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Unit 5302 · 05-23-2002, 11:47 PM

The Comp Cam's XE series isn't a cam line that I like. Lot's of people seem to really like them, though. the Xtreme Energy series attempts to compensate for poor duration with valve lift. The LSA on the cams is high which allows for good low end power, but the short duration and wide LSA isn't going to be as good for higher rpms as a similar lift cam, or somewhat reduced lift cam. Due to their high lift height I don't see how the cam could be all that efficient.

The Ford alphabet cams do not attempt to favor the exhaust side of the head. 75-80% of intake flow is what you'll want the exhaust to flow. The stock E7TE heads look terrible by just peeking at the flow number. 115cfm exhaust or so. 155cfm intake, but when you do the math, they are right about where they should be in relation. You don't need the exhaust to flow as good as the intake because you have a piston forcing the air out of the cylinder under pressure. The GT-40Y heads definately need some help. Their exhaust flow numbers are terrible. If your heads flow worse than 75% exhaust compared to intake N/A, a cam that favors the exhaust is a better investment. If you're forced induction, you want it about 80%.

Cam manufacturers know what works, but they also have to cater to people who think they know what should work. I could say why doesn't anybody else make anything like the XE series? Camshafts have traditionally been more duration oriented than they are now. The B303 cam is an excellent example. It's poor in LSA, makes poor low end power, has little lift for an aftermarket cam, but it has a solid amount of duration, and quite a bit of overlap. Really the cam needs more lift to put down real power. People often go the route of 1.7's on the B303 to get some good lift numbers. The B303 was the first of the hydraulic roller SVO cams. So what is better? It soooo depends on exactly what you want to do with the car. That's where people like AFM can come into the picture. They know cams, and they should be able to pick out something that meets what you want the car to do.

The F303 cam you are running is respected in the world of forced induction because that's what it was built for. It's a good off the shelf supercharger cam. It looks somewhat similar to a B303 on 1.7's at first, until you look at the LSA. The F cam has a much wider LSA than the B cam. LSA is very important to a blower cam. Too much overlap and you allow the boost to go right out the exhaust. For a N/A car, the F303 has a spotty reputation. Again, here's where the LSA comes into play. With the right setup, some people like their F cam, but most do not.

Here's kind of a template.

High lift, long duration, narrow LSA. Race cam. It's gonna be peaky, lack low end power, make crappy vacuum, but when it's gets some rpms, you're gonna fly.

High lift, medium duration, medium LSA. High performance borderline streetable cam. The LSA will trade higher rpm race cam power for drivability and vacuum allowing you to keep power brakes and what not.

High lift, short duration, wide LSA. Street/strip cam. XE series cams fit in here for the most part. Good low end power, solid midrange, lacking a little higher up, but most cars don't run that high anyway.

Medium lift, long duration, narrow LSA. Best used at the track, definately not going to pass emissions. Low end power stinks, midrange is probably okay, higher rpms really wake up. Probably not the best EFI choice.

Medium lift, medium duration, medium LSA. Street/Strip cam. Pretty traditional in the setup. F cam probably fits in the weaker section here.

Medium lift, short duration, wide LSA. Entry level XE series? Good street cam. Better power than stock, good low end power, and the extra lift keeps the car more alive at higher stock EFI engine speeds.

Low lift, long duration, narrow LSA. Turd cam. Not enough lift to flow good, and it sacrifices sreetability too.

Low lift, medium duration, medium LSA. Emissions cam. The B303 falls inbetween the above category and this one. Low end not too great, but the cam makes up for it if you have gears and some aftermarket parts, maybe ported heads. Old school thinking.

Low lift, short duration, wide LSA. Stock cam type of performance.

To give a very rough estimate of what I'm talking about

High lift. .530+
Medium lift .500-.530
Low lift. .444-.500

Long duration. 228*+
Medium duration. 220*-228*
Short duration 216*-220*

Narrow LSA < 109*
Medium LSA 109*-112*
Wide LSA 112*-116*

Obviously there are tons of combos that don't exactly fit the parameters, but you can think of it as a little bit of a general picture.

