[FINALIZED] What's it worth? Beams turbo

[Peter Gidden]

do you mean the Carina gearbo, not the avensis ?

No, i mean the Avensis.

[Protok]

Looking at the dyno graphs I'd want the map checking anyway...they just don't look right to me

Why so?
If it's cause of the curve then all turbo'd beams go straight up like that

Mine was making 1bar of boost at 2300rpm though with the disadvantage of nothing after 6700rpm.

Nope- I get the torque curve as it spools up, pretty much what you'd expect on a smallish framed turbo on a 2l engine. What I don't get is that torque then instantly takes a nose dive, flattens back out briefly before tailing off again...Makes for a very strange power curve, I'm guessing when you drive it, it goes, feels a bit flat, then picks up again...

My guess is that the variable cam is activated around 5.1k rpm, which gives the engine a bit more airflow allowing the turbo to flow better and so pushing the torque curve to the right a bit.

Can you tell the cams when to come in? If it was me I'd be trying to map them in around 4.7 - 4.8k instead- you might avoid the nose dive in torque at that point then, and would probably increase peak torque attained.

That's my guess anyway...would certainly be worth playing with on the dyno......

VVTi isn't VTEC, the cam doesn't come in.
Put simply what that curve drop is is the engine outflowing the turbo or at least that's what happened to mine.
But on standard beams, the torque curve goes down and back up at around 4000-5000rpm on practically every dyno sheet I've seen.

[ashley]

vvti adjusts the timing of the camshaft in relation to the cambelt, from memory it advances the timing of the intake valves opening at higher rpm...that's exactly what I meant by the cam coming 'in'. I've always assumed that advancing the valve timing at higher rpm's is designed to increase the ve of the engine, and hence my guess that the pick up in torque at about 5.1k rpm is due to this effect effectively making the engine act like it has bigger cams, and so extending the useful flow of the turbo.

My question was whether you can adjust when the cam timing changes (i.e is it electronically controlled), and so use it as one of the mapping variables. Again- it strikes me from those graphs that if you could initiate the vvti 500rpm ealier you may not get the flat power band between 4.6 and 5.2k rpm, but rather increased torque (and power) at 4.8k instead.

Hope that explains my thoughts better for you

[gavinda]

The older vvt system had a switchover rpm point whereas vvti keeps moving ie advances further as rpm rises.

You can make the cam move where u want with the right ecu tho.the torque curve should be much wider, I personally have never liked looking at a dyno graph from Thor, I think at Surrey rolling road or other dynodynamics the graph would look more impressive.

[ashley]

Good info Gav

[Rogue]

The VVT on this engine is continuously variable and under ECU control. The VVT actuator was modified to restrict the amount of movement that could be achieved electronically to mitigate the risk of piston to valve contact in the event that ECU control was lost for any reason.

[samgpr50]

No longer for sale thanks guys!

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