Tue Aug 02, 2011 6:14 pm by Guest
This guide is created leaning towards 16v. However the information is still relevant for an 8v but costs and tolerances will be different. Im also only going to refer to the popular cams, because these are tried tested and proven to work. This guide also assumes you have fitted a high flow air filter (green cotton/induction kit). And a high flow exhaust/manifold combination. Using cams with a standard air filter and exhaust will restrict the amount of power gains you'll see.
Cams are a great way to change the characteristics of your engine, however, there are so many choices out there and each one has specific requirements that need to be met to produce the required outcome. You can change the profile of your cam whether you plan to stay N/A or go boosted. Cams are either Mild or Wild, all will be explained.
So what does a cam do?.
Simple, one end of the cam is connected to a pulley, which has a belt around it. Your timing belt. The cam is then forced to turn when your engine moves. On the cam their are little raised notches called lobes, these are the important bit;
The lobe of the cam is what opens and closes your valves as it turns. So if the lobe sticks out further the valve opens more. If the lobe is wider the valve opens for longer. So you get more air/fuel going in/out of the cylinder for longer.
So a Mild cam is one that has a slightly longer duration and a slightly higher lift. As a mild cam only has slight changes the standard ECU can usually accommodate for these small changes and provide the right mixture. This is why mild cams idle smooth and don't necessitate a remap. However a remap is required for all major engine modifications to get the full potential from it, so unmapped you may be only seeing a percentage of the actual power the cam can unleash.
A Wild cam has a very long duration and a very high lift, so long and high that the valves will hit the piston when it travels back up the cylinder. So for a wild cam you need pocketed pistons, which are also 99.9% of the time high compression. This is also why you need to remap the ECU as the amount of air going into the cylinder is too much for the ECU to match with fuel under it's standard parameters.
You will also need solid lifters, the standard ones are hydraulic and are lubricated by engine oil but the hard harsh hit of the valve from the wild cam usually causes them to jam shut.
Valve springs may also require changing for harder ones to prevent the valves from bouncing, as these specification of cams usually hit their peak power above 8000rpms. At this pace the valve spring can't compress the valve with enough force so as it hits the valve seat it bounces back open. This causes a compression loss and thus power loss.
Often throttle bodies and larger injectors are needed to even allow enough air and fuel into the cylinder to let the ECU be remapped. The standard ECU can be remapped to run this setup however an after market ECU is the best option as they are designed to run these exact set-ups. As you can see the difference between a Mild cam and a Wild cam is huge.
So how much can all that cost?.
Solid Lifters - £200~
Double Valve Springs/ Stronger Valve Springs - £200~
Pocketed High Compression Pistons - £500~
Aftermarket ECU - £600~
Remap - £300~
Throttle Bodies - £1000~
=£2800
So you need to know exactly what you want before you buy anything. The choices are fairly simple you'll fall into these categories;
1.)A bit more power but i havn't got much cash and i need the car everyday.
2.)More power, ive got some cash but I need the car everyday.
3.)Lots more power, ive got the cash, the cars not needed everyday.
So whats it matter if the cars needed everyday, ive got the cash?. I can go without it whilst the works getting done!. Yes but when you change a camshaft to gain more power you don't get that power for free. You move the power around the rev range, so one cam can give you 10bhp more at 5500rpm but may take 10bhp at 2000rpm.
So if you fit a Wild cam your car will not idle below 1200rpms and will not have any power until at least 4000rpms. The wildest of cams are classed as Race Cams, these often don't get the power above 50bhp until 4500rpms, so under that rev range you'll be using a scooters power to get your saxo around town.
Now you've decided what you want, its time to look at the specifications of cams.
The most popular cams are Newmans PH3 & CatCam 708. So lets take a look at them;
These cams fall under the 'Fast Road & Rally' category. This is because they steal a fair bit of power below 3500rpms and put it above 4500rpms. They also cause a rough idle and can make emissions tests harder to pass.
