Why such huge air inlets?

[Michael88]

Dumb question and maybe to specialised for that forum, but I couldn't find an answer even with google.

Why do F1 cars from the early 70's have such big air intakes at the top of the engine and most 5 year older F1's from the late 70's dont have them? What changed during that time? Its not limited to F1's only if you look at the Porsche 936 1978.

Is it the air intake for the air that is needed for the engine to burn fuel or ist a combination of radiator and engine air inlet? Or ist just a radiator inlet? -But I've seen cars having two radiator sidepots and the giant air inlet, and cars without radiators at all at the side.

Lets compare two cars fro m the same team: TYRRELL:
Tyrrell 73' #006 with two radiators and huge air intake.

Tyrrell 008 79' (?) with two side radiators and no huge air inlet.

Suddenly the didnt have the air inlets anymore? Ban?

 

[Kylehnat]

Turbochargers. If the engine is turbocharged, there is no need for a large opening for forced-air induction.

 

[ROAD_DOGG33J]

Turbochargers. If the engine is turbocharged, there is no need for a large opening for forced-air induction.

That's what I was thinking, but I looked it up and the 006 wasn't turbocharged.

I'm guessing that maybe it was for cooling the engine and later on they found out how to keep the engine cool without having a huge inlet sticking out. But I'm sure someone has the proper reason.

 

[Michael88]

I'm guessing that maybe it was for cooling the engine and later on they found out how to keep the engine cool without having a huge inlet sticking out. But I'm sure someone has the proper reason.

But if you look at the F1 cars from mid 60's the didnt have the giant air inlets either, like the Porsche 936 from 1978 did have one and the Porsche 917 from 1969 not.
Turbochargers surely not. They started to use them a lot later, engines back then were mostly NA V8's.

Heres one from the mid sixties: One single radiator at front an no other air inlet.

I dont think its a radiator either, if they would have needed more cooling radiators they just could have made side radiators larger. The air inlet on the top must create a lot of drag and makes the rear wing a lot less effective. Maybe it was ''spot'' cooling? But for what?
They appeared on a lot of 70's racecars llike the can-ams, F1's, LeMans sportscars etc.....

 

[Kylehnat]

The airbox on top of the car has nothing to do with cooling--that's the job of the radiators on the side--it's all about feeding air to the engine. The airboxes today act a bit like turbos--compressing the air as it enters the intake. In really older cars (like the one above), air was drawn in through the carburetors (huh? what the hell is a carburetor?) on top of the engine, which was exposed to the air outside.

 

[Michael88]

The airbox on top of the car has nothing to do with cooling--that's the job of the radiators on the side--it's all about feeding air to the engine. The airboxes today act a bit like turbos--compressing the air as it enters the intake. In really older cars (like the one above), air was drawn in through the carburetors (huh? what the hell is a carburetor?) on top of the engine, which was exposed to the air outside.

They still had carburators? That explains a lot, carburators needed a big airflow to create a vacuum that forces air and fuel into the cylinders. Today the fuel injection pump does the job of the vacuum creating air.

But did they really have caburators back than? Fuel injection was widely accepted in the mid to late 50's! And wherese the air inlet of carbuartors in the 60's F1 cars?

 

[TopHat]

They still had carburators? That explains a lot, carburators needed a big airflow to create a vacuum that forces air and fuel into the cylinders. Today the fuel injection pump does the job of the vacuum creating air.

But did they really have caburators back than? Fuel injection was widely accepted in the mid to late 50's! And wherese the air inlet of carbuartors in the 60's F1 cars?

In Europe maybe. EFI wasn't prevalent here into the 80's or 90's.


Pssh. Fuel injection is for panseys. Give me a Four barrel carb anyday.

 

[Michael88]

In Europe maybe. EFI wasn't prevalent here into the 80's or 90's.


Pssh. Fuel injection is for panseys. Give me a Four barrel carb anyday.

Hmm, but AFAIK the early 70's lotus' and Ferarris had the strange air inlet too:

And McLaren

Miraculous....

Pssh. Fuel injection is for panseys. Give me a Four barrel carb anyday.

👍

 

[Scaff]

And wherese the air inlet of carbuartors in the 60's F1 cars?

You see the silver air trumpets on top of the engine.

Here's a clearer picture

That's the engines are intake, most of the sixties engines had the air intake trumpets open, can't get a much bigger intake than that. All that aside F1 cars have used fuel injection since the '50's.

Regards

Scaff

 

[Michael88]

That's the engines are intake, most of the sixties engines had the air intake trumpets open, can't get a much bigger intake than that. All that aside F1 cars have used fuel injection since the '50's.

Regards

Scaff

So the final result is that the giant air inlet is just a help to get more air flowing to the cylinder intakes to get better and stronger ignition of fuel to increase engine power without useage of carburators.

