Nissan GTR
18 July 2011, 12:10 PM
#121
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GTRs don't like dynos, and even the sites that can dyno them have to run with VDC off and often need to clear fault codes. The load, airflow, cooling is all unrealistic. Best to map to known good boost, fuel, knock levels where it is going to be used on track or road. The built in widebands and knock control are very good. The datalogging and tuning remotely on a known spec will give better results than a tune in person from someone that is not as experienced with them. We've mapped competition winning cars that we've never seen that are fast and reliable.
Exceptions are complex setups with speed density, built internals, large turbos etc.
Exceptions are complex setups with speed density, built internals, large turbos etc.
18 July 2011, 12:35 PM
#122
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GTRs don't like dynos, and even the sites that can dyno them have to run with VDC off and often need to clear fault codes. The load, airflow, cooling is all unrealistic. Best to map to known good boost, fuel, knock levels where it is going to be used on track or road. The built in widebands and knock control are very good. The datalogging and tuning remotely on a known spec will give better results than a tune in person from someone that is not as experienced with them. We've mapped competition winning cars that we've never seen that are fast and reliable.
Exceptions are complex setups with speed density, built internals, large turbos etc.
Exceptions are complex setups with speed density, built internals, large turbos etc.
18 July 2011, 01:00 PM
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What was the problem? And why?
18 July 2011, 01:12 PM
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20k later, 60+ launches.....no further issues to report
.......touchwood
18 July 2011, 01:21 PM
#126
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The GTR knows what gear it is in, it knows the gear ratio, it knows the estimated engine torque from the airflow, it knows the longitudinal g and it knows the tilt of the car. It knows things aren't right on the dyno and frequently complains about it with fault codes that most dyno operators don't seem to understand, and half the time don't know they are there because not all of them show CELs.
Add in 98% rear torque distribution with an active centre differential that shuffles things around very dynamically and you get a situation on the dyno where it can be difficult to get the front and rear wheels with the torque distribution they would experience on tarmac.
Unrealistic loading results in changes in knock threshold and boost response.
When your standard is best acceleration on tarmac, the dyno is a poor simulation, especially on a car like this.
So I laugh when people think that dyno tuning a GTR is the optimal. It is a convenient but poor simulation for roughing in a difficult map for safety reasons.
18 July 2011, 03:52 PM
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Aerodynamics, ramp rate, tyre deformation, abnormal airflow over the MAF sensors and insufficient engine and transmission cooling for a start.
The GTR knows what gear it is in, it knows the gear ratio, it knows the estimated engine torque from the airflow, it knows the longitudinal g and it knows the tilt of the car. It knows things aren't right on the dyno and frequently complains about it with fault codes that most dyno operators don't seem to understand, and half the time don't know they are there because not all of them show CELs.
Add in 98% rear torque distribution with an active centre differential that shuffles things around very dynamically and you get a situation on the dyno where it can be difficult to get the front and rear wheels with the torque distribution they would experience on tarmac.
Unrealistic loading results in changes in knock threshold and boost response.
When your standard is best acceleration on tarmac, the dyno is a poor simulation, especially on a car like this.
So I laugh when people think that dyno tuning a GTR is the optimal. It is a convenient but poor simulation for roughing in a difficult map for safety reasons.
The GTR knows what gear it is in, it knows the gear ratio, it knows the estimated engine torque from the airflow, it knows the longitudinal g and it knows the tilt of the car. It knows things aren't right on the dyno and frequently complains about it with fault codes that most dyno operators don't seem to understand, and half the time don't know they are there because not all of them show CELs.
Add in 98% rear torque distribution with an active centre differential that shuffles things around very dynamically and you get a situation on the dyno where it can be difficult to get the front and rear wheels with the torque distribution they would experience on tarmac.
Unrealistic loading results in changes in knock threshold and boost response.
When your standard is best acceleration on tarmac, the dyno is a poor simulation, especially on a car like this.
