Hi guys,

I have sourced an AU2 VCT 6 which will go into my jetboat, and want to know if an AU1 VCT computer will run it (therefore allowing a smartlock bypass to be fitted).

I can source an AU1 VCT ECU, but need to know whether it will be compatible. The engines are identical from the little bit of research I have done.

Anyone ???

Warren

Or this maybe another option:

Can a megasquirt II be used to run an AUII VCT engine, and does it have the capability of switching the VCT on at a certain (3000rpm) rev range.

This motor is going in a jetboat, so I only need limited operation (ignition, fuel etc.)

Any thoughts / suggestions appreciated.

Warren.

Would you be better off locking the cams with a vernier and ditching the VCT if it is for a boat?

The idea was to have a harder revving engine as we don't change gears or anything. The VCT revs harder without consuming the fuel levels associated with beefy cams (like a 1636 etc.) across the board.

The idling quality won't be lost also.

It's just a matter of controlling the thing, whether it be by bypassing the Smartshield, or controlling the motor with an aftermarket ecu. The MSII looks the good price wise, as long as it can control the VCT.

Thoughts ??

Warren.

If the revs you are running are constant then VCT plays no part. Get a custom cam optimised for the RPM band you need.

whats the diff port wise and cam duration wise between std xr6 and vct?

where does the extra 8kw come from?

The revs aren't constant, thats the problem. The range of revs determines the speed we can travel at, and at some stage we use the entire range.

A lot of time is spent travelling at eight knots (around 2000 revs), yet in open water the higher the revs, the faster we go. That's why a VCT would be ideal, the low rpm speeds and smoothness are as important as the flat out high rev speeds.

Otherwise I would have just installed an EL 4.0 litre with a 1636 cam, and avoided all the smartshield issues.

Another thread mentioned someone on this site selling a smartshield bypass. I think the name was projetec, protejet or something similar.

Any idea who this is, and what he actually sells to get around the smartshield.

Also, would installing a key barrel and coded key somewhere in the wiring solve the problem ?

Warren...

But while you are accelerating don't your revs maxed out unlike a car where they build up? I don't see that advantage in VCT for a boat.

With an outboard or prop shaft the revs max out, with top end being achieved once boat speed catches up to the slippage of the prop.

With a jet unit, the water is all contained within the unit (the stator), so the resistance is far greater (not unlike the rolling resistance of a car on a drive shaft). The propulsion in a jet boat is all centrifical, it relies on the water being shot backwards to provide forward motion.

A prop on the other hand derives its power from the pitch of the blades biting through the water.

The diameter of the outlet, the number and pitch of the impellors (propellors) within the unit, the hp of the motor all have a direct relation to the revs you will achieve.

Warren.