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Hey,

I went through three full sets of tires and 4 full tanks of gas tonight racing around Tsubuka Long.

I'm driving my Trueno. It's a D400 car.

I haven't done any engine mods, so it's the stock 97 kW, 152 N-m engine. I've gone through and done all the platform mods to max (clutch, suspension, driveshaft, gearbox, anti-roll bars, racing weight reduction, etc), and put on lighter alloy wheels, and 205/R17 tires (the largest there is, or is that 215/R17?). I also have the full body kit on - including the rear wing, the front spoiler, and the rear bumper kit.

It currently weighs in at 823 kg.

On Tsubuka, I'm running consistent laps below 1:03. I would say that 50% of my laps are below 1:02.300, 90% are below 1:02.500, and 99.99% are below 1:03.

Usually, if I run a lap over 1:03, it's because I'm pushing it hard to beat my lowest lap, and make a mistake. My lowest lap I've done so far is 1:02.035. So close to the sub 1:02 mark and I really want to get it below 1:02.

I set a 1:02.218 on cold tires (on the second lap of the course) and a 1:02.179 on tires that were about 45% worn. So with that in mind, I'm confident I can get it below 1:02 with the right setup.

Here's the details of my current setup:

Tires: Kuhmo

Pressure: Front: 2.07 Rear: 2.07

Gearing: Final: 4.00, 1st: 4.50 2nd: 2.85 3rd: 1.90, 4th: 1.50, 5th: 1.25, 6th: 1.10

Alignment Camber: Front: -0.5, Rear: 0, Toe: Front: 0.3, Toe: 0, Caster: 5.00

Anti Roll: Front: 9.07 Rear: 10.12

Springs: Front 54.33 Rear 50.18

Ride Height: 13.8 cm Front Rear 13.8 cm

Damping: Rebound: 6.6 Front Rear 5.9 Bump: Front 3.3 Rear 2.9

Aero: Front: 20.4 kg, Rear: 29.9 kg

Brakes: Balance 50/50, Force 100%

Differential: Acc 33% Dec 33%

 

As you can see, I'm using very little downforce. I figure that the back straight before the finish line needs the extra top end speed. But I don't know if perhaps I should add some more downforce to get through the final corner before the straight faster.

The car has very little understeer - it seems to bite in well at turn in and hold on well too. I'm happy with that. The only thing I would really like to address is the back end which seems to come out very easily under acceleration. I can't put the power down as soon as I would like to. That's one of the reasons I don't want to increase the spring rates, or add any rear camber for better grip in the corners. I've considered more downforce to try and address this but I don't know if sacrificing the top end speed is worth it.

Ride height is relatively low for the spring rates used. It can create problems if I even tap a curb, I will admit.

I drive manual with no driver aids (line, STM, ABS, TCS all OFF).

Any suggestions on improving my setup would be handy.

I don't consider myself a "tuner" - but I do enjoy driving other people's setups...

I tried to build the car out to your specs, but the tires / wheels ended up a little different ( I think ) as I was having trouble hitting that PI-400 mark.

No Engine changes
All Race Upgrades for Platform / Handling
Avon Race Tires
Tire Width - #4 out of the 5 options (215/40R16 - 214/40R16)
Rim Size - #3 out of the 4 options
Stock rim style

Result is:
  Speed  3.0
  Accel  3.3
  Braking  6.4
  Handling  5.8
  Power  97 kW
  Torque  152 N-m
  Weight  821 kg

I used your Tuning specs, except Tire Pressures at 2.00 F / 2.00 R

That had me running at about the same lap times as you...

I then changed 4th Gear from 1.50 to 1.40 -- that gave me just slightly less acceleration, but I no longer had to shift up to 5th Gear anywhere on the track.

That change gave me a Hot Lap of  1:01.724

I then added a touch more downforce, setting Aero to  24.9 F / 34.5 R

Back on the track, and I ran a  1:00.951

( I also drive manual with no driver aids (line, STM, ABS, TCS all OFF) )

Nice car to use!

