I never said there was a 'magic snail' and downsizing the turbo doesn't change just change transient response, it changes the powerband/torque curve (reduces lag).

...and I don't think I'll be taking my physics from you because they CAN work that way. If you alter cam phasing, fueling, igntion timing or exhaust temps; you can alter the transient response. Likewise the mass of the compressor and turbine wheel effects transient resonse while still on the same size turbo.

Also you'll find that twinscroll has diminshing returns with the higher the RPM. The strength of the exhaust pulses start to diminish and the signal becomes flattened. Even the people who did the originial development in the diesel world start to find this to be true...in the 3000 RPM range. If you don't believe me, call and engineer at Honeywell, Holset or Borg Warner, if you know one. If you need a few numbers I can give them to you.


/threadjack...back to NA talk.

Not really talking at you Micah, more at the masses.

well the personal attacks are nice. im not even arguing, im just saying that your supports to your claim dont really support your claim. saying you dont want forced induction because of turbo lag is like saying you dont like sex because of aids. i dont think i know everything but i dont know why you think arguing against things i think are wrong is sad.

Come on now, that's hardly a fair analogy.

maybe not but not all forced induction suffers from turbo lag just like all sexual partners have hiv. im aware there are many downsides of FI. turbo lag surprising you out of a corner shouldnt be happening in a properly tuned car and linear power isnt unique or inherent to n/a. were all allowed to have our own opinions. our opinions dont even have to be backed by facts but to sit here and give reasons that dont apply to the spectrum of FI is just silly reasoning

But superchargers do come with parasitic loss, added weight, pulleys wear down, or you have to address increased heat...all extra issues do deal with....

yeah those are better reasons except maybe for weight. i think with power equal FI can take that as an advantage...maybe. its looking like im a little bit of a forced induction fanboy right now. im not, im just saying the reasons listed in that little debate werent really reasons to not want FI

I think there was a symptom/problem misunderstanding. Mid corner lag was the symptom. Poorly sized turbo was the problem.

I still believe there will always be the transient response issue (however slight) with turbos, but they should never upset a car mid-corner.

I probably shouldn't say this since I haven't even driven the car, but sometimes I wish the motor was 2.2 NA with more aggressive tuning/cams and about 230 hp...I think it would have been perfect at that point (and also 5G's more).

I was with you until the "5G's" bit. The price is where it needs to be in order to be competitive. 230 HP would not be enough for $5k more.

I don't want it to be 5G's more, I am just saying that with that type of powerplant, it probably would be starting to creep up to that range.

As it is now, the FRS is at the upper point of my spending budget...I am not making payments unless I can get something like 0.9% APR, so 30K would probably make me reconsider buying the car.

* I have a feeling that the Sti version of the BRZ will be at least 5 thousand more, with around 230-245 hp (if they decide not to turbocharge it). Granted, it would be coming with better brakes, tires, and suspension in addition to the power bump.

If the STI Brz is turbocharged, we could be looking at much more than 30-45 extra hp...but who knows until it is actually released.

By the time the warranty is up, I sincerely hope this car becomes the next "rx7" in terms of LSX swaps. Pure win.

Oh, I can't disagree with that but in the same regards, their is a throttle response delay with NA as well. Every system will have it. You can't change the laws of physics and gas dynamics.


For the others, yes, turbo lag is always terrible.
http://i145.photobucket.com/albums/r...5_Tune_002.jpg
It is ALL about sizing.

Now what I can't emphasize enough and most seem to lack the grasp of is that lag is not the same as a delayed response in throttle (or transient response or 'throttle response'). If your turbo lag is over at 3k and you are into your torque curve, coming back into the throttle from a corner at say 4000 RPM, there may be some slight delay in power onset, this is your transient response. If you are coming off the corner at 2500 (you suck at driving), you are dealing with lag, as the turbo can't be spooled yet. It's the same as 'falling off the cam' on built NA engine. Out of the powerband is out of the powerband and that is on the driver.