05-23-2002, 11:47 PM	#4
Unit 5302 Registered Member Join Date: May 1999 Posts: 5,246	The Comp Cam's XE series isn't a cam line that I like. Lot's of people seem to really like them, though. the Xtreme Energy series attempts to compensate for poor duration with valve lift. The LSA on the cams is high which allows for good low end power, but the short duration and wide LSA isn't going to be as good for higher rpms as a similar lift cam, or somewhat reduced lift cam. Due to their high lift height I don't see how the cam could be all that efficient. The Ford alphabet cams do not attempt to favor the exhaust side of the head. 75-80% of intake flow is what you'll want the exhaust to flow. The stock E7TE heads look terrible by just peeking at the flow number. 115cfm exhaust or so. 155cfm intake, but when you do the math, they are right about where they should be in relation. You don't need the exhaust to flow as good as the intake because you have a piston forcing the air out of the cylinder under pressure. The GT-40Y heads definately need some help. Their exhaust flow numbers are terrible. If your heads flow worse than 75% exhaust compared to intake N/A, a cam that favors the exhaust is a better investment. If you're forced induction, you want it about 80%. Cam manufacturers know what works, but they also have to cater to people who think they know what should work. I could say why doesn't anybody else make anything like the XE series? Camshafts have traditionally been more duration oriented than they are now. The B303 cam is an excellent example. It's poor in LSA, makes poor low end power, has little lift for an aftermarket cam, but it has a solid amount of duration, and quite a bit of overlap. Really the cam needs more lift to put down real power. People often go the route of 1.7's on the B303 to get some good lift numbers. The B303 was the first of the hydraulic roller SVO cams. So what is better? It soooo depends on exactly what you want to do with the car. That's where people like AFM can come into the picture. They know cams, and they should be able to pick out something that meets what you want the car to do. The F303 cam you are running is respected in the world of forced induction because that's what it was built for. It's a good off the shelf supercharger cam. It looks somewhat similar to a B303 on 1.7's at first, until you look at the LSA. The F cam has a much wider LSA than the B cam. LSA is very important to a blower cam. Too much overlap and you allow the boost to go right out the exhaust. For a N/A car, the F303 has a spotty reputation. Again, here's where the LSA comes into play. With the right setup, some people like their F cam, but most do not. Here's kind of a template. High lift, long duration, narrow LSA. Race cam. It's gonna be peaky, lack low end power, make crappy vacuum, but when it's gets some rpms, you're gonna fly. High lift, medium duration, medium LSA. High performance borderline streetable cam. The LSA will trade higher rpm race cam power for drivability and vacuum allowing you to keep power brakes and what not. High lift, short duration, wide LSA. Street/strip cam. XE series cams fit in here for the most part. Good low end power, solid midrange, lacking a little higher up, but most cars don't run that high anyway. Medium lift, long duration, narrow LSA. Best used at the track, definately not going to pass emissions. Low end power stinks, midrange is probably okay, higher rpms really wake up. Probably not the best EFI choice. Medium lift, medium duration, medium LSA. Street/Strip cam. Pretty traditional in the setup. F cam probably fits in the weaker section here. Medium lift, short duration, wide LSA. Entry level XE series? Good street cam. Better power than stock, good low end power, and the extra lift keeps the car more alive at higher stock EFI engine speeds. Low lift, long duration, narrow LSA. Turd cam. Not enough lift to flow good, and it sacrifices sreetability too. Low lift, medium duration, medium LSA. Emissions cam. The B303 falls inbetween the above category and this one. Low end not too great, but the cam makes up for it if you have gears and some aftermarket parts, maybe ported heads. Old school thinking. Low lift, short duration, wide LSA. Stock cam type of performance. To give a very rough estimate of what I'm talking about High lift. .530+ Medium lift .500-.530 Low lift. .444-.500 Long duration. 228+ Medium duration. 220-228* Short duration 216-220 Narrow LSA < 109* Medium LSA 109-112 Wide LSA 112-116 Obviously there are tons of combos that don't exactly fit the parameters, but you can think of it as a little bit of a general picture.