- Don

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GT: Don Ente



Video - Forza vs. Real World at Road Atlanta

Did the car come in at D400?

Using the Avon's, my car came in at like C404 or something. I wanted to keep it in the D class.

But then I noticed you used the stock rims, but smaller rims. I must be running 225/R17's. So perhaps the 225/R17's aren't really needed for that car, and the extra weight from the stock rims offset the extra grip from the Avons.

I also noticed your car came in at 821 kg. I remember when I tried to cut another 3 kg from my car, it went into the C class. So maybe I can get away with cutting exactly 2 kg to bring it down to 821.

Are you sure you used the same gear settings as me? Because I find myself getting all the way up to 6th on the back straight. I have a very high final drive ratio (4.0), and the gears close together (the revs drop about 500 rpm below the peak of the torque band from the red-line). With that set up, I find that I take even the hairpins in 3rd gear, then accelerate into 5th on the straights, and 6th on the main straight.

I'll check out that set up. Sounds awesome.

Awesome lap times BTW.

MykeMichail:

Did the car come in at D400?
...
Are you sure you used the same gear settings as me? Because I find myself getting all the way up to 6th on the back straight. I have a very high final drive ratio (4.0), and the gears close together (the revs drop about 500 rpm below the peak of the torque band from the red-line). With that set up, I find that I take even the hairpins in 3rd gear, then accelerate into 5th on the straights, and 6th on the main straight.

Yep ... D-400

And, yep... I used the gearing you posted - I just moved 4th gear from 1.50 to 1.40 - so I'm only in 3rd and 4th gear for the whole track.

I doubt I can beat my Golf time on Tsukuba (1:00.351) so I can't get you a ghost to follow, but I did run this car on the Tsukuba Exhibition race, so you can watch the replay and see the telemetry. My time is around #34 on the scoreboard... It's only a 3-lap race, and I managed a 1:00.870 on the third lap.

As I said, I don't consider myself a tuner, so any tweaks I make are pretty much just based on feel. In many cases (and I think this is one of them) it feels to me like I lose more time with the extra shifting than I would gain from it. So, I'll often push the revs right up to the limiter, even if the power / torque drops off a bit.

Take a look at that replay, and see how my shift-points differ from yours, and how that affects the top speeds... who knows, maybe I could get a touch faster by shifting earlier...

- Don

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GT: Don Ente



Video - Forza vs. Real World at Road Atlanta

I am not sure if you remember me, but you gave me great advice on tuning and such when I was tuning the Porsche Carrera. I saw your post here, and I wanted to see if I can even come close to your posted time.

I tried hard over the past 4-5 days, did over 200 laps, and I could do no better than 1:02.078. I race with all assists off, but I do use the braking line for assistance.

I am reading the Skip Barber racing book, so I'll keep at it. Wish me luck. Don Ente, think we can get together some time and see if you can figure out what I am not doing right? BTW I have watched your replay at least 5 times, and I'll keep at it till I reach 1:01.000 or less, heh.

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GT: Echiban

I've been working on one of these little motors of late as well, I had it working pretty well :) (1:00.568).  Corner exit oversteer is my biggest problem when pushing hard, the rear end just feel like it want to squirm! 1st corner seems to be the biggest problem but it can happen at all the major turns...

Tried lot's of stuff to try and cure this but nowt is working, difficult to believe when the car has just 130bhp weighs next to nothing and has fat sticky slicks...

Can't seem to build any rear tyre temperature either!

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Gamertag: graveltrap

FYI It sounds weird but put 1-2 but never over 3 degrees of POSITIVE camber to your rear wheels. This keeps the back end tracking the front end on the corner exits and should not effect your lap times negativly. I would watch the camber change though, and make sure it doesn't heat and change your tire pressure. I notice a good positive feel out of corners on these little cars. Try it at one, and if you don't notice anything, bump it to 2. If still nothing set it at three and start checking temps on all 4 tires in the second lap, just after full heat has reached.