Why are they so popular then?. Well because you don't need a remap to be able to start your car after fitting. You don't need to change anything to use them to their full potential. And you don't loose so much power down low that the car is difficult to drive calmly. So they are a perfect choice for a road going car with a bit of extra power. The average gains on these cams can be quite large, many forum members have touched 160bhp with these cams after having them remapped. (Unmapped can see as little as 10bhp gains). Before going ahead and fitting this cam you may need to check you head, if it has been skimmed heavily you will not be able to fit these cams - Checking is cheaper than replacing bent valves.
So if you are in Category 2 = More power, ive got some cash but I need the car everyday. Then these are perfect as the cams are usually £300 and the remap is usually £300.
If your in Category 1, you still have options. There are Newmans PH1, CatCam 705 & 718.
PH1 - This is a 'Road Cam', you wont gain any power up top however you will gain power around the low and mid range of the revs so a good choice if you want to get a bit more poke but don't want to risk changing the way your engine responds and avoid having a remap.
Catcam 705 -These are very slightly milder than the PH1 but almost identical.
Catcam 718 - This is a 'Fast Road' cam, this cam increases power over the mid range, you will loose some low down power and suffer a slightly rough idle. You will need to remap after fitting this cam for full potential.
Piper cams seem to fall into category 2 but the Newmans and CatCams consistently out perform them and the CatCams have more RR figures available on-line so im excluding the piper cams. Hate mail me at peril.
Now if you want a cam in category 3 you have the largest selection, as once you get past the PH3/708 cams you start to head into expensive territory but also motorsport territory so there are plenty of choices and plenty of different specs to mate with your cam choice. And you'll need more than this guide to help you out. SO im going to list only the few common ones so you can view the specifications on the manufacturers website and compare them to any others you think may suit you. But generally with the PH4/850 you will need to spec your engine to handle above 180bhp. Once you get to the CatCam 802's you can hit 200bhp and above.
Newmans PH4 - Can't be run on the standard air inlet, if you don't want to use throttle bodies with this cam the PH3 would suit you better. Needs pocketed pistons. Doesn't 100% need solid lifters but hydraulic ones will need replacing which are £150~ so for the extra £100 for solid lifters you might aswell. You will need bigger injectors but not huge, IWP042 PICO injectors will do, these are cheap as they come from the Clio 172/182/192. And obviously a remap/aftermarket ECU.
CatCams 850 - Same as the PH4 but will need solid lifters.
An engine of this spec isn't cheap however they are popping up alot more now due to cheaper parts. The main expense is always the throttle bodies, then the internals.
The next step up is;
CatCam 802 - You will need the same stuff as above however you may need to rebore the engine and fit oversized pistons if fitting to a well used engine. You wont really get an idle, you will need to spec the engine to rev well into 8000rpms (lifters/springs/crank balancing/fresh bottom end bearings/conrods), you'll need larger injectors - maybe 330cc @3bar. And to make the bigger power you will need larger valves and the inlet and exhaust ports matched to the. You will need a stronger clutch, an excellent cooling system for oil and water, you will need to be able to cope with the hardships of running such a highly strung engine as they don't play ball very often and when they do its usually not for very long when driven how they should be.
For an engine of this spec your going to be spending alot of money, and alot of time. And the worst part about it is most of the work requires the engine in bits so you can't do a bit with each pay packet. On this forum the most detailed progress thread with a spec of a mental N/A engine belongs to the moderator Ryan. You can see from his setup its not easy, you need alot of knowledge, money and time. And you really really need to do your research.
http://www.catcams.com/index.htm
http://www.newman-cams.com/
http://www.pipercams.co.uk/NewPiperW...CamFrames.html
Example Power Figures;
182bhp Achieved with
Newmans PH4
AT power throttle bodies with 70mm trumpets
High Compression Pistons
4-2-1 manifold with decat exhaust
Standard ECU mapped by chipwizards
157bhp Acheived with;
Newmans PH3
BMC CDA
4-2-1 manifold with decat exhaust
Standard ECU mapped by chipwizards
112bhp Acheived with;
Standard 8v Engine
Please take these with a pinch of salt, some engines are fucked from the beginning, some engines are brilliant from the beginning. Some rolling roads are full of shit and some rolling roads are full of more shit. There are so many variables the figures are just examples
Cams are a great way to change the characteristics of your engine, however, there are so many choices out there and each one has specific requirements that need to be met to produce the required outcome. You can change the profile of your cam whether you plan to stay N/A or go boosted. Cams are either Mild or Wild, all will be explained.