So I laugh when people think that dyno tuning a GTR is the optimal. It is a convenient but poor simulation for roughing in a difficult map for safety reasons.
For example can't you override the ECU torque-split to a steady-state for dyno tuning? I'm sure it is not impossible.
If you can test/tune a multi-million dollar aero-engine in a wind tunnel and test-rig then I am sure you can tune a four-stroke petrol engine.
I'm just an amateur but I wouldn't get my car tuned at a place which rubbished dyno tuning. Road tuning has many variables which are not controlled plus it's not very safe either IMHO.
18 July 2011, 04:39 PM
#128
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The VDC/ABS/AWD hasn't been worked on because the return on investment would be negative. Those are the problem modules here, not the ECM which is well understood.
You can get around it to some degree and do useful work on a dyno like you can with other AWD cars with active centre diffs and autboxes, but it is still a poor simulation of the real world. Some take off the propshaft to the front wheels. Some pull fuses. But it is a kludge to make a simulator work that wouldn't be required if the car didn't know it was on a (poor) simulator.
I'm just a professional, but I wouldn't let an amateur talk me into dyno (only) tuning my car. You'll note Andy Forrest's opinion on dyno tuning as well.
What variables are not controlled in road tuning? Most of the ones that people think are uncontrolled have far worse counterparts in dyno tuning that are worse than uncontrolled but are spurious effects. Agree about safety, hire a track/airfield is the best option.
Your average chassis dyno in the hands of a typical operator is nothing like as sophisticated.
You can get around it to some degree and do useful work on a dyno like you can with other AWD cars with active centre diffs and autboxes, but it is still a poor simulation of the real world. Some take off the propshaft to the front wheels. Some pull fuses. But it is a kludge to make a simulator work that wouldn't be required if the car didn't know it was on a (poor) simulator.
I'm just a professional, but I wouldn't let an amateur talk me into dyno (only) tuning my car. You'll note Andy Forrest's opinion on dyno tuning as well.
What variables are not controlled in road tuning? Most of the ones that people think are uncontrolled have far worse counterparts in dyno tuning that are worse than uncontrolled but are spurious effects. Agree about safety, hire a track/airfield is the best option.
Your average chassis dyno in the hands of a typical operator is nothing like as sophisticated.
18 July 2011, 05:01 PM
#129
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I can't believe how cheap these GTR's are, especially 2nd hand. I assume the running costs are extremly high as these are bargains for circa £40k. A friend is looking at either a E92 M3 or GTR and I am struggling to find any case for the M3.
18 July 2011, 05:24 PM
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The tyres are about 1K per set, fuel economy seems no worse than a circa 450bhp+ tuned Scooby from what I read.
Anders
18 July 2011, 05:25 PM
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The VDC/ABS/AWD hasn't been worked on because the return on investment would be negative. Those are the problem modules here, not the ECM which is well understood.
You can get around it to some degree and do useful work on a dyno like you can with other AWD cars with active centre diffs and autboxes, but it is still a poor simulation of the real world. Some take off the propshaft to the front wheels. Some pull fuses. But it is a kludge to make a simulator work that wouldn't be required if the car didn't know it was on a (poor) simulator.
I'm just a professional, but I wouldn't let an amateur talk me into dyno (only) tuning my car. You'll note Andy Forrest's opinion on dyno tuning as well.
What variables are not controlled in road tuning? Most of the ones that people think are uncontrolled have far worse counterparts in dyno tuning that are worse than uncontrolled but are spurious effects. Agree about safety, hire a track/airfield is the best option.
Your average chassis dyno in the hands of a typical operator is nothing like as sophisticated.
You can get around it to some degree and do useful work on a dyno like you can with other AWD cars with active centre diffs and autboxes, but it is still a poor simulation of the real world. Some take off the propshaft to the front wheels. Some pull fuses. But it is a kludge to make a simulator work that wouldn't be required if the car didn't know it was on a (poor) simulator.
