XRT_si

iTrader: (2)

Is it worth keeping on a turbo application?

I understand it allows it to be more drivable, but its going in a car that will be taken to Ford shows and Pod only.

Chip suggested the other night for this reason leaving it off, as it complicates the mapping side of things too..

Anyone got any knowledge/expereience VVT & turbo drivibility and mapping?

vroooom ptssssh

Anyone who can map a car properly I doubt would have a problem keeping the VVT, I'd 100% keep it! why would you not?

TimC

iTrader: (1)

Si what management are you using?

I know on zsoc there is a person with omex 600 who can't seem to get the vct working on there throttle bodied puma engine. Im not sure if it was todo with omex or instalation or whatever but Track and Road aint been able to get it working.

It's Czech Mate

Why wouldnt you keep it?

Only problem would be if mapper couldnt handle it IMO

Big Will_

OMEX600 doesn't have truly mappable VVT/VCT/VTEC control as I remember. However, it can fire a solenoid controlling oil pressure by activating an ECU auxiliary output. A bit like activating a shift light at certain RPM.

TimC

iTrader: (1)

Will that explains alot. So really ECU choice could play a role in if its worth (or can function) the VVT

cjwood555

the problem is that the vvt changes the ve of the engine and has an effect on turbo spooling, so you can find yourself going round in circles come mapping. yes it can make a big difference e.g. spooling a big turbo quicker. is it absolutely necessary in a highish compression engine with modern turbo and proper management and boost control, i wouldnt necessarily say so. personally, as its there, id keep it functional and maybe map it flat for now to save time and money, then consider having it fully mapped when funds allow and more power is desired!!!

XRT_si

iTrader: (2)

Good point on that theres no point in loosing it, just didnt want to over complicate things if need to by creating problems...which apparentely there are using my ECU (Omex 600 would you believe )

I read Omex 600 could run cam control but thats for electronic based only I am guessing?

Looks like Ill have to leave it out then!

XRT_si

iTrader: (2)

Interesting, I am aiming for around 350+ bhp and on a T34.63, so wouldnt mind making it a little less laggy if possible.

Will - Is mapping it a lot more trouble (than its worth essentially?)

crazycage

if you only want that power then a standard black top head will it no probs and be much easier to map, just my opinion tho and yes i have been down the vvt road .

XRT_si

iTrader: (2)

I remember reading you had mate, and I remember you saying how good it was and how is worth the extra mapping/complications at the time, but then you changed your mind?

No point in using a blacktop head over a ST170 head without the VVT though? They have solid lifters and bigger ports and valves?

crazycage

i did change my opinion on it mate .but a blacktop head has solid lifters aswell and only the inlet ports are bigger and the inlet valves are only 0.5mm bigger,all you get is a head that can get more air in at a slower speed but cant get it out fast enough and the cams are a bit on the aggressive side for turbo but again just my opinion on it.

SiZT

Agreed a blacktop head with a standard inlet cam and 105 exhaust would give very good spool up.

If you find the cams are strangled for power you could get them re-profiled for more lift

tabetha

VVT and turbo can, and has been mapped 100% perfectly, with outstanding results.
The VVT massively helps economy on lighter throttle openings, not that your concerned with that.
tabetha

XRT_si

iTrader: (2)

I knew the blacktop head had solid lifters too, and I know only the inlet ports are bigger. Why do you say the cams are aggressive? Ive read they react to turboing well?

And what made you change your mind about the ST170 heads anyway?

OldDan

Yes.

crazycage

i got fed up spending a fortune on mapping mate+ a few other things that i don't want to go into.
but when i compare this engine to my st170 this one would piss all over it mate ,when i was comparing the vvt spool up i was unplugging it so it made a massive difference !!! or so i thought lol my blacktop is more responsive and more powerful far more simple easier to map cheaper to build and does what it says on the tin.

but dont let me put you off mate if want to use it go for it and let me know how you get on with it.
rick off here is also going down the st170 /vvt road at the moment.

Rick

The issue is that VVT is very difficult to control. Most ECU's cannot even read the 5 tooth cam wheel! It needs a very clever closed loop algorithm in order to keep the cam position constant for any given load site. A couple of very expensive ECU's advertise they can do this, but i haven't seen it implemented yet. Megasquirt 3 will be able to do it once they have rewritten the code to work with angle clock, which is how the OEM's do it.

The other option is the on/off method. With power off, the cam is very retarded at 145 degrees. With power on, it's at 85 degrees. These are huge extremes, and i doubt the OEM setup ever gets to these extremes except in limp home mode. I haven't tested yet, but i don't think that these extremes will be anywhere near optimum for power.

On my car at the moment, i have retimed the inlet cam with a dti/degree wheel so that in the most retarded position, the inlet is at 110 degrees - around what the timing would be setup if it was fixed. I never power the solenoid, so the timing stays here all the time. Simple way of removing VVT, until I sort some proper closed loop control.

Rick.

andy130

iTrader: (2)

what is vvt?

Robs Frst

Variable valve timing.

t4 and greys

iTrader: (5)

variable valve timing mate

google it as cant be assed explaining

andy130

iTrader: (2)

aw ok thanks