Rb25Det Neo Vct Question

[Krille]

Im trying to get some infos on what rpm to activate the VCT controller when using Link G4 plugin system, standard ECU activates it on pretty low revs if im not mistaken?

The engine and head is pretty standard, atm running 370hp on the wheels, but the power curve is first raising at 3000rpm (Where the VCT is not set to activate)

then it goes down a tad, and after 4500rpm it goes up, gonna push out some more Hps soon just had to replace the FPR, and gonna try get the curve a bit smoother.

Or should i disable the VCT completly?

[JonnoHR31]

do a run on the dyno without it then a run with it engaged from idle to 6000rpm then whenever the lines intersect on the dyno graph is your switch points.

Edited June 30, 2011 by JonnoHR31

[Lithium]

I'm real fussy and actually tune for both VCT on and off, if you just change the point without adjusting anything then you get a misleading impression of what the potential of what VCT really gives. With VCT on, the engine actually likes more timing (at least up till around 5000rpm or so) than with it off - which actually changes the curve.

If you want to find the perfect point for your car, optimise the tune for both on and off then overlay the "best" for both and set the engagement and disengagement points to allow the highest torque curves to be utilised

[GTSBoy]

Neo is not just on-off. It's continuously adjustable.

[gotRICE?]

Neo is not just on-off. It's continuously adjustable.

See i thought this too, but i got my ass flames for suggesting it in a different thread about VCT.

Lith tuned mine both on and off, theres quite a remarkable difference in the 1500-4500rpm range.

It takes more time, but if you want the tune perfect, its definitely worth it.

I believe mine is set to 1400rpm, 70'C water temp ON, 4900rpm OFF

[Krille]

Thanks for the tips, gonna try this next time on the dyno then, hopefully this weekend

[bubba]

Neo is not just on-off. It's continuously adjustable.

No, it's not.

[PM-R33]

Yeah it aint. I swear that rumour originated on this forum years ago.

[SS8_Gohan]

so the purpose of VCT to retard/advance on the intake side (for Rb25's) yeah?

the amount it's retarded or advanced changes depending on RPM?

if so, how does 'constantly' variable differ? we talk about VCT being on or off, but surely 'on' doesn't mean a set retard or advanced state and if that's the case, how is it different to adj cam gears?

i've probably said a lot of newb things, so excuse my newbiness, just trying to get my head around RB25 VCT and how it varies to constantly variable

[JonnoHR31]

it advances the intake cam 20 degrees when activated, its not variable at all, its either at 20 or 0. the advantage to just having an adjustable gear is you can switch it on and off at different rpm, 20 degrees advanced is good for midrange but bad for top end.

[bubba]

^^ this.

[SS8_Gohan]

wow, 20 degress ok, so when you're talking 4-6 for Rb26 adj cam gears, i can see how that would be a good thing.

that clears that up, cheers