Only one thing still buffles me: Why did the top-of-the-engine air box dissapear that sudden? Why did all F1 cars change back to the trumpets after 5 years of using them without replacing the top air box with air boxes anywhere else on the car?

 

[daan]

The size of the airbox was restricted in 1976. Perhaps the new size made them not worth the extra aerodynamic drag that they're bound to create.

EDIT: Just found this.

New rules - designed to curb the speed of cars and the greater excesses of designers - were brought into force before the Spanish Grand Prix and several of the teams fell foul of them. The rules limited the overhang of rear wings and reduced the overall height of the cars which forced the designers to re-design the airboxes.

 

[TheCracker]

Tyrrell 008 79' (?) with two side radiators and no huge air inlet.

The engine probably drew it's air from the two NACA ducts you can see on the side of the car just below the drivers head. Regulation changes and trends in aerodynamics were probably responsible for those huge air-intakes disapearing in the late 70's.

Like Scaff pointed out, the DFV always ran with mechanical fuel injection. My dad ran a special saloon Escort in the late 60's, early 70's with a Cosworth FVC engine which was basically half a DFV which also ran mechanical fuel injection. MFI was pretty much standard on race engines by this time. I'm pretty sure the engines of the cars with tall airboxes still ran with trumpets. All the airbox does is create a mild ram-air effect and the trumpets are still needed to concentrate the airflow.

 

[Pupik]

The size of the airbox was restricted in 1976. Perhaps the new size made them not worth the extra aerodynamic drag that they're bound to create.

Correct, they also were not permitted any air inlet to the engine above 40 cm from the base of the car.

This is from the 1976 German GP:

Once ground effect appeared in 1977, and took over the paddock by 1978-79, the cars required a "cleaner" profile along the top of the cars.

 

[wfooshee]

The big air scoops created an intake pressure slightly above atmospheric. They were removed by the rules to reduce performance.

These cars were not carburated, they were injected.

The trumpets were always there (and still are) under the air scoops. Sometimes the scoops were fastened directly to the trumpets, sometimes just over the engine.

Ground effects had nothing to do with needing a "cleaner" line on the car. If the rules had permitted, they'd have used the giant scoops to pressurize the intake.

 

[Pupik]

Ground effects had nothing to do with needing a "cleaner" line on the car. If the rules had permitted, they'd have used the giant scoops to pressurize the intake.

Teams almost completely abandoned the ram-air scoops by 1978; but I'm also noting the size of radiator inlets increased a lot as the size of the side pods increased in cubic area (to allow for an as-large-as-possible floor of the car). Since there wasn't any regulation on the size of the radiator intakes (since they were mounted so low), the design trends went in this direction.

By 1985-86, the radiator inlets were quite large, since side pods housed radiators, oil coolers, intercoolers, turbos and their duct work, and ground effect was abolished. Soon after, aerodynamics were playing a role in the design of the entire car, especially with the 3.0-liter cars which were about 100-200 horses down on the 1.5-liter, 4.0-2.5 bar-restricted turbo cars.

The only turbo team to return to the high-mounted airbox was the Zakspeed 184 of 1985-86, and then a few of the normally-aspirated 3.0-liter DFV runners in 1987 (March 871 and Tyrrell 017, for example). By 1989, every team (except AGS, they waited until 1990) returned to the airbox as we see it today.

 

[Michael88]

And what was the reason to ban them exactely? Does anybody know the reason?
What was wrong with the big air boxes, they just increased in a simple way power of the engines so it wasnt safety concearned, right?

 

[livemusic]

Wow, F1 cars used fuel injection if the '50s already? I think fuel injection was introduced over here only in 1991. My '95 Uno is carburated...

 

[Venari]

Fuel injection was available on the 1957 283cuin Corvette (and some other Chevy cars.) The Rochester Mechanical Fuel Injection System was fairly reliable, if maintained... but with so few workshops possessing the knowledge, they often got junked for carbs when they 'went wrong'. Shame, they're worth a fortune now.

As for airboxes, well, air inlet restrictions later became part of the rulebook, but the larger the intake, the higher pressure available at the throttle plates, which means more air. Oh, and just because a turbo engine is smaller doesn't mean it can run with a smaller intake - required intake cross section for a given pressure drop is proportional to engine power output - not displacement. Those 1,200-1,400hp 1.5litre monsters required all the air they could get, and they had to force it through intercoolers too.

Also, a carefully calculated plenum size can assist the combustion process at a given (small) rev range, by using pressure pulse tuning affects to force even more air into the chamber. Racing cars with overlap and tuned exhaust systems (read, every 60's on NASCAR you ever saw) are actually drawing air into the combustion chamber at extremely high velocities due to the scavenge affect drawing trough the entire system. For more on this phenomenon, I suggest you read the works of David Vizard for one. There are plenty of other texts available.