GT-R(evisited) - Possible side project?

[Blooze]

Well here comes a voice from the other side of the room...

I have just now got this together and ran 3 laps on Tsukuba in a career race.  The best was 56.215, which is inside of .2 of my AWD Integra time and better than my GS time.  I thought it handled like a dream and am pretty exicited about it in that it has a better top end than the AWD Integra.

Sport Exhaust
All Race Handling including Wr
Toyo Slicks
Widest Tire - 265 mm
Fiske Profil 5S
Forza Rear Bumper (only)

Tires: 29 / 30
Gears: FD = 3.92  1-6 = 3.02; 2.06; 1.55; 1.22; 1.01; .85
Align: -0.8 / -0.6 ;  0.0 / -0.2; 5.3
ARB: 11.43 / 9.57
Springs: 487.4 / 406.5
Height: 6.6 / 6.7
Rebound: 7.2 / 6.0
Bump: 3.6 / 3.1
Brakes: 48 / 104
Front Diff:  56 / 40
Rear Diff: 56 / 56
Torque: 58 / 42

This hasn't been tweaked yet - there will be a bit added to the ARB and Springs most likely, but it will be small and an equal amount.  btw - this is a straight up 54.5% Wb build.

Give it try, lemme know whacha think...

$

[Ske]

Firing it up as we speak... watch this space

I'm gonna try and visit Silverstone with this build, to see how it behaves in the first chicane and 90 degree'ers there... those bits were giving me a proper headache.

I also see you're running a stiff front diff like I was leaning towards...

[Blooze]

I have the thing torqued to the front, I want it to dig...  and it does, you can lay into it pretty early in the turn if you have the entry angle right...  if you are always late, you may want to add .1 to the front toe.

The transmission - shift the first 3 gears just after the redline, shift the last three just befor the redline...

$

[Ske]

Your tune seems to have solved a few issues, But I still struggle with front end grip under deceleration. I'm having a bit of problems in corners 2-5 on Silverstone GP and the first few corners on Atlanta to name a couple of troublesome spots. It responds slowly and has a tendency to "overreact", which can end with sliding on all fours in a random direction. Both our tunes still have a bit of that, especially in the spots I mentioned.

- I use the springs, ARBs and most of the alignment and diff setup from your tune now - but I ended up changing some settings along the way.
- Added front wing@75lbs and Michelin slicks... doesn't seem to need the rear wing with this setup, but it's not faster without either. Might put that on too, and see if I can add some power with the Toyos - I think it could use a bit more punch out of corners.
- I misread and put 58% rear split instead of front - which actually suited me better. I think it felt heavy with 58% to the front. Somewhere along the line I also dropped the rear decel to 40%, hoping to reduce get rid of some twitching... not quite sure if that worked.
- The dampers felt a bit bouncy, unsettling the car in quick transitions (lifting off through chicanes). I swapped in my ol' Lexus dampers instead, which calmed it down.
- Some of the turn-in understeer was cured by dropping the brake pressure to a wimpy 60% - yikes... the brake rating on this thing is seriously overrated, although it's manageable as long as I nurse the pedal. I still think it locks up too quickly.

As usual, I like a bit more caster - 5.7 in this case, and I dropped the front camber one click to compensate... It seems to like running even less camber, need to look into that (I haven't read telemetry yet, just going by feel). Added a click of toe-out up front for Tsukuba, not sure I want it for the faster tracks.

Although it felt quite a bit better and more consistent than my old build, it was a full second slower around Silverstone... I'll see what happens if I install the parts I were using earlier with this tune. I did run some decent laps on other tracks though, 1.24.1 on Road Atlanta and a 55.1 on Tsukuba... I had no problems running consistently in the 55.5 range either.

There's still a bit of chronic understeer and transitional oversteer/late response "whiplash", but it's heading in the right direction. I'm puzzled by that lost second at Silverstone, though...

[Big Mooing Cow]

Well, I just bought a Skyline.  Gave it sport cams, a sport exhaust, all the suspension/weight mods, Michelin slicks, and some goofy body parts (no aero).  I took it right to Silverstone, no tuning.  I have to say, it felt pretty good out of the box to me.  It's a very tight car.  It won't get loose on you if you drive it normally.  The only way I could coax the back end out a bit was to tap the brakes on turn-in and floor the throttle.  The gearing is absolutely awful out of the box, but I swallowed my pride and left it as is. 

I did a little bit of tuning to it... I set camber to -1 all around to equalize the tire temps a bit (still should go further on this).  I set the brake bias to 45% front, 80% pressure (my standard setting, works OK here).  And I set the diffs to 40/0, 50/20, 70% rear.  Everything else is stock.

All this made the car a little more happy to turn in, and let me keep the throttle down a little more in sweepers like Stowe.  I trimmed a full second off my stock time... I set a 1:52.906.  I'm sure I could pull a bunch off this with proper gearing (Club and Luffield are in a dead zone between first and second, which is killing me onto two of the longest straights), but as an exercise I think the car handles pretty well for me.

Ske, I'm not sure what to tell you, cause my impressions are completely different than yours... I imagine we have very different driving styles to see such different results with effectively the same car.  I haven't raced side by side with you so I don't know how we differ, but I might suggest trying to brake a bit earlier and in a straight line, so when you reach corner entry you can trail brake on initial turn in.  Late braking is the most common cause of corner entry understeer.  You might also try running a later apex to avoid power oversteer at corner exit.  Finally I suggest rolling into the throttle more slowly on corner exit.  Weight transfer takes weight off the front tires when you accelerate hard, so easing into the throttle a bit will help prevent spinning the fronts.

