28 replies to this topic

[Art]

With the reduction in physical size and weight of the Mercedes engine how are they doing it? 3 Liter engines need x bore x stroke water cooling pasages combustion chambers and so on. The new Merc has a sound like nuthing before it is their a chance that they are running an engine of less than 3 Liters to reduce size and weight? And gaining the power needed with a much higher rpm?

[Ray Bell]

I hardly think that likely. To gain sufficient reduction in dimensions they would have to drop just too much capacity.

[Christiaan]

Ray is right, also, a decrease in capacity just to reduce physical size might compromise the driveability.

[BRG]

I have heard it said that one way that weight and size savings have been made on F1 engines in recent years has been in the water jacket and cooling area. As a F1 car is basically always moving (and usually very fast) when the engine is running, except for very brief pit-stops, the cooling capacity can be very small. This is why fans are now put in the side pods when stationary, something we have only seen in the last few years.

I wonder if after the turbo engines, which needed a lot of cooling, were banned, there may have been a carry-over period when the normally aspirated engines carried more cooling capacity than they needed, and that this has now been whittled away?

Of course once a designer has seen the possibility of weight and size gains in this area, he may continue to look for more savings by new technology. So I wonder if there are some new tricks being devised for cooling systems instead of the very traditional pressurised water system? Other than Gordon Murray’s abortive surface radiator experiment on the Brabham BT46, I cannot recall any innovations in this area at all, but perhaps some of you can?

More generally, there is a lot of hype around in new car/engine launches. Typically, everyone claims 20% less weight or size or rigidity etc. If all the cumulative improvements were to be analysed over several years, you might find negative figures! These are PR exercises, to gain publicity and to confuse rivals, not proper engineering briefings. So I suggest that a pinch of salt (that’s 12% less salt than last year of course!) is advisable.




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BRG

[Janzen]

Cooling is a big area in weight reduction.
I know that they pressurizes the cooling system to get higher temps but better cooling.
The air intakes (sidepods) have been getting smaller and smaller and i know they use somekinds of shutters so they can regulate the air going through the cooling system on different tracks.
I also read that some team had reduced moving parts in the motor. I was kind of interested in getting more info on that.

[whatcom]

I'll say they've been getting smaller Janzen. Look how small they are on the MP4-15.

[Nathan]

One technique I dont think ever published or spoken of is the idea of different angled cylinders. I have put some thought into it and I belive it makes sense and could work. If the cylinder are not perfectly aligned and are slightly offset it would allow the cylinder to be closer together. For example say each row of cylidners goes as follows. 72-80-72-80-72 degrees per pair of cylinders. This slight offset between pairs of cylinder would as I said allow for a shorter engine and still look like a 72 degree angle becuase each end of the engine are 72 -degrees. Any thoughts on this??? Im not sure if anyone understand sthis. I could draw a diagram and post it...

[Art]

Nathan.

This sounds like a sound idea for shortening the engine block. Any ofset would be hiden by the exhaust headers. Honda may of used this on their three cylinder F1 bike engine as the center cylinder was ofset quite a bit from the out side cylinders.

Art

[Ray Bell]

'twould be a big juggle in the valve train and cam layout design.... but possible.
But then, work out the savings at the bottom of the bores - close to the crank, how much room can really be saved here?

[DangerMouse]

Nathan, you're thinking along the same lines as me, I've wondered for a while why F1 engines do not have a staggered cylinder layout, this will do two things firstly it'll shorten tne block as you've stated, secondly due to the shape of the block (all curves rather than flat) the block would be stronger therefore it could be made thinner and lighter.

If Ilmor have done this it could account for the strange sound of the engine, if they've had to compromise one of the sets of cylinders so the conrod is not straight at TDC, this would effectively change the timing (reletive to the other bank of cylinders) causing a big bang effect where the cylinders do not fire at uniform time periods.
Indeed even if they bores are not staggered, Ilmor may have just introduced a big bang firing order (by running the crank at wierd angles) to optimise traction out of the bends, much like they do in Motorcycle GP racing.

[HK]

Ray Bell, I know what you mean the head would be a nightmare

[desmo]

I can't think of any way of doing it without adding too much mass and complication to the valvetrain. Art: Honda used this basic concept on their NS500 GP bike, but the offset was, I believe over 90 degrees, and 2-strokes tend to get wide (transversely on a bike) because of the transfer ports when run in a line.

[This message has been edited by desmo (edited 02-08-2000).]

[Nathan]

Okay I have realized one problem with the my staggered cylinder theory and that is the camshafts. You would have to have atleast 3 cams per bank of cylinders. You cant bend cams. But I belive I heard Mercs dont use cams no more, rather the valves are opened by compressed air. If this is the case then Im sure they use offset cylinder. The benefits of this air system are not that great, weight on bulkiness is more than with standard cams. But that extra weight would be offset by a smaller, lighter block, So the weight would be the same, but the length, height and center of gravity could be smaller and lower.

