Camshaft upgrades: what owners fitted on the NA and Turbo

This is what owners said about changing the cams. We have no dyno results of our own, and owners disagreed about how much a cam change gains, so read it as a map of the options and the pitfalls, not a recommendation. For the factory valve gear see Camshafts and sprockets (NA) and Camshafts, pulleys, oil seal and sensor (Turbo).

First, will it gain much?

• One owner said a cam change on an NA is changing volumetric efficiency at different rpm, usually gaining a few percent in one part of the curve and losing elsewhere. He said that forced induction gains far more for the money.
• Another owner asked in 2018 whether it was worth spending a lot on cams for little gain, when he already had reground cams with the same duration and lift as the new ones on offer.
• A 2009 Turbo owner was told by another that it was not worth the cost with a standard head, as the turbo is the biggest restriction and cams just trade torque for power.
• Standard cams are mild. One owner put the NA at about 244 degrees of duration.

Reading cam specs

• Duration is measured differently. Some makers quote it at 1 mm lift, others at 0.050 in, others at 0.1 mm, and the figures aren't comparable. Check the measuring point before comparing (an owner in 2018, repeated by another).
• The same duration and lift can behave differently. The shape of the lobe, and when the valve starts to open, change the result. One owner described a pointed lobe against a more oval one with the same numbers.
• What you want matters. An 8,000 rpm screamer, or low-down torque for the road, are different choices, and the cam makers' peak power rpm moves up with duration.
• Lift at TDC and the pistons. One owner said 1.2 mm of lift at TDC is nothing much and won't need piston work, while a lairy cam with about 4 mm would hit the pistons. He grouped cams by duration: up to around 295 to 300 degrees is sedate, above that lairy, and over 315 wild. That is his view.
• Check them. A 2009 owner warned that two sets of reprofiled cams with identical specs from the same maker gave 171 and 160 bhp on two engines, because the lift was different. He suggested measuring cams before fitting.

NA: the options owners mentioned

• Piper regrinds. Your own cams are reground, which is cheap, and took about six weeks in 2007. One owner said they are cheap and work well. Another found that in his early experiments the regrind profile wore severely within a year, and his power fell. Another owner described Piper as less aggressive than the others, with 260 degrees and 10.74 mm lift (0.423 in).
• Schrick. New cams, about double the price of regrinds in 2007, described as the most aggressive available and used by one race workshop on prepared heads. The question whether they need cylinder head work was asked and not answered. One road owner found a 2.4-litre manifold with them better than a Dbilas manifold, back to back. A quoted spec was intake 252 degrees at 12 mm lift and exhaust 248.
• Dbilas. One owner called them a stage 1 cam (2014). Specs quoted in 2007 were 264 degrees and 10.8 mm lift.
• CatCams. A broad range was listed in 2007. One owner said their 259/259 degree cam with 10.75 mm lift and 1.2 mm at TDC was the one for NA road and track. They are a European race supplier with a good record, according to another.
• Comp Cams stage 2 or 3. In 2014 one owner said these are fine, and he had run stage 3 for years with throttle bodies. He also said stage 3 needs uprated valve springs and retainers, and stage 2 suits 7,800 rpm.
• Kent. In 2003 an owner posted the seller's figures for a 2.2 Ecotec sports injection cam (256 degrees, 10.16 mm lift) with a quoted gain of 12 hp. Nobody reported trying it. Another Kent cam at 314 degrees was for the older belt-driven engine, not the Z22SE.
• Some owners listed about a dozen suppliers across Europe in 2007. Several of the links are old, so check the company still trades.

ZZP and Comp cams (2018)

• An NA owner on throttle bodies compared a Comp Cams stage 2 set (part 113300, as he read it) bought direct with a ZZP stage 2 set. The ZZP cams have a machined slot for the Z22SE pulleys.
• ZZP's stage 2 cams are supercharger cams for the Saab head, with two long cams (one for the exhaust cam sensor), whereas a standard Comp set has one short exhaust cam, according to one owner. The Comp blower cams are different again. Figures quoted: ZZP intake 251 degrees and 0.423 in, exhaust 256 and 0.419 in; Comp blower intake 252 and 0.423 in, exhaust 262 and 0.436 in.
• For throttle bodies, one owner said Comp stage 2 or 3 or CatCams are best, and the blower cams are a stage 1 and stage 2 that would work okay. The ZZP cams can be cut down to a short exhaust cam, as the factory did.

Timing them

• One owner said Comp cams' timing is notoriously off with the standard slotted sprockets, so ZZP checks the timing and writes the measured figures on the box. Another owner ran ZZP stage 2 on standard sprockets in a 2.0 LSJ and said it ran pretty well.
• With Saab keyless sprockets you can time them exactly. Two owners used them. Setting up with dial calipers takes time.

