Jump to content
SAU Community

  

40 members have voted

You do not have permission to vote in this poll, or see the poll results. Please sign in or register to vote in this poll.

Recommended Posts

So I was reading on a website that when this crazy p-plater gave his car a bit, he/she pushed the car past the limits of the speedo, doing roughly 200km/h, and his/her car started to make a funny noise that was hard to describe.

Apparently it's a sort of buzzing noise.

Is this a limiter or can the engine seriously not go faster than this?

What's limiting the engine from going faster?

Also, should I get a banana bread with my coffee this morning?

Edited by SKITTLES
  • Replies 58
  • Created
  • Last Reply

Top Posters In This Topic

haha- good luck with this one mate, i can see people trying to f**k you up the arse for even asking this one.. But too me, i would think a na rb wouldnt have too much past 200. Probably comes down to gearing etc, but i think real world its probably got not too much more. And yeah man, b-bread is the shit, once you start you wont go back haha

I got there, had epic heart burn, struggled with coffee so I got a toasted ham/cheese crossaint. Banana bread can be tomorrow when i get paid :)

> i can see people trying to f**k you up the arse for even asking this one..

So can I, but it's a valid question.

I can imagine you're right about it being an issue with gearing, apparently this guy was revving out to 6k in 4th gear to get to around 170 then into 5th, but once it was in fifth it didn't go to like 4k or shit it went to 5k and went back to around 6k after passing the 180.

It wasn't hitting the rev limiter.

Can anyone explain how the gearbox things work?

If I were to change the gears so that they were longer or something, but kept the engine the same, would there be a performance issue with acceleration?

Would it be a case of faster top-end, slower acceleration?

If I had a turbo with longer gears, would the power then give me a better acceleration and top end?

Just trying to wrap my head around things :)

What your saying about it not getting any more in fifth is pretty standard i would assume.. I know when i was an enthusiastic p-plater (idiot driver haha) and i max speed ran my bommodore, it hit 200 in third, then when it hit 4th (overdrive, auto) it was still 200, but at like 3000rpm and wouldnt go any higher.. it actually kept dropping back to third.

I think the issue is that the na engine doesnt have enough torque to keep it revving out the last gear, that and the fact the last gear is very long in order to keep the rpm low at highway cruising.. I would assume a turbo model would pull all the way to redline in final gear.

So it doesnt have a limiter ??

I know my 32 (auto) is limited to 180 and definetly wont go any higher then that.

Even at 180 it physically doesnt feel like it could get much higher then 200 (although a rb25de would have a bit more grunt then the shitty rb20de).

LOL at just how sh!t how the RB25DE motors are.

My E46 BMW was a 2.5L straight-6 making roughly 150-160 rear-wheel horsepower and I hit 240km/h......didn't take too long to get to 200, but then it took a bit to get to 240.....and that was on a dead straight/flat road.

I even ran it down the 1/4 mile, ran a 15.1. The only performance-enhancing mod on my E46 was a full 3" exhaust system with no cats. Never had it on the dyno, so not sure of exact horsepower/torque figures, but there was an evident torque gain with the full exhaust system.

Also, banana bread if f*kin awesome. Remember, sharing is caring :)

I got there, had epic heart burn, struggled with coffee so I got a toasted ham/cheese crossaint. Banana bread can be tomorrow when i get paid :)

> i can see people trying to f**k you up the arse for even asking this one..

So can I, but it's a valid question.

I can imagine you're right about it being an issue with gearing, apparently this guy was revving out to 6k in 4th gear to get to around 170 then into 5th, but once it was in fifth it didn't go to like 4k or shit it went to 5k and went back to around 6k after passing the 180.

It wasn't hitting the rev limiter.

Can anyone explain how the gearbox things work?

If I were to change the gears so that they were longer or something, but kept the engine the same, would there be a performance issue with acceleration?

Would it be a case of faster top-end, slower acceleration?

If I had a turbo with longer gears, would the power then give me a better acceleration and top end?

Just trying to wrap my head around things :)

Gearing is always a compromise. You can have a gearbox that will accelerate unbelivably quick but will only reach 140kmh. Or you can have slow acceleration with a top speed of 300kmh (and risk never getting there)

You need power to overcome wind resistance (Drag) and there is an element of mechanical drag as well from the moving parts along the driveline.

This is why the Bugatti Veyron can go 400km/h and your car can not lol. Lots and lots of power, and long gearing.

In racing the idea is to get the gearing right so you are in top gear right near the limiter on the longest straight/fastest part of the track. When I used to do karting, I had to change sprockets to get the right gearing. In Formula 1 they do the same thing with the gear ratios for the different tracks (There will be a Monza spec gear set, Bahrain spec gear set etc etc). If you've been watching this year with the Drag Reduction rear wings they are hitting redline early on the straights because they have to keep a good gearing for the race where they cant use the DRS for the whole track

Thats enough talking

  • 2 weeks later...

Gearing is always a compromise. You can have a gearbox that will accelerate unbelivably quick but will only reach 140kmh. Or you can have slow acceleration with a top speed of 300kmh (and risk never getting there)

You need power to overcome wind resistance (Drag) and there is an element of mechanical drag as well from the moving parts along the driveline.

This is why the Bugatti Veyron can go 400km/h and your car can not lol. Lots and lots of power, and long gearing.

