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Embarrasing turbo-lag at two-lane turns?

bigup2010-08-18 06:13:23 +0000 #1
When I'm sitting at the front of a two-lane turn, once the light turns green I start off in first gear, and shift to second about half way through the turn.

Today I had trouble keeping up with an older 2.5 Mazda3 driving in the right lane - it took what seemed like an eternity to pass him, with my foot firmly planted in second gear. The same happened recently with a late model 4 banger Camry driven by an old woman.

I'm not trying to race these people, but it's embarrassing struggling to keep up!

Why is there so much lag? I thought 2nd gear would have sufficient pull once in motion. I used to use the same technique in my previous car, a Saab 9-3 which had far less power/torque (175hp/200tq) -- never had problems staying with and passing traffic on these turns - certainly didn't need to floor the accelerator!

Do I really need to stay in first gear all the way around a turn? Seems odd for a 300hp/300tq car. In certain situations my 335i seems slower than my old Saab - and it feels like I have to really work the gears to stay in the usable power band/boost.

[/book]

Feel free to let me know if you don't understand what I'm talking about -- it's late! Cheers.

09 335i MT E92 .. 7,000km-ish. Stock.


e90fanatic2010-08-18 06:16:09 +0000 #2
its twin turbos (not even high pressure turbos), its almost lag-free. it's the way you drive it.
my922010-08-18 06:34:14 +0000 #3
If you're flooring it and the other mazda or camry is driving normally and you're not significantly ahead of it, then your car is having problems. Even a 328i should leave those in the dust
akburst5102010-08-18 07:02:53 +0000 #4
You're probably like me, I feather the gas when the light turns green and I see all these camry's and hondas just zoom past me (thats when I just keep up behind them because I don't really care). What I realized was that most people jam their foot on the accelerator to get to speed...because of cars like ours. I know I used to
och2010-08-18 07:22:06 +0000 #5
Thats what you get for getting a manual

Next time, buy an auto
RPM902010-08-18 08:34:23 +0000 #6
Quote:

Originally Posted by bigup

When I'm sitting at the front of a two-lane turn, once the light turns green I start off in first gear, and shift to second about half way through the turn.

Today I had trouble keeping up with an older 2.5 Mazda3 driving in the right lane - it took what seemed like an eternity to pass him, with my foot firmly planted in second gear. The same happened recently with a late model 4 banger Camry driven by an old woman.

I'm not trying to race these people, but it's embarrassing struggling to keep up!

Why is there so much lag? I thought 2nd gear would have sufficient pull once in motion. I used to use the same technique in my previous car, a Saab 9-3 which had far less power/torque (175hp/200tq) -- never had problems staying with and passing traffic on these turns - certainly didn't need to floor the accelerator!

Do I really need to stay in first gear all the way around a turn? Seems odd for a 300hp/300tq car. In certain situations my 335i seems slower than my old Saab - and it feels like I have to really work the gears to stay in the usable power band/boost.

[/book]

Feel free to let me know if you don't understand what I'm talking about -- it's late! Cheers.

09 335i MT E92 .. 7,000km-ish. Stock.

It matters at what rpm you are shifting into 2nd.

Even though this engine has very good low rpm torque, it still requires exhaust pressure, which can only be made once rpm is above at least 1500rpm, but it's much better around 2k.

If you're short shifting 1st, and it sounds like you are since you state that you're shifting at midpoint in the turn after a stop, then you might be below 1500rpm. You'll feel the lag in the situation.

What RPM are you starting off at? That matters too, for the reason of exhaust pressure.

Another factor could be that, since you are in a turn you might be getting wheel slip. If that happens the the ECU will react by applying the brakes at the drive wheel, and it will reduce throttle even though you are positively applying it.

If this is happening you will see the traction light blink.

Try this same turn by starting off in 1st at around 1200rpm and don't shift until you're at least at 2krpm. There is a 500rpm drop from 1st to 2nd.

So, if you're shifting at around 1500rpm, let's say, then 2nd will drop you to 1k rpm, which is well below enough exhaust pressure to spool the tiny turbo's enough to give you good boost.

If that's not the problem, the try turning DTC off, and see if that helps.

Even though these engines build decent boost and provide good torque at low-ish rpm, don't be fooled. The engine still needs strong positive exhaust pressure to spool the turbo's. There is only strong low rpm torque with solid throttle. Driving lazily will allow lag to rear it's ugly head.
Quizarate2010-08-18 09:13:47 +0000 #7
No matter what stop light I'm at, a couple seconds after the light turns green I'm well ahead of every other car, and I'm driving normal. It's kind of embarrasing... I don't want them to think I'm racing them or anything. If I was, I'd vanish from there sight much quicker.
yabcoder2010-08-18 09:32:43 +0000 #8
Quote:

Originally Posted by och

Thats what you get for getting a manual

Next time, buy an auto

this
gos2010-08-18 06:54:08 +0000 #9
Quote:

Originally Posted by RPM90

Try this same turn by starting off in 1st at around 1200rpm and don't shift until you're at least at 2krpm. There is a 500rpm drop from 1st to 2nd.

Shift into second at 2k rpm?

Just drop the hammer and shift at 5-6k.
gos2010-08-18 09:55:14 +0000 #10
Quote:

Originally Posted by bigup

Do I really need to stay in first gear all the way around a turn? Seems odd for a 300hp/300tq car. In certain situations my 335i seems slower than my old Saab - and it feels like I have to really work the gears to stay in the usable power band/boost.

The usable power band is huge, not sure why you're trying to stay at such low RPM. Let it wind up a bit, you'll enjoy driving a lot more.
bigup2010-08-18 06:49:10 +0000 #11
Thanks all..

I'm not sure exactly what I was looking for with this post, but I'm liking the responses.

Just seems strange that it's all or nothing sometimes. Rack up the RPM in first, and going quick is no problem. Sometimes I like to try to drive normally though, and that's where I lag behind.

I just wish 2nd gear pulled me through the slow corners like my previous cars, that's all.

First gear around the corner, followed by tail-out fun on the exit it is then, I guess! I've done that once or twice, believe!

.. one thing I have noticed is that everybody seems to want to race me in this car. Especially people in Toyota Tacomas/4runners. Why!! People always backed off the Saab, maybe that's why it seemed so fast - nobody felt the need prove anything against a quirky Swedish motor!
WWONG2010-08-18 09:45:50 +0000 #12
I'm not sure whether you have 6MT, but from my experience with 6AT, it seems that the car gets more power if you floor it slower (~2 seconds) rather than pushing it til it hits that click-down point immediately.

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