cam, twincam, quad cam?

[MattB]

hey... would just like a general explanation of the benefits of twin/quad cam?
I only seem to notice twincam advertising on small 4cyl cars, like a barina or excel... I've seen on some 4wds 'quad cam' advertised... what benefit does having 4 camshafts have over 1? ...it's not for power is it? Because even the supercars only have a single cam!

Cheers,
Matt

[Danv8]

Marketing wank value really.
They make the cars sound very sophisticated for market value.
The average joe driver wouldn't have a clue or cared if the engine had variable valve timing or how many cams it has. The mrs asked me what is with the VVT badges on a Corolla I just said pointless marketing crap. :-) It just give an excuse for the sales droid to use so many terms and technical buggery to make a sale. Really to make people think its a must have item like extra paint protection crap.

It reminds me when I was buying my Rodeo the sales droid went on about how high tech the V6 engine is variable valve timing, electronic throttle DOHC 24 valves. I told him I have to ask the tyres on it and see if they care how much technical crap the engine has, because clearly I didn't. :-)

[HSV,_I_GOT_ONE]

Quad cam cars are V config motors that have 2 cams on each bank.
It's not completely marketing hype. The advantages of having twin cams/quad cams and VVT is engine efficiencies. The VVT allows the cams to be degreed according to rev range so that the power delivery is more linear and gives a little extra torque off the line while still retaining top end power. Twin cams also allow for 4 valves per cylinder increasing combustion efficiencies and power per flow of CFM. With the 2 cams as well you can have one cam that is specifically tuned for the intake and the other cam specifically tuned for the exhaust gases.
Now the reason why the old school v8's are still good for outright power.
2 valves per cylinder will give you much better CFM over 4 valves. It won't be as efficient but will allow the gasses to escape much quicker than the 4 valve will. One big cam will give you massive amounts of power up top but you will sacrifice this for the low end stuff. Twincams won't be able to match 1 big dirty stick for outright power.
Also a lot of people don't realise this but you can get more power out of a carb setup then an injected setup. Injection has its advantage in consistent tuning and better efficiencies again. But the right carb will be able to suck down a lot more air and a lot more fuel in comparison. This is why top fuelers run carb setups, so I have been told.
The technology is all about reducing emissions, fuel consumption and better driveablity (smoother engine).

[swingtan]

The difference between twin cam and quad cam has little to do with the cams and more to do with the engine configuration.

As you probably know, the cam controls the opening and closing of the valves. It controls both the timing of the valves, as well as the amount the valves open and it does this for both the inlet and exhaust valves. So the cam is a highly refined piece of gear to get all things working correctly. The push-rod based engine ( which is what the LSX engines are ) place the cam in the "V" of the block, sit "lifters" on the cam that transfer the shape of the cam to "push-rods" which then operate rockers to transfer the "up" motion to a "down" motion to open the valves. This works pretty well, until you get up in the higher rev range. All these components have weight, so take a little bit of effort to get moving and then more effort to stop them moving. to control the "valve train" ( everything from the lifter to the valve ) decent springs must be used. If you want to rev higher, open / close the valves faster or keep the valves open for longer, progressively stronger springs need to be user to control all the components, or you need to lighten the components. Needless to say, with a push-rod engine, there's really only room for one cam.

Eventually you get to a point where the valve springs need to be so strong, that other components start failing, so another solution was sought to reduce the valve train loading. This led to the OHC design, placing the cam Over the Head. This removed the lifters and push-rods and in some cases the rockers as well. Some designs that had the valves "in-line" sat the cam right over the valves and had adjustable "followers" between the valve stem and the cam lobes. Other designs "off set" the valves and use rocker arms to actuate the valves on each side of the cam. this design removed the vast majority of valve train weight, allowing for lighter valve springs. This meant less effort was required to open / close the valves so there was less stress on the components. It also meant less components which resulted in a lower build cost.

As the "cam over valve" design reduced the component count, it was seen by some as the way forward. However the practice of off setting the valves allowed for more efficient head / port design. So the idea of running 2 camshafts came along, one for inlets and one for exhaust Dual Over Head Cam. This gave the best of both worlds and allowed for the fine tunning of each phase of the combustion cycle. It allow lent its self very well to VVT, where the inlet process could be controlled separately from the exhaust.

