anarchistchiken said:
I just have one question for space monkey. Can you provide one valid fact that indicates OHC engines are better than pushrod engines? Not "OHC engines are more complex" or "This company uses OHC so they must be better"
Just one valid fact that shows that overhead cam engines are better than pushrod engines. That's all I want.
I dont have to prove much...majority of race cars out are OHC. 90% of car manufatuers use OHC. GM and Dodge are the only one actively persuing OHV designs. Ford still does but they tend to use OHC engine on better cars.
Ferrari = OHC
Porsche = OHC
TVR = OHC
Toyota = OHC
Honda = OHC
Mercedes = OHC
Aston MArtin = OHC
LAmbo = OHC
Pagani = OHC
Lotus = OHC
Nissan = OHC
Subaru = OHC
Ford = OHC
Koeinsegg = OHC
Jaguar = OHC
BMW = OHC
Mclaren = OHC
Mitsubishi = OHC
Mini = OHC
VW = OHC
Audi = OHC
Reanult = OHC
Seat = OHC
Mazerati = OHC
Bughatti = OHC
Reanult = OHC
GM = OHV
Dodge = OHV
But if you really want to know I would say Varrible timming and lift systems. Although it is rumored that GM has developed a Variable timming Pushrod engine. But the Ability to change timming is alot easier on a DOHC engine. Oil sprocket of some sort.
Why is this so important. As you know high performance cars have agressive cam profiling...which is great for higher RPMs but not great for low RPMs. Race cars dont like to idle. To counteract this Variable timming and lift systems were devloped to give better low range economy and midrange torque while not sacrficing high end performance. You want to valve to open wider at highspeeds but not so in low speeds. With a Vtech engien you really do get 2 engines for the price of 1. Which is why a car like the S2000 can rev up to 9000 rpm...thats like a rotary engine or a race tuned Ferrari. A ferrari Modena GTC peaks at 8500 rpm. Any fixed cam shaft is only optimal at one engine speed...it is not performing to its full potential at every other engine speed. Its also said that more valves means more air and more air means more fuel. Which means that it can produce more power with a smaller displacement.
Mitsibushi once tried it with MIVEC...but ditched it only to revive it back in the EVO IX. it will have more torque (also due to new turbo) and better fuel economy. And why Toyota, Honda, and Ford have or working on similar lift systems. Notice its Japanese companies who are really interested in lift systems.
How does ferrari do this?
Ferrari has a really neat way of doing this. The camshafts on some Ferrari engines are cut with a three-dimensional profile that varies along the length of the cam lobe. At one end of the cam lobe is the least aggressive cam profile, and at the other end is the most aggressive. The shape of the cam smoothly blends these two profiles together. A mechanism can slide the whole camshaft laterally so that the valve engages different parts of the cam. The shaft still spins just like a regular camshaft -- but by gradually sliding the camshaft laterally as the engine speed and load increase, the valve timing can be optimized.
Several engine manufacturers are experimenting with systems that would allow infinite variability in valve timing. For example, imagine that each valve had a solenoid on it that could open and close the valve using computer control rather than relying on a camshaft. With this type of system, you would get maximum engine performance at every RPM. Something to look forward to in the future... <!-- Page Break -->
Pushrods have alot of valve inertia (alot more load on the valves) and suffer from valve float which restricts the engine from reving too high. But engines make power with RPM. I assume to counteract this they make the engines bigger. So theres no need to make the engine rev higher to get power since its there. I believe the current LS7 revs to 7000 RPM. And obviously race tuned OHV V8s can go 8000-9000 RPM. not bad nowadays. But modern day OHC cars can also rev higher and race tuned OHC cars can rev higher too
If you said a street car can rev to 9000 rpm back in the early 90s they would probally think its crazy and non sense.
But I must admit that in a daily driver you would like low end torque and lower gearing to save gas and to have instant torque on the highway.
I think all of you were missing the point of my post. THis somehow turned into a debate between pushrod and OHC engines.
This is the truth...I pointed out what american sports cars have. Every coutnries cars have defining characteristics. Ask some dude overseas what they think of when they hear american sports car they would probally say "pushrod V8...muscle cars etc etc etc."
I'll talk about german cars. They focus intensly on engineering creating beautiful engines and systems to control the car...yet they lack zest. A feel to them unlike Italian cars.
Like BMW has never designed a MR exotic to take on Ferrari other then the M1. They develop amazing engines and slap them in existing cars like a 3 series coupe (M3) or a 5 series sedan (M5) or a 6 series coupe (M6). Same with mercedes...they typically have companies like Mclaren design there sports cars while AMG does there thing. The SL platform was given to both AMG and Mclaren...one came out with a Bi-turbo V12 and the other a SC V8 called the SLR. Mclaren and Mercedes were suppose to develop several MR exotics code name P1 and P2. ITs no wonder why the greatest BMWs are not BMW cars. They are cars like the V12 Mclaren F1 and the Ascari KZ1 (M3 powered)
British cars has the image of unreliable cars. The Lotus Elan, TVRs, ASton MArtin, Jaguar and etc. Not to blame them becasue they use to build everything from scratch instead of sourcing engines from bigger manufatuers like what lotus, Pagani, Koeinsegg has done.
