advice needed..

[boosted]

Hi guys,

i've got 2 problems..

1.:
i'm planing a total bebuild of 4G63 engine, balanced forged pistons, balance shafts removal... Now my Problem is: i have a Dash Sirius head, which i bought from someone in new zeeland. As we know, those heads have 3 valves per cylinder. when i go for forged pistons i would need a specificly matched piston to those valves.

But, i only have one of that dash head and about 5 original (8v) ones.
Lets say the dash head goes "bang", i have a perfect enginge with the wrong f... pistons in it...

What would you do?


2.

On the dash head there are the 2 cables, i suppose they're should be connected with the ecu, so the third valve can be activated at ~2500rpm

no i dont have a dash sirius ECU, whats the way to do it?




Thanks in advance and sorry for the long text.

[ADR_lancer]

There has been debate about this but I've been convinced by Starion VR4 and others that the pistons will work with either head.

I'm about to biuld an 8 valve engine using VR4 16valve pistons so I can't see you having any problem if the dash head goes bang and has to be replaced by an 8 valve one.

[SpidersWeb]

I think you'll find the 8V inlet setup wont bolt on to the 12V dash. I was told that by another DASH owner, and perhaps someone else here with actual DASH knowledge can confirm that.

If thats true, I come to the conclusion an MPI DOHC conversion to be of similar costs. Unless you find someway to make the 8V intake bolt on.

According to what I read on here earlier, applying 12V DC to the two wires you mention disables the four extra valves.

[boosted]

i actually have the inlet manifold of the dash injetion, that should be ok.
Gonna use the injection of the jb for the beginning

just that i go you right. applying 12 volt to the wires disables the extra valves. i thought i would activate them. But when its the other way round, good to know...

[NXTIME]

The 12V DASH head can be used on the 8V bottom end. Also, use the top half of the JB injection bolted onto the inlet manifold of the 12V if you plan on using the 8V ecu. This isn't the ideal set up, but is a cheap compromise. You should eventually use an aftermarket ecu.

However, I am of the opnion that using an 8V sohc head with MPI will yield significant power gains and be easier than the 12V DASH head and 8V bottom + ecu.

[boosted]

Thank Nxtime..

It would just be for the beginning. But, if i build up a proper Bottom end
With forged pistons and so on, you say the dash head would also fit onto it?!! ;-)

And sorry to go again to that wire stuff on the head, but if i don't conect them to 12volt, the extra valves will always be working?

About the Ecu, i'm not shure if i then can get the car thru the emission test then... I've got a Ecu chipped, no fuel cut.. And was thinking of adding extra injectors.. I know it's not accurate at all and quite cheap. And yeah, while writing.. You're right anyway a aftermarket ecu would be the best..
F... i've got so much parts an sh.. lying around in my garage, i don't what to do anymore :?

[dirty sanchez]

The standard head with MPFI will definately yeild more power than the dash head and standard dash manifold (note that dash engines have a different throttle body and higher flow injectors). It would be interesting to see how a dash head with MPFI would go, but I don't know anyone who has done it.

It's been a while since I messed with a dash head but as I recall I think that if you fit the head and don't wire up the controller the engine will run on 3 valves just fine. The engine idles about 50rpm lower and has slightly less power below 1500rpm, above that it doesn't matter.

If you are planning to install aftermarket engine management I'd build the bottom end for an 8 valve head and dig up an MPFI manifold. If you're planning to keep the standard computer I'd go with the dash head.