I'm just a professional, but I wouldn't let an amateur talk me into dyno (only) tuning my car. You'll note Andy Forrest's opinion on dyno tuning as well.
What variables are not controlled in road tuning? Most of the ones that people think are uncontrolled have far worse counterparts in dyno tuning that are worse than uncontrolled but are spurious effects. Agree about safety, hire a track/airfield is the best option.
Your average chassis dyno in the hands of a typical operator is nothing like as sophisticated.
He does say you can fine tune on road for say curing a lean overrun etc though.
You can't get a measure of proper instantaneous torque on the road, or apply constant loads. Plus there are lots of uncontrollable variables.
18 July 2011, 05:41 PM
#132
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I loaned my copy and didn't get it back, but it was a fairly superficial book I thought, not one I miss not getting back. It is also now quite out of date if it hasn't been updated since my copy, and IIRC didn't have much on turbocharged engines for which NA tuning techniques around MBT estimation and steady state tuning are usually irrelevant or dangerous.
Why do you need a measure of instantaneous torque? Why not just tune to best acceleration on the real world? I do ECU development work now rather than tuning, but when I did tune I was delighted when my road tuned car had 80 HP less on the dyno than a dyno tuned car but then pulled 6 car lengths on an airfield which was repeated when drivers were swapped over.
Why do you need a measure of instantaneous torque? Why not just tune to best acceleration on the real world? I do ECU development work now rather than tuning, but when I did tune I was delighted when my road tuned car had 80 HP less on the dyno than a dyno tuned car but then pulled 6 car lengths on an airfield which was repeated when drivers were swapped over.
18 July 2011, 06:05 PM
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The worry I'd have buying an MY08/MY09 is the warranty is about gone. A gearbox or engine failure could cost 10-15K to fix and that would leave a nasty taste in new marque ownership.
The tyres are about 1K per set, fuel economy seems no worse than a circa 450bhp+ tuned Scooby from what I read.
Anders
The tyres are about 1K per set, fuel economy seems no worse than a circa 450bhp+ tuned Scooby from what I read.
Anders
18 July 2011, 08:25 PM
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18 July 2011, 08:58 PM
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I loaned my copy and didn't get it back, but it was a fairly superficial book I thought, not one I miss not getting back. It is also now quite out of date if it hasn't been updated since my copy, and IIRC didn't have much on turbocharged engines for which NA tuning techniques around MBT estimation and steady state tuning are usually irrelevant or dangerous.
Why do you need a measure of instantaneous torque? Why not just tune to best acceleration on the real world? I do ECU development work now rather than tuning, but when I did tune I was delighted when my road tuned car had 80 HP less on the dyno than a dyno tuned car but then pulled 6 car lengths on an airfield which was repeated when drivers were swapped over.
Why do you need a measure of instantaneous torque? Why not just tune to best acceleration on the real world? I do ECU development work now rather than tuning, but when I did tune I was delighted when my road tuned car had 80 HP less on the dyno than a dyno tuned car but then pulled 6 car lengths on an airfield which was repeated when drivers were swapped over.
Anyway I'm sure you would agree that WOT pulls in 3rd is not all a good map is? Could you do ALL the mapping on the road?
18 July 2011, 09:04 PM
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18 July 2011, 09:30 PM
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If you can plot instantaneous acceleration I guess that might work, but normally acceleration from one RPM/speed to another RPM/speed is covered my numerous map points so you could have not be optimising in one or two points but it still 'feels good'.
Anyway I'm sure you would agree that WOT pulls in 3rd is not all a good map is? Could you do ALL the mapping on the road?
Anyway I'm sure you would agree that WOT pulls in 3rd is not all a good map is? Could you do ALL the mapping on the road?
