is it not the same engine in the kia forte? all using the theta 2 engine

While the block is derived from the same Theta II family, the powertrain is slightly different. The one on the Forte is using the 156PS single CVVT (intake side) while the one in the current Sonata and Optima (165PS) employ dual CVVT, hence the higher output. Funnily, with dual CVVT one would expect the engine to have a beefier torque curve but based on the first hand encounters of forummers here with the engine in both cars it seems that dual CVVT or not doesn't hide the fact that a 2-litre mill has to work hard in the lower rev registers on a D-segment ride.

I believe changing down to lightweight 17" wheels will do wonders for this car.

variable valve timing is actually a very very old trick known many eons ago already, just nobody did it, it was one of the easiest ways to improve power slightly but it can only do so much.

new tech like direct injection or fiat's multi air engine that changes intake time and also the volume of air intake is the next step or turbocharging

Did you say turbocharging as being the next step for car tech? Turbocharging first came to light in 1905 and subsequently saw major use in the two world wars in war machines like tanks and planes.

Btw, Hyundai-Kia's engines run with direct injection too, which raises output by about 20% over the standard multi-point injection variant. And they have a 2.0 GDI turbocharged engine with 275PS with virtually no lag. That's even higher than VAG's 2.0 TFSI which runs on similar principles (direct injection).

There's nothing so new about Fiat's implementation. It still boils down to varying the intake and exhaust lift and duration to control intake/exhaust volume and velocity, just like VVT... Main difference is that it doesn't' rely on mechanical cams to make it happen but a complex hydraulic setup instead. Yes, it does seem to be an evolution of traditional VVT but the fact remains, it is still VVT

While Fiat is working on that, other manufacturers are already working on independent electronic valve control. That is way more advanced, but it is still the same principle of VVT.

VVT came from the late 1800s on steam locomotives.

What we have today is the constant evolution of efficiency in engines, that's all. So what's your point?

don;t expect too much from basic valve timing whether double triple quadruple

I went for a test drive on the 2.0L Teana Luxury and found the Teana to have marginally better low range acceleration than the Optima. Dont know how thats possible with lower horsepower and torque figures and just marginally lighter than the Optima. Based on specs on paper, the Optima should have better fuel consumption.

But generally the Teana absorbs bumps better which is expected since its designed for comfort rather than handling. Its 16 inch rims are also suited for a more comfort based drive compared to the 18 inch rims on the Optima. Felt the leather seats on the Teana were better than the Optima but im really amazed how anybody could ever like the interior of the Teana. Its really bland and the worst has gotta be the dashboard.

No bad intent here but i really felt 10 yrs older in the Teana. The Sylphy was the worst. The dash has gotta be among the worst in its class. But the Sylphy has better legroom compared to the Teana. The Optima's legroom is similar to the Teana.

But i really wanna know how the dual CVVT 163HP and 198Nm torque Optima could possibly be sluggish on low range revs. Anybody care to provide some insight?

My father own the new Sorento with 2.4 litre Theta II, 184 horsepower... So we test drove the Optima.. Yes it is abit weak on lower rev range...

I think maybe the gearing is abit high... (Sorento can go as high as 105 km/h in 2nd gear )

But with Sorento no problem... Maybe coz it got more torque...

But to my experience Theta II engine, be it 2.0 or 2.4 need high revs to milk out the power...

FC is very good... My father Sorento 2.4 has better FC than his Accord 2.4 (K24)

This post has been edited by masz94: Feb 7 2012, 09:19 PM

It could be the gearbox configuration, which is mated more for speed, rather than pickup.

As long as you understand this formula: [HP = (Torque x RPM) / 5252] you will understand the relationship between torque, rpm and hp, and why a car with CVT will generate more power at any given rpm throughout the rev range.

This explains why in the past I could outgun a Perdana V6 (148PS) uphill to Genting, right to the top with my humble (but lightly modded) Honda City iDSI (88PS). He was behind me all the way, and with every successive hard turn I left him further and further behind. Due to a 4AT, he couldn't take advantage of his 148PS (revs climbing too slowly) while my car with a CVT is gunning uphill between 4000-5500 rpm all the way, generating most of that 88PS all the way. You should have seen his black face when we reached the top lol...

Anyway, you can't really judge a car's performance based on its max torque and max hp figures alone. However, suffice to say that the 2-litre Theta II engine isn't the most peppy engine around and you'd need to really work it to get some meaningful horses out of it. Of course there are certain soft mods that can be done to make it more responsive

er....cough cough so the 2 liter CVT lancer or slyphy is the king of uphill touge?

What is the engine oil specified for Kia?

---

Added on February 8, 2012, 1:49 pmSo whats the downside of the CVT compared to a normal 6 speed auto? Lifespan?

This post has been edited by cybermaster98: Feb 8 2012, 01:49 PM

10w-30 4L for forte...

perhaps u are a better drive than him.

Look at the torque curve of the engine and you will know why.
You don't get 198nm at low rev range. It's only at medium to high rev that you get your torque. So the sylphy engine produces more power at low rev range say from 1-4k rpm and loses only at high rev range. In fact the sylphy engine is more powerful than civic 2.0 engine up to 4.5k rpm. You can take their brochure, plot out the torque graph and you'll see why.

This is also why max torque and max hp is misleading. Nobody revs their engine up to 4000 or 6000 rpm to accelerate in normal situation.

Right on the money, that is why when i look at Elantra torque curve, all the torque is only achievable at 6,500RPM, how often do you rev the car to 6,500RPM?

when someone is chasing ur back... trust me... u need it...

Can ask what brand of OE oil they use?

Actually, the main point here is that while ordinary slushboxes will have to row through the gears (which in effect means varying torque/hp due to varying engine speeds), with a CVT the ECU will bring the engine speed up to around its max torque range (usually around 4,000rpm) and let the infinite ratios work its way up. Consider the following:

Engine A with CVT 141kW @ 6,000rpm, 245Nm @ 3,500rpm

Bring revs up to 3,500rpm. At this rev, there is 90kW at 3,500rpm available

At this point from 0km/h to maybe 60km/h, a constant 90kW of power brings the car from 0-60km/h.

Then, rev up to 6,000rpm to realize the full 141kW of power.

From this point on, the car has this amount of power consistently pulling the car forward from 60km/h to whatever speed you want to reach.


Compare this against a standard auto tranny:

1,000 rpm = 20kW
2,000 rpm = 48kW
3,000 rpm = 77kW
4,000 rpm = 102kW
5,000 rpm = 126kW
6,000 rpm = 141kW

With every gear change, you start from around 3,500rpm (90kW) and build up towards max hp, while on a CVT you are running at or close to max hp (141kW) the whole time while waiting for the transmission to gear up.

petronas but not sure which model... there're 2 types only, mineral + full syn... no semi...

that's why abit hard to explain the concept of power to lay people..
torque/force you can feel, time/angular velocity you can measure..but power is product of those measured indirectly to get the figures.. so normal people will not understand what power means.. that's why is so hard to explain why look at torque and look at peak power of the engine crank shaft is quite meaningless, and why at the end of the day the results is only measured at the wheels after going thro the gearbox to the drive wheels (i.e. on dyno)...

changing even the final drive gearing will give you different feel to the car let alone different gearbox technologies like DSG/Auto/manual/CVT whilst not even touching Engine modifications yet.