02GF74
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| posted on 21/8/06 at 07:52 AM |
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engine power vs air temperature
hey - anyone got or seen a graph that shows how engine power increases or descrease with change in temperatur of drawn at (at normap air pressure) -
for carbs not EFI.
we know at lower temps air is denser so more oxygen to brun with the fuel.
also is there a lower temperatuyr limit where the air is so cold you are using energy to keep the engine up to tempeerature?
(asking since original my carbs were covered by the bonnets so would be receiving warm/hot air that had passed thru the rad but now with bonnet cut
out., they should be drawing some air from the outside so mega loads of extra BHP!!!
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Findlay234
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| posted on 21/8/06 at 08:10 AM |
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lol, dont think its a case of mega loads. maybe a few hp up and down... It will also move the point at which peak power is produced along the rev
range.
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Nick Skidmore
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| posted on 21/8/06 at 08:23 AM |
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If your carbs have been set on a particular day on the rolling road max power will be made under those conditions.
Carbs meter fuel in to the airstream based on volume not density so only electronic fuel injection with the appropriate sensors and correction built
in to the program will compensate for changing air density (estimated by temperature).
For this very reason most carb / turbo set ups are 'suck through' rather than 'blow through'. Dellorto did do some special
carbs for the first generation if Esprit turbo's to be operated on 'blow through'.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Sacal
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| posted on 21/8/06 at 09:25 AM |
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Relative horsepower calculator
Correct in the fact that carbs meter by volume, but as cold air is more dense per volume....more O2 per volume....more O2, bigger jets, bigger HP!
Racers have been jetting like this for years, used to be a real problem for normaly aspirated F1 cars in the turbo era at tracks like Jarama where the
renault turbos kicked ass due to the elevation and temperature 
Can of worms???????
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Nick Skidmore
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| posted on 21/8/06 at 10:57 AM |
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Reading between the lines I think he was hoping for more power without resort to re-jetting, my point was there is no automatic compensation for a
higher density charge with carbs.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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zetec
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| posted on 21/8/06 at 04:25 PM |
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I'm sure I read in PPC somewhere that for every 10 deg C you could recon on loss of 3BHP. No science given but gives a rough idea.
" I only registered to look at the pictures, now I'm stuck with this username for the rest of my life!"
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chrisj
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| posted on 21/8/06 at 04:52 PM |
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BMW turbos suck their air in 2 inches above the road surface to get the coldest air possible.
Colleague of mine did an engine by submarining it in a flood !
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paulf
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| posted on 21/8/06 at 04:56 PM |
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Ive just ducted my airbox to the front of the car on one side of the radiator and have run a datallog on it and found that i have reduced the
incoming air temp by at least 20 degrees.It is now showing an inlet air temp of betwen 25 and 35 degrees when fully warmed up and used to run at 50 or
60 degrees when sucking in air from under the bonnet.
I am now trying to adjust it for some more power and have advanced the ignition a little as well as increased the fuelling at high throttle openings
with some success, so it is worthwhile if you can achieve it
Paul.
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DIY Si
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| posted on 21/8/06 at 05:01 PM |
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How's this?
 
Rescued attachment airflow.jpg
“Let your plans be dark and as impenetratable as night, and when you move, fall like a thunderbolt.”
Sun Tzu, The Art of War
My new blog: http://spritecave.blogspot.co.uk/
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