That 5K RPM Kick

[Mike@Rentech]

sluggish till it comes on cam then its fun but sadly its such a short range of 2800 rpm.

 

[Steve2004]

The 5k kick in my 182 is very noticeable and at that point the car starts to torque steer.

That's what happens with my 172.

Very noticeable indeed :approve:

 

[DaveLiquid182]

The first person to say the kick is down to VVT will get an e-slap

Im gonna get one then cos i thought thats what it was

 

[miltage2]

Mine is really pronounced. Just gets to 5k and wants to go! !

 

[Loopz]

i drove a ctr the other month, and the vtec kick seemed to be just alot of noise to me, no more pronounced shove than in my cup tbh

CTR has the 3-stage i-Vtec, wich makes the transition between cam phases pretty subtle. The Integra is a different story.

 

[Day]

Not long now until BenR comes along and puts you all out of misery...

 

[R3OBC]

CTR has the 3-stage i-Vtec, wich makes the transition between cam phases pretty subtle. The Integra is a different story.

yup, i-vtec is pish. The accord is nothing...........nothin...........nothin.............BANG Wallop weeeeee.........love it everytime it kicks in!

 

[R3OBC]

i get a slight kick at 4k in my 1.2 lol
isnt it something to do with the 2nd cam kicking in ?>

had my old 1.2 16v rollin roaded Taylor, at 4k it produced peak torque with the filter and exhaust, so 4k was the 'hot spot' in mine too

 

[jaycc]

The 5k kick on my 182 is pretty immense and agressive. Not as crazy as the turbo on the rs focus, but still crazy of a NA engine.

 

[Chris n nic]

Mine pulls like a train...then comes on cam and goes some more

Chris

 

[BenR]

Not long now until BenR comes along and puts you all out of misery...

Cant be bothered, i've written it too many times already.

But a quick search shows up:

http://www.cliosport.net/forum/showthread.php?t=166405&highlight=BenR

 

[Jones]

So does my 172 have V-tec? I thought that was only on Honda's?

 

[BenR]

you dont, you have a single stage VVT cam phasing advance system.

Read the link.

 

[Day]

For lazy muthas

By no means is the 5k kick the result of any mechanical/electronic change within the engine system, whether that be mapping paremeters or valve timing.

I think to fully understand, a base understanding of the operating system of the vvt is needed. The vvt system employed on the clio is what we refer to as cam phasing, this is where the whole camshaft (inlet or exhaust or both) is advanced/retarded. This can be in a single step as it is in the clio (single stage 16 degree advance on the inlet), or variable. The camshaft is hollow and is used as a galley to feed the front pulley (called a phaser) with oil pressure, this pressure simply acts on vanes inside to rotate it in a desired direction, and returned under mechanical pressure. The cam does not always carry oil pressure, but a vvt switch is used, and is basically a plunder activated by 12 (grounded by the ecu (a lowside switch)) which allows the passing of oil from the lifter galley to an area of the cam bearings with holes that can feed the inside of the cam, which then passes through to the nose of the cam and into the pulley (phaser).

Variable setups (like the new 197) will use the same base components as what is used today, but instead of the vvt plunger being used as a switch, the same plunger has the ability to open and bypass oil to either side of the vanes in the phaser. By using a PWM signal, you can gain full control of the phaser to advance the cam in a near infinately variable curve vs rpm vs manifold pressure vs throttle angle etc.

Honda's Vtec system is a cam 'changing' system where the actual cam profile is changed in its entirety (hence the 3 lobes per cylinder), the actual 'timing' of the primary lobe remains the same at all times. And now with I-Vtec and VVTL-i the benefits of both phasing and changing is being used at the same time to build some monster VE (volumetric efficiency) curves.

Anyway, in the clio the cam sits in its dephased state until the required parameters are met. This is above 1450rpm and 800mb manifold pressure. When it is required though, the cam is phased and the cam timing effectively advances 16 degrees, at 6800rpm it is dephased again and power drops off like a stone. No official reason, but my thoughts are that they do it so you guys shift up once there is a loss of acceleration. The reason for that is because the stock pistons just fall apart with prolongned high rpm use.

The 5k kick is the result of a few natural phenomenons within the engine. At 5000-ish rpm VE suddenly reaches a higher %'age and the resultant torque increase gives you that wahey feeling. VE increases due to the cam comming 'on'. This term has nothing to do with VVT and is quite an old term, whereby the reference is to the rpm region that particualr engine/cam combo requires to process the valve timing events efficiently.

