Speedo won't go high enough.....

yes - when I put in the L31, i may need a 300km/h speedo...

Assuming I have the early 80's 280zx box, which I'm pretty sure I do, with my standard diff at 7,500rpm I can on paper reach 325km/h.

With a 3.7 diff it comes down to 310km/h.....

Even at 6000 rpm with standard diff and assuming I have the gearbox I think I do, I can do 260km/h.

Obviously wind resistance and rolling resistance will pull it down a bit, but I reckon the L31 should be able to get pretty close to 300.... Standard speedo only goes to 240. Hmmm.

Oh yeah, and Gav, whats your reasoning behind the 260 5 speeds being better than 280 boxes? according to http://zhome.com/ZCMnL/tech/GearRatios.html, the late 260 boxes (77 - 79), assuming they are the same as US 280z's, will give you quicker acceleration in lower gears, but the earlier 260 box and to a smaller extent 280zx boxes may be better with a higher diff ratio....

I read an old artical yesterday on the 240 having a "theoretical" top speed of 180 miles an hour however the true top speed was 125 M/hour. I'm sure with higher speeds that would be brought down exponentially. Even 125 M/h sounds very high!??

What is the highest top speed any of you guys have reached in your z?

Sulio

125 miles an hour is slightly over 200km/h.... The thing which determines how much less your 'true' top speed is, is a combination of drag and horsepower - the more power and torque you have, the less the wind resistance and rolling resistance effects it. So I reckon with the extra power of a strong L31, you could get at least close to 300km/h.....

The L28ET guys might have some input on this one.....

Theres no chance I would get into a zed with a driver that has intentions of going over 200. Man these cars are nice but it's an old car and 300k/hr is the sort of thing exotic cars do! I reckon my Z would take flight if it was ever to reach that sort of speed! hehe

Sulio

Well, aparently they experience front end lift same as '69 Stingray Corvettes, I can't remember what speed it is - 180km/h off the top of my head. Fix it with a front spoiler

And with upgraded front brakes, good suspension and wide good compound tyres, why wouldn't a Zed be as safe as any other car over 200km/h? Providing of course all the steering links and suspension bushes are ok...

unless u have a like a some awesome aero kit on a Z, the aerodynamics of a Z is quite bad.... to my knowlege it will get quite unstable at the 220 mark with original Z bodywork

Im sure ashley has some track experiance on this issue,

but in my old Z, 180 wasn't to hard to get to...

the old Silvia was better, when the speed restrictor was off, cruising at 220 wasn't a problem at 6000rpm in 5th

Was your silvia a turbo, or naturally aspirated? My girlfriend is getting a 2 litre non turbo silvia, I'm curious to know what they go like....

according to many of the guys on zcar.com, the actual top speed is around the 200-220km/h mark

the Zeds have crap aerodynamics which doesn help the situation,

although there was a 280z 2+2 in the states which did get a land speed record on a salt flat...

my 260z with 3.7 diff and the 280zx low ratio box (0.86 5th) sat on 2800rpm @ 100km/h. if i recall correctly, the peak power comes in at around the 5800rpm mark...thats 3000rpm to triple the speed....

my car did 190km/h on a dyno in 4th gear @ about 6500prm. 4th is a 1:1, so theoretically on the dyno it will do 220km/h in 5th. of course wind resistance becomes a major issue there...

motor is a more or less stock 280zx efi (82kw at the wheels)

as much as I'd love to see it, I dont think its possible, except with major improvements to the aerodynamics

for the record, 180 which was with the old 260z gearbox. had more in it, but the track wasnt all that good a quality

yeah, talk to tonyd over at zcar.com about this stuff, he's the guy that holds the land speed record...but it's in a 280zx, not z. and they have much better aerodynamics....the gaping hole at the front of the z and flat firewall means that (according to tonyd) the z has a drag coefficients only slightly better than a 6 by 8 foot sheet of plywood, i think it's worse than a vx combi.

a g nose helps this, as does bonnet venting, preferably out the fenders

sorry i didn't see the reply to this thread

yes the car was a silvia turbo, sr20det, but it had alota mods so i wouldn't say it would be anything like a sr20de non turbo silvia...

but either way, they are a great car to drive, great build quality, and have good sports suspension, bit tend to understeer, with stock suspension....

a 2ltr non turbo still has 100kw and in a 1100kg car, its not to shabby, id buy one as a daily driver if had had more money, as they are hela relaible, will spin the wheels if you get a LSD< and easily converted to turbo, and heaps of cheap parts... even thinking of gettting another sr20det 5spd after i finish the Z, as much as people bag and don't like S13s, with the right setup, they are just as much fun, in a differant way as the Z....