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Rb25Det Neo Vct Question

Krille

By Krille,
in Engines & Forced Induction

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Krille Explorer

Krille

Posted
Posted

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?

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https://www.sau.com.au/forums/topic/369589-rb25det-neo-vct-question/
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JonnoHR31 Grand Master

JonnoHR31

Posted
Posted (edited)

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 by JonnoHR31
Lithium Grand Master

Lithium

Posted
Posted

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 :)

gotRICE? Veteran

gotRICE?

Posted
Posted

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

SS8_Gohan Grand Master

SS8_Gohan

Posted
Posted

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 Grand Master

JonnoHR31

Posted
Posted

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.

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