dat240z Posted October 1, 2012 Posted October 1, 2012 Hi guys, was just reading though some old posts on here. Found one about z top speeds that was last edited in 2005! Was interesting reading, especially some of the claims (like an L31 hitting 300km/h :-\) My old l28 with twins would top out at about 123mph (Barton Hwy - before speed cameras ruined that road!!) Ive now done the RB swap (FMC, POD, 3" exh) with AZC coilovers + wilwoods, bushes etc and a 3.7 r200. Not sure if im more mature now (probable) or just dont want to risk my build due to the cash sunk into it or just scared, but I was wondering what id do? Some calculators that ask for weight, power, drive reckon 175mph but I wouldnt want to try. I gave it a good hit along Wallaroo Rd in the ACT not long ago (super straight) and was too scared to go beyond 3rd gear, @ was @6500 doing 110mph... Backed off though as theres just too much to lose. Was wondering if anyone here has any similar experiences or stories? Quote
Gordo Posted October 1, 2012 Posted October 1, 2012 Yes , this is a interesting topic, I suppose there is a lot of I have this diff this gearbox and so much power with a wheel diameter of this much, not to mention the aero and drag. And how accurate is the speedo after changing all that stuff. I guess the GPS has all that sorted now. I was at PI race track a few weeks ago ,pulled 7000rpm in 5th gear, 4.1 diff and tire diam of 625mm. Peter Mac tells me it's about 240kph. Quote
Sirpent Posted October 1, 2012 Posted October 1, 2012 Buddy If the 5th gear ratio is 1:1 then top speed at your quoted 7000 rpm would be 201.0366 Kph Drag coefficient at that point has no baring as physics would stop you reaching maximum RPM if the car was a brick, the fact that the car reached 7000 rpm means that the mechanical action of the vehicle was able to achieve it, the coefficient may have slowed your progress reaching it, however you did. I have a calculator that allows tyre, box ratio's and final drive ratio's to be plugged in to demonstrate what the potential top speeds and speeds in gears and rpm's would equate to if anyone is interested. Cheers John Quote
Gordo Posted October 1, 2012 Posted October 1, 2012 Buddy 5th gear 260 gearbox with over drive. Why would you assume it's 1.1. ? Quote
Sirpent Posted October 1, 2012 Posted October 1, 2012 Lol sorry abot the Buddy bit Wasnt meant to be derogatory, I used 1:1 as a worse case scenario demonstrating what the lowest speed would be and not knowing what you are running box wise thast all, give me the 5th's ratio and I will plug it in. Cheers John UPDATE: Plugged .864 as 5th ratio which would bring top speed in at 7000 rpm as being 232.6812 Kph. Quote
dat240z Posted October 1, 2012 Author Posted October 1, 2012 Yeah I went with Autometers and use a GPS speedo. Its great and accurate - excpet for tunnels Quote
dat2kman Posted October 1, 2012 Posted October 1, 2012 Conrod straight, Mt Panorama, 2008 Combined Group s and group N historic races, division 1 (the quicks) 4.1 diff, 610mm tall rubber, overdrive box 7700 rpm Around 245 kmh Wipers lifting off screen. Lap times in 2.46's Jack Elsegood in his XY GT Falcon passes me, he said he was topping out at 270 kmh Its on video somewhere In 2010, ran the Dato 2000 Sports, geared it to do 245 kmh, lap times were 2.43's No roof had my helmet trying to part company with my head. Scary feeling, but better than sex. Quote
luvemfast Posted October 1, 2012 Posted October 1, 2012 Scary feeling, but better than sex. You're doing it wrong! Quote
peter mc Posted October 1, 2012 Posted October 1, 2012 yes the 5 speed is a over drive snake man . gordo was doing 144mph at the island . i dont speed but the old zed went very fast ... at the drags it went 140mph in 9.9 sec . with a 3 speed auto and with the 5 speed with a .73 over drive with a 3.7 diff and 8000rpm in top it was off the clock Quote
pauly_adams Posted October 1, 2012 Posted October 1, 2012 i can confirm that a 260z 2+2 with minmal mods can do over 225km/h using both speedo and gps as a gauge that was at 5800rpm- 6000rpm Quote
imackz Posted October 1, 2012 Posted October 1, 2012 i can confirm that a 260z 2+2 with minmal mods can do over 225km/h using both speedo and gps as a gauge that was at 5800rpm- 6000rpm mine has a modified speedo (300kph)due to running 300zxtt box , same setup with a guy in the US is pulling nearly 300kph (behind vh45de motor)never really know till put on either dyno and max out or find a road without state photography , but will easily pull over 260kph, have pulled over 200kph in 4th without redlining Quote