VE refers to volumetric efficiency, or the %'age of the cylinder that you can fill with fresh charge. For a 2ltr, thats 500cc per cylinder. If you can only fill that cylinder with 430cc's at peak efficiency (normally at peak torque point) thats 86% VE. The higher the VE on any engine, the higher the torque output at that specific RPM, and all engine tuning revolves around increasing or rather sustaining a good VE for as long as possible, and upto as high an rpm as possible.

Anyway, back on track. The clio with its advanced cam timing (phased) operates with an overlap value that is larger than when it is dephased (infact it has no overlap when depahsed). This overlap is part of cam design basics, and larger overlap periods are used to help generate higher VE's via scavenging and inertia ramming. At 5000 rpm the natural effects of the port velocity and pulse tuning al reach a level where they start to actively enhance the torque production with the valve timing it is running. Put in a wilder cam and it will push the 'kick' higher up if nothing else changes, but lower rpm efficiency will loose out, and peak power will be pushed up the rpm scale, along with a higher peak bhp figure. To an extent, there will be a point where you can go wilder on the cam and just loose out everywhere as the engine system as a whole does not work with the cam profile you are running.

Not very clear sorry, basis is that the 5k kick is the result of natural phenomenons within the engine, primarily port velocities and pulse tuning harmonics.

 

[Jesske]

This is what I read in an article in an official Belgian Renault magazine:

172-182: 5k kick due to variable cams
197: no kick because of PERMANENT variable cams

 

[crazycup]

mine comes in with a large kick in 2nd gear, if in the wet it has traction until 5k in 2nd and 3rd then the wheels start to slip....i love it tho!!!

 

[Chris n nic]

For lazy muthas

And I thought Ben knew his stuff....at the top he clearly should have said change and not chance

Chris

 

[Day]

lol

However I think chance is probably correct

 

[Chris n nic]

lol nice edit

Chris

 

[edde]

This is what I read in an article in an official Belgian Renault magazine:

172-182: 5k kick due to variable cams
197: no kick because of PERMANENT variable cams

Nope that wrong moant car sales man and dealers say the same as they don't know.

BenR's answers the correct one.

 

[Jesske]

But edde, why do they write that in an official Renault magazine, published by Renault?

 

[Gaz_]

But edde, why do they write that in an official Renault magazine, published by Renault?

must be like the time renault said that there would be tuning parts for the cup...... roll cages, remaps etc!!!!

 

[Rich]

Written by someone in the marketing department who has not got a clue I expect.

 

[edde]

But edde, why do they write that in an official Renault magazine, published by Renault?

Who's going to complain about it its not a huge issue realy.
Renault techies arn't going to proof read it are they. Its like many publications there proof red by peopl who don't know techie stuff. I've been reading one at work quoted as sayin VW tdi engine are all the same (which there very mush not).

 

[Loopz]

But edde, why do they write that in an official Renault magazine, published by Renault?

Renault said a lot of things. Don't mind them.

 

[Fred@BTM]

"Renault" and "Comunication" doesn't happen

99% of people know more than the dealers

 

[clio172racer]

when racing what should you take the revs up to get maximum performance wivout holding gear that bit too long, whens the time to change......

 

[edde]

when racing what should you take the revs up to get maximum performance wivout holding gear that bit too long, whens the time to change......

You need to get your car rolling road tested see where it making power and you want to maximise your time at the top of the power curve. For example I chnage up at 4.5k (max power 4k) in first as it keeps the adverage power up. However in 4th chnage at 4k as thats the best point to chnage the maximine engine power

 

[Fred@BTM]

when racing what should you take the revs up to get maximum performance wivout holding gear that bit too long, whens the time to change......

about 7k

 

[Munson]

But edde, why do they write that in an official Renault magazine, published by Renault?

I have an official Renault magazine right here on my sofa that says the 197 has drilled disks.

 

[cornburn]

mine comes in with a large kick in 2nd gear, if in the wet it has traction until 5k in 2nd and 3rd then the wheels start to slip....i love it tho!!!

Mine's always done this too, until 2 days ago that is! I took the injector cover thingy off to change the oil but didn't have time to do it that night. When I got it off I noticed the last person who had the cover off had trapped the black fuel pipe that goes in the right hand side of the rail. It had been squashed so I've now obviously moved it out the way. When mine gets to 5k power now dips for a split sec before accelerating at the same rate. The kick's completely gone!!!!!

Anyone got any ideas? I might start a new thread as I'm a bit concerned :S

 

[cliobritt]

At 40 my 172 goes better in 3rd than 2nd!
Whats that about?:S

 

[Donnie Darko]

Akin to the 4.5k kick you get in a valver.... noticable (i.e it starts to shift) but nothing special !