The "Quad cam" design is simply a DOHC design applied to a "V" shaped motor there is nothing more special about it, apart from the fact it has 4 cams instead of 2. The theory is the same. The reason you see generally see smaller engines with all this technology, is that they need it to develop reasonable power while still meeting EPA requirements and getting good economy. As they are smaller motors, they need to rev harder to develop power than a larger motor. The reason big cube motors generally don't come with quad cams is that they already develop very good power and meet emissions requirements with a single cam and push rod design.

Simon.

[ABG]

Marketing wank value really.


Beg to differ Dan. A quick, non-technical explanation of the advantages of a twin cam engine can be found here http://auto.howstuffworks.com/question562.htm

[Danv8]

The difference between twin cam and quad cam has little to do with the cams and more to do with the engine configuration.

As you probably know, the cam controls the opening and closing of the valves. It controls both the timing of the valves, as well as the amount the valves open and it does this for both the inlet and exhaust valves. So the cam is a highly refined piece of gear to get all things working correctly. The push-rod based engine ( which is what the LSX engines are ) place the cam in the "V" of the block, sit "lifters" on the cam that transfer the shape of the cam to "push-rods" which then operate rockers to transfer the "up" motion to a "down" motion to open the valves. This works pretty well, until you get up in the higher rev range. All these components have weight, so take a little bit of effort to get moving and then more effort to stop them moving. to control the "valve train" ( everything from the lifter to the valve ) decent springs must be used. If you want to rev higher, open / close the valves faster or keep the valves open for longer, progressively stronger springs need to be user to control all the components, or you need to lighten the components. Needless to say, with a push-rod engine, there's really only room for one cam.

Eventually you get to a point where the valve springs need to be so strong, that other components start failing, so another solution was sought to reduce the valve train loading. This led to the OHC design, placing the cam Over the Head. This removed the lifters and push-rods and in some cases the rockers as well. Some designs that had the valves "in-line" sat the cam right over the valves and had adjustable "followers" between the valve stem and the cam lobes. Other designs "off set" the valves and use rocker arms to actuate the valves on each side of the cam. this design removed the vast majority of valve train weight, allowing for lighter valve springs. This meant less effort was required to open / close the valves so there was less stress on the components. It also meant less components which resulted in a lower build cost.

As the "cam over valve" design reduced the component count, it was seen by some as the way forward. However the practice of off setting the valves allowed for more efficient head / port design. So the idea of running 2 camshafts came along, one for inlets and one for exhaust Dual Over Head Cam. This gave the best of both worlds and allowed for the fine tunning of each phase of the combustion cycle. It allow lent its self very well to VVT, where the inlet process could be controlled separately from the exhaust.

The "Quad cam" design is simply a DOHC design applied to a "V" shaped motor there is nothing more special about it, apart from the fact it has 4 cams instead of 2. The theory is the same. The reason you see generally see smaller engines with all this technology, is that they need it to develop reasonable power while still meeting EPA requirements and getting good economy. As they are smaller motors, they need to rev harder to develop power than a larger motor. The reason big cube motors generally don't come with quad cams is that they already develop very good power and meet emissions requirements with a single cam and push rod design.

Simon.

I see the trend on many new cars that need to have extra gear ratio's. To sort of compensate the lack of urge that smaller capacity engines produce. One thing I do notice from coming from a big cube V8 to a smaller cube high tech V6 is the lack of grunt. :-)

Although many new cars I have test driven with high tec V6's never really have the push you into the seat feeling unless they are turbo/supercharged. Thankfully my Rodeo is a manual so it has decent gear ratio's to give it some oomph. Just cant beat cubes though for grunt. :-)

[EfiJy]

multicams only come good over 4ooorpm. not much good 4 the street unless u drive a small car

[Danv8]

Beg to differ Dan. A quick, non-technical explanation of the advantages of a twin cam engine can be found here http://auto.howstuffworks.com/question562.htm

Interesting read although I rather get the feel of the power from the engine than to read about how much gizmo's it has. And I have driven plenty of cars with all these technological masterpieces and always generally felt dissapointed in the performance of them. My usual words are its average at best although with a supercharger or a turbo then it is interesting. :)

[MattB]

thanks for the replies guys! just learnt a lot of new stuff! :P

[VX-300]

This is why top fuelers run carb setups, so I have been told.

Just edit that part out.

