on road cars there is usually an intake manifold, but how come on F1 car there

are trumpets?? what does intake look like??

I think the trumpets are directly over the cylinder pistons compartments......but are the trumpets left open at the top or is there some
pump of something to draw the air in......or maybe just the ram effect from the air intake from the car in no intake manifold??

jackbbot51 - 17 May 2009 10:09 PM

on road cars there is usually an intake manifold, but how come on F1 car there are trumpets?? what does intake look like??

I think the trumpets are directly over the cylinder pistons compartments......but are the trumpets left open at the top or is there some
pump of something to draw the air in......or maybe just the ram effect from the air intake from the car in no intake manifold??

There are a number of reasons for this, having to do with engine management, simplicity and the engine's breathing characteristics.

It used to be that an engine had just one carburator, which had to feed all the cylininders, which meant it needed a manifold to distribute the fuel/air mixture. Later, when racing engines were able to turn faster, they could take in more air than one carburator could provide, so you see rows of Webber or other carbs, one throat for each cylinder. They are still mounted on a one-piece "manifold" for the sake of keeping everything in line.

This same one-piece manifold with individual throttle butterflies and intake trumpets for each cylinder continues to this day, though it doesn't look like it. Again, part of this is having all the throttle butterflies on one shaft, which simplifies throttle linkages. Also, remember that the manifold functions as a stiffening member and a cover over the valley between the cylinder banks.

One misconception is that the intake trumpets "are directly over the piston compartment." They aren't. Even in racing engines, where the intake track is as straight as possible, there is still an intake manifold between the intake trumpets -- which includes the throttle butterfly housing -- and the intake port of the cylinder head.

In diesel engines, there is nothing else between the intake trumpet or manifold runner than the manifold, itself. Engine speed is governed by the amount of fuel injected directly into the cylinder. Thus, there are no throttle butterflies or slides in the diesel engine.

Gasoline engines are different. You can't see the throttle butterflies or slides that control the amount of air going into the engine under the airbox, intake trumpets, fuel injectors (which inject into the manifold, just above the valves, rather than directly into the cylinder)but they're are still there.

These days the injectors are actually above the trumpets, and the trumpets are only 2 or three inches because of the high revs they run now. There isn't a "manifold" per se, as a manifold is a way to distribute a fuel and air source to several cylinders, and a modern racing engine has a fuel and air source at each cylinder. Where the manifold should be (between the intake ports and the throttle) you have nothing but a short tube, maybe the throttle body itself.

Have a look here and here

wfooshee - 18 May 2009 11:40 AM

These days the injectors are actually above the trumpets, and the trumpets are only 2 or three inches because of the high revs they run now. There isn't a "manifold" per se, as a manifold is a way to distribute a fuel and air source to several cylinders, and a modern racing engine has a fuel and air source at each cylinder. Where the manifold should be (between the intake ports and the throttle) you have nothing but a short tube, maybe the throttle body itself.

Have a look here and here

Is direct injection prohibited? If not, direct injection (with piezoeletric injectors) would seem to open up any number of possibilities. In street engines, greater power and fuel efficiency have been achieved all the while lowering emissions. The use of higher compression ratios has been achieved with the same grade of fuel. Changes in combustion chamber design as well as camshaft timing are possible that were not without it.

F1 2009 Technical regulation 5.7.2 - Only one fuel injector per cylinder is permitted which must inject directly into the side or the top of the inlet port.

The wording eliminates direct injection as a potential means of fuel delivery and the 2010 regulations don't show a change. With the F1 engine development freeze it doesn’t look like it will be coming to F1 for quite some time… It amazes me that direct injection has not been pushed because you would think that the PREMIER motor racing league would at least have the same technology as the latest Corvette.

Thanks for the reference to the Tech regs.

Yea, you would think that their technology would at least match that of road going production cars, but evidently not.

With the current model year vehicles, Porsche has reported increases of horsepower of 10% to 14% with no other material changes to the engines all the while getting better fuel economy!

Cheers!

In 2006 GM was saying that they had developed it but didn't expect it to reach production until 2011 or later because of the ammount of research required. If a failing american car company can do it then why can't F1.

From an above post -

" The use of higher compression ratios has been achieved with the same grade of fuel. Changes in combustion chamber design as well as camshaft timing are possible that were not without it. "

All of these are good things, but I don't believe the lack of direct injection has hindered F1 engine development in any of these areas.

agreed but the biggest problem with direct injection is adoption rate... It has been around for over a decade but it has only recently reached the market because no one is pushing for it... Hopefully the new CAFE requirements will help push it to market.

Is direct injection fast enough to cycle with an 18,000 RPM engine?

I ask because I'm not sure the injectors over the trumpets cycle or just spray while the throttle's open. (Obviously cycling would be too fast to see by the naked eye, but I don't see the point in that application of spraying for 1/600 of a second 150 times a second.)

I have seen reports of the use of five and six injections per power cycle in street engines (which turned in excess of 8k RPM) and I think that the number was simply an optimization for the particular application. The piezoelectric injectors are incredibly fast operating and do not have the mass/acceleration/momentum problems of convention injectors.