blazzer

Looking at some short gear ratio kit's.
blah blah blah, long story short I'm wondering about the final drive for 5th/6th gear.

my math is averaging around 4500-4800 rpm @75 mph.

what im wondering is if anyone has some what of a F/D and or G/R that reflects my numbers above, that you drive with? it crazy loud on the highway's? any obvious and noticeable negative effects on engine/tranny wear?

gotta mention, the engine is either a b16 or k20, it is up in the air atm, but the tranny setup would be.
k20 fd2 tranny
b16 on a 96 itr tranny.

shane(showtime)

iTrader: (1)

I have a 5.08 Final drive in my k24a4 vtec killer setup. Since your Canadian ill talk metric im about 3800 to 3900 RPM in 6th gear at 120 kph.

http://www.teammfactory.com/gear-calculator

I drive up to 7 hours to get to the track and have no issues with noise that the Mfactory final drive has to offer.

10cjennings

iTrader: (1)

45-4800 at 75mph in a 6 speed K20 trans would be like a 5.8-6.0 FD.

1st gear is already useless, that just seems excessively short.

With the oem 4.764 FD 3.5-4k = 70-80 mph on 15's, my longest trips are 3 hours. I would not want to sit in my car revving at 5k for that long for my ears sake, but the pistons speeds of my 2.4 at 4k is about where a 2.0 would be at 4800.

If you really felt the need for crazy short gears but wanted reasonable revs on the highway you could effectively gear the car as if it were a 5 speed, and then use the TSX 6th for highway cruising.

MBellRacing

Not a single "one night in Bangkok" responses to that threat title?!?

m4xwellmurd3r

Of course not. Car guys auto response tranny=transmission.

I dont have a lot of experience with this sort of stuff, but I do agree with gearing the car as if its a 5spd with 6th as a cruise gear.

VTECIntegra9

giggity.
Use the gear calculator above to figure out the exact engine speed / vehicle speed you are concerned with.

dirty19

iTrader: (1)

It crossed my mind Matt. Lol

blazzer

Guess ill be doing some math on the piston speed, i thought at a glance the piston speed would be much higher and constantly being around 4500-4800.

that is prety much what i was wanting to know.
the k, 6th gear and final i was debating with was 0.85 on either the 4.76 or 5.08 FD
so the better gearing in my mind is with the 4.76 but that leaves 6th gear; 4500 rpm @ 76.3 mph(122.79 km/h)

hmm i did not realize the tsx 6th would fit. guessing it has the same logic behind a b-series tranny. most of the family is swappable?


the Gear Box is noise does not bother me. More worried about about the engine/exhaust noise and engine/tranny wear if it is going to be over excessive or quite minor.

I quite liked m-factorys gear ratio's, i was looking at special project's gears and 1st gear is wicked long, so with a 4.76 or a 5.08 even though i would still be running the same 5th? the 1st gear compensation:

SP: 2.313
MF:3.13
stock:3.26

so the thing being, a k20 pushing MAX 230 hp right now. a first gear with2.313 on a 4.766 or 5.08 FD is that good. I did run the numbers for gear/vehicle speed but on paper vs dynamically always seem to be different. anyone have thoughts on this? obviously with the 5.08 im going to be running around 4700-5200 rpm for highway speed's. so im a little lost here and the help is greatly appreciated

10cjennings

iTrader: (1)

I'm not sure where you're getting the .85 6th gear from but doing that would be the the opposite idea of dropping in the TSX 6th.

What are you trying to accomplish via aftermarket final drives and 6th gears?

With the 5.08FD and TSX 6th, your 5th gear tops out around 125-130 depending on rev limit and you can still cruise at 80mph at 3900. If you don't see your self breaking 130 in a race that would be a good way to go.

If I was in the position of sitting at 4500 at 75mph and had concerns about sustained rpms that high, I'd just drive slower. With that gearing you're going 70 at 4000.

This is the transmission calculator I use. It automatically plots graphs where you can see mph vs rpm and you can compare two transmissions

http://www.zealautowerks.com/transcalc.php

blazzer

well the plan is to be able to drive this on the road, but it is going to see a lot of track time. being circuit/race, not drag.
Ya i have been messing around with the zeal calc. for sometime.
well the .85 is part of the gearing ratio from mfactory and special project's. im basically trying to find a balanced in between to keep the 6th gear'd for track but being forgiving on the highway to.

