SloEvo12

iTrader: (8)

Hey everyone,

I've been searching and mulling this over for some time now, so I'm hoping maybe someone can point me to data I haven't found thus far (which has been fairly inconclusive)...

I'm kicking around the idea of swapping out my final drive to a 4.11/4.10/4.08. After referencing a few sources (people who are in the trans business) I've landed on a conclusion that no one seems to really have definitive information on the change... It also seems there are a lot of opinions on which FD is the strongest/best/etc...

Can anyone show me definitive information about how a car performs with a stock FD versus any sort of aftermarket FD? I tend to believe (conceptually) that there is a power level where the acceleration of a car will stop seeing negative returns by lengthening the gearing. Of course, there's some drag racing benefits by not needing to shift if the car traps fast enough, but what about also considering daily driving, roll racing (1/2 miles/sanctioned), etc...? I've read guys saying their cars were slouches after changing FDs and they can hardly pull out on a hill (seems unlikely to be honest), I've read others saying it was their best mod and the car loads up faster and feels faster, but that all feels rather questionable and clearly it can't be opposing ends of the spectrum.

Relevant info, specific to my build - Evo 9 1st, 2nd, 5th Evo 8 3rd ,4th - 2.0LR, 3586 (1.03 A/R), 288s, Magnus V5, BR FMIC, 3.5" turbo back, etc...

Any definitive information would be appreciated - ideally some back to back comparisons would be great. I've searched quite a lot, but I know it could be buried in some thread that is named "Today I modded my Evo..." or something like that.

Thanks for your assistance everyone. I truly appreciate it!

LetsGetThisDone

iTrader: (1)

I did not like the 4.11 final drive in my car with the exact setup in my sig. I feel like the 2.0L motor simply doesn't have the torque for it, and the taller final drives should he reserved for stroker motors. Your bigger turbo will help once on you're in boost. But it'll feel like a dog when you're out of boost.

lostsoulsevo

iTrader: (10)

I'm not gonna get into the nits and grits with this. My rule of thumb is;
2.3 or 2.4L run 4.08,4.10 or 4.11
2.0, 2.1 or 2.2 stock or 4.31FD

But this is all dependent on your tire setup as well

SloEvo12

iTrader: (8)

Just to keep it in this thread for anyone else searching - "2005 Evo 8 - All the bolt-ons - FP BB Red HTZ - FIC 1650 high-z injectors and Walbro 450 - GSC S2's with GSC valvesprings - Built Trans/Tcase/Diff - English Racing tuned - Mustang dyno 452whp and 391wtq - Coilovers/Various other suspension bits - 18x9.5 +35 Konig Milligrams with 265/35r18 Bridgestone RE11's -" Is that still your correct setup you had/have with the 4.11s? Still a stock engine, correct? Stock compression? No head/intake manifold modifications? Are you still running the 4.11s or have you switched back? Any chance you happen to have any before and after 4.11 dynos/timeslips on your setup? Thanks for your help!

Abacus

iTrader: (9)

I changed my trans from the stock evo 9 to a new RSP built trans with all evo 8 ratios and 4.11FD. My car made 350/350 at that time. It had better driving manners around town but lost ALOT of snap. With that being the only mod my 1/4 mile times went from 12.3@113 to 12.9@107. Similar tune/boost/tires on pump gas.

I added E85 and made 400/400. Didn't get too much better for around town. The 10% change in gearing really hurts the cars acceleration.

I added an Fp red and at 450ish It went 11.7@119. Still much slower then it should be at that level. Eventually turned it up to 600ish and went 11.2@131 crossing in 4th around 7300 on a 25" tire. I run a 6 puck to limit driveline shock and can't launch hard or it slips.

Last year I ran the 1/2 mile and a 25.3" tire and at 8700 it went 149.70 so that worked out.

For the road course the 4.11 is great since you aren't shifting all the time and can focus on driving. My car goes 140 in 4th @8000. I can still drift the car in 2nd on the power with a 25" 255-40-17 Extreme DW tire for what thats worth.

Fuel mileage is also good, on my stock engine/cams on E85 I would get 18-21 or so with mixed hooliganism and highway. The tall 5th mean 80mph @3000 or so.

