Struggling to put the power down

[R34NeoLover]

7 hours ago, niZmO_Man said:

What's the specs of your wheels?

I have 2 sets of wheels, one for the street, other for track.

Cant quite remember offsets, but street wheels are fronts 18x8.5 rears 18x9, track wheels are fronts 18x8.5 rears: 18x9.5.  

Biggest tyres i can fit in the rear 18×9.5 is 275/35/18, but then I'd have to roll guards, that's why i opted for 265/35/18, fits without touching guards. From memory, the rears offset is +35.

 

 

[R34NeoLover]

On 1/14/2021 at 11:34 AM, Duncan said:

Since you wanted more power mostly for track use and the power is a pain on the street, adjustable boost level is a smart answer.

Then, you aim for a wheel alignment that is a mid point between street and track use. This means a little camber (-1 to -0.5) and probably 0 toe at the rear, and at the front as much caster as you can get, a little toe out and medium camber (will depend on how much adjustment your bushes and arms have). You should also upgrade sway bars, and if your shocks are shot you could look at upgrading them to something street/track suitable.

Yes a good diff will help a lot on the track but really not on the street.

Ok cool thanks, I'll look into all that if the semi slicks dont hold the power down during sandown in the next week. 

I might look into adjustable boost for the street, although i am not overly concerned about traction on the streets, i drive the car like once a week sometimes even once a fortnight, mainly just cruising around, i dont race in the streets. 

I got the car back from the dyno about a month ago, and up until a few days ago, i hadn't tried to use the full power, mainly because i use it on the race track, not the streets.

Since sandown was coming up, i thought i better try a full throttle pull in 2nd just incase something plays up, I'd still have time to take it back to the dyno.

I should probably also add, the potenzas on it right now, are years old, so i am sure a better, newer and wider tyre would help part of the issue. 

 

Anyways this will be my first track day with this kind of power, i have done plenty of track days, just not with this amount of power. I guess I'll mainly just be getting used to the car, wont be trying to set any pbs or anything, ill probably be experimenting with air pressures during the first few sessions, hopefully find the sweet spot and traction hopefully wont be much of an issue.

[The Bogan]

Street tyres according to me...

Potenza are a 380 tread wear if I recall correctly 

Good tyre for a daily taxi, and they last a long time with a good alignment, but for a performance street tyre, yeah nah

I've recently swapped 245 RE003 for 255 Hankook RS4, 200 tread wear, on my 270kw LS and the difference in grip is astounding

It still bags them up if I just mash it, but it grips up much quicker with the RS4's

I was running 255/40 17 RS4's on my old 33 which had around 380kw, with some throttle control they held up OK grip wise for the street, and lasted quite well

They are not the best when the weather is cold though, but once warm they are good value

265/35 18 RS4's are around $350, 275/35 18 are around $380, IMO they are a good bang for your buck street tyre

As for track tyres, thats not my bag

Listen to the track day junkies

Enjoy

[The Bogan]

Dooh

[niZmO_Man]

 

[Tobz]

Interesting discussion. I have 285rwkw currently and when i got the car i struggled a lot for traction. I actually loved it as it was a lot of fun to keep it pointing in a straight line! 

Now im not 100% sure what got rid of it as a i did a lot of things at once, so one of these may be the key. Just not sure which:

• Changed suspension all round to MCA Blues (mid setting, its stiff, but not rock hard)
• Changed almost all my control arms front and rear and got a wheel alignment in line with the recommendations in this forum
• Pineapples on the rear subframe
• Locked the HICAS (If it was anything, I would bet it was this)
• Changed my front and rear swaybars to whiteline (from stock)

Now the part that made no sense, I got some new 18inch wheels, but decided i would just reuse some tyres i had lying around for the street. They are 225/40 R18's and are Monster Street Series.... these are not the best tyres ever made and are ridiculously skinny for the power (i bought them as i needed to pass a rego inspection)... however somehow the car had traction.... no idea how! Once i have got the car moving, the rear does not break traction in a straight line and full power.....

Made no sense to me so i went to a dyno to check the power to make sure the car actually made 280rwkw... thought something may be wrong, but second dyno had similar power.

On the track i use 265/35 R18 Kumho V70a (Medium Compound) front and rear and i can be really aggressive on applying the power on corner exit...

sooo i dont think ive helped here, but ive definitely added more things to read.

