SeanG

I've had my MY00 UK spec turbo (no mods) for a few months now and am still learning......To get maximum acceleration through the gear range what is the best rpm to shift up at? (if that makes sense).

Sean

Blow Dog

When the rev counter starts bouncing on the limiter
Cem

Blackscooby

Shouldn't you get as near to the stage where it goes "pop pop pop" of the rev limiter without actually hitting it ?


Mind you sometimes I hit mine just for the hell of it ~ cos it sounds soooooo good with the rear window 1/4 down

Mark.

SeanG

Sorry if this thread had a bit of a Gonzo/Kermit feel to it...It wasn't meant to!

I was under the impression that you get maximum torque at a certain rpm band and once you exceed that rpm you need to shift up a gear to maintain an increase in acceleration. I didn't know where this rpm band is....Is it at the limiter?


Sean

AlastairB

Sean,

This is how I understand it - someone more knowledgeable will correct me if I'm wrong

It is true that the point of maximum torque is when acceleration (force) is greatest. This point varies from engine to engine, in the Scoob I think it's <I>about</I> 4000rpm.

Now, given that, why go to the redline? Well, it's because gears are a multiplier of force (torque), and lower gears multiply by a greater amount.

So, if you are in 3rd gear at say, 5500rpm, the engine is producing less torque than if you were in 4th gears at 4000rpm. However, 3rd gear is a greater multiplier of that torque than forth, hence the torque being delivered to the wheels (not from the engine), can be larger.

Consider an extreme (silly) case - 5th gear at 4000rpm vs 1st gear at 6000rpm. The <I>engine</I> is producing more torque in the 5th/4000 case, but the multiplying effect of first gear is so much greater, the torque delivered to the wheels is greater.

Which is why if you floor it in first, you feel like you've just been rammed by a train.....

HTH
Alastair

SDB

Hi Sean

Not sure about the absolute optimum, but scoobs really don't need to be revved that high...

Different models have different rev ranges and even though I've driven over 150 at MIRA I couldn't tell you what they actually rev to!!

But I tend to what feels like about 500 revs before the red line and that feels really comfortable.

Cheers

Simon

Blackscooby

The boost on mines doesn't waver below 18PSI right until I hit the limiter, therefore am I better holding on to the revs, or changing up earlier and let the turbo do the work ?

I've only owned it 2 1/2 years, and normal driving the torque is excellent below 4000, but above between 4000 and 7200 the power is quite brutal.

Thanks

Mark
(putting on Kermit outfit)
UK MY94

adrianl

I have always found that there isn't a best place on any car that is fixed it is all up to you what feels best and if you wish to lengthen the life of your car. But you can say it is always going to be in the last 1000 rpm before the red line. I judge it by the new push in the back and how fast it happens after you change up.

Adrian

The Zohan

I have a UK 4dr Turbo
Prior to changing the filter and b/box mine used to get a bit Asthmatic at about 6k revs in 4/5 gear, it did not seem to pull any harder so seemed little point in holding it any further.

Post filter/backbox revs clean to red line although i don't often 'take it there'

Mungo

The gear ratios are basically set so that if you change up when you are at the engine speed for maximum power, the engine speed in the next gear should be that at which you have maximum torque.

The Zohan

In the real world....

I'll get my coat!

NITO

Hi Sean,

When mine was standard I used to change up around 5500rpm as it didn't sound happy revving to the redline but since modifying it (exhaust/downpipe/filter/evc) I now shift up around 6500rpm when I'm going for it, coincidentally it's this point that I get flames too! These type of mods invariably push the meat of the power higher up the rev range anyway! According to rolling road figures mine produces max torque at exactly 4000rpm and max power at 6573rpm.

Regards,
Nito

Andrew Timmins

I remember reading that you should keep revs between peak torque and peak power for best performance.

As Mungo says if the gears are spaced correctly changing at peak power should drop the revs to approx peak torque.

Kevin2000

I am such a good driver that I usually change up 2rpm before maximum power is delivered.
Regards
Kevo

SeanG

Thanks for all your comments guys, I'll have a play around close to the red-line.

Cheers

Sean

rsquire

It's simple people

5261 and half rpm...

Duh Like that so hard to achieve

OK Move me to the Muppet Forum.. Well Miss Piggy is staying over tonight

richard

davidgoodwin1803

Sean, im not quite sure why everbody is getting so pissy as i think its a fair enough question.

the answer depends on your car, most non sti car reach there max boost and start to drop off at around 5,500rpm so i would say that between 5,000-5,500rpm is the prime time to change gear.

hope this helps David

stevebt

iTrader: (8)

I dont really think the person who started this thread cares anymore now

TonyBurns

iTrader: (3)

About 500rpm before the red line, thats when you reach your max bhp after that its all down hill though on an unmodified classic its probably more like 1k below the red line

Tony

rbaz

iTrader: (1)

PMSL

stoneface

iTrader: (6)

SeanG-gone but not forgotten!

Norman Dog

iTrader: (1)

Wonder if he's still got the Scoob