Ray wrote:I have yet to see, domestically, any benefit with more valves with similar displacement. Ford has their 4 valve Mustang engines, and their 3 valve truck engines, yet they don't make any more power or fuel economy as far as I can tell. They claim it flows better at the top end, and it does in certain cases. But a good LS1 doesn't need to. It makes it without doing all that revving. The biggest thing that shows me power wise, everything Dodge or Ford has that makes 500hp or more has either 2 extra cylinders, or a supercharger of some sort. They just can't make an engine that makes good power and economy like GM does. The new Hemi is junk too. A friend of mine has a truck with one. It's slower, less powerful and uses more gas than my little 4.8 Chevy. Not to mention they don't know how to make a decent reliable truck. Maybe now that Daimler has left and isn't hell bent on continuing to run that company as far underground as possible, they'll get back to actually making good products and money. Daimler really screwed that company up.
They make crap engines no matter how many valves they have. The only reason they use more valves is to try and make more power with less displacement, and in their case it doesn't work. It works in a Ferrari, or a Lambo, but not in the crap they make.
EDIT: In other words, they don't know how to make good cylinder heads. That's about as easy as you can sum it up. They suck, and they have always been behind Chevrolet/GM. An LS1/LS6/LS7 head is by far better than any domestic 3 or 4 valve head made by any competitor.
instead of comparing truck engies to car engines to weed wackers. why not compare the same engine with 2 and 4 valve heads.
the ford 4.6 liter modular motor would be a good starting point
2V police interceptor out of the crown vic
250 hp (186 kW) @ 5000 rpm / 297 ft·lbf (403 N·m). @ 4000 rpm/9.6:1 compression - 4.6 L V8 (Police Interceptor only)
DOHC 32-valve 4.6L V8, rated at 280 hp, came with a distributorless coil-on-plug ignition system, eliminating the use of high voltage spark plug wires. Some of the transmission internal parts were reinforced in the late 1997 models and all 1998 models. LSC models had firmer shocks and larger anti-roll stabilizer bars, for better handling and control, a lower gear ratio and true dual exhaust giving a 10 hp boost taking it to 290 hp
Engine : V8, OHV('94-'95) / DOHC('96-'98), front engine RWD
Displacement : 4,949 cc('94-'95), 4,605 cc('96-'98)
Valve : 16 valves, 2 valves per cylinder('94-'95)
32 valves, 4 valves per cylinder('96-'98)
Transmission : 5-spd manual
Fuel economy : city - 16 mpg('94-'95, estimated), 18 mpg('96-'98)
highway - 24 mpg('94-'95, estimated), 26 mpg('96-'98)
Horsepower : 240 hp @ 4800 rpm('94-'95), 305 hp @ 5800 rpm('96-'98)
Torque : 285 lb-ft @ 4000 rpm('94-'95), 300 lb-ft @ 4800 rpm('96-'98)
0-60 mph : 6.3 sec.('94-'95), 5.8 sec.('96-'98)
a little hard to read but basically the 4v engine makes 30-50 more hp in stock form. More gains are to be made in forced induction.
And valve heads do flow better than 2 valve heads there is no question here its simple physics.
Useing the ford 4.6 agin
the 4 valve has two 37mm intake valves to reach 4.57 in^2 of curtain area they need to open .500 inches
to match this with the 2 valve engine with its one 45mm valve you need to open it .812 inches
thats not going to happen in most engines with out some contact