purpose of torque dip

[swpbrz]

The more I drive this car the more I realize how much thought was put into the engineering. Lately I find myself on empty twisty canyon roads skiing around. I realized that, at times, the torque dip might be useful. It seems to provide extra fidelity in the throttle which is nice at the limits of ashesion. If I am in the upper power band coming up on a turn and let off gas and begin turn. As the weight shifts and I hear the car say yes you may wag my tail I agree. And I find that in the "dip" is a perfect range of power to add more overseer or back off.


But because of the dip in torque it seems like that range of power is ideal for an extremely light car at the limits of adhesion. It doesn't need much at the limit and I believe this car is so well engineered that may have been thought out. rather than just some terrible thing someone overlooked.


Or maybe I'm in love with a girl with glasses

[finch1750]

The prupose is MPG. I find driving in the dip is harder myself. No response from the go peddle when you need it.

[Basket Case]

You may be in love with a girl with glasses...a hot, skanky one...

[jjaisli]

The dip in torque between 3500~4500 rpm wasn't something they engineered in because they thought it was a good idea or would add to the fun. It's (likely) there in order for the car to meet emissions and possibly fuel economy requirements. I like girls with glasses. But I don't find this one particularly likeable.

[Dezoris]

There had to be a reason they tuned it that way aside from efficiency. I mean the SAE articles and testing from Subaru show DI/Port injection maps with the TQ dip there. They knew it was there and left it.

I have heard so many reasons why and how, but still am not convinced.

[Basket Case]

Originally Posted by Dezoris

There had to be a reason they tuned it that way aside from efficiency. I mean the SAE articles and testing from Subaru show DI/Port injection maps with the TQ dip there. They knew it was there and left it.

I have heard so many reasons why and how, but still am not convinced.

My guess would be for emission reasons.

[tennisfreak]

Nice theory OP.

In reality the purpose is to piss me off!

[Eurasianman]

To mimic VTEC, but at 5,000 RPM instead of 7,000 RPM?

[fatoni]

Implying the torque dip was engineered to be there is silly. I'm sure they knew it was there but I believe that getting rid of it would cause some other compromise the team would dislike even more

[Bristecom]

SWP, I originally suspected that may be the reason too. In MotoGP, the crossplane crankshaft was designed to give the engine short breaks in power in order to retain more grip when power sliding. However, this is isn't the same sort of thing and the car doesn't have much power to begin with. They'd be better off giving it more grippy tires to compensate for a little more power if that were the case. I'm pretty sure the dip was just a compromise. I just hope they get rid of it for next year.

[robwbright]

Come on, guys. I don't really get everyone complaining about the torque dip all the time. The problem is easily resolved by downshifting. Sure, the dip is there. But no 2.0 liter 4cyl I am aware of makes any significant torque at lower rpms without FI. The VTECs mentioned above aren't any different. My Prelude VTEC didn't have any significant low end torque, either. Whether or not it had a dip in a nearly non-existent amount of torque wasn't really relevant to me. I just rev'ed it out from 5,000 to 7100 in each gear... and it moved along nicely. In fact, the numbers showed it was a quick from 60-120 as a Mustang GT.

Seems to me that everyone basically has 5 options:

1: Use the power and torque where it exists - which is 5000+;
2: Get a tune (which broadens the spread significantly);
3: Get FI;
4: Get a larger motor and/or a Camaro/Mustang;
5: Get a header (with a tune).

If you didn't want to shift a lot, then you probably shoulda had a V8.

[jjaisli]

Originally Posted by robwbright

But no 2.0 liter 4cyl I am aware of makes any significant torque at lower rpms without FI. The VTECs mentioned above aren't any different. My Prelude VTEC didn't have any significant low end torque, either.

But that's not exactly correct. I think this engine is very torquey down low. Especially for a normally aspirated 2.0 liter. Around 2500 RPM it's actually pretty strong and surprisingly punchy. In fact, I don't think I've ever driven a car with a non F.I. engine this small, with so much bottom end torque on tap. The problem is that the torque falls off significantly around 3500 rpm. And that's why it's so noticeable.

[coredump4]

Originally Posted by fatoni

Implying the torque dip was engineered to be there is silly. I'm sure they knew it was there but I believe that getting rid of it would cause some other compromise the team would dislike even more

Couldn't agree more... it's a classic engineering compromise.

[ericmpena]

I agree with robwbright. Drive the car in the higher RPM's if you don't like the feel of the torque dip, or just downshift. Seems easy enough to me.