[HSV,_I_GOT_ONE]

Top fuelers are injected then? I was under the impression that they were carb. I stand corrected then.

[Danv8]

Top fuelers are injected then? I was under the impression that they were carb. I stand corrected then.

They can be either carb or injected.
Either way music to my ears when they are going. :-)

[ABG]

Interesting read although I rather get the feel of the power from the engine than to read about how much gizmo's it has. And I have driven plenty of cars with all these technological masterpieces and always generally felt dissapointed in the performance of them. My usual words are its average at best although with a supercharger or a turbo then it is interesting. :)

Agreed that F/I multi cam engines are more interesting, but there are still some great N/A versions around the traps. Just look under the cover of any F1 engine :)

[VX-300]

Top fuelers are injected then? I was under the impression that they were carb. I stand corrected then.

Mechanical Injection.
Fuel is injected by a constant flow injection system. There is an engine driven mechanical fuel pump and about 42 fuel nozzles. The pump can flow 100 gallons/minute at 8000 rpm and 500 PSI fuel pressure. In general 10 injectors are placed in the injector hat above the supercharger, 16 in the intake manifold and two per cylinder in the cylinder head.

http://en.wikipedia.org/wiki/Top_Fuel

[Dacious]

You can have 4-valve heads with pushrods - the Honda CX500 v-twin known as the plastic maggot had them back in '78. It allowed the heads to be twisted (exhausts splayed outwards) so that the carbs pointed inwards to clear the riders knees. You can also have 4 valves with a single OHC - my MZ has that (Yamaha 660 single). Various pommy bikes of the 30's-40's had two exhaust valves each driven by their own pushrod.

Although OHV was invented later than OHC, it allows manufacturing more cheaply with reduced part count and simpler castings, especially for the head and barrels. The bearing points are also simpler - you just need one, for the cam in the block which can be driven directly 50% speed off the crank. In a v-config motor it has great advantages, in that you can run the valves off one cam in the V which means the intakes face each other and the exhausts exit out of the other side of the head - neat, and relatively good for intake and exhaust paths.

If you want to see the real advantage of DOHC and 4-valves, the current diesel Astras illustrate it: the auto has a single-cam with 2-valve heads. The manual has twincams and 4 valve heads. The 4-valve motor puts out 110kw and more torque at higher revs than the 2-valve at 88kw. It also gets much better economy.

DOHC directly bearing on the valves provides precise control without exotic materials. 4 valves means smaller valves with tiny stems, retainers and collets are used which lowers reciprocating weight and drivetrain inertia and means smaller, single springs are needed to control them, not double or triple springs. That also reduces friction at the cam lobes and the imprecision of rockers which bend and work through a swiping motion causing valve-guide wear. 4 small valves have larger valve area (bigger opening) than 2, and the port area behind them is also larger.

They need to open a smaller distance to provide the same amount of flow (smaller valve lift, less friction, less mechanical noise, less stress and wear on all components). Better valve control, better flow and the flatter combustion chamber that results, with less hotspots on a flatop piston is the way to go for efficiency and low emissions. You get better combustion allowing more ignition advance without detonation.

DOHC was once an expensive motor to make, and difficult to manufacture cheaply to consistent high standards which is why they only tended to be used in the most expensive hi-po cars - with modern CNC tooling this is not so to the same extent. Even a lot of the wear and longevity concerns are overcome with modern sintered components, metallurgy and lubrication.

DOHC is the way to go for small-capacity motors for efficiency - if you think VVT Corollas are gutless, remember the cars weigh almost double what a 70's singlecam, 2-valve motor version did, and comply with far harsher emissions and noise laws yet provide far better performance and economy.

Does this mean the LSx series is a dud? Not compared to its' direct competitor. No - it uses large capacity and low-friction in a small, light external package to compete with sophisticated twincam V8s which are not only physically larger for a smaller capacity but much heavier. It's evolved off 50 years of development and uses alternate strategies to achieve a similar end.

GM Powertrain uses other tricks like sodium-filled valves to lower reciprocating weight and cool them, conical valve springs, alloy roller rockers, plastic lifters, the penthouse-shaped porting etc. Part of the early problems with the LSx were caused by not applying enough QC to the low-friction bits like the very thin rings and short-skirt pistons. Power loss due to friction is exponential - if you can save 10hp at 1,000rpm it might be 60hp at 5,000rpm.

