I was reading the Vectra Haynes manual and read with interest it's description of the 1.8 & 2 litre engines.
It says under the heading 1.8 & 2 litre Simtec 56.5 multipoint injection: "... incorporates a Variable Tract Inlet Manifold to help increase torque output. Each inlet manifold tract is fitted with a solenoid / vacuum diaphragm unit. At low engine speeds (below 3600 rpm) valves = closed. The air entering the engine is forced the long inlet path, leading to higher torque. At higher engine speeds the valves are open allowing the air through a shorter path, more suited to higher engine speeds."
Right... I've never heard of this. Does it apply to both 1.8 & 2 litre engines and if it does, does my Cav SRi (Ecotec X20 XEV) have this torque increasing feature on it?
If not, can I retro fit the Vectra gear to boost performance?
By the way, I recommend the Vectra Haynes Manual for those of us with Cavalier SRi's with the X20 XEV engine in. The Cav manual is pretty cr*p on this engine 'cos it was introduced so late. But on the Vec manual, they cover it in MUCH better detail.
Have a look at the back of your engine where the inlet manifold is.
If it's ridiculously(!) large, then it probably has.
Have a look on the top of your ECU to see which software version your running too, as the ECU controls the changeover valve (I think, without checking)
Simtec 56.5 and 56.1 - ah there's me difference then! I thought it sounded a bit strange as I have done quite a bit of work around that area and not seen this extra gumpf on the Cav.
So I take it you can't retrofit this because of the different management systems...
Thankx also for the advice on the Haynes. I actually complained to Haynes about the Cav manual not covering the Ecotec engines and they recommended me the Vectra one (which I've now got). Is it worth returning it for the cally manual?