It probably sounds pathetic, but im a little confused about how my carburator works... Im used to fuel injected cars.

Any way, two things i really want to know.

Firstly is cold air directed at the carby just as important to carbureted cars as it is coming through the cold air box in injected? Is more air better- or can you have too much?

Does the temperature of the airflow make any noticable difference?

Im new, gimme a break

The carb will consume only as much air as the throttle plates will pass, so you can't have too much air.

Desirably, the air at the inlet side of the carb will be at atmospheric pressure, so don't duct air direct from a high pressure area to the inlet of the carb. You can duct it to the air cleaner & it will work fine if excess air pressure can be vented into the underhood area.

Cold air is more dense, & contains more oxygen for that reason. This makes it good if you plan on using lots of revs most of the time, like in racing. The high gas velocity will prevent the fuel from condensing in the inlet & everything will be fine, HOWEVER,... if it is a street engine, & particularly if you do mostly city driving, then manifold heat is a BIG advantage. The heat keeps the fuel in a gaseous state, & it's gas that burns, not liquid. This results in smoother running & better fuel economy. The improvement in driveability is most noticeable in mid winter.

AS for me, i'm prepared to sacrifice an almost unmeasurable loss in top end performance in exchange for good driveability & smooth running, so my 1200 GX engine retained it's stock manifold heating setup. I never regreted it ever.
Chris

Dodgeman Chris beat me to my essay..but here it is anyway...

Quote:

Not on NA engines. Non-turbo engines like the air warm (to a point), to keep the fuel atomised. This is why factory intakes have a connection to the top of the exhaust headers to introduce some hot air into the intake, especially when the engine is cold.

Turbos heat up the intake charge..that's why cooler is better, but not HEAPS cooler. Cooler air is more dense..and can have more oxygen, Carbys are tuned for a given temperature and pressure. This is why carby cars can really be bad in "mountainous areas" eg. ski fields in Queenstown. They may be getting the right amount of air, but because it is less dense because of altitude, then there is less oxygen, and the engines run rich (and less power results). Fuel injected cars with a decent ECU can adjust the fuel to suit the air quality, based on input from the 02 sensor in the exhaust. Non-intercooled turbo motors can have air intake temperatures over 60 degrees Celcius...And you are worried about 40 degree air from the engine bay?

Example
_____________In temp____Out Temp
Turbo engine__15degC_____35degC
____________45degC______65degC
Non-Turbo____15degC_____20degC
____________45degC______50degC

The post turbo difference gets exponentially high with the rise in take temp. There is much less difference on an NA engine, taking into account regular under bonnet temps and normal intake/filter designs.

Quote:

More air is better. And for Australia (Where it can get stinking hot) a cooler intake air will help keep the engine intake temps to a reasonable range in summer.

So, what I'm basically saying is..with a carby engine cool air is good, but don't spend hundreds of dollars trying to have the "coolest intake in the world". You will see little or no benefit. With a turbo..well that's different (carby or EFI).

If you don't believe me..make the changes and take your car to a dyno, and if you gained any more than 1 or 2% under "some" conditions, I would be surprised. What I can promise you is that you'll have a lighter wallet.

Save the money for a turbo upgrade...then I know you'll be happy.

Chris

Quote:I agree.

Save money, you can still make a cold air/ram air system for almost nothing.


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1455

This one probably won't have much effect since it is not boxed in, but shows where you can hook the front end of the hose.



1456



Ok so this one will cost some dollars ...1133

If you keep the stock intake heater (i.e. just add a fresh-air tube to the stock inlet) you'll have an advantage on hot days, without any disadvantage on cold days. Without the heater (heat riser valve) you risk frozen throttle at temps just about freezing.

Cold air makes a difference and not just on the top end (i.e. ram air/high pressure). While Dodgeman is correct that the engines are originally tuned for non-cold air intake, the underhood temps can get too hot in summer in warm climes.

Even without it being very warm weather, the cold air won't hurt performance. But like Dodgeman says, you may get slightly worse fuel economy. You could jet your carb a little leaner to take max advantage of the colder air.