@ the track last year i was hitting about 180 ish (km/h) 118 mp/h, on the longest, fastest stretch. although i was not topping it out, and had way different power numbers.

basically though, my goal is to have a nice balanced ratio for the track and if i can get it, a forgiving decent 6TH for highway driving back and forth from the track.
mfactory, speical projects, seemed like pretty decent gear setup's, but upon my research in to them came across the FD and 6TH gear ratio for highway driving, did a bit more research, then posted up hear about the engine wear and engine noise about highway rpm's and speed.

appreciate the help

10cjennings

iTrader: (1)

Oh, if you aren't sure where the gearing needs to be definitely go with a stock transmission and work from there. You don't want to dump a bunch of money into aftermarket gear sets just to find it doesn't match your local track and new power levels.

blazzer

well i know where it needs to be, on paper anyways. the .85 seems like it would be quite nice for it. more thus aimed towards my original question about the highway driving about engine noise and wear if going with the .85 6th.

more a little worried that even with a 4.76 FD on the .85 6th highway driving was going to be like stupid unbearable loud with insane engine wear being at like 4500-4800 rpm for drives lasting 1-3 hours and the odd 6-8 hour drive a couple times a year.

comes down to asking because i just have not experienced that exactly yet, just looking for input and opinion on it.

Aquafina

iTrader: (3)

Unless you're trying to get several hundred thousand miles out of your engine, no need to worry about wear.

On my D16Z6 I use the MFactory close gear set (1.000 5th) with OEM 4.058 FD. I have around 70k miles on the setup and the engine runs the same as when I got it from the junkyard. I also get better fuel economy (higher RPM = less throttle needed to maintain speed = less fuel used).

The only time noise was ever an issue is when I was open header. With an exhaust (SMSP race exhaust) the noise is tolerable. With a street exhaust it is a non issue.

10cjennings

iTrader: (1)

It sounds like you are just doing trackdays? Unless you are limited to 2.0L via race regulations there is no reason to get a k20. The k24a2 is better in everyway, costs the same and you wont need to bother with this close ratio gear stuff nearly as much because you'll have a motor that actually has a midrange.

blazzer

its a mix of track days and 1 seasonal event (time attack).
part of the reason for the k20, it is readily available to and the k24 is not.

specifically what i do travel between to provinces up here for the season time attack events. my local track days there are 2 hill climb events i participate in merely for the fun and last year i was in a circuit event that i quite enjoyed but wanted too try my hand at the time attack and from there decide what to concentrate on.

the discussion between the k20vs k24 and k24 hybrids i did not like. the piston speed/stroke length of the k24 was a big turn off for me, given i cannot find many people that want to discuss it in depth with me.

and yes there are regulations for the different classes, engine family series,displacement, etc. given these specific regulations are ONLY for the time attack events that deal with engine family code and displacement. they allow head swap as long as it does not increase the engine displacement. d,b,k,h have there own classes in time event's, circuit events do not here they are "open" events based on car weight, HP limits. and a few other things i cant remember off the top of my head at the moment.

TT,it is more strict and is technically not an "open" event, meaning you have to meet the regulations so a lot of it comes down to driver.

...i feel like unless someone wants to get down and dirty with the k24 details, i am pretty set on the k20. That way i can jump between events with little to no changes to meet regulations. let alone i have no been impressed with the k24 (which im sure is partly due to my lack of knowledge on the hybrid swap and also some specs about the engine i was cringing at.)

the reason why i am set on the k20 is vs the k24 is rpm range is higher, deck height is lower, the k20 swap right now is offering more HP "out of the box" then the k24 or hybrid, if i understand correctly. I am officially not turboing so the higher compression of the k20 vs the k24 or hybrid seemed better period.

(sry if my words are jumbled, working off 4 hours sleep here haha )

10cjennings

iTrader: (1)

You don't need to swap heads with the K24a2, it already has the fully Vtec head like the good K20's. Swap the motor in exactly like the k20 and you are ready to go.

Piston speed only becomes a concern when you refer to rev limits. General rule is k24 piston speed = k20 piston speed 1k rpm lower, but the k24's and in particular the 06-08 k24's have much stronger rods then the k20's or the earlier K24's. This only holds any importance for determining how you gear the car with a slightly lower rev limit, once you get that, because of the average HP you don't need to push K24 pistons speeds any higher then the k20's if you don't want to.

The average HP (aka "midrange" aka "torque) of the k24 compared to the k20 is a totally different league.

