Full throttle for the first time

[stlgrym3]

Per tuner’s request, I need to do data logging at full throttle in 2nd gear. Couple questions:

1. I originally thought full throttle was flooring the gas paddle, but I was told for 2017 AT models we have to press even more at the end of the paddle travel to activate full throttle. Can someone confirm this?

2. What’s the top speed gonna be at full throttle in 2nd gear all the way to redline? I’m kind of nervous about doing this on a public road.

[jflogerzi]

Originally Posted by stlgrym3

Per tuner’s request, I need to do data logging at full throttle in 2nd gear. Couple questions:

1. I originally thought full throttle was flooring the gas paddle, but I was told for 2017 AT models we have to press even more at the end of the paddle travel to activate full throttle. Can someone confirm this?

2. What’s the top speed gonna be at full throttle in 2nd gear all the way to redline? I’m kind of nervous about doing this on a public road.

1. Not to sure

2. should be 55MPH ish...

[RJasonKlein]

Full throttle is full throttle - meaning pushing the throttle down to its maximum travel. I have a manual transmission equipped FR-S, but if the throttle pedal on your car works like it does in most other cars with automatic transmissions, there’s a slight detent at the end of the normal travel that you must press through to get to full throttle. Typically, the detent activates a switch used by the ECU or transmission control unit to initiate a downshift - someone with more experience with an automatic equipped FR-S/BRZ/86 can jump in and correct me if I’m wrong.

I have no idea how quickly you’ll be traveling at the end of second gear, but I’ve sometimes done my data logging on a lightly traveled highway during off hours where I can judge the gap to the next car behind me (ideally, when there is no one even viable in my rear view mirror), slowed down to about 1,000rpm, initiated the data logging software, and then running through whatever gear I’m told to data log in. You may end up speeding, but probably not by much. In your car, I assume you’ll need to be in manual mode to lock the transmisssion into second gear, and then you should be able to do three quick successive runs from 1,000rpm to redline in the same data log.

[stlgrym3]

Just finished the full throttle logging in 2nd gear. I pressed harder beyond the bottom of the pedal travel, but I did not feel the pedal went in any further to signal of activating full throttle, however, I did feel the engine gave me that extra oomph so to speak. I guess the rev limiter kicked in toward the end (since I was well into the redline), as I felt my fuel was cut.

[tyler_win_photo]

Originally Posted by jflogerzi

1. Not to sure

2. should be 55MPH ish...

Closer to 62mph for an automatic at the top of 2nd. 2017 autos did not get the 4.3 FD.

[Fred E]

Originally Posted by stlgrym3

Just finished the full throttle logging in 2nd gear. I pressed harder beyond the bottom of the pedal travel, but I did not feel the pedal went in any further to signal of activating full throttle, however, I did feel the engine gave me that extra oomph so to speak. I guess the rev limiter kicked in toward the end (since I was well into the redline), as I felt my fuel was cut.

For the future, maybe try to let off the gas just before you hit the fuel cut.

[nico_rsx]

Originally Posted by Fred E

For the future, maybe try to let off the gas just before you hit the fuel cut.

Just by curiosity, why?
Is it because since the car is not properly tune yet it's bad for the engine? Or because it's easier for the tuner to read the data if you don't hit rev-limiter?

[stlgrym3]

Originally Posted by nico_rsx

Just by curiosity, why?
Is it because since the car is not properly tune yet it's bad for the engine? Or because it's easier for the tuner to read the data if you don't hit rev-limiter?

I’m curious to know this too. I did mentioned the fuel cut toward the end of the log to the tuner.

[Fred E]

Originally Posted by nico_rsx

Just by curiosity, why?
Is it because since the car is not properly tune yet it's bad for the engine? Or because it's easier for the tuner to read the data if you don't hit rev-limiter?

The fuel cut is quite jarring for the engine and drivetrain and it's certainly not necessary to subject both to that kind of stress. I absolutely hate doing it just because of how awful it feels when it happens.

[Kodename47]

Originally Posted by Fred E

The fuel cut is quite jarring for the engine and drivetrain and it's certainly not necessary to subject both to that kind of stress. I absolutely hate doing it just because of how awful it feels when it happens.

Fuel cut limiters do not cause any stress on the engine or drivetrain. You can't stress an engine by suddenly not making power, or that would mean any time you take your foot off the pedal you're doing the same. The same can be said for the drivetrain.

Yes it feels crap, but that's because of the sudden lack of acceleration.

[Leonardo]

I remember my first time... I was test driving my car.

[RJasonKlein]

Originally Posted by Fred E

For the future, maybe try to let off the gas just before you hit the fuel cut.

I completely agree and thought the same thing when I read that he’d done that. @stlgrym3, the redline is the redline and the engine isn’t designed to exceed it. Will bumping the rev-limiter hurt it? No, but there’s just no need to do it and your tuner won’t get any useful information in the data log at 7,600 or 7,800rpm. In the future when data logging, I’d recommend just running at full throttle to 7,400rpm and then backing off. Like I explained in my first response to you, I often do three or four successive runs from right off idle (maybe 1,500 or 1,800rpm) to redline in the same data log. Your tuner can clearly see where the full throttle pull is taking place and will ignore the moments off-throttle as you slow back down to 1,500rpm again and then do your next pull.

[steve99]

You dont want to lift before rev limiter, as the tuner want to see how the engine is performing under full load ie full throttle), right up to redline.


While second gear is ok and reliatively legal on public roads, it probably better to do runs in third or even fourth gear it the car is going to be tracked, usually this requires a dyno or a racetrack but its usefull to gather that data. As the actual loads and duration of load on engine is different to say lower gears.


Note that what is refered to as "load" in Subaru ecu is not actually load it s a derived parameter based on air flow and rpm, not actual load


http://www.romraider.com/forum/viewt...hp?f=15&t=8218

[nico_rsx]

Originally Posted by Kodename47

Fuel cut limiters do not cause any stress on the engine or drivetrain. You can't stress an engine by suddenly not making power, or that would mean any time you take your foot off the pedal you're doing the same. The same can be said for the drivetrain.

Yes it feels crap, but that's because of the sudden lack of acceleration.

That's also what I was thinking. Just wanted to know if this was something to do with the fact that he's tuning.


I autocrossed my RSX for multiple years, and must have hit the rev-limiter literally hundreds of time. And the engine and drivetrain was still going strong at 175K miles. It was as abrupt as the brz.