Am not too bothered about the short ratio between 1st & 2nd as not so much into drag race. I read somewhere that Kia intentionally made 1st gear to be high. The spacing between 3rd, 4th, 5th are nicely spaced as this is what is normally needed during my spirited drives When I first got the 6AT Forte, my old skool brain had to relearn how to use all those "extra gears" I then taught myself to think that Kia 6AT 2nd & 3rd is like 2nd "low & high gear", whereas 4th & 5th is like 3rd "low & high gear" of the old 4AT ride. Taking the car up Cameron's (with 3 adults on board) via Tapah exit, impressed the hell out of me. Overtaking slow lorries & going up (& sometimes overtaking slower cars on) very steep inclines was a walk in the park on 2nd & 3rd.

As for fuel mixture, there is always a range (eg. 0.5 to 08%), & even if CO=0.5%, it would still not overheat the engine (provided the cooling system is in order). With the car being only 7 months old, I would suspect its still very much within factory specs. What I meant by "lean", is that it is set to the lower end of the mix range.

As for the lean "test", it's the old "hot palm" test on the exhaust (yes, very old skool & based on guesstimate). My old ride had a bypass screw on the AFM that allowed minor tweaking of fuel mixture. Haynes (manual) mentioned CO range of 0.5 to 1% but butt dyno & friends all agreed that 1% to 1.3% was the ideal for that old engine. It was from 10 years of tweaking the mixture that I got to know what feels lean (very hot exhaust) & what feels "just right" (nicely warm exhaust). The Forte exhaust felt "hot" (thus low end of the mix, according to the old skool guestimate). Too bad I cant get hold of a CO meter to verify this suspicion. Plus this Theta II has a hot film MAF which cant be tweak like the old AFM. Everything is ECU controlled. Perhaps driving an old low tech car for 10 years have taught bad habits that's difficult to unlearned

Based on the old ride's butt dyno, slightly richer mixture gave me the mid range torque that I normally need for spirited driving (as earlier mentioned, drag race doesnt interest me & I hardly redline. Thus trying to make full use of the mid range of torque was my goal).

Also, the sound of the engine during lean mixture is rather "hollow" (akin to banging on an empty tin) but a richer mix would get the nice idle throb & bass growl during mid-high revs. A nice bass growl would somehow make spirited drive much more enjoyable (if you ever heard a RR Merlin V12 engine roar in a Spitfire, you'll know what I mean. Absolutely spin tingling. As yet have not found a single car engine that can match that beautiful sound of a Merlin V12).

Also, got a feeling that these new engines have some sort of a lean burn technology in them, to not only meet the ever more stringent emission controls but also to reduce fuel consumption. I overhead a rumour that the Proton Inspira 2.0 (same engine block as the Kia Theta II) gives out slightly higher torque & bhp (vs Mitsu Lancer) as the ECU been tuned to less stringent M'sia emission controls.

wow Lanchio, i wish i had a brain like urs...same goes with gregy...u all really knws alot more deeper than mere mechanics...using physics on the terms..

What a difference ! The 2nd gear of the old 4 speed autobox can be revved all the way to 110km/h.... Not that it's advisable as you'll be passing the peak torque at 4200rpm by then.

That's true..2nd gear can be revved all the way to 110km/h for our 4 speed autobox..i've tried it once last time. However, mine is the 2.0 Forte..not sure about the 1.6 Forte (4 speed) whether it can achieve the same figure

Yea, good details there...

same. but unsure whether its 100km/h or 110km/h

Actually, there's more to why I would have preferred a longer 1st and 2nd, not merely for drag racing. Most of the time, for normal launches, the GB tends to shift from 1st to 2nd a tad too early. Example, making a U-turn. Before I can even complete the turn, 2nd gear is engaged. There's this u-turn that I take everyday on my way to work. Immediately after the turn it's an uphill climb. Starting a climb at the bottom of the rev range in 2nd, is quite sad really lol...

Speaking of ol skool rides brings to mind an old Mazda 323 1.5-litre Twin Carburetor I had last time. It was really fun to drive, akin to having an enlarged throttle body by today's standards. However, it was a b1tch to tune, because each carb served two cylinders and I had to make sure that they were tuned every now and then. I actually had a spark plug window car tuning device (it was a spark plug with a built in window with which to view the combustion chamber as the engine was running. By adjusting the individual idle screws I could lean out or enrich the mixture. The resultant color of the combustion (light blue or yellow) indicated if the car was idling lean or rich. Fun, right? I guess I'm one of the few ppl who's actually ever had a look inside a real combustion chamber while the engine was running lol. Whenever the combustion window revealed a light blue flame, upon checking of the exhaust emission by hand, there would be condensation spitting out from the tip. I also "tuned" my nose to smell a rich idle. Just a quick whiff, nothing serious (I hope!).

I probably used more fuel for tuning than I ever saved from tuning LOL...

As for the Forte, I get what you mean now about a lean mixture. However, two things come to mind. Firstly, since there is a Cat Con in the exhaust downstream, I perfectly understand if the ECU needs to keep a tight range on AFR. Too lean and the Cat Con won't be effective, too rich and it might get destroyed. Did your previous car come with a Cat Con? I am inclined to believe that the difference in exhaust temps at the exhaust tip of a car with and without a Cat could affect butt dyno assessment of AFR, since a Cat typically multiplies exhaust temps upon exit. Besides, modern ECUs tend to "swing" within a range of AFR values, lean one minute and slightly rich the next. It doesn't stay in a fixed position. So it could be possible that while you were assessing the temp at the exhaust tip it was in the "lean" cycle.

