20v vvti

[Steve-AE86]

is it necessary to run vvti with aftermarket ecu and a t28 turbo on a blacktop 20v?

the reason i ask is, my new engine has a broken vvti actuator.

would it be beneficial at all to blank off the hole in the side of the head, or maybe even set the actuator so the vvti is on all the time?

cheers

[Ben Wilson]

It should run with the VVTI off, as for setting it on or not, it's just like adjustable cam gears..

[Steve-AE86]

yer, i know it'll run with it off. i spose i'm really asking if, with aftermarket management, would it be better to be set on or off?

[Squid]

Surely no amount of aftermarket management can make up for the more aggressive cam timing? I would leave it on.

[Steve-AE86]

you don't reckon it'd run like shit when idling, or be sluggish in the lower rev range?

[gianttomato]

Continuously variable valve timing? There is also nothing to stop you running aggressive cams and VVTi apart from piston to valve clearance and intake - exhaust valve clash. Some clever work before you assemble the motor will allow you to ascertain the maximum amount of lift for a given amount of advance/retard at a certain point in the engine cycle.

With decent aftermarket control, you could use it to help with spool up and improve mid range torque. Drifter's paradise?

[Ben Wilson]

My silver top switched twice, it started at one position for idle and bottom end, then switched for midrange, then switched back again for top end (I think the switch points were around 1500 and 6500).

[beige_bandit]

you cant leave vvt on all the time! vvt advances inlet cam timing past 4500 rpm for better power cause you cant have the best of both worlds, get it fixed or leave it off, car manufactures do certain things for certain reason's, timing is supposed to advance more the higher the revs, you cant have the amount of advance the vvt give's at idle!

[beige_bandit]

and because those engines need like 106 RON petrol all you'll do with to much advance is fuck your engine

PING PING PING

[Steve-AE86]

what if i'm running Martini 110 in it all the time, being track only?

[beige_bandit]

with 110 ron well?

i cant say for sure, personaly i wouldnt try it

chances are you still might run into detenation problems

cause you'll have about 30 deg adv at idle

[Ben Wilson]

Um - I'm not 100% on the blacktop, but, the silvertop only adjusts exhuast cam timing and doesn't touch ignition timing at all...

[beige_bandit]

inlet cam timing, im sure its inlet cam timing

either way it will idle like turd, it would be like putting in a really lumpy cam

unless your using a fully programable aftermarket ECU you would not
be able to get desent idle

but if its a track car it wont idle often.

but i still think its risky business

[Ben Wilson]

As he has already said he is running a T28 turbo and aftermarket management, that really isn't a problem.

You're correct, the inlet cam moves, but, the distributor runs off the exhaust cam which is fixed. (I haven't owned one in years...)

For the timing figures, Bill Sherwood has them on his website here, you'll need to scroll down to the bottom.

[Steve-AE86]

the VVT runs off the exhaust cam. the intake cam is fixed.