For most performance applications on OEM ECUs then WOT pulls are what matter since the factory mapping is very good in the part throttle areas. These ECUs are fully closed loop. Until you change the cams the factory part throttle mapping is great. We tend to want to reduce part throttle torque by reducing part throttle boost or pedal sensitivity to enhance mid corner control.
The only reason to touch part throttle areas if you have more than enough torque is for economy or emissions reasons. The leanest AFR is stoich anyway, and the setup already has lots of OEM Yen behind it for the balance of emissions and economy. On this ECU there are not big gains from playing with the boring areas of the map, but if you were so inclined to improve something that is already smooth and nice then that indeed would be a better application of the dyno. I would recommend not extrapolating experience from 1990s ECU and techniques as many of them are obsolete and outdated. The same applies to many standalones which use similar tech. That is why I delight in the latest 166.66mph terminal done with an OEM ECU adapted with my code to run speed density. It is a poke in the eye to those from the beginning of my R35 work who think a standalone is needed to go fast and well.
As it is, my aim is for factory manners that just have more performance at bigger throttle openings, but still retain delicacy and control. I'm convinced that the best acceleration with the safest engine mapping is from mapping it on tarmac. The best results on dynos with the safest mapping for that situation is from mapping it on the dyno. Very often the two are quite different. On a chassis dyno you can't lock temperatures to a set value like an engine dyno, and the cooling fans of the common dynos used are similar to the top of third gear, and then only on some parts of the frontal area of the car. The turbulence upsets MAF sensors no end. Chassis dyno tuning is an illusion of control on most common setups. Chassis dyno aficionados love to criticise road tunes that knock, underboost and mis-fuel on their dynos.
Last edited by john banks; 18 July 2011 at 09:41 PM.
18 July 2011, 10:37 PM
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For most performance applications on OEM ECUs then WOT pulls are what matter since the factory mapping is very good in the part throttle areas. These ECUs are fully closed loop. Until you change the cams the factory part throttle mapping is great. We tend to want to reduce part throttle torque by reducing part throttle boost or pedal sensitivity to enhance mid corner control.
It is a poke in the eye to those from the beginning of my R35 work who think a standalone is needed to go fast and well.
It is a poke in the eye to those from the beginning of my R35 work who think a standalone is needed to go fast and well.
How do you reduce part throttle boost/response BTW? I thought this was a function of wastegate/housing size etc or is this to do with the way the throttle body is controlled on a fully computer controlled car like a R35, and you just change its mini-map or something??
I appreciate that many chassis dynos are not that controlled but I don't think this is something that could not be overcome with money and effort.
19 July 2011, 09:09 AM
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You can map the drive by wire throttle by pedal position, and I've also added custom code to map wastegate duty by throttle position and gear. There is a MAP sensor, and two pre throttle boost pressure sensors, but the MAF sensors are the main load sensors in stock form.
14 August 2011, 07:00 PM
#141
Well collected the car on Friday, long uncomfortable train ride, but was all worth it!! Drove through the peak district down to my moms, then down to Santa Pod (for the Supra day) and then finally home to Surrey.
