Roojai

As far as I know, boost level is effected by the turbo (what size it is/how quickly it spools up (which is effected by exhaust flow)), and the waste-gate which is controlled by the ECU through the solenoid.

If you put on a MBC (a dawes device) then you can control the level of the boost right.

But if the charge tempeature is high 'cos of heat soak in the intercooler, will the boost level drop, and if so why. Is it just a physical response or is there some other mechanism controlling the boost.

Thanks for any answers.

SiHethers

Roojai

The boost level doesn't drop with heatsoak of the intercooler, but the airflow will reduce as the intercooler will not be able to reclaim as much density (hot air compared to cold air will have a lower density at any given pressure). The boost drop you see with the Dawes when you get heatsoak is due to the tension in the spring inside the MBC reducing when it gets hot, so opening earlier. This is un avoidable due to the Dawes lying across the coolant return pipe from the turbo.

Simon

Roojai

Thanks very much. I must build a little casing for it.

SiHethers

Not sure I would bother, as it is a nice unintentional safety feature. So if you've been sitting in traffic so your intercooler is heatsoaked (therefore you are more likely to get detonation as charge temps are higher) your boost will be reduced slightly (usually 1-2psi). But once you've been moving and up to speed for a little while charge temps will be lower, and boost will come up again as the Dawes cools.