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Location:
Brisbane
Registered:
July 2002
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how much does heat of the day affect power?
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Thu, 30 September 2004 06:51
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just driving my car today I have found(or atleast i think thats it) that in the heat of the day(not overly hot.. but maybe around 30 degrees) the power of my car changes dramatically.
normally I can spin the wheels completely all the way through 1st and second
today with me and a passenger it didnt spin the wheels until up at around 5500 in 1st and not at all into second..
I will drive it tonight and see its not actually anything wrong.
but is that about normal?
and would tyres get decently more sticky on a hot day?
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Location:
cambo
Registered:
May 2002
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Re: how much does heat of the day affect power?
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Thu, 30 September 2004 07:10
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its turbo right? 30 degree daytime will be very noticeably slower than say a 10 degree night. especially if its humid.
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Location:
perth WA
Registered:
June 2004
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Re: how much does heat of the day affect power?
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Thu, 30 September 2004 07:13
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And on hot days be very weary of detonation 
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Location:
cambo
Registered:
May 2002
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Re: how much does heat of the day affect power?
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Thu, 30 September 2004 07:38
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on hot days you need to wind up the boost to compensate for the lack of power 
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Location:
Low Head (Tasmania)
Registered:
September 2004
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Location:
Brisbane, QLD
Registered:
February 2003
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Re: how much does heat of the day affect power?
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Thu, 30 September 2004 09:14
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| EVOSTi wrote on Thu, 30 September 2004 17:10 |
its turbo right? 30 degree daytime will be very noticeably slower than say a 10 degree night. especially if its humid.
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its been rather humid around the brisbane\gold coast area recently
i was surprised by how humid its gotten recently by looking at the sweat some of the AC componants i work on have been getting lately(as well as myself )
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Location:
Brisbane
Registered:
July 2002
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Re: how much does heat of the day affect power?
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Thu, 30 September 2004 23:23
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yah, very humid.. well my clutch fan does blow straight into both sides of IC pipes and pod.. so that doesent help.. maybe that combined with the heat of the day is whats making the power loss
would it also make less boost?
i found something coming out of the plenum today though going no-where except into the air.. so i blocked that and will see what that does(if anything)
i hope i havent hurt it
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Registered:
May 2002
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Re: how much does heat of the day affect power?
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Thu, 30 September 2004 23:44
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Higher air intake temps = less power (most significant and noticeable in forced induction vehicles). Do a search and you will find some generic estimates of roughly how much power decreases as temperature increases.
Higher ambient temps and road surface temps = more traction (makes it harder to spin the wheels). That's why the burnout before running a 1/4 can be helpful for traction, as most decent tyres will work better with some heat put into them (especially race compounds)
Higher air temps = slight decrease in boost levels, hotter air is less dense (most noticeable when running higher boost levels > 15 psi)
So in conclusion, it's normal for your car to feel a little slower on a hot day, and it's normal to not break traction as easily too. Just make sure there are no other probs adding to this.
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Location:
Brisbane
Registered:
July 2002
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Re: how much does heat of the day affect power?
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Thu, 30 September 2004 23:49
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| ke382TG wrote on Fri, 01 October 2004 09:44 |
Higher air intake temps = less power (most significant and noticeable in forced induction vehicles). Do a search and you will find some generic estimates of roughly how much power decreases as temperature increases.
Higher ambient temps and road surface temps = more traction (makes it harder to spin the wheels). That's why the burnout before running a 1/4 can be helpful for traction, as most decent tyres will work better with some heat put into them (especially race compounds)
Higher air temps = slight decrease in boost levels, hotter air is less dense (most noticeable when running higher boost levels > 15 psi)
So in conclusion, it's normal for your car to feel a little slower on a hot day, and it's normal to not break traction as easily too. Just make sure there are no other probs adding to this.
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thats what im worried about
also now if i rev out 1st(near 7k rpm)
and then go into second.. it drops in nice.. then the rpm goes down and loses all the boost it would have kept and has to build from 10 vacuum again
makes it really sluggish going into second
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Location:
Brisbane
Registered:
July 2002
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Re: how much does heat of the day affect power?
