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Bdub215 · 06-18-2010, 10:28 PM

1zz-fe: VVT-I on the Top vs Non-VVt-i on the bottom. Equal Mods. i think there is a trade-off for having VVT. i mean sure they get a increased redline and nice low end torque but mine is flat till almost redline. power is more or less the same. others please weigh in.

Bitter · 06-19-2010, 12:14 AM

you can see that torque on the VVT-i engine does not fall off as RPM rises as the non VVT-i engine does.

not to mention, 2 different dyno's so differences are moot.

Milky · 06-19-2010, 04:19 AM

the reason for the flatter torque is due to the cam differences in the head. mainly the intake having more lift and duration than the ehxaust. if you were to swap in a cam of identical specs into the exhaust side, the flatness would dissapear and you would have a slightly higher torque peak. and a higher torque peak simply equates to higher hp at a higher rpm.

now, if you could optimise the vvti for performance and not fuel effencey then the torque graph would look a bit different. that and do the aforementioned cam "trick" because the vvti models use staggered cam setups as well. (same cam specs)

Buurin · 06-19-2010, 04:58 PM

Quote:

Originally Posted by Bdub215

1zz-fe: VVT-I on the Top vs Non-VVt-i on the bottom. Equal Mods. i think there is a trade-off for having VVT. i mean sure they get a increased redline and nice low end torque but mine is flat till almost redline. power is more or less the same. others please weigh in.

If I read the image name correctly, the top one is some dude's 2008 and the bottom is yours.

Quote:

Originally Posted by Bitter

you can see that torque on the VVT-i engine does not fall off as RPM rises as the non VVT-i engine does.

not to mention, 2 different dyno's so differences are moot.

You meant "horsepower"?

If I read the graph correctly it actually reads to me that bdub's non-VVT-i has a flatter torque curve from 4000 to 5450rpm where there is a sharper decline; whereas the 2008 torque peaks at 4600rpm and falls off more gradually. So torque wise both decline after peaking. Well what's the definition of "peaking" anyway?

HP wise yes VVT-i peaks much closer to redline so you don't see the decline. But for the kind of driving a Corolla is meant for, I want HP and torque earlier, plus there isn't much difference - they're within 2hp of each other for the rev range that matters - 2500-3500rpm. If not for the inexplicable torque dip of the non-VVT-i between 2500-3800rpm I'd say non-VVT-i does better.