GT4 Tuning Guides - Part 2 added 22/03/06

  • Thread starter Scaff
  • 150 comments
  • 154,868 views
OK it's taken a while, but I have now finished the second part of the GT4 Tuning guide, it follows on from the Suspension and Brake tuning guide (link in the first post) and covers the following areas/subjects.

  • Downforce
  • LSD
  • VCD
  • AYC
  • Gear Ratios
  • Reading the circuit
  • Example of tuning in these areas

To download simply right click and save on the following link(s)

GT4 Tuning Guide Part 1 - Suspension and Brake - 2.1 meg

GT4 Tuning Guide Part 2 (the new one) - Downforce, LSD and Gear Ratios - 1.6meg

Hosting for both has been kindly supplied by Boundary Layer and my thanks to him and everyone who has helped and provided feedback on this and the original guide, in particular to Dave_George and all at the Nurburgring race series.

As before I hope that you find these useful and shoudl you have any comments and/or feedback then please let me know.

Regards

Scaff
 
do the guide has 66 page? I open it using adobe acrobat reader 5.05
page 34 is the same as page 1, page 35 is the same as page 2.
 
sucahyo
do the guide has 66 page? I open it using adobe acrobat reader 5.05
page 34 is the same as page 1, page 35 is the same as page 2.
Click to expand...

Nope it should have 33 pages (if you are talking about the second guide - the first has 42 pages).

I'm using Adobe Acrobat Reader 7 and it opens fine in that, but I will double check it and if needed re-pdf it.

Regards

Scaff
 
sucahyo
I see, my acrobat broken then
Click to expand...

Nope I've just doubel checked and it apears teh .pdf conversion tool I use has doubled the pages (no idea why at all), I've asked Boundary Layer if a 'fixed' cersion can be uploaded.

The only difference is that the current one has twich the number of pages, so as you say p34 is p1 and p35 is page 2, etc.

Regards

Scaff
 
ok, not a big problem though.
👍 for gear explanation and when to shift. It's too much for my mind to absorb at once, I should read slowly now :dopey:.
maybe you should include your gear calculator too in this page, with rpm drop too.
 
The corrected version is now up on my server. The URL Scaff posted previously will direct you to it.

Good work Scaff.
 
Excellent guide Scaff:tup: If you got my mail you will already know my thoughts on it.

I did a test using the guide BMW M3 CSL at Grand Valley, tested the car standard, S2's, No aids etc, then tested with suspension and brake balance control as per part 1 of the guide, and then tested with part 2 components, the wing being the last thing I added.

Without going into laptimes and too much detail I found Scaff's settings are worth about 5 seconds a lap in total! And thats with no power or tire upgrades.....The wing and gearbox make the world of difference.

I initially felt the car a bit too understeery (so upped the front camber by just .2 or so, again its driver preference) however after a while I found myself on my 10th lap enjoying this car immensely. Here is a setup example that adds no power at all but what it adds in enjoyment is fantastic, the car is so stable you can concentrate on the lines and braking points without fear of it biting back, its a credit to you Scaff and your expertise and polish has really been shown here. I urge everyone who reads this to have a go with the CSL in stages to feel the effects working, its a valuable learning tool.

Overall I believe this is the most usefull and comprehensive guide to tuning in GT4 that has been written so far and GTP is lucky to have people like Scaff contributing in this way, I would also suggest that links to this guide might be advertised on GTP's main page perhaps, Newcomers could benefit from tools like this....

*EDIT* After a furthur 13 laps make that 7 seconds gain from using Scaffs reccomendations over the standard car......

So 👍 and thanks to Scaff, your efforts are greatly appreciated.

regards

Dave
 
Dave_George
*snip*

So 👍 and thanks to Scaff, your efforts are greatly appreciated.

regards

Dave
Click to expand...

Thanks for the feedback Dave (don't worry I have got your mail - just not yet had a chance to reply) and it great to see the example being tested out.

The gains in lap-time are very similar to the ones I made as well and it does clearly show how effective tuning a car to a track and driving style can be.

Once again thanks for the feedback and assistance with this.

Regards

Scaff
 
Great guide, Scaff 👍 Thanks for all the hard work.

I've read through part two, and I was just getting dirty with some of the stuff about gearing. I'm having a bit of trouble, and hoping you might be able to point me in the right direction.

I'm trying to do the MPH/1000RPM calculations for the Hyundai Accent Rally Car. The only information about it's tires that I can find is on this page, but it's listed in a weird format that I can't make heads or tails of:

Wheels/Tires: 8"x18" wheels, Michelin 20x65/18
Click to expand...

