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Garrett GT3076R vs Precision 6262 vs TurboDirect GT3076R Billett 60

Garrett GT3076R versus Precision 6262 versus TurboDirect GT3076R Billett 60-1

By Chris Kambouris – TurboDirect S.A

 

Recently TurboDirect received a phone call from Precision Turbo in the USA who were unhappy about the document posted on our web page comparing the Precision 6262 turbocharger with Genuine Garrett components and the GT series Dual Ball Bearing unit from the GT3582R.  Since we receive word that many people, racers, customers and the general public are comparing our Garrett Turbochargers to the Precision units, we felt it was only fair to provide the market with information with side by side comparisons and tests.

Precision made comments to TurboDirect such as “the information inside the document was opinion and not fact….” – and “the information in the document is untrue….” And “Precision components are not similar in any way to the Garrett ones …” and comments sounding like Precision Turbos make more power than Garrett Turbos etc… naturally for those who read my articles in the local media, this got me going, and I decided to put product to the test and find out.  Please note:- this is in no way or form comparative advertising, it is very simply a performance comparison between turbochargers and related components done by an independent tester/tuner for the purpose of seeing what turbocharger makes the most power and/or performs the best under SPECIFIC conditions in the same environment, on the same engine, same dynamometer, same fuel etc – much like a car magazine would test BMW versus MERC versus VOLVO versus – you get the message.

Many times we have experienced customers mentioning that the Precision turbo products make more power than Garrett products and that they boost a lot sooner than Garrett products and they boost a lot more than Garrett products – but many of these customers land up buying Garrett products… ???

Well we came to the conclusion that the information the customers were relaying to the market was simply information carried across to them in sales pitches, opinions and information found on forums by whomever…. In almost all these cases which we were made aware of, were apples compared to oranges.

OK – lets be VERY specific in outlining this performance test:-

Firstly we are going to compare apples with oranges – yes that’s right, we will compare a larger Precision 6262 turbocharger with a smaller Garrett GT3076R HYBRID one – ‘BUT that’s not fair!!’ It certainly is not fair - but since this is a very popular comparison amongst our market perception, we going to carry it out.  Here is some history – Im not going to mention any names here, but those who play in our market and attend the race meets on a regular basis will know exactly who I am referring to in some of these cases. There is a very well known white Toyota corolla running around with a Toyota 3SGTE BEANS engine in it – the turbocharger running on this engine was supplied by TurboDirect in parts and assembled by the owner. This turbo runs a 60-1 cast compressor wheel. The output of this specific engine at 1.4bar boost on a specific dyno on a VERY HOT summers day in Pretoria was 504rear wheel HP.

Its common knowledge that the 60-1 compressor wheel is a very good choice for high HP street applications, and gives good all-round HP with lower to moderate boost levels when running on pump fuel (95 octane) 

Its also common perception is that the extremely popular GT30xxR series of turbochargers is exceptionally good at making high HP – once again for street applications on both low and high boost settings, and is a popular choice for upgrades to stock, already-turbocharged cars because of the fast boost response.

The perception around the 60-1 compressor wheel, because of its 7 blade design, is that it makes more power than most other wheels and that this is the wheel of choice amongst the ‘street racers’

TurboDirect decided to make up a HYBRID turbocharger for this test to satisfy the ‘masses’ and cover the facts and fallacies surrounding firstly the possibility of the HYBRID GT30-601R and the output of the 60-1 versus the Precision counter part.

Here is the outline of this specific test and its constraints.

Please note:  The Precision turbocharger supplied was running on the vehicle supplied by the owner, we ran the setup as is – we changed, altered, modified and replaced - NOTHING  WHAT SO EVER. The same dyno, same engine, same ECU, same downpipe, same exhaust, same intercooler, same wastegate etc etc was used, in fact the car never left the dyno rollers during this single evenings testing – here is the breakdown of the components used during this test.

