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Turbo Tech 101 and 102

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48 replies to this topic

#41
drk

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Having borg warner EFR turbos installed as we speak. Any comments?



#42
Decz11

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just read through this thread and the information is excellent! thanks bill for the insight definitely the reason i like this forum with great info shared like this. 

had a look on your web at the USM, something to potentially add to the shop list  :D


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#43
Guido

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It's always good to have more technical information on the parts that make our cars perform well.  The R & D that goes into making turbos more efficient, with more power and still spool quickly is what running a turbo car is all about.  We all want more power without losing how quickly the turbo spools.  There is a fine line between the two and everyone has to decide is slower spool is worth the extra power.  It's been interesting to watch the advances in turbo technology for the GTR over the last few years.  It just keeps getting better and better. :)



#44
socalaviator

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Having borg warner EFR turbos installed as we speak. Any comments?


EFR 6758 is what all the Indy cars use in the IRL for the past several years with great results. Imagine the abuse they have to endure to be good enough for the Indy series.
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RD Engineering. HKS GT1000 build.

#45
Bill@SiR

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EFR 6758 is what all the Indy cars use in the IRL for the past several years with great results. Imagine the abuse they have to endure to be good enough for the Indy series.

From my experience the bearing system is good, however the turbine wheel is fragile

 

It can melt from EGT (at a lower temp than inconel) and isnt as strong under load, so if over-spun it can break.  On the smaller ones like the 6758 isnt as much of an issue, but its an issue.  Indy have speed sensors and closed loop speed boost control, so thats a much better way to do it. In a 1600lb indy car on E85 and 20psi of boost on a 2.2 liter, isnt as much heat as a typical GT-R will put on it (they are generally better tuned).  It can definitely work, but you have to keep it happy. 

 

Running the turbos in the efficiency range at 700hp on an Indy car they are much happier.  Most GT-R customers run turbos much closer to the edge of the compressor map.  

 

The other thing is the 6258 IMO is the best match in that line up, the EFR turbine wheels are fairly large, but the pitch of the blades are spool optimized not flow optimized, so once you cram it into a GTR manifold the turbine wheel is what the restriction is (and if you push it your egt's will go up, see above issue!) 

 

But a 6258 is a 49.5mm turbo that can make 850hp or so (the 6758 (54mm) can make 950 ish in a GTR)

 

The Garrett Options make an additional 100-200hp more than that in their respective sizes (2867 is 50mm, 3071 is 54mm), or you can go down to a GTX2860 Gen 2 to a 46mm and make a pretty similar low 800hp or so, in a 3-4mm smaller turbo. 

 

In general (ALL things being equal) The inducer of the compressor is going to dictate spool. Lighter helps, better bearings help. But at the end of the day its size.  If 2 turbos are the same size, they will spool very similar in the same compressor and turbine housing on the same engine.  

 

The advantage is having a smaller turbo that makes the same power, or the same size turbo that makes more power.  

 

The EFR is light and has good bearings, but its just middle of the road for its size.  That compounded on the fact the CHRA is a good bit longer making it fit is more challenging.  And when the 54mm Garrett makes 200hp more than the 54mm EFR, most people can deal with a very small difference in spool for 20% more power, and something that is less fragile. 


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#46
Steve Theodore

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EFR 6758 is what all the Indy cars use in the IRL for the past several years with great results. Imagine the abuse they have to endure to be good enough for the Indy series.

 

I thought they used EFR 7163 on the Indy cars?


Steve Theodore

2014 Nissan GT-R

- Kline Inconel grade 625 full exhaust, ForgeLine GA1R Open-Lug Cap wheels

2010 Porsche 911 GT3 RS

- SharkWerks exhaust bypass, lots of OEM goodness

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- TwinsTurbo build, BW EFR 7163 twins, 1175 whp


#47
Bill@SiR

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I thought they used EFR 7163 on the Indy cars?

I believe 2012-2013 it was the 6758 and 2014+ its the 7163 with the mixed flow turbine.

 

They make it sound like its new tech (mixed flow jet turbine). Welcome to 1991 Garrett boys!. Whats old is new again.  Hey the 10 and 11 blade GTX stuff is a Caterpillar re brand from the early 90s too.  


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#48
Tim

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I believe 2012-2013 it was the 6758 and 2014+ its the 7163 with the mixed flow turbine.
 
They make it sound like its new tech (mixed flow jet turbine). Welcome to 1991 Garrett boys!. Whats old is new again.  Hey the 10 and 11 blade GTX stuff is a Caterpillar re brand from the early 90s too.


Bill, giving us the truth.
post-273-0-31146100-1438786356.jpg

#49
socalaviator

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From my experience the bearing system is good, however the turbine wheel is fragile

 

It can melt from EGT (at a lower temp than inconel) and isnt as strong under load, so if over-spun it can break.  On the smaller ones like the 6758 isnt as much of an issue, but its an issue.  Indy have speed sensors and closed loop speed boost control, so thats a much better way to do it. In a 1600lb indy car on E85 and 20psi of boost on a 2.2 liter, isnt as much heat as a typical GT-R will put on it (they are generally better tuned).  It can definitely work, but you have to keep it happy. 

 

Running the turbos in the efficiency range at 700hp on an Indy car they are much happier.  Most GT-R customers run turbos much closer to the edge of the compressor map.  

 

The other thing is the 6258 IMO is the best match in that line up, the EFR turbine wheels are fairly large, but the pitch of the blades are spool optimized not flow optimized, so once you cram it into a GTR manifold the turbine wheel is what the restriction is (and if you push it your egt's will go up, see above issue!) 

 

But a 6258 is a 49.5mm turbo that can make 850hp or so (the 6758 (54mm) can make 950 ish in a GTR)

 

The Garrett Options make an additional 100-200hp more than that in their respective sizes (2867 is 50mm, 3071 is 54mm), or you can go down to a GTX2860 Gen 2 to a 46mm and make a pretty similar low 800hp or so, in a 3-4mm smaller turbo. 

 

In general (ALL things being equal) The inducer of the compressor is going to dictate spool. Lighter helps, better bearings help. But at the end of the day its size.  If 2 turbos are the same size, they will spool very similar in the same compressor and turbine housing on the same engine.  

 

The advantage is having a smaller turbo that makes the same power, or the same size turbo that makes more power.  

 

The EFR is light and has good bearings, but its just middle of the road for its size.  That compounded on the fact the CHRA is a good bit longer making it fit is more challenging.  And when the 54mm Garrett makes 200hp more than the 54mm EFR, most people can deal with a very small difference in spool for 20% more power, and something that is less fragile. 

 

Thanks for all that insight and info!

I thought they used EFR 7163 on the Indy cars?

Last i checked I think they are utilizing twin 6758s this 2018 season.  


RD Engineering. HKS GT1000 build.




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