Carb vs fuel injection

thexav

Pro Tuner
Staff member
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407
Car
2002 Clio 172
Which gives the most power? I've always thought that fuel injection systems are best for power but I remember reading somewhere that Carb and Throttle bodied engines are better and used by a lot of drag racers?

Is this correct? Am I missing something here?
 
All petrol engines have throttle bodies. I think what you're thinking of is the multiple throttles found in high performance engines such as BMW's S52 straight six (E39 M5 and E46 M3) is one such example.

Diesel's don't have throttles so therefore no need for bodies to house them.

Fuel injection will offer better power and smoother power delivery than carburettor fed engines whilst simultaneously meeting stringent economy and emissions rules.

The reason carbs are used for drag applications is because they are not required to meet any emissions regulations, nor is fuel economy a consideration. Nor does smooth idle and low speed operation really matter too much.

Carburettors are much simpler and cheaper than a full injection system, hence their use in such applications.

So, to summarise We can conclude that dragsters produce impressive torque and power figures in spite of the fact that they are carburettor fed rather than because they are carburettor fed.
 
They also look prettier :)

They do indeed. They can also be a source of hours of frustration trying to balance airflow and fuel delivery across multiple carb setups.

Did you ever have the 'opportunity' to fiddle with those varijet SU things?

I think it was during one such session that I developed a full arsenal of new and hitherto unknown expletives. :lol: :lol:
 
Did you ever have the 'opportunity' to fiddle with those varijet SU things?

Nah, I played with pairs of DCOEs and DHLAs (but not at the same time!) on the Elan's Twin Cam engine. Hours of fun, but they do sound nice running on trumpets and no filters.
 
They do indeed. They can also be a source of hours of frustration trying to balance airflow and fuel delivery across multiple carb setups.

Did you ever have the 'opportunity' to fiddle with those varijet SU things?

I think it was during one such session that I developed a full arsenal of new and hitherto unknown expletives. :lol: :lol:

Aye, I remember my dad having fun doing that to the SU carbs on his P6 Rover V8. I must have been 7 or 8 at the time and I was fascinated by the carb bodies with their needles, they just looked very cool.
 
My dad had an Austin Ambassador 2.0 HLS which had the four cylinder O-series engine fed by a pair of SU 44 carbs. Tuning them was a nightmare. with all that oil damping business etc.
 
Nah, I played with pairs of DCOEs and DHLAs (but not at the same time!) on the Elan's Twin Cam engine. Hours of fun, but they do sound nice running on trumpets and no filters.

Echo that! My HSX Chevette ran twin 48's and at times I too ran open trumpets, had a fantastic noise! I have a matched set of twin 40 Dell'Orto's in my garage waiting for an engine! A friend of mine gave them to me whilst on a business trip in Italy, they were off his classic Alfa.

I still like to see the old school tuners set up carb run engines as opposed to remapping, boring! When I had said Chevette I used to leave it with my tuner Tom Airey to sort out, he was superb and knew his stuff.
 

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