I went from running a k20a2 for 3 years to switching to an 07 k24a2 and it's a huge difference, ignore the peak #'s (which is what HP based classing is based off, working even more so in the favor of the K24 as your k20 making 230 peak would run in the same class as your 2.4 making 230 peak) and look at the average Hp differences. Going from the k20 to the K24 I gained 15 whp on the top end, but for example at 6k the K20 is making ~175, while the k24 is making almost 220. The graphs speak for themselves, same dyo, same correction factors, both with basic bolt ons (K20 didn't have an RBC, which is why power drops so fast at 8k, it would probably have carried power to 8.5k and peaked around 225ish). You can't see the scale as easily with the 2.0 graph but look at the peak #'s and you can figure it out.

blazzer

( i had to read what you said 5 times to understand it, i gotta get more sleep hahah )
Graphs are quite helpful, thnx for posting them up :D
the thing that i wonder though, the peak rpm is about 6800 ish for the k24? so it would make sense it is near if not hitting it;s peak power, while the k20, only being at 175hp @ 6k while its peak rpm is about 8600.

so i wonder, based on my gearing, (if you are curious i can pm it to you i just don't want to publicly display it.) you think the k24 is the way to go for overall hp through out the power band?
specifically the k20 i can pick up is out of a jdm 2002 interga R from what i understand it does boast a few specs over the k20a2. but my question being does the k20-r still have some what of a crappy mid range when compared to the k24a2? kind of a dumb question i guess...
with short gearing though is it gonna matter much you think that my mid range power is less, while my top end has a lot being that i am never gonna be under 6k anyways?

i mean running on my b16 right now. obviously everything is differnt but i rarely find my self under 6k. slowing down for corners, hair pins etc. with heel-toe and/or rev matching im always trying to keep the engine rpm up for that slow in high rpm entrance and fast high rpm/power exit.

your thoughts?

maybe i am missing the point here... but is it more because the k24 is a mad climb up to peak power and holds, while the k20 is a gradual climb to peak power which is at peak rpm?

10cjennings

iTrader: (1)

6800? The K24a2 came from Honda with rev limits ranging from 71-7600 depending on the transmission. If Honda says 7600 is safe, you can bet there is a nice safety cushion beyond that. I tuned my motor to 8200 because it carried the power pretty well up there (peaked at around 7500, on the top end the stock RBC and TB couldn't keep up with the air demands. A 70mm TB and it will carry that 230 beyond 8k. I'm also running a basic knockoff header with a dented merge collector, and a relatively quiet/restrictive exhaust. High end bolt-ons would make a significant difference.). I currently have the limit set at 8k which is a generally considered safe point for extended high RPM use. But the higher you go, the higher the stresses, There's no exact defined line where it officially becomes "unsafe". If you wanted to be (imo) overly careful, the OEM rev limit at 7600 is a reasonable place to start.

Drag racers are pushing stock bottom ends a lot further then that without issues, but without cams you aren't going to carry the power much past 8k.
K20a.org has a lot of good tech on the K series.

blazzer

hmmm i got some stuff to think about now. hope you dont mind if i save those dyno graph pics.
So your thought is k24 in every aspect, low, mid, top, Hp, Tq, in comparison to the higher rpm output of the k20? just to be clear?
either way thnx for the help, got my Original question answered + more.

Kudos

10cjennings

iTrader: (1)

Yes, I prefer it in everyway to my old motor (it's even smoother with the balanced oil pump and nicer to cruise on the street, which is the least of my priorities), though at peak rpm the differences aren't as significant as elsewhere. Also down the road the room to grow with the k24 is huge. Basic rods/pistons and cams and 270/210 is commonplace.

redGSRguy

10cjennings - What do you think of swapping to a lower FD once cam/rods/pistons are upgraded?

10cjennings

iTrader: (1)

Just depends on If it matches your needs and rev limit. 8.5-9k is pretty common for stock stroke built k24s. The readily available lower fd options I know of are the oem 4.3 and gear x makes a 4.05 (and you can always get a custom FD, but that's $$). Also look at the 5 speed's gearing. Ex: For autox it has a much longer 2nd and is probably the way to go. I'm actually in a position now where 2nd is too short and 3rd is a little long. Debating between the gear x 4.0 in my 6 speed or getting the ep3 5 speed.

shane(showtime)

iTrader: (1)

what events are you running? You must be from out east just one Hill Climb out west and that's Know Mtn. The way I always try and look at my racing as a Hobby is what kind of fun am I going to get out of it at the end of the day. My two cents.. We live in Canada and nothing is going to make us money and we barley have a field of racers to keep racing.. I like my set up the Final drive is perfectly suited for my tracks I go to. Last year I had the Mfactory 3-5 gearset in my D-series box and the straight cut gears didn't bother me. Good luck in your adventures.. Like I said its all just for fun

Aquafina

iTrader: (3)

Don't change the FD unless you're topping out in 6th, otherwise it is just counteracting any additional power you have. The only time to use a higher (lower numerically) final drive is when you have lots of power (boosted) or are using a close gear set.