Edited January 20, 2021 by Tobz

[robbo_rb180]

1 hour ago, Tobz said:

Now im not 100% sure what got rid of it as a i did a lot of things at once, so one of these may be the key. Just not sure which:

• Changed suspension all round to MCA Blues (mid setting, its stiff, but not rock hard)
• Changed almost all my control arms front and rear and got a wheel alignment in line with the recommendations in this forum

 

It would have been these 2 things, MCA run a softer rear spring than most and wheels pointing the right way always helps.  

[GTSBoy]

Plus the pineapples, probably. Stopping the subframe from flapping around can keep the tyre pressed to the ground a bit better too.

[R34NeoLover]

Well i am here to give a bit of an update.

 

Took the car around sandown yesterday, first time using semi slicks and the first time taking my car out with 343rwkw.

 

I had previously taken the car to sandown a bunch of times with 200rwkw and using bridgestone potenzas re003.

 

Firstly, wow the nangkang ar1s were amazing, i had zero grip issues, and it was raining on and off through out the whole day. Only managed to get in 2 sessions because of the rain, but i could plant my foot to the floor coming out of the turns in 2nd, no issues. I kept air pressures around 35ish but i never really got the chance to get them really hot, so i cant really comment on optimum air pressure, but around this mark felt good atleast.

 

I mostly took it pretty easy as i am not used to the car with this kind of power, for me its like driving a completely different car, but i managed a 1:32:00, with heaps of room for inprovement. I would like to drop down to 1:29, so i will go again in future, i could of easily achieved my time if i wanted to, but i just wasnt 100% sure what would of happened with a slightly wet track and semi slicks.

 

I still have hicas and stock diff, i think they are fine, but i did not push the car to its absolute limits, so i am not totally sure. 

 

Stock gearbox, stock gear ratio, i hit 6,500rpm in 5th gear before i started braking. Now as my speedo only goes up to 180kph, would anyone happen to know what speeds i probably was doing? Looking at my dash cam footage, 7,000rpm in 4th gear, goes well past the 180kph mark, so i think 4th ends at about 200kph give or take, would it be too big of a stretch to assume i was doing about 240-250ish in 5th 6,500rpm?

[GTSBoy]

Just drive at 3750 rpm in 5th and double what you see on the speedo?

[Kinkstaah]

That sounds about right for that power at that track. (allowing for some accuracy with the speedo in general).

[R34NeoLover]

Awesome thanks for that. I am abit worried with the stock gear ratio though, i have been told that going into 5th gear at those speeds is extremely bad, as its mainly an overdrive gear, and at those speeds, shifting into 5th, wont be long before it goes bang.

 

But i have also heard that typically 3rd i think it was, would go way before 5th did. 

 

Dont suppose anyone has any input? I have been told that ideally i should lower the diff ratio to something like a 3.4-3.7, and to avoid using 5th at the track.

Edited January 28, 2021 by R34NeoLover

[Kinkstaah]

I would also like an answer to this.

All I ever heard was "Yeah no good idea because its an OVERDRIVE GEARRR" but I don't actually know why. Also hardly any other option. Drive on a track that maxxes out at 200kmh?

3rd seems to be the first gear to go in Skyline boxes for some reason. I don't remember anyone ever exploding 5th due to it being overdriven but maybe someone will chip in.

[bcozican]

5th is 100% fine Ive got a decent level track skyline with 550 hp++ and when I was driving it with stock box using 5th over and over again topping out in mid 245 kmphs with no problems 

As said 3rd is usually one that breaks  but mainly found that on drift cars ... in circuit cars its the 3rd to 4th gear change that kills it (whatever it munches in there) so as much as its nice to bang through that be a millisecond slower and smoother and itll last alot longer

[Duncan]

Pretty sure that sort of advice started in the 60s when the falcon and kingswood boxes stopped at 4 gears, cars with a 5th had a physically smaller (weaker) gear to cram it in the available space. Nothing wrong with 5th (or any other gear) in a skyline box until you double or more the stock power

[R34NeoLover]

Yeah ive been told that supposedly as 5th gear is an overdrive, the material used isnt as strong as the other gears or something?

[Unzipped Composites]

8 minutes ago, R34NeoLover said:

Yeah ive been told that supposedly as 5th gear is an overdrive, the material used isnt as strong as the other gears or something?

See above comments.

[GTSBoy]

4 hours ago, R34NeoLover said:

Yeah ive been told that supposedly as 5th gear is an overdrive, the material used isnt as strong as the other gears or something?

Yeah. Nah.