All that was said in the previous para, referred to idle AFR. The second thing that comes to mind, is AFR on the go. We can't really tell if a car was lean or rich during different stages of throttle input without hooking the car up to a wide band 02 sensor and a laptop via OBD-II. Then there is the CVVT to consider. I learned this fairly recently, after having spoken to a renown local tuner who's been doing wonders for many different makes of cars. The thing is, all cars out of the factory come with a generic tune that caters to the lowest common denominator, i.e., the worst case scenario. This is how aftermarket tuners are able to tune up individual rides to their highest potential. In the meantime, we have a generic tune that is both safe and economical. On whether a rich or lean condition would be better for performance, we can't really say. According to many of this tuner's satisfied customers, not only did they gain a more potent engine, they also returned better gas mileage too.

As for mid-range "growl", typically an engine is made to run rich during wide open throttle. Not sure about partial throttle, but it definitely isn't at stoichiometry for sure. As I mentioned earlier, with the ECU governing pretty much everything except your right foot, things aren't as clear cut as it used to be. You might find that enriching the AFR might not give you the result that you seek. To get what you want, it's best to consult the expert tuners. I might do it at a later stage once I'm done modding the IHE

Cheers.

i'm experienced this too, its not happened all the time, after own it for 5-6 month (24k KM). if i could remember, it only happened 2-3 times.

erm...i also not sure about this...

hi, may i know the reason? i was thinking maybe the RM100 is used to make the car plate and the money we paid is only for the number...correct me if i'm wrong

would it be dangerous to do that?

but bro SG, why when rpm hit 4.2k rpm feel the power still not enough...
need to rev until 6.2k rpm then baru omphhh...

nope... hahaha....
when someone 'cucuk'ing u from the back, u'll nvr think about the above...
all u think is run run run far away from them...

This post has been edited by epo: Sep 30 2011, 09:50 PM

Many non-performance orientated engines, including our ThetaII, attain peak torque around 4K rpm and rapidly drops off beyond that.

Once peak torque is achieved at around 4200-4500rpm, the engine will gain power most rapidly hence the acceleration surge. The engine will still be roaring loudly beyond 5Krpm as the revs climb slowly towards the peak power/bhp at 6000rpm, but the acceleration would be significantly less at 6Krpm than when it was in 4-5Krpm.

Take a look at our ThetaII's output graph (should be available in your Forte brochure). There's a nasty-looking plateau between 2-3.5Krpm which is good for fuel economy but bad for acceleration. And there's the narrow window between 4-5Krpm where you get a sudden steep rise to reach peak torque. Keep your revs in that range and you'll get maximum acceleration... and then upshift as you feel the acceleration starts to slow down (which will be around 5Krpm).

Try it (safely, of course !)... keep in 2nd gear as you accelerate past 80kmh. You should be hitting 4K rpm as you go beyond 100kmh and then immediately upshift into 3rd while flooring the gas pedal. Your revs will remain at high 3Ks as you upshift, then climb swiftly to 4K and in no time you'll be flying past 140kmh.

Do this often however, and you'll cringe at the next petrol station visit.

This post has been edited by StarGhazzer: Oct 1 2011, 10:16 AM

anyone??

I sent my car on 21th September to SC, and it's still there waiting for NAM team to finalize. Damn it, I miss my car.

In a nutshell, peak torque simply means the rate of an engine's acceleration has now peaked, but it doesn't mean you can't go further until the peak hp because the engine is still pulling the car forward. HP and torque are inter-related and shouldn't be treated as different forces acting on your engine.

Here's an explanation of the relationship between torque and hp.

HP = (Torque x RPM) / 5250

Read this for a better understanding: http://www.largiader.com/articles/torque.html

So in future, don't be misled that torque is for pickup and hp is for top speed. It confuses people into believing these two figures are somehow different forces.

HP is simply, the amount of work done over a period of time.

Torque is simply, how fast you can do the work over a period of time.


Based on the above formula, I calculated that at 4,300rpm, the Forte 2.0 is generating around 117hp. To do your own calculations, first you need to convert Nm into lb-ft and PS into hp. Use this http://www.mr2ownersclub.com/converter.htm


Simply put, there is nothing wrong in going above the peak torque when you're gunning for max acceleration, because if you were to shift at that point, your rpm will drop, so will hp.

Anyway, there is a rev limiter programmed into the ECU. If we weren't supposed to redline it, the engineers would have put the rev limit at 4,300rpm and not 6,200rpm.

just wanna ask sifu out here..

can I change our stock tyre to 215/50/R17?

FYI, my ODO already reach 40K..n I think its a good time to change tyres..
tyres lifespan is more or less 40K..sudah botak dy..

Not a problem because it is within 3% difference. It will be a bit more comfy but you will feel the car to be slightly sluggish compared to before.

hey guys hw much does it cost to respray only the bumper?

After reading what bro gregy posted and more importantly the articles from his link, I must admit I may have used the term "acceleration" incorrectly to refer to the punchy, oomph feeling. My apologies.

It seems that to gain speed faster, i.e. accelerate, upshifting at peak power which in most cars are at/near to redline is more appropriate. Peak torque is the point where you feel the oomph, but your car doesn't necessarily "accelerate" faster.

Now that's why I feel the oomph once I go past 4Krpm, and not as much as 6Krpm although in reality the car is accelerating and gaining more speed near redline.

hi, i plan to get a forte 2.0 but since now is year end do you guy think i should wait for 2012 forte?