Question from the i-VTEC retard

[dohcvtec_accord]

Quick question:

I've got some guys on another non-Honda board wondering about i-VTEC. Specifically, when does VTEC engage on these boys? I knew the crossovers for most of the F, H and B-series engines, but I'm not sure on these newer ones.

Thanks!

 

[Slammed90Lude]

the wimpy i-vtec in the civic si (k20a3) kicks in at 2300 rpm

i think the RSX (k20a2) gets into the real high cam lobe at 5800 or 6k rpm

 

[YouKnowWhoIBee]

well there is alot of differences with ivtec and vtec are different to say the least.With ivtec like in the new si (k20a3) the cams only have only 2 profiles not 3 like true vtec. on the si each lobe sits directly over an intake valve and each valve also has an independent rocker arm. As the cam comes down to open the valves one is open very slightly and not very long. And when "vtec" hits oil pressure locks the rocker arms together and the larger cam opens both valves. The exhaust has one lobe operating one rocker arm and 2 valves. And the k series use roller rockers instead of radius slippers like in the b series engines. So basically the si that uses ivtec (k20a3) engages around 2300 but the ivtec (k20a2) in the the rsx kicks in at 5800 and it is actually like the vtec in the b and h series. Intead of boasting fuel economy like the si. The rsx-s with the k20a2 has 3 porfiles and lobes though like the b series. There is ivtec with 3 profiles in the rsx-s (k20a), rsx-s(k20a2) and the tsx(k24a2).