Hot weather and performance.

[yellow fever]

Guys my cars is driving like crap the past few days.
I'm wondering if its because if the hot temp or if there is something wrong with my car.
Just wondering if you guys noticed a change in you'r car's performance in the past week or so.

Thx guys.

[TTSam]

Originally Posted by yellow fever

Guys my cars is driving like crap the past few days.
I'm wondering if its because if the hot temp or if there is something wrong with my car.
Just wondering if you guys noticed a change in you'r car's performance in the past week or so.

Thx guys.

I find it drives better in the hotter weather. Maybe it's because the oil temp gets more quickly to the middle - where in the colder weather it seems to take forever.

What octane gas are you using? I find the Petro Canada 94 works well. I do notice a bit of a drop off using 91 from Esso, Shell etc.

[yellow fever]

I never use the ultra 94 and usualy go to Shell.

[Gearhead999s]

Originally Posted by yellow fever

Guys my cars is driving like crap the past few days.
I'm wondering if its because if the hot temp or if there is something wrong with my car.
Just wondering if you guys noticed a change in you'r car's performance in the past week or so.

Thx guys.

Density Altitude has a huge effect on engine performance.The hotter it is the more power you lose.

http://en.wikipedia.org/wiki/Density_altitude

[KJ]

The hotter the air is, the less dense it is with oxygen. Also, the high humidity also leads to less oxygen molecules in the air.

Since the engine mixes oxygen and gasoline and ignites it to make power, less oxygen means less power.

Turbo cars suffer less from this problem because their turbos counteract the less oxygen dense air by spooling the turbo's longer until the required boost is reached. This may increase turbo lag, but power will still be good.

Something to look forward to in the new M3!

- KJ

[yellow fever]

I'm also being told by Parkview BMW not to use the shell gas right now as they just increased the cleaning agent in there gas by 20% few weeks a go.
Some BMW's are not reacting well to it.
Something to think about.

[Prince_of_Persia]

My car drive well in this weather, and I always use Shell 91 VPower

[apecush]

Originally Posted by yellow fever

I'm also being told by Parkview BMW not to use the shell gas right now as they just increased the cleaning agent in there gas by 20% few weeks a go.
Some BMW's are not reacting well to it.
Something to think about.

Shell seems to have a habit of doing this - 10 years ago they were responsible for a lot of engine troubles around here which they strongly denied. Never use them as a result of that and the "top tier" marketing bs.

[Gearhead999s]

Originally Posted by yellow fever

I'm also being told by Parkview BMW not to use the shell gas right now as they just increased the cleaning agent in there gas by 20% few weeks a go.
Some BMW's are not reacting well to it.
Something to think about.

I find this funny as my wife was told recently by Parkview to use Shell or Esso only in her 335is as other fuels were causing problems.especially the 94 Petro Canada I do know that the turbo v8's are having issues with our crap fuels with extremely high underhood temps and have suggested using 87 octane instead of 91 to help with this issue.

[767IJP]

Density altitude shouldn't be much of a concern. Certainly not to the point of making your car drive " like crap".

Piston airplanes. Certainly suffer from this but we are talking about pressure altitudes in the thousands of feet.

I see you're located in Toronto so density altitude would have zero effect.

[Gearhead999s]

Originally Posted by 767IJP

Density altitude shouldn't be much of a concern. Certainly not to the point of making your car drive " like crap".

Piston airplanes. Certainly suffer from this but we are talking about pressure altitudes in the thousands of feet.

I see you're located in Toronto so density altitude would have zero effect.

A higher temperature causes a higher density altitude which will reduce horsepower due to a lower oxygen content.

A 100f day at sea level is same as being at 2500 ft altitude.You loose about 2% power for every 1000 ft of altitude increase.Add in the other effects of higher heat on the operation(a/c compressor ,higher electric load due to fans)you will notice the difference in performance.Turbo or supercharged engines are worse for this with power loss vs heat.

[767IJP]

I am aware of what density altitude is. I'm just saying this will have zero to do with this guys problem. The guy is located in Toronto. I doubt even a 150 degree day would cause a reduction in power worthy of making his car drive so noticeably that it's "crap".

Turbo chargers, at least in piston powered aircraft increase manifold pressure to counteract increases in pressure altitude to make the engine keep sea level manifold pressure to altitudes where otherwise significant power losses would occur. I would say they'd likely do the same in cars so I can't see a turbo powered car performing worse than a NA car when it comes to density altitude.

I would also imagine the fuel injection system on this car is advanced enough to optimize fuel patterns when in comes to altitude/temp. I would say the density altitude argument is pretty moot. Toronto being at 570 feet A 100F day would have a density alt of about Calgary on a standard ISA day- 29.92/15C. We aren't hearing many complaints from out there.

[Gearhead999s]

Originally Posted by 767IJP

I am aware of what density altitude is. I'm just saying this will have zero to do with this guys problem. The guy is located in Toronto. I doubt even a 150 degree day would cause a reduction in power worthy of making his car drive so noticeably that it's "crap".

Turbo chargers, at least in piston powered aircraft increase manifold pressure to counteract increases in pressure altitude to make the engine keep sea level manifold pressure to altitudes where significant power losses would occur. I would say they'd do the same in cars so I can't see a turbo powered car performing worse than a NA car when it comes to density altitude.

