How must can boost change with weather?

[mechanicboy]

Can boost levels created from a blower change significantly with air density changes? I ask because on the dyno my truck peaked a little over 8psi in mid 70 degree weather but tonight I saw over 11psi peak when it was 30 degrees out.

My truck was definitely running like a rapped Ape though :banana: Pissed off a AWD turbo CRX.

 

[mustanginky]

I'm pretty sure cold weather has been the death of many a lightning

 

[mechanicboy]

I'm pretty sure cold weather has been the death of many a lightning

Isn't that because they lean out from the lack of widebands? BTW, I was watching my A/F and the onboards were reading 11.2 +/- .2

I guess I'm a little confused because Shaun said I was maxed out on blower but the boost increases with RPM all the way to cutoff at 7500 and I never thought I'd see this kind of boost.

 

[firemanmike]

I don't think that the boost increases in cold weather, but you just get much colder air going in....which will make the car run faster, making you think the boost has increased but it hasn't, I THINK??? We'll have to wait for an expert for a correct answer on this!!!

 

[mechanicboy]

I don't think that the boost increases in cold weather, but you just get much colder air going in....which will make the car run faster, making you think the boost has increased but it hasn't, I THINK??? We'll have to wait for an expert for a correct answer on this!!!

I'm going off the boost gauge. I could recalibrate it to make sure it's accurate.

 

[Brutal Metal]

I'll pick up a couple lbs in a low humidity 60 degree day as opposed to 95+ with dewpoints over 80 in South Florida..

 

[mechanicboy]

I'll pick up a couple lbs in a low humidity 60 degree day as opposed to 95+ with dewpoints over 80 in South Florida..

I've talked to a few people and they say it seems a little high but a blower definitely builds more boost with better D/A. I talked to an L guy and he said between the more boost and maxing out the MAF sensor Ls are known to blow because of this.

He stated it like this; turbos have a wastegate or BOV that regulates boost pressure so they stay the same, PD blowers do not so as the air thickens more boost is created as it has nowhere else to go.

I learn something new everyday.

 

[manolith]

i see about a pound at 50 degree weather when compared to the usual 80 degrees we see here in florida.

 

[Black*Death]

More O2 molecules in cold weather means more oxygen compressed thus increasing psi?

This is a total guess by the way..

 

[97snakebite]

i thought it only really changes with altitude...

 

[mechanicboy]

i thought it only really changes with altitude...

Shaun said it can change with cold weather or a restriction. Unless my cams suddenly did some weird shit it's the weather (no cats so they aren't plugging).

 

[itSSlow98]

The colder the air the denser the charge. Its exactly what nitrous does, it cools the air and allows more air in along with a bigger combustion.

 

[02blownGT]

Man why do i never see a change,could be 40 or 90 i see the same boost within a 1/4 of a psi.I would kinda of like to pick up some hp in cold weather.

 

[2001cobravert]

I saw a 2 psi spike in 40* weather here in PA. This was with a Procharger and Anderson powerpipe.

 

[TonyG2]

Yes, boost will increase at lower temperatures. A while ago, I derived a formula for it based on thermodynamics of an ideal gas. The formula was a little bit complicated, but the gist of it is that the final pressure depends on the initial air density. So if the ambient air density increases (in colder weather for example), the boost will increase. I don't remember if it was linear or not, I'll have to check. By "linear," I mean that if the air density increases by, say 10%, then the boost will increase 10%.

 

[Myzticsnake]

The colder the air the denser the charge. Its exactly what nitrous does, it cools the air and allows more air in along with a bigger combustion.

bingo. Cold air is more compact air. Its why it sinks to the bottom of your bathroom floor when you take a shower. Cold dry air is also denser than cold wet air.

Easy experiment is to hit a golf ball when its really cold outside, I lose 20+ yards on an average shot when its 40 degrees vs when its 85+.

 

[snakerider]

Boost does change with cooler weather. I gained 1psi in the winter.