Low End & High End

[Lancer78jas]

Heard from somewhere that during pick up (low end), car actually require warm air. In high end, it actually require cold air...

 

Is it true?

[Bern2]

Dun think this is true. Warm air would only help for start up. Cold air just packs more o2 molecules than warm air.

[Clazio71]

During day time when the weather is normally hot in Singapore, the engine tends to become hotter on the roads after prolonged driving, thus vehicles need CAI (Cold Air Intake) to cool down the engine. At night, when the weather is colder or in some countries where temperatures are generally low most of the time, vehicles will need Hot Air Intake to warm up the vehicle during driving but this is seldom applicable in Singapore given the weather conditions. To summarize, any vehicle needs a balance of temperature for optimum performance because extreme temperatures tend to damage automotive parts much easier.

[Elfenstar]

100% FALSE.

 

Colder air is better at any point in time (well except for cold startups in cold countries).

 

Denser air has more O2. More O2 = more fuel to ensure proper AFR. More fuel + more air = bigger bang. Bigger bang = more power and more torque.

Edited March 20, 2007 by Elfenstar

[Elfenstar]

CAI cools down the engine????

 

CAI = cooler air = denser air = more O2 molecules --> more fueling --> bigger bang = more power and more heat.

 

An engine is cooler in colder temps not because of the CAI but because the cooling system (i.e. coolant and rad) get cooler faster due to air temps. Don't forget that temps are only marginally cooler because if the coolant temps get too low, the thermostat closes preventing the engine from getting any colder.

 

Warm air is only beneficial during cold startups and just after to reduce condensation of fuel on the cylinder walls thus reducing wear. If i remember the temp correctly, if the cylinder walls are 13degC or higher, this will not be an issue.

 

Another use for warm air is for fuel efficiency in which warm air is allowed into the intake cycle to reduce the amount of O2 so less fuel is used. this is at the expense of power and torque and this is under the assumption that the driver has an eco-conscious/light-footed driving style.

Edited March 20, 2007 by Elfenstar

[Clazio71]

That was my perception of CAI but thanks for correcting me... I will learn from this misconcept because all the while, I thought CAI helps to maintain the temperature of a vehicle to prevent overheating for optimum performance. The intercoolant is responsible for that so I actually mix them up... I will continue to learn from mistakes for continuous improvement and that is why we have MCF.... for all of us to discuss about cars and learn from each other... Cheers Elfenstar!!!

[Wilb]

Learnt a new thing.

[Clazio71]

Ya... Feel free to post any enquiries in the forum and we have many MCF friends around to help you answer your doubts... It's the best forum to discuss everything under the sun and learn new stuffs everyday...

[Gilgamesh]

Speaking of which, we still have not reach a conclusion to the topic yet

 

OK, can some gurus list some mods that we (noobs) can do to improve low ends, mid ends and high ends? The mods should differentiate between auto-transmission and manual-transmission, eg straight thru exhaust is no-no for auto trannies, etc[:)]

[Watwheels]

There's always a compromise. If u want low-end, your high end will have to suffer. Vise versa for high-end.

 

Unless u can live with the compromise, u'll never be satisfied so why bother in the first place.

[Gilgamesh]

u forgot to mention - FC, warranty and LTA rules are compromised also

dat's why my engine and air intake still stock, except for some slight mod to the air filter and the airbox geometry.....

[Otsego]

Yeess~~ SIR!!

[Elfenstar]

I'm not going to go into the exhaust stuff for auto's. Just need to know that there is nothing wrong with a straight through exhaust for autos other than the slight loss in low end is much more noticeable.

 

Here's a (very) short list of relatively inexpensive things that can be done to improve performance.

 

Lose weight (your car, you or both ): less energy/power is needed for accelerating, maintaining higher speeds not to mention cornering speeds and braking are also improved.

 

Low viscosity oils: A good quality low viscosity oil helps as the lower viscosity means less drag on the engine components.

 

Ensure the a/c system is in tip top condition: Esp piping and compressor... the harder the compressor has to work, the more the power loss. This is the most power draining accesory.

 

Clean airfilter: No point in changing to a hi-flow air filter if its going to be clogged up with dirt restricting airflow.

 

Remove coolant hoses from the plenum: All cars have a coolant in and out on the plenum. This is for cold starts (as what i mentioned to clazio earlier). Its a white elephant in our climate and only serves to increase the amount of hot air going into our engines. The power difference is almost negligible when the engine is warmed up but every little bit counts. Just unplug both hoses and join them together.

 

Fuel: Use the appropriate fuel. Run a fuel with a ron rating in which the ignition timing is most advanced. Do note, that unless theres FC savings, theres no point running any higher than 92/95ron if the ECU does not advance timing past it.

 

Ignition timing: Factory settings are very conservative to prevent pinging. Get a tuner to advance it just a few degrees but ensure that there is no pinging. If your car runs max on 92 or 95ron you will be able to get away with v.slight pinging (during high load WOT) by running a higher octane fuel.

 

Sparkplugs:

-Platinum and irridium plugs last longer but do not improve performance... the opposite actually. Copper plugs are the best for performance as they have the best spark. Dont forget to change them every 10000kms to ensure they are in peak condition always.

-when installing single ground sparkplugs make sure the open end is facing the intake valves (i.e. the 90deg bend is on the side of the exhaust valves). Should get you 1bhp extra.

 

Thats all i can think of for now.

[Clazio71]

Wow... you are really a veteran in car modifications. Next time I have any doubts sure will ask you for advice... but from what I know, iridium and platinum spark plugs are much more expensive than copper spark plugs and justified by their smaller tip diameter for better sparking = better performance... Isn't that so? Any other expert in cars can join in the discussion...

[Elfenstar]

A spark jumps the electrode gap when the voltage at the electrodes reaches the ionization point, since the ionization point, (voltage needed to jump the gap), is lower when a small diameter center electrode is utilized, spark voltage is also lower. The thing is we need a stronger spark for performance applications (to allow for more complete combustions via a bigger bang).

 

Considering how bad a conductor platinum is the smaller center electrode is a necessity. Basically same voltage from the distributor/coilpack = smaller spark with platinum vs copper. Iridium is even worse (sparkplug gaps usually have to be reduced as well) than platinum though it lasts much longer.

[Jazzer]

Nah. Cold air all the way.