So what does a cam do?.
Simple, one end of the cam is connected to a pulley, which has a belt around it. Your timing belt. The cam is then forced to turn when your engine moves. On the cam their are little raised notches called lobes, these are the important bit;
- The length the lobe sticks out from the centre of the camshaft is referred to as lift.
- The width of the lobe is referred to as duration.
The lobe of the cam is what opens and closes your valves as it turns. So if the lobe sticks out further the valve opens more. If the lobe is wider the valve opens for longer. So you get more air/fuel going in/out of the cylinder for longer.
So a Mild cam is one that has a slightly longer duration and a slightly higher lift. As a mild cam only has slight changes the standard ECU can usually accommodate for these small changes and provide the right mixture. This is why mild cams idle smooth and don't necessitate a remap. However a remap is required for all major engine modifications to get the full potential from it, so unmapped you may be only seeing a percentage of the actual power the cam can unleash.
A Wild cam has a very long duration and a very high lift, so long and high that the valves will hit the piston when it travels back up the cylinder. So for a wild cam you need pocketed pistons, which are also 99.9% of the time high compression. This is also why you need to remap the ECU as the amount of air going into the cylinder is too much for the ECU to match with fuel under it's standard parameters.
You will also need solid lifters, the standard ones are hydraulic and are lubricated by engine oil but the hard harsh hit of the valve from the wild cam usually causes them to jam shut.
Valve springs may also require changing for harder ones to prevent the valves from bouncing, as these specification of cams usually hit their peak power above 8000rpms. At this pace the valve spring can't compress the valve with enough force so as it hits the valve seat it bounces back open. This causes a compression loss and thus power loss.
Often throttle bodies and larger injectors are needed to even allow enough air and fuel into the cylinder to let the ECU be remapped. The standard ECU can be remapped to run this setup however an after market ECU is the best option as they are designed to run these exact set-ups. As you can see the difference between a Mild cam and a Wild cam is huge.
So how much can all that cost?.
Solid Lifters - £200~
Double Valve Springs/ Stronger Valve Springs - £200~
Pocketed High Compression Pistons - £500~
Aftermarket ECU - £600~
Remap - £300~
Throttle Bodies - £1000~
=£2800
So you need to know exactly what you want before you buy anything. The choices are fairly simple you'll fall into these categories;
1.)A bit more power but i havn't got much cash and i need the car everyday.
2.)More power, ive got some cash but I need the car everyday.
3.)Lots more power, ive got the cash, the cars not needed everyday.
So whats it matter if the cars needed everyday, ive got the cash?. I can go without it whilst the works getting done!. Yes but when you change a camshaft to gain more power you don't get that power for free. You move the power around the rev range, so one cam can give you 10bhp more at 5500rpm but may take 10bhp at 2000rpm.
So if you fit a Wild cam your car will not idle below 1200rpms and will not have any power until at least 4000rpms. The wildest of cams are classed as Race Cams, these often don't get the power above 50bhp until 4500rpms, so under that rev range you'll be using a scooters power to get your saxo around town.
Now you've decided what you want, its time to look at the specifications of cams.
The most popular cams are Newmans PH3 & CatCam 708. So lets take a look at them;
These cams fall under the 'Fast Road & Rally' category. This is because they steal a fair bit of power below 3500rpms and put it above 4500rpms. They also cause a rough idle and can make emissions tests harder to pass.