Other notes

• Another owner found that removing the balancer shafts made the idle smoother on a 2.2, and that standard cams are very mild. A US problem with the knock sensor on wild cams was also mentioned.
• A 2014 owner said that for the road he would keep the 2.4-litre manifold rather than throttle bodies, which give more power and torque to around 5,000 rpm, and that a Dbilas manifold gave a low-rpm torque peak, which suggests narrow runners. That is one owner's comparison from different dyno runs.
• Changing the head. An owner fitting a new head in 2007 was told he needs: cams, roller followers, hydraulic lifters, valve springs, collets, oil seals, retainers and valves. The cams could be reground or Comp, with new oil seals. He said some of the other parts are expensive new.
• For the timing chain on the NA see NA timing chain.

NA valves, guides and head work

• What to expect. In a 2005 thread owners said nobody had passed 175 to 180 bhp, and a stage 2 got 165 to 170 bhp at most. A tuner said throttle bodies, then in development, should reach 210 to 230 bhp. In 2014 one owner reported 197 hp and 225 Nm from a Dbilas inlet manifold, 65 mm throttle body and Dbilas cam package, while another who tried a similar mix with the Piper cams struggled to reach 180. Those are single-car figures.
• The standard valves. Owners disagreed. A 2005 workshop said the stock valves are pretty good and replacing them on their own is a little pointless unless the head is gas flowed. Another owner said the standard valves are mass-produced and shaped for cheapness, while performance valves have undercut stems and are swirl polished, so even the same size flows more. One owner described the inlet port as designed for tumble at low revs at the expense of flow at high revs.
• Oversize valves. In 2013 one owner recommended +0.5 mm valves from GM Racing, or +1 mm from SI Valves. A +0.5 mm valve just fits the standard seats. +1 mm is the maximum for this head, as it opens the seat insert up fully, and the machinist must open the valve throat too. Another owner said use a proper seat cutter with a single-point cutter, not a grinder, and that this is machine shop work, not something to do yourself. One owner's +1 mm valves did well over 20,000 miles on three cars. Another said he wasn't sure whether his were from a batch that had failed on someone else's car. The thread doesn't say which. For supercharged cars an owner said the standard Saab valves are best.
• Valve guides. In 2006 an owner passed on what he said was a Lotus engine development director's view: the guides are an interference fit with very little natural wear, so measure and inspect them, and only replace if absolutely necessary, because removal can do more damage than good.
• A tapping noise that doesn't go away (2012). A rebuilt NA developed a tap after 6,000 miles. The owner replaced the hydraulic followers, then the chains and tensioners, and the tap stayed. When he finally looked at the valve springs he found one inlet valve sitting low, and the recess where the collets sit on the valve stem was wearing away so that the collets were sliding up the valve. Another owner thought the valve wasn't heat treated correctly or the collets had worn, and that the valve floated, making it worse. A new valve and collets fixed it. Another owner listed other possibilities: a split collet, a foreign object under a cam lobe, very high oil pressure in the lifters, or a misaligned follower. Look at the valve springs and collets if followers and chains don't cure a tap.

Turbo: what one owner did (2009)

• Standard cams. The owner quoted duration 251 intake and 250 exhaust with 8.5 mm lift, and about 27 degrees of overlap. He could only find C20LET details, and said the Z20LET and Z20LEH cams are the same.
• The cams he fitted. Piper reprofiled his own cams. The sheet that came with them said inlet 16/56, outlet 56/16, 252 degrees, 9.45 mm lift at 110 degrees, 0.80 mm at TDC and 32 degrees of overlap. That is symmetrical, whereas Piper's listing for the Astra VXR shows 252 intake and 240 exhaust with 9.58 mm lift and 26 degrees of overlap, so the sheet may contain a typo. He fitted them with a cam belt kit.
• How they felt. The idle was a little cammy, the needle fluttered and the rear lights throbbed, so he said the idle needed setting a little higher. The tappets are audible, and the car rattles more. It was crisper in the mid range and zipped through 3,500 to 5,000 rpm, with the boost tailing off above 5,000 as before, and a more mechanical growl at 5,000. He planned a rolling road session and a remap for idle and fuelling, and posted no figures.
• Mild cams. One owner said turbo engines tend to use very mild cams because of valve overlap problems (2007).
• Why less overlap? The owners explained that the standard turbine is restrictive, so exhaust back pressure is high, and with a lot of overlap exhaust gas is pushed back into the cylinder (reversion) at higher boost. A German tuner was said to sell sport cams for the older C20LET for that reason. One owner suggested a shorter exhaust duration, such as Piper's 240 degree cam. Another said retarding the inlet cam by half a tooth gave better results on the C20LET. These are theories, and one of the owners later said he no longer agreed with some of his own earlier comments.
• Adjusting the timing. You can only fit a vernier on the inlet, because the sensor trigger is part of the exhaust pulley. One owner said later C20LET pulleys look the same but don't fit, as the offset is too much. Another said Ford pulleys have no locating pins, so you can slot the holes and tighten up once set.
• Limits. More duration means a custom cam from blanks rather than a regrind, and the standard hydraulic tappets will only accept so much. A high-boost owner said he wanted the most lift that is safe, and that wild cams work best with a bigger turbine, because with a big turbo the engine behaves more like an NA.

See also Turbo cam belt change and Turbo stage 1 and 2: what owners did.