  1. Engine:-                   Nissan Skyline RB26 DETT
  2. ECU:-                       Haltech Platinum xxxx
  3. Manifold:-               Equal length manifold T3 flange
  4. Fuel:-                       95 octane pump fuel
  5. Turbo1:-                  Precision 6262 turbocharger AR63 T/housing
  6. Turbo2:-                  Garrett GT3076R 700382-12 – AR63 T/housing with std Cast 60-1 compressor wheel 409535-1
  7. Turbo3:-                 Garrett GT3076R 700382-12 AR63 T/housing with TurboDirect Billett 60-1 compressor wheel

Comment:- Please note, OBVIOUS tuning was required after each wheel change was necessary to maintain turbo and engine reliability. In no way or form was any of the tuning done in a biased manner, we tuned to the limit of the fueling settings with each turbo swap – in fact the timing advance was left entirely as the vehicle was received whilst running the Precision 6262 turbocharger. The same boost (1.2bar GUAGE) was run, and all tuning was done by the same tuner who was totally unbiased and irrelevant to this exercise, we simply used his dyno and tuning expertise to maintain consistency throughout these series of tests.

First things first – lets inform you with the relevant sizes and turbocharger data, so that you are aware of what we are comparing to what:-

Precision 6262:-

Turbine wheel Inducer 72mm

Turbine wheel exducer 62mm

Compressor wheel inducer 62mm

Compressor wheel Exducer 82mm


Garrett GT3076R HYBRID:-

Turbine Wheel Inducer 60mm

Turbine Wheel Exducer 55mm

Compressor wheel Inducer (60-1 CAST) 59mm Genuine Garrett Part# is 409535-1

Compressor wheel Exducer (60-1 CAST) 76mm Genuine Garrett Part# is 409535-1

 

Garrett GT3076R HYBRID BILLETT:-

Turbine wheel Inducer 60mm

Turbine Wheel Exducer 55mm

Compressor wheel Inducer 59mm – this is not a Garrett Wheel, its designed exclusively by TurboDirect

Compressor Wheel Exducer 76mm – this is not a Garrett Wheel, its designed exclusively by TurboDirect

 

The TurboDirect billet 60-1 compressor wheel measures precisely the same as the Garrett cast counterpart above and will interchange 100% into the Garrett AR70 409722-2 compressor housing with no changes required, however it is not a Garrett part at all, and not offered or manufactured by Garrett!

 

OK now lets get to it – first we need to machine the compressor housing of the GT3076R turbocharger to fit the 60-1 compressor wheel (some would say that the flow capacity of this compressor housing is not sufficient to flow the 60-1 flow ability….) – here is a pic showing the areas that require machining and/or modification, including cutting an anti surge port into the housing (which does not come standard with the GT3076R) – TurboDirect’s knowledge and experience with this compressor wheel knew that surge was certainly imminent, so the cut was made in a very specific point in the housing, very unconventional, something not many ‘copy/aftermarket/own-brand’ manufacturers know about.

Please note that ALL the engineering/machining was done by hand, although we had our CNC equipment, we chose this route to show the results with tolerances machined by hand and with the eye (which anyone with tooling and knowledge can achieve), you will notice this was done with a 3 jaw chuck – tolerances out the window …. , we used 0.5mm clearances between wall and blade and this went up to 0.65mm in some areas – nowhere near as accurate as CNC machining will provide.

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Below is a pic of the rough machining done to the housing:- (not bad for a conventional lathe) and sand paper.

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OK – here is a pic of the machined housing with the cast Garrett 60-1 comp wheel inside it, note the oversized clearance between the compressor housing and the inducer of the compressor wheel blades. This in no uncertain terms will definitely hinder performance in a negative manner and cause unwanted problems/cavitations with ‘un-uniform’ side clearances (off-centre machining) But we went ahead anyways … Please note:- that this exercise is in no way a reflection on the Garrett product range and indicates only OUR choice for engineering for time related reasons, to maintain a single evenings test at consistent temperatures and other factors. We are at any time able to engineer tolerances and clearances aswell as the radius of the compressor wheel to much tighter and more accurate tolerances.

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OK here is the TurboDirect 60-1 Billett compressor wheel inside the compressor housing, once again note the exceptionally large clearance between the housing and the blades. Although the wheel is not centered inside the housing, it’s clear that the clearance is way too much … anyway, this will count against the Garrett application in this test, let’s leave it at that.

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You will have also noticed that the wheels have the same design, same number of blades, and same root diameter/design so blade area is equal between the two blades when measured from outside edge to the inside edge where it meets the root/hub, however there is a small difference here and there, which TurboDirect obviously reserve as trade secret as a feature of this specific wheel.

