Toyota's Dual VVT-I Vs Honda's I-VTEC DOHC (K Series) Options

[Shouyi]

Hi,

with the rumours of a new 1.8L Dual VVT-I corolla, I am wondering what are the major differences b/w a Dual VVT-I unit and a I-VTEC DOHC unit. And which is more advanced. Let's discuss!

[Normal_aspirated]

wow, seems like the trend of japs & koreans upsizing their engines for new models.

[EventH]

Donno about which being more advanced.
The old Dual VVTi Altezza produce some 210hp (6MT) from 2L with 21kg.m torque. That is nearly a Honda "R" engine spec.
The new Dual VVTi V6 2.5L in the Mark X (6AT) does 212hp from 2.5L but had 26.5kg.m torque at just 3800rpm.

Actually toyota just need to put the 1.8L VVTLi from the SS2 Celica into the Corolla and the thing will also fly.

[Chenqien]

eh dual vvt-i means cam phasing in both intake and exhaust valves...

i-vtec in the k block integra type R engine uses cam phasing only on the intake but has cam changing ( the traditional vtec where there is a wild cam ) thingy.. same concept as the vvtl-i.. the rest of the i-vtec i not so sure...

both are good.. but for everyday driving there is no really need for a wild cam..

[Gary84]

sorie...correct u abit...Mark X churning out 215bhp...

[Odyssey02]

i think i'll say honda produces better engines. they're renowned for it. maybe this'll be a biased viewpoint. furthermore, there seems to be some sludging problems with some toyota engines.

[Tanjkp]

Pardon me, you mean the dual VVTi also have the higher cam lift as the the Honda Vtec ?

[W210k]

I don't think all Dual VVTi engines have the wild cam. It's dual because its required for the V6 engine's setup (quadcam vs DOHC for in-line engines).

Toyota's VVTi-L is more akin to Honda's i-VTEC. Both have phased valve timing and lift control.

[Webbyboy]

Donno about which being more advanced.
The old Dual VVTi Altezza produce some 210hp (6MT) from 2L with 21kg.m torque. That is nearly a Honda "R" engine spec.
The new Dual VVTi V6 2.5L in the Mark X (6AT) does 212hp from 2.5L but had 26.5kg.m torque at just 3800rpm.

Actually toyota just need to put the 1.8L VVTLi from the SS2 Celica into the Corolla and the thing will also fly.

There's Corolla XRS in USA with 2ZZ-GE engine but tuned to 170bhp only. on Celica GT-S/SS2 is 190bhp. add in toyota supercharger it will be bout 215bhp. adding blitz supercharger can go till like 270bhp.

[Tanjkp]

O, thks, got it. So all make now want to boost more power so as not to fall behind KR starting with DVVT.

[Watwheels]

VVTI-L

Sallah spelling lah! It's VVTL-i

[Watwheels]

Sigh! So many fancy terms, what wild cams lah ....what lift control.

Pls lah dun confuse readers can or not?

@ high rpm the air intake valves will move deeper to allow more air to enter the combustion chamber (i.e when ECU detect more air hence add more fuel to produce more power). The idea is to let in more air into the combustion chamber.

But there's a limit, the cams (shaft with offset lobes) cannot move the valves too deep or else they will hit the piston head.

It's the same concept which u learn in secondary sch on combustion nothing fancyful like u guys mentioned. More air + more fuel + ignition = bigger combustion.

This post has been edited by Watwheels: Jun 22 2006, 09:35 PM

[EventH]

I can still remember the advert where the sheep out run the race horse.

I think the main problem with the VVTLi and wild cams vtec is that the power and torque come in (shiok feeling) at rather high rpms (5-6k) That is like the redline for a regular car. Quite tiring to drive like that day in day out.

[Tanjkp]

For those who ever read about 3 stage Vtec will know what is all about.
Not necessary need to ram to red line, 2nd stage lift came in at around 2K RPM.

[Iforu]

3stages vtec is not for racing 1.
3stages = save fuel, 2k+ switch 12 to 16valves.

[EventH]

The 3 charts are manufacturer figures for SS1, SS2 and USDM 2006 Civic Si respectively.

If you look at the charts, for cruising (at 3000rpm (110km/h?), both 1.8L Celicas had around 60hp while the 2.0L Civic Si had around 80hp.

All the engines produce around 90-100hp at 4000rpm.
Even at 6000rpm, both SS1 and SS2 produce around 140hp
while the 2006 Civic Si had around 160hp.

Off course the SS1 run out of power at 6k while the rest goes all the way to around 8k rpm.

But who drive at 6-8k all the time ... even when overtaking?

This post has been edited by EventH: Jun 22 2006, 10:16 PM

Attached File(s)

 SS1.jpg ( 50.07K ) Number of downloads: 0
 SS2.jpg ( 50.16K ) Number of downloads: 0
 2006 USDM Civic Si.jpg ( 54.21K ) Number of downloads: 0

 

[Tanjkp]

Post: 3stages vtec is not for racing 1.
3stages = save fuel, 2k+ switch 12 to 16valves.

That's right, that's how it sells with economy + power.

[Tanjkp]

Thks for the charts, they are talking about max torgue, max power.
The Vtec lift don't kick in at high RPM only.

Most drivers will hardly use up to that high power / RPM.

This post has been edited by Tanjkp: Jun 22 2006, 10:26 PM

[EventH]

The amazing thing for the new vtec engine is that its max torque can be achieved at 3000rpm.

[Davidtch]

In modern era car technology, variable valve technology is basically split into 2 school:
1. Cam-Changing VVT; &
2. Cam-Phasing VVT.

Cam-Changing VVT
For eg, Honda VTEC, basically, it use the intake camshaft to vary the timing of valve. For 3 stage Honda VTEC, @ low RPM, 1 intake valve is open. @ Medium RPM, rocker arm connect both intake valve. @ High RPM, rocker arm will open both valve for a longer period. All this happen during the intake phase.

Cam Phasing VVT
For eg, Toyota VVT-I or BMW Vanos. Basically, otto cycle engine comprised of 4 cycle, intake, compression, explosion & exhaust. B4 VVT, all these cycle operate independantly. Under Cam Phasing VVT, there will be overlapping between this cycle. Under this set-up, Cam Phasing VVT, can be implemented in either intake valve only or both intake/exhaust.

For intake valve only, during compression cycle, intake valve do not close up until piston reach certain angle. This allow more air into combustion chamber to achieve a leaner burner. This is the basic set-up for Toyota VVT-i. The i (stand 4 intelligence) allow ECU to vary the timing of intake valve depending on engine load & other factors.

For intake/exhaust, compression cycle is the same as intake valve. The only difference is that exhaust valve continue to open during intake cycle. This is the basic set-up for Toyota dual VVT-I and BMW double vanos.

Cam-changing + cam-phasing VVT
It combine both technology during intake cycle, which allows more petrol into combustion during high RPM. This is found in Honda I-VTEC & Toyota VVTL-I. However, honda I-VTEC toward lean burning. The reason Toyota VVTL-I is not as powerful as Honda VTEC is the component used. If Toyota Celica using VVTL-I upgraded to TRD engine parts, power output will increase from 180HP to 200HP. Do rem that Toyota celica is 1.8L