Think of your second lap as your hot lap, and everything past lap 2 is race pace.

Let me know if this helps!

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GT: PrimSRT10

Added 4 clicks to rear rebound and 0.1 of negative camber and that seemed to sort out the oversteer, it could however have been me being much smoother with my inputs...Set consistent high1:00 minute laps with a best of 1:00.618...Car felt more consistent anyway

Tyre temps are low at the back, around 160 degrees, just can't get them up to decent operating temps, not sure if it's the setup or just the way the car is.  Yes I am running the fattest slicks, but the car is built specifically to attacks short twisty tracks. but pressures are good.

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Gamertag: graveltrap

graveltrap:

Added 4 clicks to rear rebound and 0.1 of negative camber and that seemed to sort out the oversteer, it could however have been me being much smoother with my inputs...Set consistent high1:00 minute laps with a best of 1:00.618...Car felt more consistent anyway

Tyre temps are low at the back, around 160 degrees, just can't get them up to decent operating temps, not sure if it's the setup or just the way the car is.  Yes I am running the fattest slicks, but the car is built specifically to attacks short twisty tracks. but pressures are good.

If you need to get them a bit higher (optimal performance is around 180-200 degrees), run a smaller tire width. Even just one step down can make a 10-20 degree difference, depending on the camber, toe, caster, etc.

I'm gonna have to try one of these bad boys...

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FrEaKyxXxStYLey
Absinthe Minded Auto Haus-Tuner/Tester
Free Tune/Test Drive Request Thread

Tried one size smaller already (215's) made no difference as far as I could tell to tyre temps, lap times where a touch slower...

I spent the PI that was now available reducing weight (14 inch rims), and using a slightly more sticky tyre compound. BHP cost's far  to many points :(

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Gamertag: graveltrap

graveltrap:

Tried one size smaller already (215's) made no difference as far as I could tell to tyre temps, lap times where a touch slower...

Well it all depends on your camber/toe settings. I've got mine so that I don't worry about the camber or toe, I try to bring the width up or down. I run -1.0 Front and -0.5 Rear Camber, 0.2 Front and 0.3 Rear Toe, and 5.4 caster. Figured I'd tell ya for the hell of it.

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FrEaKyxXxStYLey
Absinthe Minded Auto Haus-Tuner/Tester
Free Tune/Test Drive Request Thread

I am so sorry, take everything I said and replace it with TOE, I meant up to 3 degrees toe in on the rear wheels. And these guys are right you need higher temps to get full grip. Try the less width.

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GT: PrimSRT10

If you wanna free up a few PI points, I suggest running stock brakes as theres not that much weight or power to stop. Don't worry if you don't use ABS, you'll get the hang of it after a few laps.

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XBL GT-Tweek88UK

The car is already running stock brakes (no ABS either), I'm also using the Bridgestones, on 15" rims, from memory it weighs in at 1779Lbs....

I'll try the narrower wheel/tyre combo again, and drop back to the smallest rims as well.  I'll also try adding more toe in at the rear to get those tyres up to temp.

TBH it's probabley the driver thats run out of skill rather than the car, but I can't help tweaking to find out!!  It would be nice to improve my time and get the car into the top 100 ;)

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You have 20 seconds to comply!

Gamertag: graveltrap

After reading this post, I just HAD to try one of these things. So I bought one, tuned it to your original specs, and ran 10 laps, best being a 1:02.339. Not very great. I was having trouble with the throttle oversteer.

So I decided that I wanted to tr it myself. I bought another one stock, built it to my own configuration, and ran another 10 laps, best being a 1:01.888. I completely eliminaed the throttle overster, but I had increased the understeer a slight bit, causing me to take a different line than I'm used to.

Then a lightbulb went off. I noticed that the gears on the original setup were pretty good, so I put them into my personal tune. That made a difference for sure. Ran a 1:01.717 as a best and every lap after the first was sub-1:02.

