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

Hi guys

I have searched for some dyno results(you may have already seen) of FRS/BRZ. Each of them shows that there is a "low output" during about 3000rpm to 5000rpm. Please see the attachment.


Could someone help to explain the reason? Why the torque outputs like that?

When doing dyno, I think they should not shift the gearbox.

DI

I'm sorry i can not understand why direct injection will make such.
could you please explain more or give some url/reference ?

No one is sure for now, but many engines have a dip in the midrange, which is possibly due to intentional tuning for a "dual powerband", low range and high range as a compromise between daily driving and performance driving.

Tuning in the broadest sense of the word.

3k~5k is DI only, that's one of the reason for the drop of tq.
~3k it's dual injection.
3.5k~4.5k is single injection
5k~up dual injection again

Frankly speaking, I don't agree with it .

1. The dip is so big. please refer some other DI engine ( GM, VW/Audi ), yes they also have dip, but much smoother...

2. Dual powerband , i don't agree.. because 205NM for a 2.0NA enigine is not hard, it is a very easy target. Please rever PSA 2.0NA code EW10A which was built in 2006? http://image.xcar.com.cn/attachments...igWFwHzCaU.jpg

or some bmw engines or honda engines. most of them can reach 200NM without DI.



But i don't know the reason ,and it might be a pity... i think.:iono::iono::iono:

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.

Pity? What's the difference between GM, VW, Audi, BMW & FRS/BRZ engine?

It's call BOXER ENGINE! Search all the NA 4 cylinder boxer engine dyno

Untill the Ecu gets cracks now one can answer this, honestly I find this thread pointless as its been covered everywhere around this fourm

Easy now... True, we had this debate on several threads before, but it's not pointless ;)

Sorry that came off harsh I didn't mean for it to, I hate reading and typing as you never can tell someone's tone

Just throwing out another possibility, it could caused by intake resonance creating a low pressure in that rpm range.

Also thanks for your typing

You forgot to use the font SARCASTICA BOLD