Rb25De Not Hitting Over 200Km/h && Should I Get Banana Bread?

[SKITTLES]

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 May 15, 2011 by SKITTLES

[jahn-15]

I dunno about the rb25de Q's but definitely get some banana bread and then order some overnight parts from china for your 2jz no shit!

[cannabiscorpse]

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

[SKITTLES]

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

[cannabiscorpse]

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.

[cannabiscorpse]

And yeah man, generally shorter gearing will get you snappier acceleration, i definitely wouldnt advise longer gearing! You would need the hp to get away with longer gears.

[PSI-FED]

180kmh @ roughly 5000rpm in 5th gear and struggling to get any more speed out of it. Did have the speed limit cut out on it too. Done on the track ofcourse

[zebra]

FOrget Banana bread ya phag

Eggs on toast is where its at.

[aussietroy]

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).

[syfon]

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

[89CAL]

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

[Grey]

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

[iseekool]

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.

[XY33]

I did 170kmh twice... the car nearly fell to pieces when i was braking I would try 200kmh on hwy with my RB25DE once i decided to suicide.

[Mayuri Krab]

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...

[cannabiscorpse]

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.

[SKITTLES]

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.

[cannabiscorpse]

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

[zoidbergmerc]

The Power required to overcome the aerodynamic drag is given by:Note 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.

[Jack-]

I've gone past my speedo (180km/h) in my na 34, can't remember the rpm. Was a bit surprised thought it would be limited at 180.