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Fri, 01 October 2004 00:25
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just went for a drive then and yeah.. its pretty hot..
only making 12 psi now as opposed.. will i generally make less actual boost pressure on hot days?
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Registered:
May 2002
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Re: how much does heat of the day affect power?
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Fri, 01 October 2004 00:40
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making 12psi now, as opposed to what normally????
Mine as an example, below 5 degrees air temp the gauge will read 21.5psi, on a 25 degree day it will be 20 - 20.5 psi. A small but noticeable difference.
A drop of 1 psi is noticeable in how the car drives, especially if you are running around 14 or 15 psi.
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Location:
Brisbane
Registered:
July 2002
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Re: how much does heat of the day affect power?
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Fri, 01 October 2004 00:44
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| ke382TG wrote on Fri, 01 October 2004 10:40 |
making 12psi now, as opposed to what normally????
Mine as an example, below 5 degrees air temp the gauge will read 21.5psi, on a 25 degree day it will be 20 - 20.5 psi. A small but noticeable difference.
A drop of 1 psi is noticeable in how the car drives, especially if you are running around 14 or 15 psi.
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normally around 13.5-14 psi
only got 12 before
and its not extraordinarily hot yet(though hotter than days when i was getting the hihger boost)
but yeah.. whole car feels alot more sluggish
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Registered:
May 2002
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Location:
Brisbane
Registered:
July 2002
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Re: how much does heat of the day affect power?
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Fri, 01 October 2004 00:59
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| ke382TG wrote on Fri, 01 October 2004 10:55 |
1.5 psi to 2 psi is quite a signicant drop at a set 14psi just due to higher air temps.
I would do a quick search for a leak somewhere, if it is still idling at the rpm as it always has I would check for leaks anywhere between the turbo compressor and the throttle body.
I know that my turbo is at the limit of it's efficiency range on 20psi on my engine so I am not surprised that I see a slight drop in boost (of 1 to 1.5 psi) once the air temps increase form below 10 to over 25.
I wouldn't have thought that 14psi would have your turbo's near their limit and I assume you run a decent intercooler too? As even if you can maintain the exact same boost levels but in one case your engine is taking in nice cool air and in the other case it's taking in hot air the cool air will make more power and more importantly feel better to drive.
Edit: Saw in your sig that the IC dimensions and that should be doing a fine job.
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ill check again for a leak but i dont think there is one there...
at 14 psi its at the top of 1jz's turbo's safe limit i guess...
The intercooler does an awesome job.. also ive got no shroud around clutch fan atm and blows onto both ic pipes and the pod.. so that wouldnt help matters on an already warm day.
I was amazed to see it only making 12 psi aswell.. ill give it a good look over tomorrow morning
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Registered:
May 2002
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Re: how much does heat of the day affect power?
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Fri, 01 October 2004 01:02
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Good one, give it a check and let us know how you go.
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Location:
Brisbane
Registered:
July 2002
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Re: how much does heat of the day affect power?
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Fri, 01 October 2004 12:12
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tried it tonight.. not a hot night.. but not an overly cold one
still dead on 12 psi
cant find any boost leaks
was at 14 the other day and the only thing ive done since then was change old shitty spark plugs that were fucked to new ones gapped at .8mm
any idea's?
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Location:
Brisbane
Registered:
July 2002
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Re: how much does heat of the day affect power?
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Sat, 02 October 2004 12:50
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im such a dick.. problem was the throttle cable i put back on with too much slack.. i think i now have it on better than ever
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Location:
Sydney
Registered:
May 2004
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Re: how much does heat of the day affect power?
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Sun, 03 October 2004 02:18
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lol if that was me i would have kept it to myself haha
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Location:
Brisbane
Registered:
July 2002
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Re: how much does heat of the day affect power?
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Sun, 03 October 2004 09:22
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| Celica_John wrote on Sun, 03 October 2004 12:18 |
lol if that was me i would have kept it to myself haha
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hahaa..
the heat of the day does still affect 
but the 2 psi loss i was seeing wasnt because of it
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