I would also imagine the fuel injection system on this car is advanced enough to optimize fuel patterns when in comes to altitude/temp. I would say the density altitude argument is pretty moot. Toronto being at 570 feet A 100F day would have a density alt of about Calgary on a standard ISA day- 29.92/15C. We aren't hearing many compliantly from there.

When you dyno a engine in order to know the true horsepower it is developing you must do a correction factor based on temperature and pressure altitude.I have had lots of turbo cars over the years and they all fell off big time in the heat and had lots more turbo lag in normal driving.My wifes 335is is also very much like this and makes really dislike the idea of the next M3 being F!.
A good practical example of supercharged powerplants suffering in the heat was at Mosport 2 weeks ago with the Mustang guys.My M3 with maybe 350-RWHP has no problem pulling 500+RWHP Stangs up the straight on a 35c day.These guys were all complaining about how much down on power their cars felt compared to the cooler AM.Some engine management systems probably loose more power than others in these conditions but I have noticed this in everything that I have owned over the years.

By the way I have over 5700 hrs TT with 5300 M/E.I used to spend a lot of time over FL20 in piston aircraft working photo survey so I am pretty familar with the effect of temperature & altitude on performance of piston engines & airframes.

[767IJP]

Hey man. I'm not being disrespectful.

I just think your density altitude argument is pretty irrelevant to what this guy is talking about. It's minute power decreases in the grand scheme of things. It's not an issue that would cause a car to drive like crap.

I have pretty much zero clue about turbos on cars so I'll take your word there. But this car ain't turbo'd is it? This car at 100F is at the same density altitude as Calgary on a 15C day. We aren't hearing Calgary drivers complaining about their cars driving like garbage on nice spring days. I think you're barking up the wrong tree a bit.

And I hope FL20 is a typo. Theres no such thing.

[Gearhead999s]

Originally Posted by 767IJP

Hey man. I'm not being disrespectful.

I just think your density altitude argument is pretty irrelevant to what this guy is talking about. It's minute power decreases in the grand scheme of things. It's not an issue that would cause a car to drive like crap.

I have pretty much zero clue about turbos on cars so I'll take your word there. But this car ain't turbo'd is it? This car at 100F is at the same density altitude as Calgary on a 15C day. We aren't hearing Calgary drivers complaining about their cars driving like garbage on nice spring days. I think you're barking up the wrong tree a bit.

And I hope FL20 is a typo. Theres no such thing.

Back when I was flying we wrote everything!No personal computers for another 15 years!I meant to say over 20000 ft In a lower powered car I used to find 2500 ft of altitude increase was quite noticable but that was also before the complex engine controls of today.

[767IJP]

Lol I figured it was a typo. The engines on my a/c are big ole jets. Been a loooonnnng time since a saw a prop spinning away in front of me!

Now the most interesting thing in this thread to a guy who's had his car for a very short time is this gas issue.

I've had my car 2 days since redelivery after ED and put Petro Can 94 in it and I read many using Shell 91. What gives? This I'd like to know about. Am I hearing Shell is putting ethanol in the 91 now? What's wrong with the 94 at Petro Can?

[Gearhead999s]

Originally Posted by 767IJP

Lol I figured it was a typo. The engines on my a/c are big ole jets. Been a loooonnnng time since a saw a prop spinning away in front of me!

Now the most interesting thing in this thread to a guy who's had his car for a very short time is this gas issue.

I've had my car 2 days since redelivery after ED and put Petro Can 94 in it and I read many using Shell 91. What gives? This I'd like to know about. Am I hearing Shell is putting ethanol in the 91 now? What's wrong with the 94 at Petro Can?

I was told specifically not to use the PC 94 because of a higher ethanol content and my last 3 M's have run very poorly when cold when using 94 even when it was Sunoco.They all ran better on the 91 when cold to be frank I never really noticed much of a difference otherwise.

[767IJP]

Geez I'm surprised PC adds ethanol to their top tier gas. Shell didn't On their 91. Has that changed? Are there any other places you'd recommend?

[tibra1]

There is so much confusion on this thread..not sure where gas and octane factor in here..high compression engines such as this needs high octane fuel so thats one point by itself.

Regarding hot weather and performance..yes ofcourse the hotter it gets the less power you make..hot air is not as dense with oxygen as cold air is...hence you lose power when its hot..same can be said about altitude..the higher you go the less oxygen dense the air is..so again you will lose power

I can say definitively my car runs way stronger in the colder months.

[767IJP]

Would you say it affects it enough to say it runs like crap? Doubt it.

I would say a bad tank of gas is more likely a culprit. I ask about gas because apparently a company with a 94 octane gas is making cars run worse than a 91 octane. The 91 not containing ethanol and the 94 having the additive. As mentioned previously in this thread.

[tibra1]

Believe it or not it is actually a noticeable difference with the M3 in cold and hot weather..car feels as if its more labored..descriptions are subjective so saying it runs like crap may seem extreme to us but maybe not to the OP

My suggestion throw a bottle of techron in the tank and see what happens..again just taking a shot in the dark here.

[767IJP]

Tibra? You guys in the states are your premium brands of gas (and high octanes), do they have ethanol added?