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Posted By: Scooby Increase Horsepower - 2nd Dec 2005 12:59am
I would like to increase the horsepower of my car's engine. What's the best way to do this?


Any car that you buy today from a normal automobile manufacturer has a number of compromises built into it. These compromises are caused by several factors:

  • The attempt to fit the car into a certain price range
  • The need to meet emissions standards
  • The desire to provide maximum life and reliability

These compromises often give you lots of room for improvement in terms of performance! There are many different ways to create more horsepower from a stock engine. Here are several examples (generally in order from least to most difficult/expensive):
  • Change your computer chip -- sometimes, but certainly not always, you can change a car's performance by changing the ROM chip in the engine control unit (ECU). You usually buy these chips from aftermarket performance dealers. It is valuable to read an independent review of the chip you are contemplating, because some chips are all hype and no performance.
  • Let air come in more easily - As a piston moves down in the intake stroke, air resistance can rob power from the engine. Some newer cars are using polished intake manifolds to eliminate air resistance there. Bigger air filters and reduced intake piping can also improve air flow.
  • Let exhaust exit more easily - If air resistance or back-pressure makes it hard for exhaust to exit a cylinder, it robs the engine of power. If the exhaust pipe is too small or the muffler has a lot of air resistance then this can cause back-pressure. High-performance exhaust systems use headers, big tail pipes and free-flowing mufflers to eliminate back-pressure in the exhaust system.
  • Change the heads and cams -- Many stock engines have one intake valve and one exhaust valve. Buying a new head that has four valves per cylinder will dramatically improve airflow in and out of the engine and this can improve power. Using performance cams can also make a big difference.
  • Stuff more into each cylinder - If you can cram more air (and therefore fuel) into a cylinder of a given size, you can get more power from the cylinder (in the same way that you would by increasing the size of the cylinder). Turbo chargers and super chargers pressurize the incoming air to effectively cram more air into a cylinder. Many manufacturers make aftermarket turbos and super chargers for many different cars.
  • Cool the incoming air - Compressing air raises its temperature. You would like to have the coolest air possible in the cylinder because the hotter the air is the less it will expand when combustion takes place. Therefore many turbo charged and super charged cars have an intercooler. An intercooler is a special radiator through which the compressed air passes to cool it off before it enters the cylinder.
  • Make everything lighter - Lightweight parts help the engine perform better. Each time a piston changes direction it uses up energy to stop the travel in one direction and start it in another. The lighter the piston, the less energy it takes. Lighter parts also allow the engine to rev faster, giving it more horsepower.
  • Increase the compression ratio - Higher compression ratios produce more power, up to a point. The more you compress the air/fuel mixture, however, the more likely it is to spontaneously burst into flame (prior to the spark plug igniting it). Higher octane gasolines prevent this sort of early combustion. That is why high-performance cars generally need high octane gasoline - their engines are using higher compression ratios to get more power.
  • Increase displacement - More displacement means more power because you can burn more gas during each revolution of the engine. You can increase displacement by making the cylinders bigger.

As soon as you start to try increasing displacement, you might consider the economics of buying a new high-performance engine and trying to fit it into your car -- it may be easier and cheaper!
Posted By: camaroz Re: Increase Horsepower - 21st Mar 2009 10:28am
Originally Posted by Scooby
[*
Stuff more into each cylinder - If you can cram more air (and therefore fuel) into a cylinder of a given size, you can get more power from the cylinder (in the same way that you would by increasing the size of the cylinder). Turbo chargers and super chargers pressurize the incoming air to effectively cram more air into a cylinder. Many manufacturers make aftermarket turbos and super chargers for many different cars.
[*]Cool the incoming air - Compressing air raises its temperature. You would like to have the coolest air possible in the cylinder because the hotter the air is the less it will expand when combustion takes place. Therefore many turbo charged and super charged cars have an intercooler. An intercooler is a special radiator through which the compressed air passes to cool it off before it enters the cylinder.


Great write up.

Stuff more into each cylinder & Cool the incoming air that's the best way in my opinion.
One way to achieve this without tearing down your motor is to use nitrous.
This for some reason has quite a bad reputation.
As long as you have a sound motor, this is the way to go. Why mess with the expense of larger valves, cams, heads just to gain single figure HP gains here and there.
When your car is bottle fed you have the perfomance you've got anyway. When the need arises, at the flick of a switch you can have another 100 horses ready to fight with.
Extra performance only when you need it .
I been using nitrous for over 15 years.
Set up right you cant go wrong.
Any how thats my 2 cents worth..
Posted By: Token Re: Increase Horsepower - 26th Apr 2009 10:44am
yeah but put nitrous on a bike...... lol
Posted By: Dave100e Re: Increase Horsepower - 26th Apr 2009 4:39pm
Did anyone ever see Gary Rothwell's Turbo Nitrous Hayabusa? hehe

Theres a couple out there now. Very naughty.
Posted By: Wench Re: Increase Horsepower - 26th Apr 2009 6:15pm
Has he still got his shop in Crosby??
Posted By: Dave100e Re: Increase Horsepower - 26th Apr 2009 10:44pm
Its still there but its closed down now. Last i heard of it was about 5 years ago, and i drove past a few months ago and it hasnt been touched since he left it.
Posted By: Wench Re: Increase Horsepower - 26th Apr 2009 10:48pm
Wasn't he building a race track or something??
Posted By: Dave100e Re: Increase Horsepower - 28th Apr 2009 6:40pm
Ive no idea. I havnt heard much of him for some time since the Cafe days when he turned up on a goldwing doing wheelies. Saw footage of him at shows and that a few years ago but thats it. Do you know if hes still on bikes? I know he was trying to get into fast cars with the garage alongside the bikes.
Posted By: Wench Re: Increase Horsepower - 28th Apr 2009 7:25pm
I'll ask a few of the lads and see what I can find out wink
Posted By: camaroz Re: Increase Horsepower - 25th Jun 2009 7:24pm
Just "googled" Gary Rothwell and found this vid.
You've all probs seen it, and I know it's old - but here it is anyway - AWESOME !

http://www.metacafe.com/watch/2105928/fastest_speed_dragged_behind_a_motorcycle/

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