[Christiaan]

Nathan, I have wondered the same, but with an even more complex layout. A staggered system with cylinders of different volumes to compensate for vibration effects. I have not done the calculations yet , but I do thgink it could work.

[This message has been edited by Christiaan (edited 02-08-2000).]

[Art]

I think Ray Bell is right that the bottom of the cylinder bores would prevent shortening of the block with off set cylinders. I think we are all expecting to see a micro minature engine when we are really talking about 1/2 inch in length and width. Which can be done with thinner castings.

Art

[DangerMouse]

Nathan, nothing to stop you running a single cam in between two staggered cylinders, wih the two inlet valves coming from opposite angles.

Art, you can only got so thin with castings before lack of strutual rigidity becomes a problem, I sure all F1 engines are on the limit in that area already. The staggered block would be stronger by nature of its shape thus allowing thinner castings.

[desmo]

Camshaftless F1 engines are pure science fiction right now. The valves are closed not opened by air(N). DM, I see your point, now we're down to 3 cams per bank. Smaller? Lighter?

[Art]

Danger Mouse.

If you bring inlet valves in from opposite angles do we not do the same with the exhaust valve angles also? Which would give you intake and exhaust ports on both sides of the cylinder head? And as for thinner castings it would depend on what alloy is used and how the core support is set up.

Art

[Ray Bell]

There has to be rigidity in the crank as well, giving finite limits to web dimensions and bearing sizes, all of which contribute to length.
There are other prospects, like a W engine, but these will necessarily get into the airstream at the sides.
The odd-sized cylinders proposition sounds interesting. I once approached Phil Irving with some ideas I had, and admittedly he was pretty old at the time, but his rebuff was borne of a man with much experience. I think you would find the same of any engine designer. You'd have to build it yourself to prove it and then be ready for the world to copy!

[mono-posto]

Ray,

you mentioned a W engine which is what I was thinking as I was reading along.
VW's narrow angle V-6 is essentially what your discussing. It has a 15 degree offset between two banks of 3 so that they can share a cylinder head.
Their more publicized W-12 was two narrow angle 6's joined at the crank. If you made that two v-5's you'd have the required 'stagered cylinder V-10'. VW had some impressive horsepower stats from that engine and I've no doubt that if an experienced F1 team was able to work with the basic design, they could produce a very formidable powerplant.

[Martin]

Why do the cyclinders need to be round (except of course they would no longer in geometric terms be cylinders)? If you wanted to shorten the length of the engine you could make oval or elliptical section cylinders. With modern computer controlled machines this should be feasible shouldn't it?
I, of course, don't know what I'm talking about, so I expect there are many reasons why this would not work.

Come to think of it, I had an old knackered BMW once that had oval bores - problem was the pistons were still round. It certainly did nothing for performance (and oil consumption)!

[mono-posto]

An elliptical section piston would work just fine except for the fact that the FIA technical regulations explicitly state that the piston section needs to be circular.
(pesky regulations always getting in the way )

[davo]

The Porsche design Auto Union (The other half of the "silver arrows") had (from memory) an interesting cam and actuator set up.

One cam high up operating a splayed head (i.e. offset inlet and exhaust like a twin cam) valve design with BOTH banks operating of the one cam. Alternatively I could be delusional as I cannot relocate the book, which I own.

A sketch or cut away would be useful, if anyone could help.

[Ray Bell]

Honda built an oval piston engine, which led to quite a fuss and probably the rule banning them. I can't remember if it was in cars or bikes, however.

[Art]

Ray Bell.

The oval piston Honda was a bike engine. With something like 10 valves per cylinder?? and created a real problem with designing piston rings. It used 2 rods per piston and was raced a few times. The idea was to eliminate the space between cylinders and reduce engine size. I think they produced a limited edition of this bike at about $75,000.00 I hope I am correct on this.

Art

[desmo]

The "oval" cylinder Honda in question, the NR500, which had 8 valves per cylinder was basically a V-8 with siamesed cylinders. The design was just an attempt to circumvent the FIM's maximum of 4 cylinders in the 500 GP class. Here's a cutaway of the street version's (NR750) engine:

[Art]

Desmo

Tnx for the nice photo I wasn't sure about the number of valves but there was a whole bunch in there. Can you find a picture of the VW W12 I can't find one any where?

Art

[Art]

Desmo.

Are you sure the GP engine was a v4? I only saw one picture of the engine a sneak shot in the back of the Honda Truck. And it doesn't seem like the engine was any where near this big? But that was many years ago.

Art

[jsadie]

The technical specs released by Mercedes says 2 camshafts per bank and 4 valves per cylinder.Guess they don't have camshaft-less engines yet.Check it out at Formula1.com