Anyone have any idea what "20" and "65" refer to? 20 can't be the width of the tire (2cm tires :scared: ) and 65 would be an awfully tall sidewall on a rally car :eek:
 
Luxy
Anyone have any idea what "20" and "65" refer to? 20 can't be the width of the tire (2cm tires :scared: ) and 65 would be an awfully tall sidewall on a rally car :eek:
Click to expand...
maybe a mistype ?
should it be 205x65/R18? 20.5 cm width, 2*0.65*20.5+18" tire diameter?
 
Luxy
Great guide, Scaff 👍 Thanks for all the hard work.

I've read through part two, and I was just getting dirty with some of the stuff about gearing. I'm having a bit of trouble, and hoping you might be able to point me in the right direction.

I'm trying to do the MPH/1000RPM calculations for the Hyundai Accent Rally Car. The only information about it's tires that I can find is on this page, but it's listed in a weird format that I can't make heads or tails of:



Anyone have any idea what "20" and "65" refer to? 20 can't be the width of the tire (2cm tires :scared: ) and 65 would be an awfully tall sidewall on a rally car :eek:
Click to expand...



I dont think its a mistake, more how they quote tyre sizes for these cars perhaps?

Im Sure the 65 is short for 650mm tyres as can be found HERE regarding the Focus WRC car.

1 inch = 2.54 cm - so 18inch wheel in cm is 45.72 cm so maybe the tyre is 65cm.....

The 20 could be the width in cm also....

The car would use smaller wheels for rally events but I expect the rolling radius would be kept the same for your calculations process, We need Scaff to add his knowledge to this one I think!

regards

David
 
Hmm ... both of the above seem plausible (although a 0.65 aspect ratio doesn't seem quite right to me).

With the stock gearing, the car has an actual top speed of 248.6kph (tested in Power & Speed, it just hits the rev-limiter, otherwise it'd probably go a few kph faster, but it's basically topped out).

Redline is 7500rpm.


Option #1:
If I assume:
- 20 means 200mm
- 65 means an aspect ratio of 0.65
- 18 means 18" wheels

I get a diameter of 28.24" and an estimated top speed of 276kph.

In Scaff's example, he estimates the Celica's top speed to be 155mph, but says the actual top speed of the Celica is only 140mph (about 90%).

248 / 276 = 0.898 = 89%

I assume the aero and other losses would differ from car to car though :confused:


Option #2:
If I assume:
- 20 is 20cm (200mm)
- 65 is 65cm (650mm), and that's the overall diameter of the tire

I get a diameter of 25.59", and a top speed of 250kph, which is pretty close to the actual top speed, but doesn't account for any losses :confused:

Scaff ... help! ;)
 
Luxy
Hmm ... both of the above seem plausible (although a 0.65 aspect ratio doesn't seem quite right to me).

With the stock gearing, the car has an actual top speed of 248.6kph (tested in Power & Speed, it just hits the rev-limiter, otherwise it'd probably go a few kph faster, but it's basically topped out).

Redline is 7500rpm.


Option #1:
If I assume:
- 20 means 200mm
- 65 means an aspect ratio of 0.65
- 18 means 18" wheels

I get a diameter of 28.24" and an estimated top speed of 276kph.

In Scaff's example, he estimates the Celica's top speed to be 155mph, but says the actual top speed of the Celica is only 140mph (about 90%).

248 / 276 = 0.898 = 89%

I assume the aero and other losses would differ from car to car though :confused:


Option #2:
If I assume:
- 20 is 20cm (200mm)
- 65 is 65cm (650mm), and that's the overall diameter of the tire

I get a diameter of 25.59", and a top speed of 250kph, which is pretty close to the actual top speed, but doesn't account for any losses :confused:

Scaff ... help! ;)
Click to expand...

I would go with option2 I think, my own testing with a Skyline GTR has shown the gearing in GT4 on that car at least (R34 V specII Nür) to be quite accurate.

However will be interesting to see whats actually correct!

David
 
Luxy
Hmm ... both of the above seem plausible (although a 0.65 aspect ratio doesn't seem quite right to me).

With the stock gearing, the car has an actual top speed of 248.6kph (tested in Power & Speed, it just hits the rev-limiter, otherwise it'd probably go a few kph faster, but it's basically topped out).

Redline is 7500rpm.


