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24 Dat

Challenge Bathurst 2018

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There is Richard, its called Production Sports Cars. There are even two levels of competition, 2F with limited mods and 2B where you can go further. But you still have to use the L series engine and no forced induction.

My old green car was still competitive over a championship in Queensland, and looking at the times of the current Queensland cars, I would be looking at picking up silverware if it hadn't met it's demise.

Only problem is you need deep pockets and a lot of cash to play in a car that is near 50 years old and be up the front. My S14 still owes me less than $15k for all the bits I have laying around and fitted. I just need the time to put it together, which is another couple of years off with my current work situation.

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19 minutes ago, PZG302 said:

There is Richard, its called Production Sports Cars. There are even two levels of competition, 2F with limited mods and 2B where you can go further. But you still have to use the L series engine and no forced induction.

My old green car was still competitive over a championship in Queensland, and looking at the times of the current Queensland cars, I would be looking at picking up silverware if it hadn't met it's demise.

Only problem is you need deep pockets and a lot of cash to play in a car that is near 50 years old and be up the front. My S14 still owes me less than $15k for all the bits I have laying around and fitted. I just need the time to put it together, which is another couple of years off with my current work situation.

What are the best 2F and 2B lap times around Lakeside and Bathurst? What I have seen of MX5's around Bathurst they would be  a tough nut to crack there, current tech vs 60's tech, big ask.

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here  you go this is video of my fast laps on Sunday Morning

Here is from the start of the last run 

Here is the Friday afternoon  (now a bit of a tradition) line up of the groups entrants, CB 19 this will be a major event 50 + com cars on one side and 50+ S30's on the other

  

 The last 2 gives you a bit of an idea of the view from  corporate suites sorry for the over exposed footage, new camera and not use to it

 

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At lakeside, to be a front runner in 2F you need to be doing 59's. for 2B, a 56.

Not impossible, but much deeper pockets than I have for a S30. Hence why I went for a S chassis, dirt cheap at the time and so many parts off the shelf available to go fast. And now with the rule changes for turbo cars, so much cheaper to make a lot more power. Has meant a total rethink on turbos, manifolds and intercoolers, but the basic unassembled long motor I have in the study will be a very good base. The suspension all up has cost me about $4k for some very nice custom coilovers, and fully rose-jointed adjustable arms, strengthened cradle and solid mounted bushes for the rear.

The most expensive single item purchased for the S14 was the cage, which cost $5k to be fabricated and also included seam welding teh emgine bay and the floor in the cabin.

2B would be the class to target as you can run a big stroker with injection with a lot of freedoms in suspension, gearbox and body. 

Weight would be the easy performance boost, mine was 960kg ready to race with around 30-40 litres of fuel. The only non-steel panel was the bonnet, and I ran plastic windows. I reckon I could have gotten another 10kg or so out of the car if I really tried. Things like rewiring the car, carbon bonnet and hatch, carbon door skins a lighter seat.

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Quick Question: What is the diff ratio that most of the Datsun crew are using for the Mountain.

Cheers, Enzo.

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46 minutes ago, Enzo said:

Quick Question: What is the diff ratio that most of the Datsun crew are using for the Mountain.

Cheers, Enzo.

Hi Enzo, myself and a few of the other guys around me are running a 4:44 Subaru diff R180,  i'm running 16 " Hankook Z214's final drive .83 from a 280ZX box, would like a tiny bit higher as the shift light is set at 7.2 and its on for a long time going down conrod,  but i need the lower gearing going up the mountain 

Edited by 24 Dat
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4 hours ago, Enzo said:

Quick Question: What is the diff ratio that most of the Datsun crew are using for the Mountain.

Cheers, Enzo.

I run a 3.9 diff for Bathurst as I don’t pull the same revs as so,e of the other guys with mine maxing out at 6,500.  Pay for it going up the hill though.

https://youtu.be/27axDgWwXwU

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On Bathurst diff ratios for the S30, how would it be if a higher (less revs) ratio was used that was ideal to exit onto Mountain Straight using a lower gear than usual eg second instead of third? That would sort out Mountain Straight but I have no idea how it suitable it would be for the rest of the circuit ???

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32 minutes ago, 260DET said:

On Bathurst diff ratios for the S30, how would it be if a higher (less revs) ratio was used that was ideal to exit onto Mountain Straight using a lower gear than usual eg second instead of third? That would sort out Mountain Straight but I have no idea how it suitable it would be for the rest of the circuit ???

I use 2nd coming out of Forrest's Elbow and thru The Dipper and The Cutting 

Edited by 24 Dat
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The best diff would depend on the motor type. A high revving peaky screamer you would be better off using a 4.3 or 4.4 diff for the climb up the hill, but you need to be able to spin the motor all day to around 8000rpm to make the most of it. For a more torquey or more standard motor a 4.1 or maybe even a 3.9 diff would work best, but you will be using 2nd gear at the cutting and most likely Murray and Hell corners as well, and maybe even Griffin bend. You will probably be able to run down the hill in 4th, only using 5th to save the engine when you hit the aero brick wall.