I only spent about 30 minutes on the car total, so I know I can ge this thing much faster than it is now. If you would like the tune just ask for it, I'll post it up.

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FrEaKyxXxStYLey
Absinthe Minded Auto Haus-Tuner/Tester
Free Tune/Test Drive Request Thread

I've been tuning this car for a while now and managed to eliminate the nasty corner exit oversteer. Running 1:01 consistently.  If you would like to try the setup, see #47 exhibition Tsukuba.

Car Details D400
Speed                3.0      Power 130HP
Acceleration        3.3      Torque 112 Lb-Ft
Braking               6.1      Weight 1772 lbs
Handling             5.8

Tires: F/R 30/28
Gearing: Final - 1st - 2nd - 3rd - 4th - 5th - 6th
            3.5 - 2.96 - 2.11 - 1.58 - 1.4 - 1.25 - 1.10
Alignment.
Camber F/R -1.2/-0.8
Toe F/R 0.2/-0.3 (to get some heat into the rear tires)
Caster 5.4

ARB F/R 5.5/21.2

Springs F/R 550.9/91.8 lb/in

Damping
Rebound F/R 8.2/3.6
Bump F/R 5.4/3.2

Aero None F/R 45/50

Breaking N/A

Differential F/R 60/45

Car parts:

Engine All stock
Body All Race except Stock brakes
Tyres Race Avon 215/50R214 and OZ Record rims
Aero All Forza parts.

I am driving to my limits, maybe a better driver can do the extra second. The car has potential.
Awaiting your replies.

 

Thanks for posting this thread. I have a Trueno in C class that I love but never thought of trying it in D for some reason. Turns out to be a killer car. Not as fast as the GTI but handles better and I have been able to be by GTI times on almost every track, including Tsukuba. My setup isn't exactly the same as yours but pretty close. I am not crazy about your gear ratios but after trying them out they do seem to work pretty well.

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GT: EXOR dVitterMan
http://www.exodusracing.net/

Tried the narrow(er) boots, and didn't like the effect they had on the car, so back to the 225's for me!

Been messing with the build a little, now running the lightest possible 14 inch rims, rather than 15's still using Bridgestone slicks though. Had to drop some other bit's but wanted to see what effect reducing unsprung weight had, little to sod all seems to be the answer!

Looks like it's me thats hit the wall rather than the car, no matter how much tweaking and testing I do I just can't improve my best lap time (1:00.568).  Got close a fair few times, but that seems to be my limit. All I want is 3 or 4 ths and I'm a happy chap :(

Still running stock gear ratio's so I guess thats the next thing to look at...

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You have 20 seconds to comply!

Gamertag: graveltrap

I'll dig out my old setup and notes for this track, about 12-18 months back I setup a class d challenge which shed a lot of light on tuning for this track that may be of some help to you.

However, the Trueno isn't the best car for this track, it is one of the best granted but my best time/setup was in an MR-S... if looking for a Golf beater try the MR-S.

As I said, I'll get my notes out and posted tonight if I get the chance, it may also pay to check my topic "the class D challenge" from a while back if you can find it.

I think I also have some replays saved too which, if I can find my box of tricks, I'll capture and post showing my prefered, and possibly best driving line (it's a lot different to the one the assist shows).

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I'm not looking for a Golf beater really, just want to extract as much performance out of the AE86 as I can!!  Had a breakthrough yesterday, seems I'd got the wrong end of the stick about tyre pressures, small adjustment there and some tweaking of dampers netted a 1:00.414 (LB Pos 117 at the time).  Just want 50 hundredths and I'll be a happy chap (and should put the car into the top 100).

I've got two tuned D400 MR-S's from the TM, but really need to build my own as they don't seem to agree with me, maybe I just need to spend some time with them.

I've also started work on a Civic VTi, which has already run a 1:00.7xx with minimal development!!

Piccy of my AE86 just for the hell of it...



If I can get the paint up to scratch I might even try and sell a few ;)

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Gamertag: graveltrap