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Potential Top Speed?

gt-ahhh!
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gt-ahhh! Proficient

gt-ahhh!

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Posted

hello, just wondering what people think of the potential top speed of my car. i mean, i could get out on the highway and test my theory, but i figured this would be slightly more advisable.

R33 RB25det, pushing 240rwkw (perhaps more)

i havent got an a/m speedo. but theoretically, over 180, you can calculate the speed based on the rpm.

ie: 3000rpm in 5th = 120kmh approx.

so:7000rpm in 5th = 280kmh approx.

i know the car pulls very hard all the way to the redline in other gears, so im assuming it would do the same in 5th. but is 240kw at the wheels enough to make 280?

what do you think? also, is there anywhere in syd where you can do this stuff? im guessing wsid isnt long enough.

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Timeb0mb Enthusiast

Timeb0mb

Posted
Posted

As far as i know unless you change your gear/Diff ratios you could have 1000kw and your top speed will be the same as standard, youll just get there quiker :D

also if your running standard computer youll be speed limeted to 180kmh

when i *tested* this speed limeting, it stoped at 5000rpm and was doing about 20km per 1000rpm (if that makes sense)

my guestimate put top speed at about 220km at 7000rpm

Trooper Experienced

Trooper

Posted
Posted
i would love to test that also

with a power fc i would say 250 is easy said?

PFC stores top speed for each trip, got mine to 242, but could have gone a bit more (not on public roads obviously)

I recall there was quite a difference between PFC and speedo reading

gt-ahhh! Proficient

gt-ahhh!

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also if your running standard computer youll be speed limeted to 180kmh

when i *tested* this speed limeting, it stoped at 5000rpm and was doing about 20km per 1000rpm (if that makes sense)

my guestimate put top speed at about 220km at 7000rpm

really? i am absolutely certain there is no limiting on my car, because, well lets just throw it out out there, i have already done at least 230. and that was when i only had 180rwkw.

now im not bragging or indicating that this behaviour is acceptable. im just including it for the sake of this discussion.

i feel the only thing preventing 280 would be wind resistance, ie: not enough power to overcome it.

Timeb0mb Enthusiast

Timeb0mb

Posted
Posted
really? i am absolutely certain there is no limiting on my car, because, well lets just throw it out out there, i have already done at least 230. and that was when i only had 180rwkw.

now im not bragging or indicating that this behaviour is acceptable. im just including it for the sake of this discussion.

i feel the only thing preventing 280 would be wind resistance, ie: not enough power to overcome it.

in that case yes more power would do the trick,

However standard jap computers are electronicly speed limeted to 180...

i belive this to be the case in all jap delivered nissans as my mates 180sx and another mates S14 is the same

unless you have an upgraded ECU i didnt think it was possible to get around it???

unless you have changed the gear box and that is some how changing the speed the ECU thinks you are doing???

i know when i did it (i have since grown out of this sort of behaviour) the speedo read past 180 probly more like 190 but the revs topped out at 5000rpm

more then likely inaccuracy of the speedo as such high speeds

Samon Proficient

Samon

Posted
Posted
really? i am absolutely certain there is no limiting on my car, because, well lets just throw it out out there, i have already done at least 230. and that was when i only had 180rwkw.

now im not bragging or indicating that this behaviour is acceptable. im just including it for the sake of this discussion.

i feel the only thing preventing 280 would be wind resistance, ie: not enough power to overcome it.

Well I know on mine, I belted through first, second, third, and fourth... about 6000RPM-ish in 4th and it just was like it couldn't go any quicker... The speedo was sayin' a little past the end (180). I'm told this is the limiter. I mean I was accelerating up and up to that point, then it just stopped revving any higher.

Timeb0mb Enthusiast

Timeb0mb

Posted
Posted
Well I know on mine, I belted through first, second, third, and fourth... about 6000RPM-ish in 4th and it just was like it couldn't go any quicker... The speedo was sayin' a little past the end (180). I'm told this is the limiter. I mean I was accelerating up and up to that point, then it just stopped revving any higher.

yeah thats sounds about right, it doesnt bounce or anything like that it just cuts off at 5000rpm

or in your case 6000rpm in 4th

i was on the motor way so didnt really hammer 4th all the way thru

Samon Proficient

Samon

Posted
Posted
yeah thats sounds about right, it doesnt bounce or anything like that it just cuts off at 5000rpm

or in your case 6000rpm in 4th

Yeah I'm in a N/A... so it's probably something to do with the different diff ratios...

redevil Proficient

redevil

Posted
Posted
hello, just wondering what people think of the potential top speed of my car. i mean, i could get out on the highway and test my theory, but i figured this would be slightly more advisable.