Why are they so popular then?. Well because you don't need a remap to be able to start your car after fitting. You don't need to change anything to use them to their full potential. And you don't loose so much power down low that the car is difficult to drive calmly. So they are a perfect choice for a road going car with a bit of extra power. The average gains on these cams can be quite large, many forum members have touched 160bhp with these cams after having them remapped. (Unmapped can see as little as 10bhp gains). Before going ahead and fitting this cam you may need to check you head, if it has been skimmed heavily you will not be able to fit these cams - Checking is cheaper than replacing bent valves.
So if you are in Category 2 = More power, ive got some cash but I need the car everyday. Then these are perfect as the cams are usually £300 and the remap is usually £300.
If your in Category 1, you still have options. There are Newmans PH1, CatCam 705 & 718.
PH1 - This is a 'Road Cam', you wont gain any power up top however you will gain power around the low and mid range of the revs so a good choice if you want to get a bit more poke but don't want to risk changing the way your engine responds and avoid having a remap.
Catcam 705 -These are very slightly milder than the PH1 but almost identical.
Catcam 718 - This is a 'Fast Road' cam, this cam increases power over the mid range, you will loose some low down power and suffer a slightly rough idle. You will need to remap after fitting this cam for full potential.
Piper cams seem to fall into category 2 but the Newmans and CatCams consistently out perform them and the CatCams have more RR figures available on-line so im excluding the piper cams. Hate mail me at peril.
Now if you want a cam in category 3 you have the largest selection, as once you get past the PH3/708 cams you start to head into expensive territory but also motorsport territory so there are plenty of choices and plenty of different specs to mate with your cam choice. And you'll need more than this guide to help you out. SO im going to list only the few common ones so you can view the specifications on the manufacturers website and compare them to any others you think may suit you. But generally with the PH4/850 you will need to spec your engine to handle above 180bhp. Once you get to the CatCam 802's you can hit 200bhp and above.
Newmans PH4 - Can't be run on the standard air inlet, if you don't want to use throttle bodies with this cam the PH3 would suit you better. Needs pocketed pistons. Doesn't 100% need solid lifters but hydraulic ones will need replacing which are £150~ so for the extra £100 for solid lifters you might aswell. You will need bigger injectors but not huge, IWP042 PICO injectors will do, these are cheap as they come from the Clio 172/182/192. And obviously a remap/aftermarket ECU.
CatCams 850 - Same as the PH4 but will need solid lifters.
An engine of this spec isn't cheap however they are popping up alot more now due to cheaper parts. The main expense is always the throttle bodies, then the internals.
The next step up is;
CatCam 802 - You will need the same stuff as above however you may need to rebore the engine and fit oversized pistons if fitting to a well used engine. You wont really get an idle, you will need to spec the engine to rev well into 8000rpms (lifters/springs/crank balancing/fresh bottom end bearings/conrods), you'll need larger injectors - maybe 330cc @3bar. And to make the bigger power you will need larger valves and the inlet and exhaust ports matched to the. You will need a stronger clutch, an excellent cooling system for oil and water, you will need to be able to cope with the hardships of running such a highly strung engine as they don't play ball very often and when they do its usually not for very long when driven how they should be.
For an engine of this spec your going to be spending alot of money, and alot of time. And the worst part about it is most of the work requires the engine in bits so you can't do a bit with each pay packet. On this forum the most detailed progress thread with a spec of a mental N/A engine belongs to the moderator Ryan. You can see from his setup its not easy, you need alot of knowledge, money and time. And you really really need to do your research.
http://www.catcams.com/index.htm
http://www.newman-cams.com/
http://www.pipercams.co.uk/NewPiperW...CamFrames.html
Example Power Figures;
182bhp Achieved with
Newmans PH4
AT power throttle bodies with 70mm trumpets
High Compression Pistons
4-2-1 manifold with decat exhaust
Standard ECU mapped by chipwizards
157bhp Acheived with;
Newmans PH3
BMC CDA
4-2-1 manifold with decat exhaust
Standard ECU mapped by chipwizards
112bhp Acheived with;
Standard 8v Engine
Please take these with a pinch of salt, some engines are fucked from the beginning, some engines are brilliant from the beginning. Some rolling roads are full of shit and some rolling roads are full of more shit. There are so many variables the figures are just examples