2017 diff swap

[Tcoat]

Originally Posted by Tokay444

You're thinking of 50 over...

Yep.

[ermax]

Originally Posted by ZDan

Changing diff gearing is IMO overrated. Power/weight is unchanged, overall performance largely unchanged. You will see modest improvements in 0-60 time, but acceleration from a given speed will either be modestly better or significantly worse if you have to be in a taller gear. At the track, it totally depends on how fast critical corners are. 4.3 could be better or could be worse vs. 4.1.

Also, the difference between 4.1 and 4.3 is so minor there's no way it's worth the effort anyway.

https://www.caranddriver.com/reviews...al-test-review
Predictably, a 5-hp gain and marginally shorter gearing do little to improve measured performance. Our 2017 test car hit 60 mph in 6.2 seconds and covered the quarter-mile in 14.8 seconds—improvements of 0.1 second across the board relative to the last manual BRZ we tested, a 2016 model. Trap speed remained the same at 95 mph.

Gearing for sure is track dependent. Years of competitive sim racing where changing ratios is a mouse click away will teach you that. It’s had for a car to come from the factory with a one size fits all. It does seem a little odd they would change it from 4.1 to 4.3. You would think if they made a change it would have been in the opposite and go with a 3.9 or just enough to get to 60 in 2nd to make all the spec sheet obsessed people happy. IMO the car could stand to run lower revs in 6th at 80mph. But I would rather achieve that with a taller 6th and keep the final the same.

[Summerwolf]

I believe most states in the US is 35 MPH over is the impound cut off.

[stevesnj]

Originally Posted by mrg666

You assert that final drive swap is "great: without giving any reason.

Years of car building experience.

Then ask "what is your goal?"

Logical question

as if you care.

I do, this is a forum and I like to help. If it's not to your liking so be it.

How is "great"? How does that greatness fit to the "goals" you asked?

We are discussing a technical topic, I would expect a little more logic and reason in the discussion.

I said what I said, it's logical to understand a gear swap suggestion and, to me, is a logical first step compared to FI. I think that without knowing the OP's goals your opinions are as valid as mine. Maybe they don't want FI. Maybe they do. Seems like a logical question to ask. But it's fine you don't agree.

[mrg666]

Originally Posted by stevesnj

Years of car building experience.

Logical question

I do, this is a forum and I like to help. If it's not to your liking so be it.

I said what I said, it's logical to understand a gear swap suggestion and, to me, is a logical first step compared to FI. I think that without knowing the OP's goals your opinions are as valid as mine. Maybe they don't want FI. Maybe they do. Seems like a logical question to ask. But it's fine you don't agree.

Okay, thanks for taking the time to respond. Gear swap is commonly done for preparing race cars for a specific track. But I wouldn't consider gear swap to compensate power shortage on a daily driver unless there is an obvious design error from the factory. I think addressing the real problem, power shortage, is the solution. And, I agree, FI is not for everyone. But a simple header+tune can be a more suitable alternative.

[Tokay444]

Originally Posted by mrg666

Okay, thanks for taking the time to respond. Gear swap is commonly done for preparing race cars for a specific track. But I wouldn't consider gear swap to compensate power shortage on a daily driver unless there is an obvious design error from the factory. I think addressing the real problem, power shortage, is the solution. And, I agree, FI is not for everyone. But a simple header+tune can be a more suitable alternative.

All completely subjective.

[nextcar]

Originally Posted by mrg666

Okay, thanks for taking the time to respond. Gear swap is commonly done for preparing race cars for a specific track. But I wouldn't consider gear swap to compensate power shortage on a daily driver unless there is an obvious design error from the factory. I think addressing the real problem, power shortage, is the solution. And, I agree, FI is not for everyone. But a simple header+tune can be a more suitable alternative.

And what about people in California with strict smog inspections that want to retain the reliability and convenience of a naturally aspirated engine that can be serviced anywhere?

[nikitopo]

Originally Posted by nextcar

And what about people in California with strict smog inspections that want to retain the reliability and convenience of a naturally aspirated engine that can be serviced anywhere?

+'17 OEM header and tune

[mrg666]

Originally Posted by Tokay444

All completely subjective.

Of course! Do you have any technical comments to share?

[Tokay444]

Gearing can have a drastic affect on the way a car performs, all on its own.

[FRS Justin]

Originally Posted by mrg666

You are still not showing any equations and/or data that shows top speed increases with 4.3 final gear ratio. A ton of blah blah though that I won't even read.

Here two more references
2013 BRZ Top speed = 140 mph
2017 BRZ Top speed = 134 mph

We are done.

Bro you cant go off a spec in a car magazine. While your theory has some merit it is wrong because you left out the 2013 has a different engine config and tune than a 2017 and it has a different hp ratings. The car will go 6 more mph with the additional hp get their faster and it takes less engine output to achieve goal with a higher ratio. if you want to use math to back it up you need to include all the variables like max rpm tire size drag coef gear ratio in trans and diff then factor in your torque curve and several other factors to get the correct answer its not a simple equation

[FRS Justin]

Originally Posted by JOE APO

Has anyone attempted to swap out their stock differential with the new 2017 rear diff? I've been thinking about doing this to mines due to the more aggressive gear ratio,but i'm not sure if the new diff has different dimensions that would cause some sort of issues. If you've tried this or have some insight, comment below. Thanks guys!

Best bang for the buck period. I have used several different ratios in my FRS from 4.10 to 5.71. Buy a complete diff on ebay sometimes you can find them for 600 bucks. You wont be able to have it done cheaper than 600 bucks unless you do the install then its still close to 600. If you don't like it switch back to your factory and sell the 4.3. I suggest 4.56 tho it gives you great performance with the least amount of loss what I would call the best of both worlds
Good luck

[mrg666]

Originally Posted by FRS Justin

Bro you cant go off a spec in a car magazine. While your theory has some merit it is wrong because you left out the 2013 has a different engine config and tune than a 2017 and it has a different hp ratings.

So, I should believe "you" instead of a car magazine (not one btw)? You are so funny.

[nikitopo]

Originally Posted by mrg666

So, I should believe "you" instead of a car magazine (not one btw)? You are so funny.

You shouldn't say this. FRS Justin is a very knowledgeable member.