DOHC is efficient at producing power, but it costs a lot to make two heads and drives for a V8 and chews a lot of power up. Working on one is a comparative nightmare. Just imagine the complexity of a head gasket change on a Ford 5.4 compared to a LS1? In the 80s a Ford Cosworth F1 V8 used nearly 80hp just to drive the belts, high-lift cams, 32 triple valve springs and overcome inertia. Plus you end up with very large, heavy casting, cams, gears and chains sitting up high on top of your motor, adding weight exactly where you don't want it. On a large capacity motor this is definitely a consideration.

You can have 4-valve heads with pushrods - the Honda CX500 v-twin known as the plastic maggot had them back in '78. It allowed the heads to be twisted (exhausts splayed outwards) so that the carbs pointed inwards to clear the riders knees. You can also have 4 valves with a single OHC - my MZ has that (Yamaha 660 single). Various pommy bikes of the 30's-40's had two exhaust valves each driven by their own pushrod.

Although OHV was invented later than OHC, it allows manufacturing more cheaply with reduced part count and simpler castings, especially for the head and barrels. The bearing points are also simpler - you just need one, for the cam in the block which can be driven directly 50% speed off the crank. In a v-config motor it has great advantages, in that you can run the valves off one cam in the V which means the intakes face each other and the exhausts exit out of the other side of the head - neat, and relatively good for intake and exhaust paths.

If you want to see the real advantage of DOHC and 4-valves, the current diesel Astras illustrate it: the auto has a single-cam with 2-valve heads. The manual has twincams and 4 valve heads. The 4-valve motor puts out 110kw and more torque at higher revs than the 2-valve at 88kw. It also gets much better economy.

DOHC directly bearing on the valves provides precise control without exotic materials. 4 valves means smaller valves with tiny stems, retainers and collets are used which lowers reciprocating weight and drivetrain inertia and means smaller, single springs are needed to control them, not double or triple springs. That also reduces friction at the cam lobes and the imprecision of rockers which bend and work through a swiping motion causing valve-guide wear. 4 small valves have larger valve area (bigger opening) than 2, and the port area behind them is also larger.

They need to open a smaller distance to provide the same amount of flow (smaller valve lift, less friction, less mechanical noise, less stress and wear on all components). Better valve control, better flow and the flatter combustion chamber that results, with less hotspots on a flatop piston is the way to go for efficiency and low emissions. You get better combustion allowing more ignition advance without detonation.

DOHC was once an expensive motor to make, and difficult to manufacture cheaply to consistent high standards which is why they only tended to be used in the most expensive hi-po cars - with modern CNC tooling this is not so to the same extent. Even a lot of the wear and longevity concerns are overcome with modern sintered components, metallurgy and lubrication.

DOHC is the way to go for small-capacity motors for efficiency - if you think VVT Corollas are gutless, remember the cars weigh almost double what a 70's singlecam, 2-valve motor version did, and comply with far harsher emissions and noise laws yet provide far better performance and economy.

Does this mean the LSx series is a dud? Not compared to its' direct competitor. No - it uses large capacity and low-friction in a small, light external package to compete with sophisticated twincam V8s which are not only physically larger for a smaller capacity but much heavier. It's evolved off 50 years of development and uses alternate strategies to achieve a similar end.

GM Powertrain uses other tricks like sodium-filled intake valves to lower reciprocating weight and cool them, conical valve springs, alloy roller rockers, plastic lifters, the penthouse-shaped porting etc. Part of the early problems with the LSx were caused by not applying enough QC to the low-friction bits like the very thin rings and short-skirt pistons.

DOHC is efficient, but it costs and chews a lot of power. In the 80s a Ford Cosworth F1 V8 used nearly 80hp just to drive the belts, high-lift cams, triple valve springs and overcome inertia. Plus you end up with very heavy cams, gears and chains sitting up high on top of your motor, adding weight exacgtly where you don't want it. On a large motor this is definitely a consideration.

[Danv8]

Excellent post Dacious as always.

[VZGEN4]

Very informative thread!

Not that I know much about the ford 5.4L DOHC V8 engine or engines generally, but is it a decent motor? They seem to produce fairly reasonable power for a lower cubed engine? How would you go with power upgrades such as cam upgrade? Would you change all four??????????