And Japanese cars will always try to be light yet focus on economical needs. Honda designed the NSX with a daily driven mentality...low gas milage and etc. They most likely will never come out with a 500 hp V8. Although a high HP V10 maybe in the work as they are fiercly competing with toyota. What toyota does Honda will do. If toyta say they are comming out with a V10 super car...so is honda I suppose. Use to be there cars were light so smaller engiens could power them. Nowadays they need bigger engiens because there cars are getting heavier.
Italian cars will always push the limit with no target budget in mind. They dont car about money. Even if it bankrupts the company like Bugahtti. But they will always focus on the looks of the car. Bughatti Engineers when designing the EB110 said,
"okay lets make this car a V12"
"this isnt good enough lets put 4 turbos"
"this still isnt good enough lets put DOHC"
"this still isnt good enough lets pu 5V per cylinder"
"okay im satisfy with the engine now lets craft the dash out barzillian amzon rainforest wood."
"the body need to be lighter"
" it needs AWD...with a center diff"
that was in the 80s well ahead of its time.
the pagani Zonda can be ordered with OStrach leather if you wanted...any color or any shade. PLus you get a pair of racing shoes made by the popes personal taylor. It italians will always be leaders and pioneers in design...looks wise and pushes the boundry in everything they do. Modena italy and milan italy. If you been to italy it takes forever to get something. Becasue they spend alot of time crafting it to make sure its perfect...even if it takes longer then expected and more money. Word of caution when you travel to italy do not leave any food on your plate or they will hound you and ask you whats wrong. They even gave me dirty looks for putting salt on his precious spagetti. its just how they are. I hear italians take tremendous pride in there work. They arent the hardest working or fast at it but they are the highest quality. Good cruise ships are built in Italy...not scandavia. There craftmanship is top notch.
Ferrari will realease the Ferrari Enzo FX (nonstreet legal). This car cost 1.3 million dollars but what do you get out of it besides a race tuned suspention? A membership in Team Ferrar (F1 team) for 2 years. Basically you race in Ferrari race events around the world.
Nowadays you see alot of them joining forces in creating the most beautiful exotics in the world. Like the germans do what they are good at...desiging engines and the italians do what they are good at...desiging. what comes out of this? Cars like the Lambo Mercelago, PAgani Zonda F and even the Bughatti Veryon. Some of the best italian cars are designed by both German and italian engineers.
like what Jermy clarkson said, "you want the italians to be making the food. But you want the Germans to be makign the hamper."
French cars will always have funky designes to them.
Americans will always be big...everything is bigger. We drive SUVs...we like V8s. Roads are twice as big...most people here are bigger and taller. Were not really concerned about conserving like other nations. Like int Europe they rebottle water (you dont throw away glass). Hence why carbonated water is so popular...so you know its new and fresh (for the rich). The fact that we have never been taxed on big displacement engine allowed pushrods to survive in the states. We laugh at punny 1.8L honda engines but drool at big block V8s.
of course these are sterotypical...there are companies that break the sterotype like Ford and Porsche. And there are also companies breaking international boundries as they own many oversea companies and combine many resources.
not partcularly saying which on is better...all cars has its draw backs.
people will always have there likes and dislikes...its called opinions. For example You can make a RX-7 very fast but alot of people are turned off by the rotary engine. It can be a lemans winner and a Daytona Legend (racing beat Savana RX-7)...but there are people (alot) that will call it a POS with a spining dorrito. So thats life...too bad.
It can be so reliable that the Red Baron used a Rotary engine in his plane...yet people will say it will blow up because its not a 2JZ pushing 1000 hp. What can you say. You can make a suzuiki Swift dominate on a SCCA course...doesnt mean I love its engine or the car...although its "fast."
I'll respect a car for what it can do but doesnt mean Im dying to get one or I think everyone should or that I love everything on the car. Infact for the price of a Corvette I would msot definately choose a Lotus Elise...but thats just what I like.
Corvette maybe a fantastic price, great gas milage, and great performance (perfect car by all accounts...happy now?)...but you know what....
SO IS A SRT-4 COMPARED TO A MSP....and guess what im driving?
That was my answer to this:
BradC said:
I have learned that it doesn't matter what style of motor or suspension it has, it matters how the engineers put it all together and that they are drivers themsleves...
enough rambling...I am a CAR person. Not a OHC person or an import person. I like fast s***...
