which engine model

[corradophil 3]

There two cams, inlet and exhaust which control when the valves open, the exhaust is the same on the KR and 9A, but the 9A has a "milder" cam with less lift and duration, so the valves open less and for less time thus less fuel/air mixture gets in. Swap the 9A inlet cam for a KR inlet cam you get more air/fuel and a little extra power at higher revs. The 50mm inlet manifold is larger diameter than std on a 9A, therefore you can flow more air thorugh it, but in practice it has been shown that the original is better.

 

So fit a KR inlet camshaft if you want more power at high revs, plus ability to rev it a little harder, but keep the original inlet manifold.

 

Think of your engine as a pump, the more air you pump through it the more power it makes, thats a very simple way of explaining the effects you try to achieve from all these mods.

[saysomestuff 0]

I think it's fair to say, that for noticable everyday driving performance increase, the head/manifolds need porting/polishing. This liberates a lot in terms of torque as well, which I would say is more important than bhp for me. Look at Phil's sig, that'll do me nicely thanks :)

[Kevin Bacon 5]

The best mod for daily driving is 2 KR (or 9A, they're the same) exhaust cams. The exhaust cam has 0.5mm more lift than the KR inlet and 1mm more than 9A inlet.

 

The second exhaust cam needs the woodruff key slot remachining to a new position to adjust the cam timing for use as an inlet.

 

On one of my 1800 Golf valvers, I had this mod and K star, vernier a cam wheel, 42mm inlet, WUR mod etc. Running on 95 UL and with standard zorts and filter, it made 154bhp with 140 odd pounds....and it had 125K on the clock!

 

The WUR mod basically entails removing the warm up regulator, drilling a 6mm hole through the brass tamper proof cover on the back of it, and adjusting the revealed screw to lower the base pressure, which enrichens the fuelling across the whole rev range.

 

The precise details of both the exhaust cam modification and the WUR mod are something Stealth can advise on.

 

With all that done and the base CO set to 2.0%, it makes for a really nice engine and flattens the torque curve off, making it nicer to drive below 4000rpm, but it's still got that valver kick at 4500rpm, only harder :-)

[saysomestuff 0]

good advice Kev, spot on.

 

here's ianb's 9A with 202bhp