Originally Posted by gtengr (Post 3049084)

You would look at everything related to ignition timing and see that the engine is protecting itself from knock during the torque dip if your theory was true.

Originally Posted by nikitopo (Post 3049114)

You have answers and these are not assumptions. It looks that Toyota insisted to keep the dip and have a more economic and environmental friendly car. They never wanted to fix the dip. Maybe to provide a refinement, but never to fix. This is the most official reply you can get:

http://www.ft86club.com/forums/showp...8&postcount=51

Originally Posted by NoHaveMSG (Post 3049117)

So. Why. Is. There. No. Dyno. Of. A. Stock. Car. That. Has. Been. Tuned. By. The. Aftermarket. That. Has. No. Torque. Dip?

Originally Posted by NoHaveMSG (Post 3049117)

So. Why. Is. There. No. Dyno. Of. A. Stock. Car. That. Has. Been. Tuned. By. The. Aftermarket. That. Has. No. Torque. Dip?

I don't know how much more simple to put it then that. Not trying to flame you, or say that your wrong. But if there is not an aftermarket tuner that has removed the dip on a stock car I would say this is not true. There are plenty of examples of tuned stock cars. Still have the dip.

Man I am really sorry to the OP. I always thought the ACE header was kind of over blown but after seeing all the charts, without even bothering to look at the numbers, it obviously works well.

Originally Posted by Irace86.2.0 (Post 3049120)

Is that a common choice for manufacturers to design into a sports car?

Originally Posted by justinco (Post 3047689)

I finished up my dyno comparison with the ACE A-350 header versus my previous Revworks UEL setup. I'll post the full video and then some of the graphs and things here if you just want the nitty gritty :) The video does, however, contain all my thoughts on the how's and why's of the results, too much to type.

Notes: These tests were done at Denver altitude, so dyno weather correction is in effect. My estimation is 1%-2% deviation give or take, based on my experience doing sessions at this dyno the past 4 years, on 3 different cars. RPM's are not exact due to it being difficult to exactly align the dyno with the car, but you get the idea. It is also a Mustang dyno. Enjoy :)

Mods for the pre-ACE baseline dyno session:
Blitz drop-in filter (2017)
Perrin inlet tube (2017)
Revworks UEL header (ceramic coated)
Perrin overpipe (ceramic coated)
Berk HFC front-pipe
Custom 2.5' exhaust, stock resonator, Magnaflow muffler

Mods for the ACE dyno session:
Same as above except swapped Revworks UEL & Perrin OP for ACE A-350 w/ CSG Spec ceramic coating. Re-tuned by Zach @ Delicious.

Image 1: ACE (solid) versus Revworks/Perrin (dotted)
Image 2: ACE (solid) versus bone stock 2017 BRZ (dotted)
Image 3: Fun little heat map to show power differences every 100rpms

http://www.youtube.com/watch?v=ggQspB1P7a4

Originally Posted by Irace86.2.0 (Post 3049124)

His claim was the dip was designed, whether through tuning, exhaust system, intake system, valve timing, or a combination of things. If it is true then only trying to tune it out would work if they only did it through a tune.

Originally Posted by Irace86.2.0 (Post 3049001)

I don't know if they did it for economy. It is certainly possible, and I have even said that same theory in the past, but it was only conjecture. What evidence is there for that? If they cared so much about mileage to create a torque dip then why would they change the final drive on the 2017 to be more aggressive?

I'm of the belief that the torque dip is a product of a 12.5:1 compression motor trying to avoid knock, something that could be alleviated with a long tube catless header, but they need a precat, and they need to heat the precat fast during cold starts for emissions, something that a long tube header doesn't allow.

Originally Posted by Irace86.2.0 (Post 3049007)

Sorry, I'm fairly naive about the details of tuning...

Are you saying the Motec system doesn't use the knock sensors to automatically adjust timing/etc to avoid knock?...that the Motec system only runs on set parameters like open tune only (maf only)?...did I butcher that?

Originally Posted by Harey (Post 3049046)

Correct, either way it's not just in the tune as someone else said previously. In another thread on here all they did was punch out the internals of the cat and the torque dip was gone. Don't think it gets any more conclusive than that.

Originally Posted by nikitopo (Post 3049125)

Do you have any idea what Toyota was selling before this?


Anyway, this is it guys. Have a nice evening and a good morning for me :)

Originally Posted by CSG Mike (Post 3049135)

A Motec can be tuned to, quite literally, do whatever you want, however you want, (and of course, bad combinations can have disastrous results).