 

Here is a picture of the engine bay with the Precision 6262 turbocharger next to the mounted GT3076R HYBRID with Cast 60-1 compressor wheel – what you should notice is that the comp housing was modified as per the first drawing showing the red arrows, so that it will fit the stock piping that the GT3076R replaced so no other changes were made to the engine bay, components etc. You will also note that the outlet of this welded-on, additional pipe is exactly the same size as the Precision 6262 outlet.

Please note: we blocked out a name on the engine cover for confidentiality and anonymous reasons, that’s why you see a weird coloured smudge mark on the tappet cover below the Precision 6262 turbocharger.

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Pics below -- of the compressor housing and the cast Garrett 60-1 wheel removed – ready for the TurboDirect Billett 60-1 compressor wheel to be fitted.

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Below Is the TurboDirect Billett compressor wheel attached – ready for testing, tightening up the comp housing bolts, and away we go.

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OK – lets get to the dyno graphs – This picture is a photo of the dyno SCREEN, and not a print out – the printer was out of ink that evening.

Here are the results of testing at 1.2bar (GUAGE) boost pressure – Run1 was the 6262, Run 2 was the Cast compressor wheel and Run 3 was the TurboDirect Billett 60-1 compressor wheel.

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Discussion:-

The first thing you will notice is that its clear that the 6262 is ‘laggier’ than the GT3076R HYBRID – naturally it would be because it’s a larger turbocharger than the GT3076R HYBRID. Secondly, the power delivery of the 6262 is not as linear as the GT counterpart, which might indicate that at higher engine RPM (which in this specific case the engine is not able to rev higher) it might make more power. Our test concluded at no more than 7500RPM.

Although the RUN1 was only taken to 7000RPM, it is not an indication that the Precision 6262 turbocharger was ‘don-in’ or ‘robbed’ in any way, as its clear that this graph is not going anywhere near the same power as the other turbochargers made.

The GT3076R HYBRID with the Garrett cast compressor wheel makes power throughout the entire RPM band, and increases much faster than the 6262 does. 

The GT3076R HYBRID with the TurboDirect Billett 60-1 compressor wheel makes even more power than both the previous turbochargers.  

Its clear that even though we used a smaller Garrett GT3076R Hybrid turbocharger with a turbine and compressor wheel combination a lot smaller than the Precision 6262 - was able to make more power than the larger Precision 6262. A lot of people who were present during this test, and who heard about this test, could not believe the test results! Let me clarify something here the reason we used boost pressure of 1.2bar was simply that was all we could achieve on the pump fuel 95 octane in the tank. The most commonly used application is street use, and generally 1.2bar boost is the most street cars will run on pump fuel. (Depending ofcourse on engine compression, setup, tuning etc)

The turbine housing used was the same A/R 0.63 along with flange face on the inlet and 4 bolt outlet as the precision unit used, except it was a Genuine Garrett turbine housing. We used this so that no piping or exhaust modifications had to be made for this test.

Conclusion:-

The 6262 is a much larger turbocharger and should make much more power than the smaller Garrett GT3076R with 60-1 compressor wheel throughout the RPM range, especially at higher engine RPM considering the size of this engine, being a 6 cylinder. The fact that the Precision 6262 has a much larger compressor wheel which should outflow the GT3076 hybrid – should result in a better power reading.

The fact that the poor machining accuracy of the hybrid turbocharger still managed to produce more power throughout that entire engine RPM range, proves one thing – the critics and street racers are certainly correct in saying that the 60-1 compressor wheel is the boss!

Let this be an informative test proving quite simply that bigger is not always better, and that in this specific instance the Precision 6262 turbocharger tested against a much smaller Garrett GT3076 Hybrid failed to match the output of the smaller counterpart! The final result is much better boost response, better performance, and in the end for any application (drift, drag, street, rally) the GT3076R HYBRID turbocharger proves the one to beat.

Please note:- the results of the above test are indicative of an independent comparative test carried out by an unbiased tuning company, intended to research the best performance options for the specific vehicle tested. The intention of the test was not to identify or slander any product, and the results may differ on other test applications, however for the case identified, the results were conclusive and in no way tampered with.