Please educate me!

[Steve Brown]

Can someone please, in simple terms, explain why these throttle body thingys that everyone is going on about, produce more power than the standard injection / induction system. How do they differ, (other than the obvious improvement in under bonnet looks)? How much difference do these alone make without the additional ECU, cam swap, valve porting etc?

[Mike Bees]

Generally the provide a freer flow of air into the engine - the more air the engine gets the more fuel it can burn and the more power it can make.

 

I don't know of any engine which can run throttle bodies on the original manufacturer-supplied ECU, so if you switch the TBs you have to change the ECU for a programmable one.

 

Mike

[Tony Martyr]

The power of an engine is determined by the mass of fuel in the cylinders. Getting the right amount of the liquid component (petrol) is the job of the injectors controlled by the ecu. Getting the maximum amount of air which contains the other fuel component - oxygen, into the cylinder is effected by the friction head of the air path. Modern cars store a quanity of air in the inlet plenum, when the throttle opens a partial vacuum is created in the plenum and air is sucked into the cylinder via a quite tortuous route. In a supercharged or turbo charged design that plenum would be under positive pressure so more oxygen would get into the cylinder to be mixed with more petrol and produce more power.

Throttle bodies offer the most direct route for air to get into the cylinder. The trumpets shape the air flow so that there is as little turbulance as possible to gain the most air per gulp.

There is a down side in that when the throttle just open from idle there is no air stored on the cylinder side of the throttle so there can be a slightly rougher pick-up that the average tin-topper would not like.

The power gain without an ecu change may not be evident because the air-fuel mix has to be re-mapped to realise any benefit.

Like lightened flywheels it is a modification that only comes into its own on the track but it may also add pose potential in the pub car park

[CHRIS CLARK]

Try Dave A's site

 

http://hometown.aol.com/DVAndrews/ems.htm

 

 

[Roger King]

Think of a standard injection system as being equivalent to a standard carburettor. Throttle bodies are then the equivalent of a pair of WeberDCOE carburettors.

 

O.K. I know that this analogy is nowhere near perfect,(a standard injection system is better than a standard carburettor), but it gives an idea.

 

Power gains will vary depending on engine type, but generally reckon on 10bhp - 20bhp.

[Richard_E]

Looking along the same lines, what would be the benifit of changing a 1.6 supersport over to TBs & ECU. Would you you still see a power increase over the supersport option?

[Red SLR]

A 1600 SS engine with D2H TB kit and ECU made 153bhp on the rollers recently.

 

X777CAT

[Richard_E]

Thanks Simon,

 

If I was to upgrade to TBs etc. would I lose any bottom end power or would the car become generally more responsive thougout teh rev range?

 

Any response is greatly appreciated.

 

If only I was a windbag.

[R500 CYA]

Richard,

 

Sent you an email.

 

Nick