Angry Slipper

Long story short:
Does any mfg produce closer ratio gear sets for 6spd Evos? I mean LOWER max speed, MORE shifts, but more torque at wheels. I know most people here tend to install lower final gear from sheptrans (4.11 vs 4.5 stock) resulting higher max speed, but I want the opposite! Or better stock final gear, but "closer", higher ratio 1-6 speed gears. Don't want to switch to 5 speed for the same reason.

The car will be tuned for 500-600whp.

Any ideas?


Full version:
I have 2 JDM evos - 1996 evo4 and 2003 evo8 which I bought a year ago, both with entirely stock engine (still). Evo8 is what I'm driving now. Evo4 came with 5spd "close-ratio" gearbox, which results max. speed being only ~110mph @ 7000rpm, but the thing accelerates like crazy! It outperforms evo8 0-60 and at cornering (assuming driver doesn't suck at shifting gears).

The following is relevant to my driving habits, some of you may disagree:
I rarely go faster than 130mph, but I often go slower than 30mph. With stock gears you have to reach certain speed in 1st gear before turbo spools-up, that means you basically CAN NOT corner slower then at certain speed, otherwise you won't have any torque! No torque means no control over your car.

I never allow rpms go lower than 4000, I never shift up sooner that I reach 6500 rpms. Even if I drive in relaxed kind of manner, rpms are still guaranteed to be between 4000 ad 6500 rpm. I drive like this ALL the time.

I'm gonna install larger turbo which spools later than stock and, naturally, that means with stock gearset I'm gonna have even wider low-torque speed range on 1st gear which isnt' good. I absolutely don't mind sifting a lot. Actually I got used to it so much on Evo4 that I had to change the whole driving style when I switched to Evo8.

Here's one more thing about shifting. If you want your clutch to last you want to not let it slip all the time. That means you have to match revs of the engine with revs of transmission depending on the gear you are shifting into. For instance, if you're shifting from 7000rpm you 1) engage the clutch, 2) shift into next gear and WAIT while revs drop to ~5200 rpm 3) disengage the clutch. If you have stock flywheel (like I do) you will have to wait 1-2 seconds only for the RPMs to drop!

Now if you have closer ratio gear set, revs should drop from 7k rpm to ~6200 rpm which makes your being able to shift 2 times faster without extensive clutch wear.

So, I guess this is it. Would be awesome to hear comments from people with similar driving habits as mine.

ktk

iTrader: (9)

You bring up an interesting request. Do you have a list o the gear ratios that are in your Evo 4? I'm curious as to how low they are compared to the Evo 8, which itself is pretty low geared car. Pretty much all Evos have sprint gearing compared to normal cars!

In any case, it sounds like you are a big fan of quick spooling torque available at around town speeds. I think rather than changing gearing a better solution to consider instead of going for shorter gearing, will be to go for 264 cams, 3" turbo back exhuast and a retune.

If you would like to retain a pretty smooth stock idle and very civilized feel, HKS 264 cams are a good choice. With HKS 264s you can retain stock springs and retainers.

Any 3" full turbo back exhaust will be fine, choices of mufflers and cats have a small (~5-15hp) impact on power at this level but in all honesty, how much/what kind of noise it makes is usually a bigger issue for most street/daily Evos.

That will get your Evo 8 to around 280-300whp and it will have very quick hard hitting torque and fast spool. It will feel MUCH quicker than stock around town, and has reasonable top end power, but since you are not really looking for top end this should be a perfect match for you.

The main reason i suggest this route instead of changin gearing, is that since you plan to upgrade power as you go, much shorter gears are going to bite you in the ***. My car is a 2.3L stroker with a slightly larger turbo it makes only 400whp/ 380tq but the torqueband kicks in so hard and early that even from slow rolls there is nearly NO time to shift from 1st to 2nd and 2nd to 3rd and that is with stock gears! I can't imagine trying that with even shorter gears it would be insane.

The low gearing might work ok on stock power, but with more power the ratios being too close will make it really hard to shift fast enough to get the maximum speed out of your factory manual trans consistently.

Angry Slipper

As for Evo4, not entirely sure, but I believe it should be like this (as per Co-ordSport's transmission paper)
1st gear - 2.785
2nd gear - 1.95
3rd gear - 1.444
4th gear - 1.031
5th gear - 0.72
final - 4.875

I am going to tune Evo upto 500whp (bigger turbo, 2.3L and all the related stuff).

ktk, What about rpm drop I mentioned? Whatever power you have you still have to wait for rpm to drop before you disengage the clutch. What kind of flywheel do you have on your car?

