What's the reason for Torque dip in BRZ Dyno ?

[Memphis]

I think it will be fixed with tuning so nobody needs to worry about it. It has been said by Tada I believe that they could have released it with 220bhp from the factory but had to dial it back because of emissions.

We have already begun to see how corked up this engine is from recent dynos from Perrin and other companies with aftermarket exhausts being manufactured that it is going to be quite easy to get power down the road.

How many NA engines do you see gaining 7whp from a cat back exhaust upgrade alone? Thats not even including the mid pipe as they have not even shown that dyno yet.

There is a dyno supposedly showing a 30hp increase from just an exhaust and what many speculate as a tune.

The point is the engine is being held back more than was first expected and the dip while part of the reason is nothing to worry about as it will be fixed in due time.

[Visconti]

Take a look at my avatar....see the HUMP in the map

[Boosted2.0]

Our testing showed the same dip

Its possible that it is only tuning, but I would guess that its more likely tuning coupled with some sort of unfavorable harmonic. May be able to affect it with intake manifold and header re-tuning.

[Boosted2.0]

Sorry - pic to go with the above post:

[Visconti]

Originally Posted by Boosted2.0

Sorry - pic to go with the above post:

here's a better pic

[Boosted2.0]

Originally Posted by John@TheShopCT

here's a better pic

23 by 17 maps?

What an odd choice.

[WingsofWar]

Long standing discussion, and have many theories.

1. Direction Injection switching
2. Timing retardation to work with DI
3. Intake Acoustics
4. Non-optimized AVCS
5. Combination of 2 or more of the above.

Personally i believe its the result of DI...
The IS350 with similar injection has similar TQ fluctuations when switching to DI for relying on intake pressures and higher cylinder compression to form a homogenous mixture.


as well as the GS350


While just looking at this curve may turn you off, its actually the best way to make this much power while using the least amount of fuel and pumping out the least amount of emissions. While a similar conventional port fuel injected system can make the same power or more...it will also use more fuel and not pass our ever stricken global emissions laws. Even the Civic R FN2 has been discontinued due to not passing emissions in Europe and it makes a similar powerband that of the FA20.

[Dimman]

There doesn't sound like there is any actual 'switching' of port and DI. There is continuous changing fueling of both from the sounds of it. Like they have 2 simultaneous, continuously changing fuel maps that run together.

The other thing to keep in mind is from the dyno graphs, that 'dip' is ~ 85% of peak torque. The low rpm peak and the high rpm peak are very close to BOTH making peak torque.

It isn't so much that there is a horrible dip, but that the motor manages to create a LOT of torque in the 2500-3200 rpm range. (Name another 2.0L NA motor that makes ~150 lb-ft @ 3000 rpm...)

[WingsofWar]

Originally Posted by Dimman

There doesn't sound like there is any actual 'switching' of port and DI. There is continuous changing fueling of both from the sounds of it. Like they have 2 simultaneous, continuously changing fuel maps that run together.

Yeah, sorry what i meant by switching was the cylinder environment. Direct injection is on all the time...while port fuel supplement is on at 0-3000rpm and around 6800-7400rpm. Making DI the primary source of fuel giving off a consistent weak strat across the revboard. Didn't mean it like a on and off switch...

I think the issue here is how ignition timing is effecting the two fuel maps especially at the "switch" when port comes off. Especially since DI loves lots of retarded timing, and that there are really different cylinder pressure differences between the two maps.

[arghx7]

Has anybody hooked up current probes and taken data on the injection timing yet?

[YukiHachiRoku]

Originally Posted by Memphis

I think it will be fixed with tuning so nobody needs to worry about it. It has been said by Tada I believe that they could have released it with 220bhp from the factory but had to dial it back because of emissions.

We have already begun to see how corked up this engine is from recent dynos from Perrin and other companies with aftermarket exhausts being manufactured that it is going to be quite easy to get power down the road.

How many NA engines do you see gaining 7whp from a cat back exhaust upgrade alone? Thats not even including the mid pipe as they have not even shown that dyno yet.

There is a dyno supposedly showing a 30hp increase from just an exhaust and what many speculate as a tune.

The point is the engine is being held back more than was first expected and the dip while part of the reason is nothing to worry about as it will be fixed in due time.

I wonder when complete bolt ons from header all the way to cat back, will I fail emissions test?

[Symbiont]

Originally Posted by Dimman

There doesn't sound like there is any actual 'switching' of port and DI. There is continuous changing fueling of both from the sounds of it. Like they have 2 simultaneous, continuously changing fuel maps that run together.

The other thing to keep in mind is from the dyno graphs, that 'dip' is ~ 85% of peak torque. The low rpm peak and the high rpm peak are very close to BOTH making peak torque.

It isn't so much that there is a horrible dip, but that the motor manages to create a LOT of torque in the 2500-3200 rpm range. (Name another 2.0L NA motor that makes ~150 lb-ft @ 3000 rpm...)

While this is true (and impressive), I really am interested in seeing how some tuning can smooth that out. Whether it is handled by bolt-ons or a remap, this would be worth quite a bit to me, as long as it is CARB legal. Fuel mileage isn't as much of a concern to me as feeling uninhibited in my shift points.

[noAE86]

Originally Posted by Dimman

There doesn't sound like there is any actual 'switching' of port and DI. There is continuous changing fueling of both from the sounds of it. Like they have 2 simultaneous, continuously changing fuel maps that run together.

The other thing to keep in mind is from the dyno graphs, that 'dip' is ~ 85% of peak torque. The low rpm peak and the high rpm peak are very close to BOTH making peak torque.

It isn't so much that there is a horrible dip, but that the motor manages to create a LOT of torque in the 2500-3200 rpm range. (Name another 2.0L NA motor that makes ~150 lb-ft @ 3000 rpm...)

exactly what i think too,
im more inclined to say, "toyota/subaru found more low end TQ" rather then "oh they lost some TQ in the middle,

reminds me of the arguments i have about open stack trumpets on quad throttles,
can i have long trumpets = yes but you loose some power at high rpm,
oh then can i have best high hp = yes but you need very short stacks,
can i have high hp but with long trumpets = NO
why = helmholtz resonance....20 minutes later

[Matador]

Originally Posted by serialk11r

I never said DI had anything to do with it, and I don't think it does, although it's possible it does.

What I think is that the cams have peak efficiency at 6000 or whatever, and the intake has peak efficiency at like 2500, so you get 2 peaks. The drop isn't that bad really, as a percentage of peak torque. But these are all guesses.

Also keep in mind that the rev range here is 7500 rpm, so it's natural to see more variation in torque than when the rev range is only 6000.

...... -__-