Now I have a high compression 2.2 and at 530+ it drives really well and is pretty fast. Unless you have a 100mm crank or are going to road course the car I'd leave the stock FD. They make a 4.31 but It "seems" like its got less teeth and more noise then a mitsu FD.

I would control gearing with tire size. That might mean a 25.5" tire or taller tire . If you are into drag racing match your tire size to what mph /rpm its going to cross at.

Tall FD really need a 94/100mm crank IMO.

SloEvo12

iTrader: (8)

So you're rule of thumb is based upon torque output more than anything? I've considered the 4.31, but it's a ~5% overall increase. I wasn't even sure if that's enough to justify the expense or if that's enough to start messing with tire sizes. At the moment I have a set of FDs with QTPs for drag racing, but for street driving I'm running 255/45/17s IIRC. The 4.11s are around a 10% increase, which didn't seem too crazy at first consideration. I recognize off boost response could be a consideration, but my setup should end up right around a 9.5:1 CR and everyone seems to be running 10-10.5:1 CRs as of late, so I would imagine that's still plenty responsive.

Coming from other platforms, a 4.11 FD would still be pretty "short." Even other 4 cylinders (i.e. VW - http://www.eurospecsport.com/product...nsmissions.htm) are running taller FDs with similar gear ratios on similar or smaller displacement. Even 2.0 WRXs (as do 2.5s) ran taller gears than a 4.11 FD would net (sans first gear). I'm just trying to understand if there's some definitive information about how much differently these perform as a platform with the taller FD. It does seem like the Evo 8 first is a better choice for the taller FDs.

SloEvo12

iTrader: (8)

Thanks for the feedback. Awesome videos, by the way! Car looks great!

It's amazing that your 1/4 mile dropped that severely from the FD change. I suspect, since you were stock engine, you were shifting into 4th on both of those 1/4 mile passes instead of riding 3rd out on the taller FD? Or did you drop that markedly and make one less shift as well?

How's the RPM drop between gears? Obviously a lot of this is that the car accelerates more slowly, but maybe first gear is just too long? With the FD change maybe the key is to explore a shorter (than 8) first, but that only matters if the platform performs once it's moving? Maybe the key is a shorter first gear and leave the remainder untouched?

Abacus

iTrader: (9)

Thanks man!
Yes, shifting into 4th on both passes.The stock turbo falls off after 6500 and 3rd doesn't go that fast.

Rpm drop is the same as an Evo 8. The final drive just makes the gears longer but the split between gears is the same.
I chose the evo 8 ratios for the short 1st and tall 5th. A 4.11 with a evo 9 tall first may be pretty hard to get going on a 2.0 and a heavy duty clutch.


In your case, I would just change tires and leave the stock FD. Play around with different street/drag tire combinations.

LetsGetThisDone

iTrader: (1)

Still the current setup. Stock block, manifolds and head except for the S2 cams and valve springs. I went back to a stock final drive. No back to back time slips. I don't drag race my car.

lostsoulsevo

iTrader: (10)

Yes you're correct my response was referring to torque output. A 4.11 would be fine with a Evo 8 first gear and a smaller tire like 24.5 but your taller gears will fall on their face. It's easier to choose your FD when you decide which motor you will be going with.

Evo8ftw

iTrader: (10)

Just sell your rust box and get an sti. ��

TrendSetter

iTrader: (1)

i have a stock motor with s2 cams and some other stuff, and i feel like the stock final drive isnt enough. i really feel like it needs more stroke or a shorter tire.
the car just feels lazy off the line unless i really hit it hard.
If i ruled the world i would have a deeper first, a little bit more second gear, and a longer 6th. but i am 99.5% driving around town and 0.5% goof off at the drag strip.

lostsoulsevo

iTrader: (10)

And what turbo do you have? Please don't say stock....

There's plenty of cars on the 2.0 running 160+ on the stock FD w 26" slicks

LetsGetThisDone

iTrader: (1)

Cams hurt off boost performance a decent amount. Part of the trade off.

TrendSetter

iTrader: (1)

its a ss green.
but i didnt say i COULDNT do something. i said the car FEELS lazier than i WANT.
i come from the v8 world and my other car is a twin turbo full size pickup truck.
my statement was entirely subjective and i tried to make that clear.