In racing the idea is to get the gearing right so you are in top gear right near the limiter on the longest straight/fastest part of the track. When I used to do karting, I had to change sprockets to get the right gearing. In Formula 1 they do the same thing with the gear ratios for the different tracks (There will be a Monza spec gear set, Bahrain spec gear set etc etc). If you've been watching this year with the Drag Reduction rear wings they are hitting redline early on the straights because they have to keep a good gearing for the race where they cant use the DRS for the whole track

Thats enough talking

Exactly right - wind resistance increases roughly exponentially once you start going above 105km/h. High speed you need more horspower.

LOL at just how sh!t how the RB25DE motors are.

My E46 BMW was a 2.5L straight-6 making roughly 150-160 rear-wheel horsepower and I hit 240km/h......didn't take too long to get to 200, but then it took a bit to get to 240.....and that was on a dead straight/flat road.

Even my mum's auto Camry (3L V6 version) could top out ~200km/h, although it would take ages to get there...

Not that im proud to have been apart of it, and it was f**king scary, my mate had his excel 195. We were however typical 17 year old douchbags. lol

It also took forever and had a downhill run- but still not bad.

i got about 160kmh on 5000rpm gear 5, don't know if it would go any faster the car was vibrating lots

That's not that amazing tbh. I've heard of people hitting around 4500-5000rpm in 4th gear at 170 in a bone stock car.

Not that im proud to have been apart of it, and it was f**king scary, my mate had his excel 195. We were however typical 17 year old douchbags. lol

It also took forever and had a downhill run- but still not bad.

my friend reckons he took his mums excel to 220 or something on a freeway.. they take a fair beating.

I took mine to 180 when I was 17. Totally not worth it.

my friend reckons he took his mums excel to 220 or something on a freeway.. they take a fair beating.

I took mine to 180 when I was 17. Totally not worth it.

haha- definitely not! The thing rattled and shook so much we took up two lanes.. My dick attempts in my commodore only got me 200- but at least it was smooth lol

The Power required to overcome the aerodynamic drag is given by:e31430f0898268091f410282a89503b1.pngNote that the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power.

In short, you go twice as fast, you need 4 times the power. But because you've doubled the speed, you're hitting twice the amount of air, so you really need 8 times the power.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • Seat of the pants assessment of the new intake: The car is way less "doughy" when hitting the loud pedal, especially off idle when stopped or in traffic, I did use a cheapo lazer thermal thingo to measure the temp around where the pod filter got its air, it was between 55 - 60°C, in saying this the car was shut off and not moving, so the OEM intake pipe was not supplying any fresh air to where the pod was when the car was at least moving A weird bonus was induction noise on the throttle in the cabin increased a bit,  I was worried that I was actually going to lose some of that induction noise I love so much, outside though, when I got the daughter to do a WOT drive by pass for me, the induction noise has increased alot when on the throttle, not quite ITB doort, but well up there I'm extremely happy with the results and have been exploring the country roads in the region  As for house mods: 1.New front fence is up and is awesome, it really upgraded how the joint looks from the street, and the added security is nice 2. Electricians have replace some interior lights, and with more lighting in the garage, a few new motion detecting lights out the front above the garage, front room, and at the front door, which I have already found heaps helpful coming and going, also now has fancy pants CCTV all round the house The only hold point for power though is the solar and batteries due to supply issues, although this will happen over the next few weeks 3. I have done a heap of landscaping out the front and I'm almost ready to do a new small retaining wall with some nice blocks to replace the brick and cemented in rocks around the raised garden beds cemented in river stone "was the fashion at the time" the house was built. I currently have a pallet of retaining wall blocks and 2 bulka bags of 20mm blue metal to replace the wood chip that is in the raised garden beds around the house 4. I now have 3 big raised garden beds for out the back to grow some vegetables, about 70cm high, 200cm long and 100cm wide 5. My 2 compost bins are already pretty full with brown, green and kitchen waste from the landscaping I'vedone so far, but they will probably take a few months to break down, so anything else that gets chopped, trimmed, and kitchen waste will just start filling the base of the raised garden beds to about 30cm before I start throwing 40cm of good compost, and stuff, for the vegetables to grow in, I'll need a few ton of compost and soil, but the local supplier can sent me bulka bags of the stuff Basically the logs, wood chips and a few strategically placed rocks for drainage, will give the beds some good organic materials down low to break down over time, and they will hold moisture during the warmer months to save the water in my big arse water tank if we don't get alot of rain So, all in all, the car and house mods are going well, and I'm really enjoying being retired, I sleep in too 0700 and slowly plod around inside until I feel like actually doing anything, and only work in the yard for as long as want, which has actually been alot over the last few weeks,  although when you look at it, it seems that not a huge amount of work has been done,  until I look at the before I started the work pics Happy days and good times indeed 
    • hahaha yeah. Plan is to get side skirts and probably just rear pods. But going to do them one-by-one. I've got a set that I really like from RHDJapen, but that one isn't shipped to AU. So need to find someone who can get it for me
    • Here's an idea, answer the questions I asked you as they are trying to work out WHY the LSD will be binding up in a straight line.
    • You haven't driven many modern cars then have you? Most of them have sfa steering feel with their stupid electric bullshit steering systems.
×
×
  • Create New...