What are the improvements in the 2007 Sienna’s Drivetrain?

[Tonto]

I’ve been hearing a lot lately on how much livelier the 2007 Sienna is to drive with the new 3.5L V6, it seems to be the quickest minivan currently available now. Even faster than a 2007 Odyssey! I wonder if any body can elaborate on the key differences that make this new engine so great. I have come up with a list of features that may be true (or not) and wonder if some one can clarify.

Also I guess what I’m really getting at is, can any of these improvements be installed onto the 3.3L V6 in my 2004 Sienna? So far I’ve discovered that the new 3.5L V6 has:

-Larger displacement (a given)

-VVT-I Variable timing now on both intake and exhaust (but I thought my 3.3L also had this feature, or was it only on the intake?)

-Direct-Fuel-Injection (ahh this could be expensive to add onto the 3.3L, but probably is the main reason for the power increase…is this correct?)

-Probably a new intake manifold to go with the new Direct-Fuel-Injection.

-New electronics for the 5 speed transmission. It now has intelligence (or maybe it’s a new tranny altogether) I’m wondering if it’s just a new control module on the same 5 speed transmission that’s in my 2004?

[Tonto]

I went to a Toyota dealer today, and while I was ordering parts to do oil change and tranny flush, I got talking with the parts manager. I asked him what improvements he knew about between the 3.5L V6 in the 2007 as compared to the 3.3L V6 in my 2004 Sienna.
What he told me was that:
- I was correct in that there is now variable valve timing on both the intake and exhaust valves.
- That there is no direct fuel injection being used on the 2007 3.5L V6 at this time, but may be used on future models.
- There is supposedly much better engine management software in the 3.5L V6 that is making the power difference.

What I was surprised to hear was that the 3.5L V6 now has a timing chain driven valve train instead of using a drive belt. I think that’s an excellent move towards longevity and longer interval between major engine service.

I wished that my 3.3L V6 at least had that improvement as my 2004 Sienna already has 106,000 klms on it and the drive belt , I’m told is due for replacement. Drive belt replacements are usually one of the first major engine services right after the warranty expires. Hope this new timing chain in the 3.5L V6 prolongs or prevents any need for this costly engine service.