While I was at the Detroit Auto Show, The guy presenting was saying how much more technology goes into the VVT-i engine. I haven't ever used a Toyota with a VVT-i engine but I do have the S2K and when VTEC kicks it's amazing. I just wanted to know which is better?

 

VVT-I is just Toyota's version of VTEC. BMW call it VANOS and in the UK MG call it VVC.

They all do roughly the same thing. A standard VTEC engine on say a Civic/Prelude only alters the cams on the intake(?) whereas the S2000 alters both intake and exhaust. BMW also has the double VANOS which is like the S2000 i.e. intake and exhaust.

 

The VANOS that bmw and porsche have are very different from the 'other' ones. For instance VTEC has only 2 setting - one for low revs and one for high revs. VANOS systems are 'analogue' and they vary the timing for every possile revs ie. they have an infinite number of settings (not infinite literaly). That is why VTEC 'kicks in' while Porsche or bmw don't - they are always 'in vtec' - it just changes all the time.

[Edited by DavidM on 03-22-2001 at 02:45 AM]

 

David is quite right about VANOS (forgot that). I think the new generation of i-VTEC engines will work in a similar way. The benefit is more torque in mid range.

 

The S has two separate cam profiles. This is very different to just changing the cam timing. It's like revving up to 6K, then jumping out, pulling out the standard cams and dropping in some high lift race cams, getting back in an revving to 9k (all very quickly BTW)

 

Just be careful doing that, you can hurt your fingers...

[grey]--------------------------o0o---------------------------[/grey]

[grey]2000 S2000 - 1998 VFR800 - 2000 Atos[/grey]

 

I have read that BMW's VANOS (and Porsche's system) are much different than Vtec, yes. They seem to be very cool systems! I'm looking forward to reading about i-Vtec and how well people like it.

As for Toyota's system, I test drove a Celica GTS when the new ones had first come out. (Spring of 2000.) Decent car, and maybe it's because it was new, but I didn't feel a lot of "kick" with the VVTi system. It didn't feel like the Vtec I'd experienced with an Integra GS-R and a '99 Prelude SH.

*shrug* Like I said, it could've just been me.

 

I think there are two things here... VTEC is just the adjustment of the duration and lift of the valves. Then there's the new i-VTECs which also adjusts the cam timing. It adjusts the overlap better the intake and exhaust vavles. I can see the cam timing being contiously various, but not valve lift and duration. I think VANOS has both features and it's the cam timing that's conitously varied. VVT-i is the same way. Nissan used to have VTC (vairable timing control) but do to problem(not enough lubrication in the system causes them to start ticking after 60k miles) they stopped using it in the maxima after 94. VTEC didn't have this feature until honda instroduced i-VTEC.

-Shing

 

I wonder what "lucky" person bought that GTS after you had reved the squat out of it?

 

Thanks alot for the reply, I really appreciate it.