Why did Ferrari move back to 4 Valves with the 430 engine

Issues:

1. A greater number of smaller valves aid in cooling the valves (ratio of periphery to area, etc.)
2. Since valves are round, more valves actually "open" a larger area of the cylinder head to improve volumetric efficiency which improves HP.
3. The 460 engine was a tiny step backwards in HP/liter from the Challenge Stradale; if you believe the published numbers. It is a shame that Ferrari failed to advance the technology and instead threw displacement at the problem.
4. The 430 engine appears to have been designed and tuned to better accommodate the average driver's use (0-60MPH-0) in-town driving providing better torque at low RPM.

 

this is good info, but I dont think they took a step backwards with the engine.

Its a big improvement over the 360CS engine because it is harder to have a big midrage, more displacement and still retain the same HP per liter

As engines get larger, it is increasingly harder for the engine designer to make high HP per Liter. since the engine grew ~.7L and it remained a v8 (did not add cylinders) the engine is moving away from the ideal cylinder volume.

Another thing to note is the increase in midrange, while maintaining the same or similar hp per liter. usually midrage and topend are a trade off, but Ferrari was able to improve both.

 

F1 motors went back to 4 valves years ago. 5 valves was an interesting idea but not an improvement to a well designed 4 valve head. The greater # of small valves do not run cooler in a water cooled motor. They run hotter and is a contributory factor in the 355s needing valve jobs as often as they do. With 5 valve seats clustered together in such a small space it left no room for the coolant that should surround them to cool them.

4 valves was a step back forward.

 

Also, the additional valves add valvetrain weight offsetting the gain.

 

Well said.

 

I heard that you could rev a 5 valve engine higher because the smaller valves and associated valvetrain were lighter and had less momentum?

 

Sales pitch for 355's. True in exterme cases but has little meaning in practice.
Winston Cup motors go comfortably over 9000 with 2 big valves, 2 big rocker arms and a big ugly pushrod and do it all day.
All those 4 valve F1 motors don't seem to have trouble doing 19,000 rpm. Besides how high do you want to rev a street motor?
High reciprocating rates = high wear.

 

Each smaller valve weighs less so the springs can handle higher speeds. The overall weight will likely go up. Two different things.

 

Its also known that with less inletvalves, the airspeed that passes thru is faster and vacuum is higher at low rpm.


This results in better cilinderfilling and improves driveability at low speed...

 

It would be interesting to know the official ferrari factory reason for going back to the 4 valve system. All we will realy get on this thread is personal opinion as to why unless some one knows the offical stance.
My own personal opinion is becourse it would be much easyer to adapt the Mazza unit, no mystery there then

 

From what I've been able to gather is that the 3 liter V8 has been developed since the time of the 308, 328, 348, 355 and the 360 being the final version with capacity bored out to 3.6 liters. At that point in 1999 the 3 liter engine reached its full potential 400 hp that got further tweaked with the Stradale at 425 hp. (rough power figures for U.S. cars).

Around 1999 Ferrari began development of the then Ferrari owned Maserati...and heralded the much ballyhooed return to the U.S in 2002 of the Maserati Coupe with a 4.2 liter V8 pushing 380 hp (not tuned higher as not to compete with the Modena). By 2004 this engine was further tuned and used in the then upcoming Quattroporte (400 hp)...So when time came for the upgrade to the 360...(the F430) the logical choice was the already developed 4.2/4.3 liter Maserati engine...which was easily tweaked for peak power around 490 hp...with less Torque than the Maser....this is how ended the 3 liter V8 design that was around for 20 plus years...and in the new era of the 2000s...bigger displacement 4.3 or more is needed without turbo/super charging to compete with players offering 500hp plus cars.

 

Cylinders fill based on the total circumference of all valves involved, not their area. The analogy is any other "flow", current for example. Vacuum and airspeed are like resistance and voltage. However charge volume is like current and that's where the power is.

So I would think, but perhaps some of you who actually work on these beasts will tell me I'm wrong, that all the air speed and vacuum aren't worth a hoot unless the volume is there.

