Talk to me about the VVT System, and best cams for Standalone.

[Laine_16v]

Right, my situation. I was all into the highly tuned mad sped F7R for my mk1, it was a pretty flat out spec High Comp F7R on jenveys, 11.75mm catcams blah blah, anyway i blew it up.

I am now in possession of a ph2 172 engine, ive stripped it down to do a few personal improvements, and am putting the jenveys on it. but im a bit perplexed by this VVT system.

I understand its there to help emissions and idle, and that it kicks in at 1750rpm and disengages again at 6500rpm or whatever, and during this time it retards (or advcanes?) the timing 16 degrees or so.

But heres what im asking, do i NEED to have this wired up, am i going to loose a chuink of performance if its not engaged? what are the official RPM's it kicks in and out at? Is it suitable to bypass VVT on standard cams or will it mess the whole drive up?

Im looking to cam it maybe in the future but keeping a standard bottom end for now, whats the wildest one can go on a std BE?

If the valve springs needed upgrading thats not a problem, will i run into valve to piston clearance problems on high spec cams on standard pistons?

C&B? CC 421's? CC428's? Pipers? Lumpy idle isnt an issue as i have standalone.

Talk to me people! thanks.

 

[sideways danny]

Cat 421s work well. C&Bs seem to be performing well too. Neither will give clearance issues. Give 428s a miss if you're on standalone, they're very mild.

Wire in the VVT, no question. TBH it's only a switch, you should have an output for it. Switch on at 1600 rpm, and decide on the off revs during mapping. it will make a difference on the dyno.

 

[Laine_16v]

Thank you sir, never thought about changing the rpm switch off while on the dyno, good shout!

422's a bit to mental on std BE?

EDIT: looking at 422 specs on catcam websites seems they have a substantial valve overlap thats not going to work on std pistons?

 

[sideways danny]

you need to machine pistons or get forged with larger cutouts for 422s

421s are a good match for std CR anyway, seen some impressive results when paired with ITBs

 

[Laine_16v]

OK brilliant, two last question, are uprated valve springs required for the 422's? and just in your opinion would they make the car *too* peaky?

 

[sideways danny]

yes, springs are required, and IMO 422s are too wild for what you want. Would be good to see what C&Bs can do if you're up for trying them

 

[en035]

C&B + Henk's custom remap ----- ultimate solution

 

[sideways danny]

C&B + Henk's custom remap ----- ultimate solution

except he's not using the standard ecu

 

[Laine_16v]

Craig @ APD will be doing my mapping

 

[Andyman]

How does the VVT physically work as a component ?

Looking at it its just a sort of tube with holes in with a switch on top that sits inbetween the cams :S

 

[sideways danny]

that's the solenoid. That part allows oil pressure to the pulley which changes the position. When you switch off pressure drops, and springs inside the pulley move it back

 

[Lee-182]

How does the VVT physically work as a component ?

Looking at it its just a sort of tube with holes in with a switch on top that sits inbetween the cams :S

You will get different storys from differemt people.

Theres a thread that BenR wrote which explains it.

 

[sideways danny]

You will get different storys from differemt people.

Theres a thread that BenR wrote which explains it.

no, what you're talking about is the "5k kick"

the majority of what he wrote about that was nutsack.

this question was about how the components physically operate, which i just answered

 

[Lee-182]

no, what you're talking about is the "5k kick"

the majority of what he wrote about that was nutsack.

this question was about how the components physically operate, which i just answered

which every body says is the vvt and talking about nutsack, iirc someone corrected you on the last vvt 5k kick thread.

 

[sideways danny]

correct me all he likes. doesn't mean i'm wrong. Saying it's nothing to do with fueling, but it's caused by an accel fuel delay......erm, that's fueling. There's no kick with properly mapped standalone, so that proves the claim that it's due to mechanical factors (engine peak VE) is not correct.

Anyway, major thread hijack over