What torque dip?

[ill86]

Originally Posted by Gardus@Supersprint

The thing is, IF it was possible to correct this throught ECU tune, they would have don it from the factory.
If you analyze the OEM intake and exhaust you'll notice a number of resonators, I think they are there to reduce the issue.

The torque dip is engineered to be there. It is to enhance driveability around the city.

Most folks believe it it's an error..it is not.

[gmookher]

Originally Posted by pdreams

I think the car on stock ecu has enough to deal with the torque dip.

Running on Perrin overpipe and front pipe and Greddy Axleback w drop in filter.

Massive difference after the Perrin parts.

More than enough torque and power to move around w this setup.

Am on 98 fuel but I don't think thats going to make much of a diff.

So does a tuned ECU make the car any much more better?

Opinions?

use a drop in filter and the over pipe as well and feel the same as u..91 fuel
an ecu tune DOES help in my case

[topazsparrow]

Originally Posted by ill86

The torque dip is engineered to be there. It is to enhance driveability around the city.

Most folks believe it it's an error..it is not.

how does a lack of low - mid range torque increase driveability???

It's always been my understanding that the torque dip was a byproduct of the dual fuel injector setup. It's optimized for low rpm torque and fuel economy via the Port injection, then switches over to direct injection to get the power in the high RPM's where it can more accurately introduce fuel.

The torque dip isn't intentional, but it's accepted as a byproduct of the engines "dual power band" characteristic. As shown in above graphs, you can tune it out to an extent, but at what cost? Fuel savings?

[Dimman]

Originally Posted by topazsparrow

how does a lack of low - mid range torque increase driveability???

It's always been my understanding that the torque dip was a byproduct of the dual fuel injector setup. It's optimized for low rpm torque and fuel economy via the Port injection, then switches over to direct injection to get the power in the high RPM's where it can more accurately introduce fuel.

The torque dip isn't intentional, but it's accepted as a byproduct of the engines "dual power band" characteristic. As shown in above graphs, you can tune it out to an extent, but at what cost? Fuel savings?

You mean the massive amount of torque in the low rpm range, given the size of this motor?

And I don't know why I bother, but it's not a DI issue.

[Drift-Office]

Originally Posted by draggin_az

i have the FA20club 93 octane tune and the dip is 95% gone. its there but not near as bad as it is on a factory tune.

Could we at least see a dyno chart to quantify the above statement please?

Regards,


Bob @ Drift-Office, LLC

[ill86]

Originally Posted by topazsparrow

how does a lack of low - mid range torque increase driveability???

It's always been my understanding that the torque dip was a byproduct of the dual fuel injector setup. It's optimized for low rpm torque and fuel economy via the Port injection, then switches over to direct injection to get the power in the high RPM's where it can more accurately introduce fuel.

The torque dip isn't intentional, but it's accepted as a byproduct of the engines "dual power band" characteristic. As shown in above graphs, you can tune it out to an extent, but at what cost? Fuel savings?

You are incorrect in thinking it is not intentional. The response I have given is from the "horse's mouth". Fuel economy and driveability is why it is there.

When driving on a race track if shifting at or near redline you will not fall in this "dip" on the next upshift.

Around town it is desirable to shift before the torque "dip" to maintain decent low end torque and fuel economy.

I have not encountered any situation where the "dip" has caused me grief. On the street or on track. YMMV.

Peace.

[mike2100]

Originally Posted by Dimman

You mean the massive amount of torque in the low rpm range, given the size of this motor?

And I don't know why I bother, but it's not a DI issue.

Hopefully one of the smart people on the forum will make a huge FAQ one of these days. I've been on the forum for 3 years, reading religiously and I still miss things now and then.
It's kind of sad we have a comprehensive master list of wheels/sizes/pics but not even the beginning of a FAQ. But then I guess you don't need to know anything about the engine to get that mad tyte hella flush look y0

[ayau]

There was a graph the showed where your rpm would fall after an up shift. I'm trying to find it. It basically shows that you miss the end of the torque dip as long as you shift at or near the redline if I reall correctly.

[Dimman]

Originally Posted by mike2100

Hopefully one of the smart people on the forum will make a huge FAQ one of these days. I've been on the forum for 3 years, reading religiously and I still miss things now and then.
It's kind of sad we have a comprehensive master list of wheels/sizes/pics but not even the beginning of a FAQ. But then I guess you don't need to know anything about the engine to get that mad tyte hella flush look y0

Just click on arghx7's icon and select the find more posts thing. Read everything he has posted and attached.

[Calum]

Yup, then read it five or six more times until you actually understand what he's saying. I thought I knew something about engines and thermal dynamics. Not a lot, but something. Then I read a few of his posts...

[sierra]

Originally Posted by ayau

There was a graph the showed where your rpm would fall after an up shift. I'm trying to find it. It basically shows that you miss the end of the torque dip as long as you shift at or near the redline if I reall correctly.

A 6000rpm shift should keep you above 4500rpm most of the time.
No need to red line it.

Just worked out where to shift to get 4440rpm for the next gear.
Should be pretty accurate?

1 to 2 7400rpm
2 to 3 6300
3 to 4 5700
4 to 5 5350
5 to 6 5800

[pdreams]

Originally Posted by dwx

Nothing is as cost effective as a tune for helping make power and helping "fix" the torque dip.

Here is someone's dyno with similar mods as you, the lower run is without the tune, the higher one is with the tune, and this is on 93 octane. Even without the exhaust it will still do more than an exhaust will.

Thats nice..I did enquire about ECUTEK and have access to a tune.

As it is I am pretty comfortable with the car now, probably a more efficient intake than the stock one to come, hopefully Perrin or Syms.

My concern is with the hot weather and high track temperatures over here, will the tune for the US market be suitable here.

The car has caught me by surprise slightly with the bolt-on improvements and with the insane price that the BRZ cost in my part of the world, I just cannot afford any down-time or issues with a flash.

I guess for now, I will carry on until I do a dyno with the intake on top of my current bolt-ons.

[Gardus@Supersprint]

Correct me if I'm wrong, it's just an hypothesis:

At the moment all the "tune guys" are working on the Subaru ECU, which manage the indirect injectors, while the Toyota DI ECU is still untouched, am I correct?

I think the dip in the torque depends on a A/F ratio too lean, or it's connectect to the variable timing system.

If you look as this dyno chart (it's from our full exhaust, notice the lambda curve) you see the peak of the O2 sensor is close to the torque dip:

[wparsons]

^^ As far as I know there is only one ECU, and it's 100% Toyota's. They run a similar D4S (port and DI) system on a couple other cars in their fleet.

I know Visconti said he is playing with the port/direct injection stuff to try to improve fuel economy, and that's with a single flash tune to a single ecu.