Option #1:
If I assume:
- 20 means 200mm
- 65 means an aspect ratio of 0.65
- 18 means 18" wheels

I get a diameter of 28.24" and an estimated top speed of 276kph.

In Scaff's example, he estimates the Celica's top speed to be 155mph, but says the actual top speed of the Celica is only 140mph (about 90%).

248 / 276 = 0.898 = 89%

I assume the aero and other losses would differ from car to car though :confused:


Option #2:
If I assume:
- 20 is 20cm (200mm)
- 65 is 65cm (650mm), and that's the overall diameter of the tire

I get a diameter of 25.59", and a top speed of 250kph, which is pretty close to the actual top speed, but doesn't account for any losses :confused:

Scaff ... help! ;)
Click to expand...

Option 2 would be the one to use here, unfortunatly motorsport tyres do sometimes use differing standards for sidewall markings (the formula I provided is fine for road tyres). This may help

Sidewall Markings - A guide


I regard to the aero losses differing from car to car, thats spot on (drivetrain losses do effect this but not as much as aero), its also worth noting that road cars with six speed boxes generally have the sixth gear set for economy rather than speed. A lot will actually hit v-max in fifth, with aero causing the car to slow down in sixth.

Race and rally cars are geared to make full use of the power avaliable (fuel economy is not generally an issue) and as such may well not have the same issues, however they may need to be tweaked for each track.

Hope that helps (and sorry for the delay in getting back on this one - I've been decorating).

Regards

Scaff
 
Awsome :) Thanks for clearing that up Scaff 👍 Option A didn't make much logical sense to me, but being new at this I didn't want to make any assumptions.

If it's as accurate as that at predicting top speed, it'll be a great tool. One thing I've noticed annecdotally in the past is that a car's top speed on Test Course seems to be a lot higher than on other tracks (on Dottinger Hohe on the 'Ring, for example).
 
Luxy
Awsome :) Thanks for clearing that up Scaff 👍 Option A didn't make much logical sense to me, but being new at this I didn't want to make any assumptions.

If it's as accurate as that at predicting top speed, it'll be a great tool. One thing I've noticed annecdotally in the past is that a car's top speed on Test Course seems to be a lot higher than on other tracks (on Dottinger Hohe on the 'Ring, for example).
Click to expand...


No problem. 👍 It is a very useful tool, you just need to keep in mind the drag limits (aero reductions).

Interesting one on the top speed, I will have to have a look at that (any particular car you've noticed it with).

Regards

Scaff
 
The car I'm thinking of specifically was a Lotus Elan I used for the 1000 Miles championship. I wanted to find a good cruising gear for Dottinger Hohe and the Hunundaires (sp?). I set the gears at Test Course so that the car could just barely get to redline in 6th, but I could never reach redline on either of the two actual courses, and top speed was maybe 15-20 kph lower. Sorry for the vague info, it was a while ago and I didn't take the time to properly investigate ...
 
Good guide. Found that article a little long winded, but still worth reading if you want to understand it all. Thanks scaff.
 
identti
Good guide. Found that article a little long winded, but still worth reading if you want to understand it all. Thanks scaff.
Click to expand...

Thanks for the feedback 👍

The article is a bit on the long side, which is why I did put the intro to it saying that its not vital to setting gear ratios, still glad to see you found it worth reading.

Its one of those pieces that I find is just worth getting through, as it does help answer so many issues with regard to gearing.



Luxy
The car I'm thinking of specifically was a Lotus Elan I used for the 1000 Miles championship. I wanted to find a good cruising gear for Dottinger Hohe and the Hunundaires (sp?). I set the gears at Test Course so that the car could just barely get to redline in 6th, but I could never reach redline on either of the two actual courses, and top speed was maybe 15-20 kph lower. Sorry for the vague info, it was a while ago and I didn't take the time to properly investigate ...
Click to expand...

OK I had an idea about what the problem may be and wanted to put it to teh test (as it's in the area of a discussion in the Damper Value Thread)

Not knowing you exact settings I took an Elan and fitted it with a good range of mods, it ended up with about 200bhp (NA tune), FC suspension and FC gearbox.

I ran it at the Test Track and played around with the Auto gear tool and was topping out at about 164mph with Auto 15. Now keep in mind that the test track is very smooth.

I then ran the car (all suspension settings were left stock) at Le Sarth, and the max I could get on the Hunaudieres straight was around 160mph with the car skipping and jumping.