Absolutely love the car
Just a bit annoying that the car has to be run-in, but through nearly 400 miles in auto mode @ 3500RPM (max). 200 more and rev limit goes up to 4000RPM and I can use the paddle shift 
Some pics:
http://www.flickr.com/photos/24070925@N08/6042027799/http://www.flickr.com/photos/24070925@N08/6042027799/ by http://www.flickr.com/people/24070925@N08/, on Flickr
http://www.flickr.com/photos/24070925@N08/6042026521/http://www.flickr.com/photos/24070925@N08/6042026521/ by http://www.flickr.com/people/24070925@N08/, on Flickr
http://www.flickr.com/photos/24070925@N08/6042572142/http://www.flickr.com/photos/24070925@N08/6042572142/ by http://www.flickr.com/people/24070925@N08/, on Flickr
http://www.flickr.com/photos/24070925@N08/6042570826/http://www.flickr.com/photos/24070925@N08/6042570826/ by http://www.flickr.com/people/24070925@N08/, on Flickr
Absolutely love the car
Just a bit annoying that the car has to be run-in, but through nearly 400 miles in auto mode @ 3500RPM (max). 200 more and rev limit goes up to 4000RPM and I can use the paddle shift Some pics:
http://www.flickr.com/photos/24070925@N08/6042027799/http://www.flickr.com/photos/24070925@N08/6042027799/ by http://www.flickr.com/people/24070925@N08/, on Flickr
http://www.flickr.com/photos/24070925@N08/6042026521/http://www.flickr.com/photos/24070925@N08/6042026521/ by http://www.flickr.com/people/24070925@N08/, on Flickr
http://www.flickr.com/photos/24070925@N08/6042572142/http://www.flickr.com/photos/24070925@N08/6042572142/ by http://www.flickr.com/people/24070925@N08/, on Flickr
http://www.flickr.com/photos/24070925@N08/6042570826/http://www.flickr.com/photos/24070925@N08/6042570826/ by http://www.flickr.com/people/24070925@N08/, on Flickr
Last edited by grahamc; 14 August 2011 at 08:28 PM.
15 August 2011, 08:59 AM
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Nice one, lools great.
I asked the squealer about the run in process on my test drive and he said 0-300 miles auto mode, no more than 3,500rpm for 300 miles. Then manual gearbox 300-600 miles up to 4,500rpm and then 600-1200 miles up to 6,000rpm.
I can't see the higher revs harming it, each engine is run a 7,000rpm for 10 minutes in the factory as part of it's initial bed-in!
I'm aiming to have mine by weekend of 10th Sept.
Anders
I asked the squealer about the run in process on my test drive and he said 0-300 miles auto mode, no more than 3,500rpm for 300 miles. Then manual gearbox 300-600 miles up to 4,500rpm and then 600-1200 miles up to 6,000rpm.
I can't see the higher revs harming it, each engine is run a 7,000rpm for 10 minutes in the factory as part of it's initial bed-in!
I'm aiming to have mine by weekend of 10th Sept.
Anders
15 August 2011, 10:18 AM
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Here's a copy and paste from manual, it's not that clear...
Please observe the following types of driving until the mileage shown below has been reached.
Until 300 miles (500 km):
. Do not depress the accelerator pedal more than halfway and avoid rapid acceleration.. Drive with the engine speed kept at less than 3,500 RPM.
. Avoid unnecessary quick steering, abrupt braking and driving on poor roads.300 to 600 miles (500 to 1,000 km)
. Avoid rapid acceleration in a low gear (1st to 3rd gears) with the accelerator pedal fully depressed. Depress the pedal slowly.
. Avoid unnecessary quick steering and abrupt braking.
. Drive with the suspension setup switch in the COMF mode to allow more suspension stroke.
. Avoid rapid acceleration in a low gear (1st to 3rd gears) with the accelerator pedal fully depressed. Depress the pedal slowly.
. Avoid unnecessary quick steering and abrupt braking.
. Drive with the suspension setup switch in the COMF mode to allow more suspension stroke.
600 to 1,200 miles (1,000 to 2,000 km)
. Drive with the engine speed kept relatively high. Shifting is recommended between 1st and 4th gears.
. Avoid unnecessary quick steering and abrupt braking.
. Drive with the suspension setup switch in the COMF mode to allow more suspension stroke.
. Drive with the engine speed kept relatively high. Shifting is recommended between 1st and 4th gears.
. Avoid unnecessary quick steering and abrupt braking.
. Drive with the suspension setup switch in the COMF mode to allow more suspension stroke.
Even though the mileage reaches over 1,200 miles (2,000 km), the clutch may take longer to properly engage if the vehicle is mainly driven in town at a low speed. NISSAN recommends breaking in the clutch at a GT-R certified NISSAN dealer.
Anders
15 August 2011, 10:31 AM
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