I hope this helps!

[Ske]

Ske, I'm not sure what to tell you, cause my impressions are completely different than yours... I imagine we have very different driving styles to see such different results with effectively the same car.  I haven't raced side by side with you so I don't know how we differ, but I might suggest trying to brake a bit earlier and in a straight line, so when you reach corner entry you can trail brake on initial turn in.  Late braking is the most common cause of corner entry understeer.  You might also try running a later apex to avoid power oversteer at corner exit.  Finally I suggest rolling into the throttle more slowly on corner exit.  Weight transfer takes weight off the front tires when you accelerate hard, so easing into the throttle a bit will help prevent spinning the fronts.

I hope this helps!

Most of my remaining issues are in the braking zone, that's for sure. On power it's close to where I want it, but it seems to lose front grip way too suddenly when decelerating. The only oversteer I'm getting is when braking through chicanes at high speed... can't really blame the car

That being said, i noticed I could hold the last sweeper at Tsukuba at the same speed as my MR-S.. which means I could very well just be entering too fast. I wish it gave a bit more warning before letting go, though. It's quick, but I don't like the feel of it.

[Big Mooing Cow]

I'd definitely alter my braking lines rather than altering the car, in that case.  You can go to extreme lengths to get the turn-in under braking you want (I'd call 60% rear brakes and a front wing extreme!), but you'll probably be faster overall if you just give up on that quest and brake a bit earlier, leaving the turn in to be done without heavy braking.

Another option is to go get an AWD car with a shorter wheelbase.  Long wheelbase cars aren't known for their turn-in!

[Ske]

Another option is to go get an AWD car with a shorter wheelbase.  Long wheelbase cars aren't known for their turn-in!

...but where's the challenge in that?

I think you're misunderstanding me slightly, as I didn't say I wasn't fast in the ol' pig... it gave me two top 350 times straight out of the box, which isn't bad at all for me. My point is just that it wasn't enjoyable to drive. What I want to do with this project is to make it an easier or less stressful car - like I think it should be. The Skyline's always been known for being flattering and easy to drive fast. I've always had a soft spot for the Skyline since I started playing Gran Turismo 10 years ago... but it never felt quite up there in Forza.

Anyway, I refitted the Nür engine and the wing, installed a lighter hood (the black one) and some Michelins to hit the 850 mark... and somehow the car sorted itself out! It's miles better now than it was without even opening the tuning screen 

I ran five laps on each track, hitting 1.52.6 on Silverstone and 55.3 on Tsukuba... Almost matching my fastest times. I think it has the potential to match the other builds on the respective tracks, though. I'm not sure how, but after that parts exchange the car gives me lots of feedback warning me when I get close to the limit. It's also much calmer through chicanes - because of the wing, no doubt.

I'm actually pretty happy at the moment... The car's softer and more predictive - a LOT easier to drive than it was. But I'll try it on again tomorrow and see. I still think there's room for improvement, but I think the outline is coming together. I'll try your diff setup too, BMC... I still think running a 56/40 front diff is a bit weird (no offense )

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Stats: 5.2/5.4/6.1/5.8; 373hp/318lbft/2543lbs

Parts: Nür engine, sport intake. Michelin 265/25R20 on Fikse Profil 5. Nismo skirts, Top Secret hood and full Forza kit.

Tires: 29/30
Align: -0.7/-0.6; 0.1/-0.2; 5.6
ARB: 11.43/9.97
Springs: 486.8/405.6; 6.6/6.8
Dampers: 7.1/6.5; 6.4/4.4
Aero: 75/100
Brakes: 48/52; 65%
Diff: 56/40; 56/40; 45/55

[Big Mooing Cow]

If you're going for a true-to-life Skyline, I believe the AWD model has a 90% rear torque bias normally?  Of course we don't know how much torque Forza will push between the front and rear axles, so that might not give the most realistic feel....

[Blooze]

LOL - this thread is a poster child for "different strokes..."

But then we have always harped on it when dealing with the sheeple, tunings are as unique as the people that drive them.  I had no trouble with my tune at all.  In fact, I am kind of excited about getting back to A class and finishing that car up, and a similar car - a Silvia S15 with the R-34 powertrain.  I am shaping up to have a real dawg fight in A class for top QR...

Good luck with the car...

$

[Ske]

If you're going for a true-to-life Skyline, I believe the AWD model has a 90% rear torque bias normally?

The ATTESA E-TS as it's called is an active system that operates as RWD most of the time, only applying power to the front when the rear is losing traction. I'll have to try running the stock diff on this car, to see if it's simulated or not.

LOL - this thread is a poster child for "different strokes..."

Hehe, I believe you may be right... although I'm definitely happy with where the car is going right now. I also tried it with DOTs and a bit more power, and it was only half a second off the pace at Tsukuba. It also felt a bit "firmer".

I'm not too fond of 2WD>AWD conversions myself, so I think I'll let you handle the Silvia.. I'm interested in setting up a RWD one though

[Blooze]

Good luck with that - I tried to stay RWD in B class with it and it was plumb assed squirrelly.  That's how it made to A class with the AWD setup...

  $

[bimmerlovere39]

Well... heck.

I've been looking for an excuse to make a Skyline!

watch this space.