The problem I believe was the bumpy nature of the circuit and the stiff default suspension settings (dampers mainly) not allowing the tyres to react quickly enough to the series of bumps found along the Hunaudieres straight.

So I simply tried lowering the damper values from the default 8/8 front and rear, now remember this was just quick stuff - not true settings. With a dampers setting of around 2/4 front & rear the car would now reach closer to 163mph.

The speed loss I was getting was lower than that you recall, but that could be down to different mods and set-up (I never bothered with any weight reduction or stiffness).

Now the effect of the bumps we can't remove completely, as the magnitude of hitting even a small bump at speeds in excess of 100mph is huge. The severity of a bump increases roughly as the square of the speed, so a small bump at 50mph is going to be roughly 16 times worse at 200mph (for a very technical explination of this see the Physics of Racing series - Part 15 Bumps in the road).

This would explain why the problem is occuring for you at the two loactions mentioned, which are very bumpy for racetracks, but not at the Test Track, which is very, very smooth.

Lowering the damper value allows the suspension to react quicker to the bumps, which in turn ensures the tyres remain in contact with the road for more time, which means you can get closer to the Test Track top speed.

I hope that makes sense (and give me a shout if it doesn't).

Regards

Scaff


Regards

Scaff
 
I went back and had a look. I was running a Lotus Elan, stock except for N1 tires and an FC Transmission (111hp, Auto: 4, FD: 3.550).

On Test Course, top speed was 203.8kph

On the 'Ring: 190kph

On Sarthe (without chicanes): 202kph

The biggest thing I noticed though was my speed on Le Sarthe varied from 199 - 202, depending on small hills. Maybe Dottinger Hohe is slightly uphill, and I've just never noticed it? If it were the bumps, I ought to have been much slower on Sarthe, which is bumpier. Oh well, not important, I was just curious ;)
 
Luxy
I went back and had a look. I was running a Lotus Elan, stock except for N1 tires and an FC Transmission (111hp, Auto: 4, FD: 3.550).

On Test Course, top speed was 203.8kph

On the 'Ring: 190kph

On Sarthe (without chicanes): 202kph

The biggest thing I noticed though was my speed on Le Sarthe varied from 199 - 202, depending on small hills. Maybe Dottinger Hohe is slightly uphill, and I've just never noticed it? If it were the bumps, I ought to have been much slower on Sarthe, which is bumpier. Oh well, not important, I was just curious ;)
Click to expand...

Test course is a lot smoother than Curcuit De La Sarthe.:)

You won't get the same top speed there as testcourse.

Cheers

T4 GTR
 
Luxy
Maybe Dottinger Hohe is slightly uphill, and I've just never noticed it?
Click to expand...

Dottinger Hohe most certainly is uphill!! Goes downhill from T10 and then back uphill again towards the bridge, noticeable more in smaller engines cars, this WEBCAM shows this to good effect:tup:

regards

David
 
Hi Scaff, I hope I'm not too OT here, but is there a text version of your guides available as I can't install Acrobat on my PC for obscure technical reasons?
Scaff
With regard to the BMW damper settings, one thing I have found with GT4 is it forces you to think about the weight transfer a lot more.
Click to expand...
For fun, I've been having a go at tuning the little Ginetta G4 and I found empirically that, although I couldn't really get it to handle much better, I was able to make massive - race winning - improvements in its acceleration and braking with springs and damper settings alone. I'd guessed that weight transfer might be behind this - I never really noticed this before in any tuning I've done as I wasn't looking for it - and I'm particularly interested to see what your guide's got to say on this topic as it seems very relevent.

regards

al1
 
Scaff awsome guides i downloaded them some time ago and found them very useful 👍

also i was wondering if you have the settings to help me make the mazda 787b race car reach 300mph or higher?
thanks
gt 123
 
gt 123
Scaff awsome guides i downloaded them some time ago and found them very useful 👍

also i was wondering if you have the settings to help me make the mazda 787b race car reach 300mph or higher?
thanks
gt 123
Click to expand...


Thanks for the feedback and I'm glad the guides have been useful.

I don't have any 300mph settings for the 787b to hand and would suggest a look in the 300mph thread first.

https://www.gtplanet.net/forum/showthread.php?t=69076

If you don't have any joy there (or you have already looked) then let me know and I will put some together.

Regards

Scaff
 
Hey everybody! I am new here and I want to ask you guys a question. Is there a paint shop in gt4? I heard there is and it was unlocked when you reached 5000 for your skill level. how do you get to the paint shop?

Thx!
 

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