 

Remember, the 430 motor is a direct takeoff or rather the Maserati V-8 design which is a proven design and therefore makes the transplant to the 430 a good fit. By the way although it is a modified Maserasti design, the engine is manufactured totally at Ferrari.

 

At low lift flow is determined by total circumference x lift.
At high lift flow is determined by total area.

That presupposes very well designed ports. Also to be remembered is that a racing or very high performance motor will have valve lifts high enough that the valve can be removed and flow will not increase. IIRC on a 2 inch valve that happens at about .600 lift.

A valve train spends most of its valve open time at partial lifts and since at partial or lower lifts the flow area is determined by circumference x lift the multi valve motors have a great advantage in cylinder filling with valve timing durations suitable for the street. It also means that less overlap is required or even desired and that equates to less pollution and broader powerbands.

One of the advantages of a 4 valve head over a 5 is that the 4 valve allows, almost requires a pent roof combustion chamber. One of the most efficent chamber shapes ever concieved. It is not really suitable for a 5 valve head. So while a 5 valve may flow more (Just a guess) the 4 valve does put the fuel to better use. Also 5 valves require some goofy valve timing to keep the intake valves from crashing into each other. All 3 valves in the chamber do not open and close together so valve timing as a practical matter is a compromise.

 

So, in conclusion if Ferrari adopted a NASCAR or Viper engine you guys would be celebrating a profound advancement in engine technology??? Using F1 or NASCAR engines as examples is just silly. Retail vehicle engines must satisfy complex trade-offs of cost, reliability, lifetime, emissions, weight, etc. which are VERY different.

Regardless of # of valves, I'm simply disappointed that Ferrari would throw displacement at the problem and fail to advance their engine technology in the 430 and for that matter recycling an existing engine (Enzo) for the 599.

 

5 valves have the following issues:

1.) Room for valves and spark plug, plus cooling galleries. All this in a small space=trouble.

2.) Cam actuation of 5th (3rd?) valve. The valve has to be place on a angle relative to its left/right mate and this makes cam design difficult/awkward.

3.) At most cars, 5 valves does not increase RPM or power enough to compensate for added cost/complexity.

4.) Extra valves can effect the flow characteristics of intake charge. You can negatively impact the swirl and or tumble characteristics, which hurts power but especially emissions. (Mercedes went from 4 valves to 3 valves because of emissions issues.)

5.) Added complexity to intake manifold.

 

All good points, well made. Thank you!

 

Nice job Dave, enjoying the CLK63?

 

All I know is that my 5 valve CS sounds way better than the 4 valve 430.

 

Same as my 355...........the 5 valve motor does sound different.

 

Thank you T!

Now talk about AMG throwing pure displacement out there and doing away with the super/turbo charger or trick valves for the AMG 63 series cars...here's a 6.3 liter V8 4 Valve per Cyl engine(rounding up from 6.2) producing 481hp/475hp in the U.S. CLK63 Cabrio...possibly the fastest production 4 seat convertible today! I believe Mercedes is being ultra conservative in their accel times...the car absolutely smokes anything on the road with its massive 460 lbs/ft of torque and its 7 speed paddle shift transmission....the torque number due to the fat displacement is around 120 lbs/ft higher than the F430's natural 4.3 V8...but credit F car technology for matching AMGs horsepower figures with 2.0 litres less displacement.

By the way Formula One chose the Mercedes CLK 63 AMG as their Safety/Pace car for the entire 2006 F1 season...probably the reason why I bought it!

Hope to see you at CC soon.

 

It must be the valve count then, not the exhaust which is typically more responsible for aural differences. ::rollseyes::

Don't worry, Porsches are boring, the F430 sounds terrible, your car is the best car in the world.

 

Actually many people and reviews have commented on the 355/360 sounding better than the 430.

listen to a 355. http://videos.streetfire.net/category/Ferrari/7/98411778-105e-4479-abfc-e4415944cc2b.htm

 

The 5 valve setup is chiefly responsible for the sound difference between 355/360 and 430, not the exhaust system.