[ABG]

Great post Dacious :)

[iamhappy46]

I see the trend on many new cars that need to have extra gear ratio's. To sort of compensate the lack of urge that smaller capacity engines produce. One thing I do notice from coming from a big cube V8 to a smaller cube high tech V6 is the lack of grunt. :-)

Although many new cars I have test driven with high tec V6's never really have the push you into the seat feeling unless they are turbo/supercharged. Thankfully my Rodeo is a manual so it has decent gear ratio's to give it some oomph. Just cant beat cubes though for grunt. :-)

6 speeds keep the engine in its peak torque output longer to make it accelerate faster.


multicams only come good over 4ooorpm. not much good 4 the street unless u drive a small car


You can have 4-valve heads with pushrods - the Honda CX500 v-twin known as the plastic maggot had them back in '78. It allowed the heads to be twisted (exhausts splayed outwards) so that the carbs pointed inwards to clear the riders knees. You can also have 4 valves with a single OHC - my MZ has that (Yamaha 660 single). Various pommy bikes of the 30's-40's had two exhaust valves each driven by their own pushrod.

Although OHV was invented later than OHC, it allows manufacturing more cheaply with reduced part count and simpler castings, especially for the head and barrels. The bearing points are also simpler - you just need one, for the cam in the block which can be driven directly 50% speed off the crank. In a v-config motor it has great advantages, in that you can run the valves off one cam in the V which means the intakes face each other and the exhausts exit out of the other side of the head - neat, and relatively good for intake and exhaust paths.

If you want to see the real advantage of DOHC and 4-valves, the current diesel Astras illustrate it: the auto has a single-cam with 2-valve heads. The manual has twincams and 4 valve heads. The 4-valve motor puts out 110kw and more torque at higher revs than the 2-valve at 88kw. It also gets much better economy.

DOHC directly bearing on the valves provides precise control without exotic materials. 4 valves means smaller valves with tiny stems, retainers and collets are used which lowers reciprocating weight and drivetrain inertia and means smaller, single springs are needed to control them, not double or triple springs. That also reduces friction at the cam lobes and the imprecision of rockers which bend and work through a swiping motion causing valve-guide wear. 4 small valves have larger valve area (bigger opening) than 2, and the port area behind them is also larger.

They need to open a smaller distance to provide the same amount of flow (smaller valve lift, less friction, less mechanical noise, less stress and wear on all components). Better valve control, better flow and the flatter combustion chamber that results, with less hotspots on a flatop piston is the way to go for efficiency and low emissions. You get better combustion allowing more ignition advance without detonation.

DOHC was once an expensive motor to make, and difficult to manufacture cheaply to consistent high standards which is why they only tended to be used in the most expensive hi-po cars - with modern CNC tooling this is not so to the same extent. Even a lot of the wear and longevity concerns are overcome with modern sintered components, metallurgy and lubrication.

DOHC is the way to go for small-capacity motors for efficiency - if you think VVT Corollas are gutless, remember the cars weigh almost double what a 70's singlecam, 2-valve motor version did, and comply with far harsher emissions and noise laws yet provide far better performance and economy.

Does this mean the LSx series is a dud? Not compared to its' direct competitor. No - it uses large capacity and low-friction in a small, light external package to compete with sophisticated twincam V8s which are not only physically larger for a smaller capacity but much heavier. It's evolved off 50 years of development and uses alternate strategies to achieve a similar end.

GM Powertrain uses other tricks like sodium-filled valves to lower reciprocating weight and cool them, conical valve springs, alloy roller rockers, plastic lifters, the penthouse-shaped porting etc. Part of the early problems with the LSx were caused by not applying enough QC to the low-friction bits like the very thin rings and short-skirt pistons. Power loss due to friction is exponential - if you can save 10hp at 1,000rpm it might be 60hp at 5,000rpm.

DOHC is efficient at producing power, but it costs a lot to make two heads and drives for a V8 and chews a lot of power up. Working on one is a comparative nightmare. Just imagine the complexity of a head gasket change on a Ford 5.4 compared to a LS1? In the 80s a Ford Cosworth F1 V8 used nearly 80hp just to drive the belts, high-lift cams, 32 triple valve springs and overcome inertia. Plus you end up with very large, heavy casting, cams, gears and chains sitting up high on top of your motor, adding weight exactly where you don't want it. On a large capacity motor this is definitely a consideration.

