GT-R clutch problems at 16+ psi of boost...

[JeremyBlackwell]

Hey guys, we just received this message on April 10 via email from Rick at Endless Racing in Japan. He said they just made it publicly known:

Just to add, we have also cracked the ECU, removed the speed limiter, removed nissans 1.0bar boost limiter...and upped the boost to test. Our re map gave:
0.75bar 520hp/62kgm,
0.9bar ???,
1.1bar ??? (engine was fine, but clutchs had a problem, seems the 90kgm quoted by nissan is a little on the strong side)....maybe 80-85kgm is closer. Will provide more details as and when I am allowed.
But we are also now going to be supplying 2 ECUs to the market....more details very soon.
1: speed cut with 1bar boost cut removed (future proofing) 520hp/62kgm
2: 0.9bar boost with the options listed in number Price:TBC Rick

[Ev0H8t3r]

errr ENDLESS JAPAN is a great CO. So I believe their testing...I met member of the team before...

so you think anyone will offer Aftermarket Clutches? err that will be $$. man this car is gonan cost a lot of money to mod....

[UAE-GTR]

Jeremy, Thanks for the Information keep us update ;)


Hey guys, we just received this message on April 10 via email from Rick at Endless Racing in Japan. He said they just made it publicly known: "Just to add, we have also cracked the ECU, removed the speed limiter, removed nissans 1.0bar boost limiter...and upped the boost to test. Our re map gave 0.75bar 520hp/62kgm 0.9bar ??? 1.1bar ??? (engine was fine, but clutchs had a problem, seems the 90kgm quoted by nissan is a little on the strong side)....maybe 80-85kgm is closer. Will provide more details as and when I am allowed. But we are also now going to be supplying 2 ECUs to the market....more details very soon. 1: speed cut with 1bar boost cut removed (future proofing) 520hp/62kgm 2: 0.9bar boost with the options listed in number Price:TBC Rick"

[Leebunnyz]

i hope the clutch is the problem when modding this car.

[Phoenix]

Good Info. I have been wondering what some of the EOM limits would be for a mild increase in boost levels. definitely additive.

I am wondering whether this slipping or whatever, was detected on the dyno or during a road tune or other? It seems that the rollers on a dyno can be significantly more stressful to a clutch. The street / track max may be slightly higher. Nevertheless, probably a really good marker to hold for maximum torque / boost numbers while using OEM equipment.

So I did some math based on the following assumptions:
Nissan Factory Data:
a) 433 lb-ft torque
b) 0.7 bar max factory set boost
c) sea level
d) linear relationships between TQ / HP / boost as you travel nominally up the curve from 0.7 - 1 bar (10.2 - 14.5 psi) of boost

Boost TQ
(bar / psi) lb - ft
0.7 / 10.2 433
0.9 / 13 551
1 / 14.5 618.6

And the relationship between kgm, horsepower, and boost
520 HP / 62 kgm / 0.75 psi (am I quoting correctly?)

So this is probably more inline with the under-reporting that dyno numbers are showing versus preliminary manufacturers data.

Another table for the above, it suggests:
HP Kgm
520 62 (@ 0.75 bar)
670 80
712.9 85
754.8 90 (factory specified limit)

The factory has boost cut at 1 bar / 14.5 psi. The clutch appears to run into a ceiling (according to Endless) around this point which equates to approximately 618.6 lb/ft of torque and 712.9 HP using math and not real world testing. The IHIs probably approach less efficiency as you approach this point of the power band anyways.

For me, this is good news. Anything more than 600 lb/ft of TQ gets ridiculous for most applications.:D
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Caveat: there is definitely a difference between math done on paper by an arm-chair vs. actual street use and dyno performance
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[Phoenix]

Can someone check my math?

[Leebunnyz]

good stuff phoenix

[JeremyBlackwell]

On paper (going off what Nissan has said), it looks about right, but you know how that goes :) If I'm not mistaken Amuse made 570hp on 14psi, but I'm not sure if that's at the wheels or crank...

[Cucuy]

OMG 700hp+ from 14psi wow... I just want 600-650awhp max. so I guess clutch will hold?

[Phoenix]

On paper (going off what Nissan has said), it looks about right, but you know how that goes :) If I'm not mistaken Amuse made 570hp on 14psi, but I'm not sure if that's at the wheels or crank...

my number crunching was based on crank; that's how they test at the end of the engine build at the factory as far as I can tell from the videos I have seen...

I really wish there was more Dynojet testing. The dynapack and mustang dynos, I find highly unreliable / inaccurate. I have only used them in the past to make judgements on performance gain from baseline after adding a modification.