Saxperience - Citroen Saxo Forum - View Single Post - Read Me Before you start a new thread!* Looking for more Power? Read in here, all you need to know.

-Dan- · 8th June 2009, 19:43

So now what you ask?

Well this is where big power gains are to be had, and where big money is starting to be spent.

Uprated Camshafts * Credit goes to Balance Motorsport

Camshafts probably change the character of an engine more than any other component. The aggressive profiles available for race engines by people such as CatCams and Newmans do for sure.

By controlling the timing of the inlet and exhaust valve opening this simple component can change an engine from a low revving, economical and docile specification to a high revving race engine. The biggest issue for the driver looking for more speed in todays world is catalysts.

If your vehicle will be still for road use and is equipped with a cat it will affect cam choice. All out race cams are designed to operate well at high RPM and often run poorly at low rpm.

That said with modern engine management and vernier cam pulleys you can get even very highly tuned engines through an MOT and then optimise for maximum performance on the track.

Honda's VTEC range of engines utilise 2 distinct cam profiles, one of which is akin to a race specification cam. This engages when the revs are above say 5500 rpm. Anyone who has driven one of these will know what you can expect from the top end of the rev range by fitting an uprated camshaft.

The key to successful cam selection for your engine is matching it to the engines intended use. Many cams suggest the intended application in their name. Race for instance generally means race use only.

Bear in mind though that cam choice is influenced by the ratio volume of the cylinder to the valve area. In a nutshell a bigger engine with the same valves will be more flexible at lower revs and probably not rev as high with the same cam as a smaller engine. e.g fit the same cam in a 1.6 and 2.0 engine that have the same head design and the 1.6 engine will be much more inflexible in its power delivery.

If you fit a hot cam with a largely standard head the engine will be more tractable than with a big valve head. The big valve head will get into it's stride higher in the rev range and make more power though.

These are all important considerations if you are opting for a capacity increase or if you are fitting a cam into an an engine with 2 valves per cylinder (such as the VTS). 2 valve heads usually flow less air but can often stand a hotter cam and remain flexible at low revs.

Due to the costs involved, most people don't tend to Cam Saxos lower in the range than the VTR. This is simply because the gains aren't proportionate to the costs involved.

Rough cost of Cams can range upwards of 210+Vat (for a VTR) up to £1000s depending on model, make etc. Factor into this the cost of a remap and your looking at about £1000 to get the cams set up, timed and having the whole lot remapped to use the best power.

* (following credit goes to WilliamsVTS)

*When choosing a cam you want to leave about 1.5mm valve to piston clearance, you never know what could happen.

*lift on standard cam is 8.49mm and has valve clearance of 3.01mm, so you can work it out from there (although this would need to be worked out from lift at TDC). if you were wanting cams with more lift you would either need your pistons rebated or some forged pistons. you would also need to consider throttle bodies as cams with that much lift would be being restricted by the standard inlet.

So to simplify things - you can buy:

Mild Cams - These aren't a huge amount different than standard, and once mapped will give nice smooth idle. Power gains Once mapped would probably see about 15 bhp on a VTS. An Example would be the Newmans PH1.

Mild Fast Road/Track Cams - These are the ones that most people go for, and offer a good compromise of everyday useability with good power gains. Once mapped on a VTS would see probably pushing 20-25bhp. An Example would be the Newmans PH3

Full Race/Rally Spec Cam - Only realisticly usable in a track car, will give even better gains due to the wildness of the cam, but not recommended for use in a road car. An example would be the Newmans PH5.

8th June 2009, 19:43	#3
-Dan- Established Member Join Date: Jul 2008 Location: Taunton, Somerset Posts: 1,182 Car(s): Millenium Falcon iTrader Score: 2 (100%)	So now what you ask? Well this is where big power gains are to be had, and where big money is starting to be spent. Uprated Camshafts * Credit goes to Balance Motorsport Camshafts probably change the character of an engine more than any other component. The aggressive profiles available for race engines by people such as CatCams and Newmans do for sure. By controlling the timing of the inlet and exhaust valve opening this simple component can change an engine from a low revving, economical and docile specification to a high revving race engine. The biggest issue for the driver looking for more speed in todays world is catalysts. If your vehicle will be still for road use and is equipped with a cat it will affect cam choice. All out race cams are designed to operate well at high RPM and often run poorly at low rpm. That said with modern engine management and vernier cam pulleys you can get even very highly tuned engines through an MOT and then optimise for maximum performance on the track. Honda's VTEC range of engines utilise 2 distinct cam profiles, one of which is akin to a race specification cam. This engages when the revs are above say 5500 rpm. Anyone who has driven one of these will know what you can expect from the top end of the rev range by fitting an uprated camshaft. The key to successful cam selection for your engine is matching it to the engines intended use. Many cams suggest the intended application in their name. Race for instance generally means race use only. Bear in mind though that cam choice is influenced by the ratio volume of the cylinder to the valve area. In a nutshell a bigger engine with the same valves will be more flexible at lower revs and probably not rev as high with the same cam as a smaller engine. e.g fit the same cam in a 1.6 and 2.0 engine that have the same head design and the 1.6 engine will be much more inflexible in its power delivery. If you fit a hot cam with a largely standard head the engine will be more tractable than with a big valve head. The big valve head will get into it's stride higher in the rev range and make more power though. These are all important considerations if you are opting for a capacity increase or if you are fitting a cam into an an engine with 2 valves per cylinder (such as the VTS). 2 valve heads usually flow less air but can often stand a hotter cam and remain flexible at low revs. Due to the costs involved, most people don't tend to Cam Saxos lower in the range than the VTR. This is simply because the gains aren't proportionate to the costs involved. Rough cost of Cams can range upwards of 210+Vat (for a VTR) up to £1000s depending on model, make etc. Factor into this the cost of a remap and your looking at about £1000 to get the cams set up, timed and having the whole lot remapped to use the best power. * (following credit goes to WilliamsVTS) When choosing a cam you want to leave about 1.5mm valve to piston clearance, you never know what could happen. lift on standard cam is 8.49mm and has valve clearance of 3.01mm, so you can work it out from there (although this would need to be worked out from lift at TDC). if you were wanting cams with more lift you would either need your pistons rebated or some forged pistons. you would also need to consider throttle bodies as cams with that much lift would be being restricted by the standard inlet. So to simplify things - you can buy: Mild Cams - These aren't a huge amount different than standard, and once mapped will give nice smooth idle. Power gains Once mapped would probably see about 15 bhp on a VTS. An Example would be the Newmans PH1. Mild Fast Road/Track Cams - These are the ones that most people go for, and offer a good compromise of everyday useability with good power gains. Once mapped on a VTS would see probably pushing 20-25bhp. An Example would be the Newmans PH3 Full Race/Rally Spec Cam - Only realisticly usable in a track car, will give even better gains due to the wildness of the cam, but not recommended for use in a road car. An example would be the Newmans PH5. Last edited by -Dan-; 10th January 2011 at 12:35.