You can have 4-valve heads with pushrods - the Honda CX500 v-twin known as the plastic maggot had them back in '78. It allowed the heads to be twisted (exhausts splayed outwards) so that the carbs pointed inwards to clear the riders knees. You can also have 4 valves with a single OHC - my MZ has that (Yamaha 660 single). Various pommy bikes of the 30's-40's had two exhaust valves each driven by their own pushrod.

Although OHV was invented later than OHC, it allows manufacturing more cheaply with reduced part count and simpler castings, especially for the head and barrels. The bearing points are also simpler - you just need one, for the cam in the block which can be driven directly 50% speed off the crank. In a v-config motor it has great advantages, in that you can run the valves off one cam in the V which means the intakes face each other and the exhausts exit out of the other side of the head - neat, and relatively good for intake and exhaust paths.

If you want to see the real advantage of DOHC and 4-valves, the current diesel Astras illustrate it: the auto has a single-cam with 2-valve heads. The manual has twincams and 4 valve heads. The 4-valve motor puts out 110kw and more torque at higher revs than the 2-valve at 88kw. It also gets much better economy.

DOHC directly bearing on the valves provides precise control without exotic materials. 4 valves means smaller valves with tiny stems, retainers and collets are used which lowers reciprocating weight and drivetrain inertia and means smaller, single springs are needed to control them, not double or triple springs. That also reduces friction at the cam lobes and the imprecision of rockers which bend and work through a swiping motion causing valve-guide wear. 4 small valves have larger valve area (bigger opening) than 2, and the port area behind them is also larger.

They need to open a smaller distance to provide the same amount of flow (smaller valve lift, less friction, less mechanical noise, less stress and wear on all components). Better valve control, better flow and the flatter combustion chamber that results, with less hotspots on a flatop piston is the way to go for efficiency and low emissions. You get better combustion allowing more ignition advance without detonation.

DOHC was once an expensive motor to make, and difficult to manufacture cheaply to consistent high standards which is why they only tended to be used in the most expensive hi-po cars - with modern CNC tooling this is not so to the same extent. Even a lot of the wear and longevity concerns are overcome with modern sintered components, metallurgy and lubrication.

DOHC is the way to go for small-capacity motors for efficiency - if you think VVT Corollas are gutless, remember the cars weigh almost double what a 70's singlecam, 2-valve motor version did, and comply with far harsher emissions and noise laws yet provide far better performance and economy.

Does this mean the LSx series is a dud? Not compared to its' direct competitor. No - it uses large capacity and low-friction in a small, light external package to compete with sophisticated twincam V8s which are not only physically larger for a smaller capacity but much heavier. It's evolved off 50 years of development and uses alternate strategies to achieve a similar end.

GM Powertrain uses other tricks like sodium-filled intake valves to lower reciprocating weight and cool them, conical valve springs, alloy roller rockers, plastic lifters, the penthouse-shaped porting etc. Part of the early problems with the LSx were caused by not applying enough QC to the low-friction bits like the very thin rings and short-skirt pistons.

DOHC is efficient, but it costs and chews a lot of power. In the 80s a Ford Cosworth F1 V8 used nearly 80hp just to drive the belts, high-lift cams, triple valve springs and overcome inertia. Plus you end up with very heavy cams, gears and chains sitting up high on top of your motor, adding weight exacgtly where you don't want it. On a large motor this is definitely a consideration.

Excellent post.

However, in answer to some other repsonses...

Multi valve/multi cam engines can make peak power below 4000rpm quite easily, as you can adjust the LSA(Lobe Seperation Angle) by fitting adjustable cam gears which can set how the engine responds and where peak torque/horsepower occurs.

For example, the Nissan SR20VE and the Honda K20A make a bucketload of torque at low rpm but once the variable valve lift and timing kicks in(no crappy variable valve timing here), then the engine basically will rev like a motorbike and power climbs like nothing else... I am sure a few of you have seen the Honda Civic/Integras at the Willowbank/WSID with a K20A conversion... also check out the SR20 video I posted in the multimedia section

[German Statesman]

Very informative thread!

Not that I know much about the ford 5.4L DOHC V8 engine or engines generally, but is it a decent motor? They seem to produce fairly reasonable power for a lower cubed engine? How would you go with power upgrades such as cam upgrade? Would you change all four??????????