R33 RB25det, pushing 240rwkw (perhaps more)

i havent got an a/m speedo. but theoretically, over 180, you can calculate the speed based on the rpm.

ie: 3000rpm in 5th = 120kmh approx.

so:7000rpm in 5th = 280kmh approx.

i know the car pulls very hard all the way to the redline in other gears, so im assuming it would do the same in 5th. but is 240kw at the wheels enough to make 280?

what do you think? also, is there anywhere in syd where you can do this stuff? im guessing wsid isnt long enough.

KW does not equal top speed... as stated you could get the same top speed with 100kw it's the gearbox and diff configuration which governs your top speed.

and your 280kmh theory is based upon being able to redline in top gear which is extremely hard to do and would require a massive straight.

gt-ahhh! Proficient

gt-ahhh!

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Posted
KW does not equal top speed... as stated you could get the same top speed with 100kw it's the gearbox and diff configuration which governs your top speed.

and your 280kmh theory is based upon being able to redline in top gear which is extremely hard to do and would require a massive straight.

yes what you have said is true. BUT what i was hoping to learn was whether 240rwkw is enough power to overcome the wind resistance and actually get to 280.

i can guarantee, say, 180 at the wheels, would not be enough to push 280kmh. the wind resistance is enormous at that speed. esp in a skyline with a fmic pushing into the air like sailboat in reverse. therefore the top speed of a 180rwkw R33 might be 240kmh, but a more powerful one...

240rwkw is another story, you can get past 200kmh in no time with that kind of powah! anyone who owns that much donk knows that. but im not going to try it on the road, because at 240kmh you travel a kilometre every 15 seconds... and at 280...well you would be going almost 3 times the speed of any other traffic. and most street tyres arent rated for that. (mine are, but they were $425 each)

so yeh, anyone with any actual knowledge or experience, maybe of driving on an airstrip? that would be cool.

RubyRS4 Grand Master

RubyRS4

Posted
Posted (edited)

This is such a squid topic :D

I've done 260kph with 110rwhp ...

... on a race track, in a controlled environment, no traffic, ambulance at the ready, on a well prepped and scrutineered machine (motorcycle of course), full protective clothing, and with alot of training and 20 years experience behind me.

Anything less is squid talk.

Edited by RubyRS4
Timeb0mb Enthusiast

Timeb0mb

Posted
Posted
This is such a squid topic :D

I've done 260kph with 110rwhp ...

... on a race track, in a controlled environment, no traffic, ambulance at the ready, on a well prepped and scrutineered machine (motorcycle of course), full protective clothing, and with alot of training and 20 years experience behind me.

Anything less is squid talk.

you make a good point,

however im assuming this topic is theoretical and in the name of sience and plan old interest in the 'what if' style

gt-ahhh! Proficient

gt-ahhh!

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  • Author
Posted
don't alot more factors come into this than whats been stated?

such as?

i think drag is the biggest one (but i have a gtr wing set at like 0deg lol). maybe mechanical limitations like driveshaft speed?

gt-ahhh! Proficient

gt-ahhh!

Posted
  • Author
Posted
mate you could have no wind resistance at all and not be able to get to 280kph as it has been stated UNLESS YOU CHANGE GEARBOX AND DIFF RATIOS...........

what are you basing this on? in 5th gear, if the engine is doing 4000rpm at 160kmh, all logic would indicate that at 7000rpm the car will be doing 280kmh. and if you go into the redline, maybe 300kmh (power permitting).

is my speedo or tacho out of whack? im pretty sure in 5th the speeds are approx:

1000rpm - 40kmh

2000rpm - 80kmh

3000rpm - 120kmh

4000rpm - 160kmh

therefore, since its a directly proportional relationship:

5000rpm - 200kmh

6000rpm - 240kmh

7000rpm - 280kmh

im pretty sure my reasoning is correct. and the only thing preventing 280kmh is friction and drag.

hsc physics ftw!

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