl in the combustion chamber. This is an emissions and fuel economy measure as opposed to the Y6. There is already strong swirl induced by the inequality in the primary intake lobes and the head will flow a lot better by matching the bad port to the good one in contour.)

With the B-series (specifically the VTEC models), such measures weren't necessary because the intention of the B-series Cylinder head design was even more performance-oriented, while still preserving some essence of fuel economy. But that engine wasn't as sensitive to overall exhaust energy and even changes in behaviour of performance because the flowbench design of the B-series VTEC head was much more efficient than the D-series when retrofitting a turbocharger. Top end power may not have been affected between B & D series engine(the turbo will do what it can regardless of engine used as long as backpressure and exhaust manifold design aren't obstacles.), but behaviour under the rpm curve DOES get affected. The variance is just larger with the D-series as opposed to the B & K series.

Remember, we use the the theories of fluid dynamics when it comes to turbine exhaust energy utility, and not aerodynamics. That means, the more efficient the cylinder head starting off, the better the turbine will behave in the end.

I know that sounded a bit convoluted, but please let me know if you can't understand me completely. I am still a bit foggy from my vaccination last week.

 

Good info! It brings me back to whether or not the .63 turbine housing would outperform the .82 in terms of faster spool based upon the better efficiency of the B engine as I had theorized, unless I missed your explanation (?)

 

.63 a/r will start the chain of events that makes the turbo produce possivte pressure faster. If you are just reving it to 8400 you wont see a bottleneck anywere. If you were on GSC T1 and you had 9600 rev limit trying to do 650 hp, it would hurt you yes.

 

Yeah if I had the money for a EFR I would consider it but just too much to spend at the moment.

my bad I meant I start making positive pressure around 3k. Full boost comes in around 4700 rpms. Hard to tell though as my vtec engagement is set to 4500. I think i'll have to just buck up and spend the money on a new turbo sadly. Don't think the housing swap will make that big of a difference after talking to a few people.

yeah I def need more of a gradual build up of boost! with my current power it hits like a ton of bricks and its just wheel spin and rev limiter. That Fn2 is moving btw

checking my pm now sir!

 

Just from reading through this thread it brought to mind the Garrett T3/60-1 with a .82A/R exhaust housing ratio. It maxes out around 600hp, so you can still make the power you want (550+) and it should not spool too bad since it’s a T3 exhaust housing. It’s affordable at about $730 new.

 

To give you an idea my setup is pretty close to what you’re aiming for only main difference is you’re 84.5mm and my 81.5mm and I’m just running gsr cams. I went with the gtx3071 Gen2 and am more than happy with it. Spool is close to instant when over 3500rpm and power band is very smooth. I have a build thread in here if you want to check it out. But here is the dyno sheet to give you an idea of the power band. Made 420hp with 17 psi on a fairly conservative “break-in” tune

edit: FYI this is with a .63a/r turbine housing

 

Good numbers and nice powerband!! I follow dynamotorsports Instagram I saw this a few months ago lol. You also have a LS crank which I think helps a lot more vs the bore size. At what rpm do you reach positive pressure?

 

Tony’s probably the best tuner in my area, and he does more than just Hondata which is awesome because I’m switching to haltech atm.


I think I t reaches positive pressure around 35-3700 but may be even lower than that. Tbh tho I never really paid that much attention as I was just getting everything broken in at the end of last season. Only had it out a handful of times before putting it away for winter.

I took a few friends out in it and they said they can barely feel any lag, especially compared to another friend who has a similar set up but with a gt3076.

once I get it tuned on the haltech I’ll be doing a lot of datalogging so I’ll be able to see exactly where it starts making positive pressure.

one thing I will say having the quick spool and extra mid range makes traction a little more of an issue so a good boost control tune will really help