I know a cop in Seattle that speaks highly of the 4.6 modular V8 they get in their Crown Victoria interceptors. Despite the pic going around on emails lately, they are a very strong engine and there was no need to put the 5.4 SOHC truck motor in this full-sized car to meet law enforcement acceleration requirements.

There's a bit of an urban legend amongst the blue oval camp about the 5.4 engine. Ford Aust asked Dearborn about a hi-po version of the 5.4, knowing a 4.6 DOHC wouldn't cut the cheese in a BA against a Gen 3 equipped VY. Yes, Dearborn replied, we have a supercharged version of the 5.4 in the F150 Lightning and you're welcome to use that. No, said Ford Aust, the insurance costs would be a killer to our customer base, and we had a supercar scare not so long ago in '74 which killed all muscle car development. How about we put the 4.6 DOHC heads on the SOHC 5.4 long motor????

Can't be done!! the Dearborn whitecoats laughed. Don't see why not, Ford Aust says, they've got the same modular block/heads/valvetrain. Not possible the Detroit boffs huffed, besides you're in Australia, what would you know about our engines??

Three months later, one of the pilot build BA GTs (a manual no less) complete with 290kw DOHC 5.4 arrives in Detroit, the address tag being Powertrain Engineering, FoMoCo, Detroit.

Inside was a 'With Compliments' slip from Broadmeadows with three words...

"Yes it can."

[toyocharged]

The problem with the Ford 5.4 is the stroke, its far too long, its an under square engine longer bore than stroke, the Ls series engine have a better design being oversquare bigger bore, shorter stroke which usually equals better HP but less torque. The LS series engine overcomes this by pure cubic inches.

The new ford motor being designed is oversquare to reduce the piston speed at high revs and also a capacity increase.

new ford V8 (http://en.wikipedia.org/wiki/Ford_Boss_engine)


HSV I GOT one originally posted

Quad cam cars are V config motors that have 2 cams on each bank.
It's not completely marketing hype. The advantages of having twin cams/quad cams and VVT is engine efficiencies. The VVT allows the cams to be degreed according to rev range so that the power delivery is more linear and gives a little extra torque off the line while still retaining top end power. Twin cams also allow for 4 valves per cylinder increasing combustion efficiencies and power per flow of CFM. With the 2 cams as well you can have one cam that is specifically tuned for the intake and the other cam specifically tuned for the exhaust gases.
Now the reason why the old school v8's are still good for outright power.
2 valves per cylinder will give you much better CFM over 4 valves. It won't be as efficient but will allow the gasses to escape much quicker than the 4 valve will. One big cam will give you massive amounts of power up top but you will sacrifice this for the low end stuff. Twincams won't be able to match 1 big dirty stick for outright power.
Also a lot of people don't realise this but you can get more power out of a carb setup then an injected setup. Injection has its advantage in consistent tuning and better efficiencies again. But the right carb will be able to suck down a lot more air and a lot more fuel in comparison. This is why top fuelers run carb setups, so I have been told.
The technology is all about reducing emissions, fuel consumption and better driveablity (smoother engine).

You speak about 2v getting more fuel/air in and out of the combustion chamber, but on the ther hand you speak of the 4Valve being more efficient, you have completley contradicted yourself.

4 valve engines have better NA volumetric efficiency than a 2 valve, because they are more efficeint at getting air/fuel in and out of the combustion chamber.

Carbs dont suck air the engine does, the size of the throttle body, cam, cam timing etc control the amount of air going into the engine, give me fuel injection preferabley ITB's than a carby anyday.

Where the cam is located doesnt change the hp, timing, lift, overlap does

[EfiJy]

You speak about 2v getting more fuel/air in and out of the combustion chamber, but on the ther hand you speak of the 4Valve being more efficient, you have completley contradicted yourself.

4 valve engines have better NA volumetric efficiency than a 2 valve, because they are more efficeint at getting air/fuel in and out of the combustion chamber.

Carbs dont suck air the engine does, the size of the throttle body, cam, cam timing etc control the amount of air going into the engine, give me fuel injection preferabley ITB's than a carby anyday.

Where the cam is located doesnt change the hp, timing, lift, overlap does

good points.

u can tell who the wannabes are in the forum eh?