Scando Posted October 1, 2012 Posted October 1, 2012 At PI in 2009 I was hitting the 6,300rpm limiter at the end of the straight with a 3.54 diff, 0.75 5th, and approx 625mm diameter tyres (255/40's). Works out at just under 280km/h. That was with an L28ET, only making about 400HP but it was pulling around 200km/h coming onto the straight and the last little bit of the straight is down hill. I'm not sure that a power to weight based calculator would give a very accurate top speed. As Gordo mentioned, aero has a lot more impact on top speed than weight. Quote
PZG302 Posted October 1, 2012 Posted October 1, 2012 Using the gear calc program mentioned in another topic, the top speed of my 240 was a theoretical 249km/h at the 7200rpm in 5th gear running a 4.1:1 diff and 0.852:1 overdrive 5th with 640mm diameter slicks. This woulld need to be done down conrod so the thing could wind right out and the down hill run would overcome the brick wall that is aero. This would feel about right as the revs I pulled in 4th at QR and Lakeside equate to what the car has been clocked at, so about 210-215km/h through the kink at Lakeside. Was also clocked at 187km/h at the turn in point at Eatern Creek, so approaching the corner at about 215-220 at the braking marker there. I must point out that there are a lot of people who have optimistic speedos and belief in how fast a Z can actually go, they are aerodynamically like a brick without substantial work on the front and rear ends, and spook or BRE/Nismo front spoiler and bob tail don't cut it, neither will a rear diffuser unless a shit load of work is done to make the floor pan a venturi like structure. Quote
Whittie Posted October 2, 2012 Posted October 2, 2012 Conrod straight, Mt Panorama, 2008 Combined Group s and group N historic races, division 1 (the quicks) 4.1 diff, 610mm tall rubber, overdrive box 7700 rpm Around 245 kmh Wipers lifting off screen. Lap times in 2.46's I must be doing something wrong, this was me in 2010: 3.9diff, 205/55 rubber, SR20 box 6500rpm 245kph Wipers way off the window Lapping 2:55 I think most of it is due to the diff, way too tall going back up the hill lugging all the excess weight it used to have, but wouldn't be able to do 245 down again as would be on the limiter at less than that. Quote
reverendzed Posted October 2, 2012 Posted October 2, 2012 I got close to 340KPH...Oh hangon that was in my 454 corvette - This is a bit like a fishing story thread or to be more Aussie a 'pissing' contest! Who cares how fast it goes, it's about how much fun it is to drive! Rev. Quote
dat240z Posted October 2, 2012 Author Posted October 2, 2012 Ease up mate, if you dont want to partake in our "pissing contest" put it back in your pants and go to the next thread!! Quote
reverendzed Posted October 2, 2012 Posted October 2, 2012 Someones forgotten to take their 'humour' pills today...Chill bro! Rev. Quote
dat240z Posted October 2, 2012 Author Posted October 2, 2012 Ha, sorry I was trying to add one of the faces for expresison but missed it! Quote
peter mc Posted October 2, 2012 Posted October 2, 2012 It would be cool to check top speed at the z nat at the island next year, top speed under the bridge Quote
PZG302 Posted October 2, 2012 Posted October 2, 2012 It would be cool to check top speed at the z nat at the island next year, top speed under the bridge And I think a lot of people would be suprised at the speed they actually go....... Quote
luvemfast Posted October 2, 2012 Posted October 2, 2012 under the bridge Sometimes I feel like, I don't have a partner. Sometimes I feel like, my only friend. I tell you what though. I can't even tell you how fast I'm going a tracks. If you've got time to look at you speedo at the point you are reaching your top speed, you're either going to miss the next corner or you not goin fast enough. And if you're reaching these speeds on the road. Don't brag about it, cos you're clearly a massive tool. If you want to drive fast. Do it on the track! For the record. My cars JDM, so speedo max's out at 180kph Quote
Gordo Posted October 2, 2012 Posted October 2, 2012 I wonder if Sinisha has read this thread. He would be making our PI speeds at Sandown. Wonder what he would do at PI. My brother and I were talking about taking his V8 zed to the SA salt lake speed trials one year. Would be a great few days camping out there trying to get top speed out of the cars. Quote
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