jgiachino

I might just be losing it, but i could swear that my boost is down a few psi during the middle of the day (arizona) when it's hotter than ****.....

In the morning (90-95*) i hit approx 35psi, during lunch / after work (105*+) it's around 30psi.....anyone else notice or does this make sense based upon diesel principals? or am i loosing it?

JG

CButler610

Cooler air is more dense.

The humidity -and- temperature is what we fight here.


http://www.engineeringtoolbox.com/ai...ity-d_771.html

CamperAndy

It is not diesel principals that control this but you are correct and noting that as temperatures rise the boost pressure will decrease for a give turbo speed, which is controlled by the mass flow though it.

Hot dry air is less dense and does not compress as well and will result in lower boost pressures and higher EGT's. Add water injection pre turbo compressor and that will both cool and add mass that will increase boost.

HOHN

Exactly.

I once nailed by truck WOT when it was about 15° outside and the truck was fully warmed. The thing took off so hard it slipped the clutch! That was the first and only time the clutch slipped with that combination of mods.

At the time, I was used to seeing 32psi of boost. I was seeing 35+ under these conditions.

Density is your friend. Humidity is your enemy. Water injection helps to cool things down, but that additional humidity alone doesn't increase boost-- just mass flow.

Cold dry air is best overall.

JH

CButler610

The more I consider this water/meth idea, the more I like it. The water (compound) can't provide O2 directly, but will cool things down and provide a more dense mixture as it uses energy (heat) to go from a liquid to a gas much like our A/C units. About like having a more efficient intercooler. I believe the Methanol can actually provide some O2 as well.

I wan't to try this NOW.

jgiachino

Thanks for the inputs....at least i'm not crazy! :-)