clio 172 hitting 5000rpm with uprated cams

[ryangt]

has anyone got a video of the noise the 172 makes with uprated cams is it a lot more than standard ?

 

[scotty2hotty81]

5000 rpm kick is the vvt which you loose when fitting the new cams.

 

[172Ben]

No it's not and no you don't.

Iirc vvt kicks in at 1800, and is retained if selecting the correct cams which allow you to.

 

[franx]

^^ that depends on the cams. Most aftermarket cams retain VVT

When having very nasty cams you put on adjustable pullies for the ability to fine-tune them, losing VVT


*** EDIT *** 172Ben beat me to it !

Mine runs Colombo&Bariani cams. When mapped Henk (Fastchip) put in a VVT disable at around 7000rpm . Up untill that high rpm the VVT works

 

[theduck]

the vvt system in the 172/182 range is there simply to allow the renault engineers to run a wilder camshaft without any of the problems you would associate with larger overlap cams on a plenum with a classic speed density system.

The vvt system is a simple 1 step phasing operation which advances the inlet cam only by 16 degrees. In its resting (depahsed) status it sits with the valve events netting a zero overlap status. This gives a strong map signal and constant manifold vacuum at idle and low throttle angle, which makes smooth mapping at lower rpm and throttle angle easier, along with better emissions and economy.

As soon as you increase manifold pressure to 800mb+ and go above 1450rpm, the ecu will advance the cam. Its such a low rpm threshold because the cams are not that wild, but wild enough to cause problems at idle.

The kick at 5000rpm is simple the 'on cam' phenomenon where all operating parameters favourably meet and you get a sudden increase in volumetric efficiency.

Love BenR

 

[SBV116]

Love BenR