The main part of Bathurst that gets you time is the run across the top and down the esses. Big balls needed to go fast there and get that right you will have a quick time. The next most important part of the track is getting up the hill, particularly through the cutting to set you up for the run across the top. In coming down the hill, the set up for and through the Chase is more important than the straight line speed. 

Basically if you can carry more speed through the corners and get up the hill, you will go faster than someone who has concentrated on getting a maximum speed down the hill to brag about.

The old green car never got the chance to do a full lap, but I and it did a few hillclimbs and Chase Descents over the years.

I used a 4.1 diff with maximum revs being about 6800.

Typically for the tracks I ran on using 240/640/18 or 245/650/18 slicks the diff ratios were:

Amaroo - 4.4 or 4.1

Oran Park (South) - 4.4 or 4.1 

Oran Park (GP) - 4.1

Wakefield - 4.1 or 4.4

Eastern Creek - 4.1 or 3.9

Winton - 4.1 or 4.4

Hillclimbs (various Tracks) - 4.9 and 15 inch wheels with 205/50/15 Toyo RA1

Using such a big tyre in comparison to most, I could always go one higher diff ration than others with Zeds could run.

Going up the hill on the maintain straight hill climb which starts at the hump and ends at Reid Park I used 3rd for Griffin Bend and had the choice of holding 3rd or grabbing 4th quickly before the cutting. The cutting was taken in 2nd as 3rd was just a touch to low in revs to suit my engine, but I was looking to change into 3rd as I passed the big brick gate posts on driver's right and then held it flat getting into 4th as you climbed up around the right hander before you changed direction to enter Reid Park.

Coming down the hill, starting at the first hump for the chase descent it was flat in 4th through the kink at about 210km/h going off the gear calc program and start braking at the bottom of the dip into the chase, back to 3rd for the left/right up to 4th under the bridge, and then back to second for Murrays corner.

On the full track I my car would have been in 4th across the top, 3rd gear for the esses and dipper, up to 4th for the run to Forest Elbow, then back to 3rd for the Elbow and run it as hard as I can down conrod. I would assume I would be in 5th gear topped out at about 230km/h going on the gear calc program and speeds at EC. Lakeside and Morgan Park the car achieved. 

My engine was a truck motor with peak torque around 3500rpm with a fat curve under the torque and it ran out of puff at about 6600, dropping off power at 6800 and the engine being able to spin to 7200. I never ran it much past 6800 as there was no point. It did however pull very well out of corners and carried a lot of corner speed thanks to 240/640/18 slicks and good brakes, plus relatively light at 1080kg with me in the car and 60 litres of fuel for a one hour enduro.

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"Instructional article by Australasian correspondent Matthew Ryeland."

Edited by Léon

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5 hours ago, Léon said:

"Instructional article by Australasian correspondent Matthew Ryeland."

Well I have been around for a while......

And started racing before you worked out how not to shit your pants :)  :)  :) 

 

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Cheers for the info regarding diff ratios guys.

My hat goes off to those that competed on the weekend.

By the end of next year I should be moving back to Orange  ( 1/2 hour from Bathurst ) after an absence of about 37 years, so I should get to the Mountain. Probably as a spectator only though.

David.(Enzo).

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I’m far from being an expert but I did run at  Bathurst on the weekend for the first time and had a bag of fun.

My car runs a standard bore and stroke warm street motor and i used a 3.9 ratio Subi LSD diff. Best lap was a 2:52.5. I think the car could have gone a bit quicker up, down and across the top of the mountain if my balls were larger than they are.

from Harry’s GPS lap timer I Video’d most of my laps which are overlaid with speeds and sector times etc. for some reason I can’t upload it to YouTube. YouTube says invalid video, asset not readable (I am a dinosaur)

For my car, I found changing back to 2nd was slower than holding 3rd through the cutting and forest elbow.

I’ll see if I can’t upload the vid but in the meantime, I used 3rd for hell corner, reached 180 in 5th heading up mountain straight down to 3rd for griffins, a short stint in 4th then back down to 3rd for the cutting. Back in to 4th at Reid park for the top of the mountain doing between 130 - 150. (Speed through here is a direct relationship to size of balls) down to 3rd at Skyline holding it all the way down to and through forest elbow. Top speed of 213.8 on Conrod but wimped out on holding it flat through the kink (a few more laps and I might have done it) 3rd through the chase and Murray’s corner.

I had a great time driving the mountain and look forward to getting back there again sometime. I would recommend it to anyone that likes a little Adrenalin.

also had a great time with all the other like minded people and it was nice to put some faces to names.

Gordo, good to meet you on the weekend and, great job on taking and posting so many pics and vids for us all. I have enjoyed reminiscing already. Cheers Mate.

Mick

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