Epix_

http://www.sheptrans.com/transmissions/evo.htm

Look at the options

Angry Slipper

I did. Don't see the gear ratio options. 4.11 final gear is not what I' looking for.

ktk

iTrader: (9)

You are actually very right about this. In order to minimize stress on a clutch, making sure the engine speed matches the transmission speed before engaging the clutch is a must. I'm not new to it, I daily drive a 400whp stroker evo with 78k miles that is still on the stock clutch and flywheel

The tradeoff is that you have to wait a short time for revs to drop. Now going to a lighter flywheel will shorten that time, but there is a practical limit to how light you should go with a flywheel. Too light will make it difficult for the car to idle properly, and it will stall more easily on start from a dead stop. The factory flywheel in the Evo 8 is already "aftermarket" meaning it is similar to what other cars would see as an upgraded aftermarket flywheel.

Unfortunately there is no easy fix for this issue. If you shift very fast, your clutch WILL take more stress as it rubs to reduce engine speed to match transmission speed. With low power cars (close to stock) you can get away with this sort abuse only because the stock Evo clutch is pretty damn strong for a stock clutch.

If you plan to race or a up power significantly, or you drive very aggressively a lot of the time, your only option will be to go to a stronger clutch, that will better be able to deal with the abuse, without failing.

If you launch your evo at all, then forget the stock clutch altogether, it does not do well with launches, even on slightly modified cars, it will severely shorten the life of the stock clutch.

ktk

iTrader: (9)

Ah yes, I just saw your edit and target or 500-600whp! I gotta warn you man, with that much power and shorter gears shifting 1-2-3 is going to be retarded. You will have to move with the quickness and misshifts and overrevs and tires breaking traction it will be chaos. And you will end up in the ditch lol or with a broken car!

If you want to go to very radical low gearing in such a high power car, you are going to have to get a sequential gearbox to make the shifting more doable. I still think it is not necessary, traction is going to limit your 1-2-3 acceleration from low speeds in a 500-600whp car especially on street tires on the road!

Big turbo and all will tend to give you high end, but in teh process of chasing 600whp, you will almost definitely loose a bunch of quick hitting low end torque. Its a trade off. Big high end power will end up costing u low end response, spool, and torque usually.

Angry Slipper

Thanks for such a reply man

I've already ordered Excedy HD. It comes with flywheel which is supposed to be somewhat lighter than stock. Light flywheels are awesome to drive (i once did) , everything happens faster - shifts, revs going up and down, acceleration etc. Yes you have to get used to it, but... well.. so what?

As for 500whp and close ratio gears.
The most thing that bugs me is not having to wait for revs to drop (that I can fix with lighter flywheel) or anything but not being able to powerslide at slow speeds. For example, when you do a U turn, you slow down almost to a complete stop and you do have to accelerate as fast as possible on your way out of the turn. Which you can't, cause your revs dropped to low throwing you out of torque curve even on 1st gear. I'm not a drag racer, more rally-style actually

Yes I though about "how the hell am I gonna master 500whp with close ratio gears" and you do make a point there... probably I should first get the engine built/tuned, actually drive 500whp and then decide if I want to change the gear ratios...

ktk

iTrader: (9)

hehehe sliding the back of an Evo around is gonna be a handful especailly a 500whp Evo on tarmac. on gravel you can do it easily with half the power, but if you are looking for tail out control and fine throttle steering, you need a RWD car! The Evo is designed to grip and it doesn't like to let go hehehe. And if it does in a corner with a top heavy powerband and sudden boost, controlling that back end will be exciting to say the least!

If you are aiming for a rally/curvy backroad style car, then I might suggest a stroker motor and a small to medium size turbo some where between FPred and Gt35 nothing bigger. Anything more than that will have unacceptable lag for curvy roads. I would also suggest 272 cams instead of 280, becuase they will help to keep your spoolup characteristics while still having decent top end kick. 280 cams tend to sacrifice too much on the bottom end, for anythign but drag racing.

Combination of 2.3L stroker with a upgraded turbo will give you quicker spooling hard hitting torqueband you don't easily get with the 2.0. You won't have to rev as high but you will have a much meatier fat torqueband to play with on the backroads where speed varies greatly and you are constantly in 2-3-4 gears. That's basically how I have my car setup too.

Good call on building the car first and trying it with gears to see if that's what you like or not. Best of luck! 500-600whp and quick spooling for hard hitting torque out of the low speed corners is a difficult balance to find!

Angry Slipper

That's exactly what I have in mind. Already bought 272 Kelfords. The problem is to choose turbo setup that would still spool fast and get me to 500+whp. To my mind FPred or FPgreen wont be enough, i think I wanna go twiscroll but can't decide on actual setup yet. What kind of turbo do you have and which stroker did you do with? What are revs limited to?

ktk

iTrader: (9)

Hmmm...I'm afraid I'm not sure what turbo to go with to get 500whp AND very quick spool.... HTA35 twin scroll? you will need to have meth/alky injection i think though.

I went with a JAM stroker, and a Turbonetics 60-1

GPTourer

I think a custom dogbox is what you are looking for, but if its anything like what it is for DSMs, you will lose fifth gear entirely.

MR. EVO MR

iTrader: (9)

great read so far