Hhkhw

Camshafts.

Off the mark, a camshaft change to something more suitable will give you more 'bang for your buck' compared to a cylinder head. Having said that, it will not give initially as much power with the standard head as a stage three head will with a standard cam.

There is a multitude of camshaft options available, and most of them will have been tried by some one, somewhere. The problem is, many of them will have been tried in combinations that really didn't suit them - be this the wrong combination of parts, or used for the wrong application. It's no good fitting a camshaft that doesn’t start working until 5,000rpm shows on the tacho when you spend almost all your time driving in traffic. Likewise, a mild road cam isn't the best option for a circuit racer. Unfortunately, too many folk get lead down the wrong path here, and end up with a completely unsuitable cam for their particular situation. No more so than where road use is concerned.

I've run the gambit on just about every size of Mini engine in almost every possible situation along with a huge variety of camshafts. One thing stands tall above all the others - I have nearly always gone back to a relatively mild profile for roadwork. Something that gives it's best between 1,500-5,500rpm almost irrespective of engine size. The reason being this is where you tend to spend most of your time when driving on the road. Needing to run much over this means you either have an unsuitable final drive ratio, or just use the engine for scaring the local community at the weekend.

Considering the engine size and the operating range, this really does cut down camshaft choice to something in the 'mild' as opposed to 'wild' area. In my book the 997 Cooper profile takes some beating and would be my first recommendation to anybody wanting a decent road-burner. Or did until a few months ago - but more of that in a moment. It gives the right spread of power without being fussy or peaky. And the gain is pretty impressive over the standard item in an otherwise completely standard engine. Not only that, but it will idle smoothly and quietly and give emissions passing CO and HC readings. Something many of the 'modern' breeds of camshafts simply can't do without much frigging and fudging. With this in mind it was my first choice for the test I recently carried out for Mini Magazine where the criteria given matched almost exactly the aforementioned points.

Unfortunately I'd already built and installed the engine before I got my hands on one of Swiftune Racing's SW5 cams. This is the one I really would have liked to test, as it is something new that has been giving unbelievable results in practically all engines it's been tried in. I'm not allowed to give out specific details, what I can say is it is a 'modern' version of the 997 Cooper cam - which goes to prove that the old profile was pretty good in the first place and hard to beat by later 'developments'.

Rocker Gear.

It's pretty widely known that high-lift rockers don't give good results on 998s. The standard rocker gear, however, is a little short on what's required. Despite being 'accepted' as giving 1.25:1 ratio, they don't. You'd be lucky if the pressed steel versions give 1.23:1, and wildly lucky if the later sintered type gave 1.22:1 (they generally only manage a paltry 1.21:1). The 998 needs around 0.340" valve lift to make good use of the head mods - but not much more. The 997 camshaft has a lobe lift of 0.263". To get the required lift means rockers with a real lift ratio of 1.3:1 are needed, so I used the MSC/MM 1.3 roller-tip versions for the SBU. These give the required lift within a few thou.

As a footnote to this section, using the SW5 camshaft means sticking to the standard rockers as it develops more lift at the lobe.

Power Gains.

So what do we get after all our deliberation and hard work? The tests were carried out on the same rolling road I use for all my testing now that I live in the 'northern wilds' - GRV at Littleborough, home of the British Vita Racing Cooper Ss run by Harry Ratcliffe and Geoff Goodliffe (the 'G' & 'R' in the title). The exception was the stage one kitted Mini with a stage three head fitted. This was done by a good friend of mine, Steve Harris (ex-Downton man and well known Mini engine builder). But this doesn't matter over-much as actual bhp readings are not what we're looking for, as they are meaningless considering standard power outputs vary so much. It's the percentage we're interested in for comparative purposes.

A good, low compression 998 gives 30bhp. A good stage one kit (mod1) boosts this to 36bhp. The 997 Cooper camshaft and standard head (mod2) gave 42bhp and the 997 Cooper camshaft/stage three head/1.3 roller-tip rockers combination (mod4) gave 48BHP. Using percentages is a more relevant way of comparing results from different sources, so converting the aforementioned we get the mod1 kitted motor giving 20% more, mod2 giving a 40% increase over standard, and mod4 giving a whopping 60% over standard! Add into this equation the 43% increase that Steve Harris got by adding a stage 3 head to the stage one kit (mod3) on a standard engine and we've a full house of results -

Percentage power increase with each step:

Stage one kit
+20%

Standard engine plus 997 Cooper cam
+40%

Stage one kit plus Stage 3 head
+43%

Stage one kit plus 997 Cooper cam, stage 3 head and 1.3 rockers
+60%

A 60% increase is mighty impressive - especially when you consider it still idles sweetly, gives very low CO and HC readings at idle without any MOT/vehicle testing 'fore-play', and actually gives more miles per gallon than standard! I largely suspect the Swiftune SW5 cam would give a few more bhp, but more importantly an increase in the over-all torque out-put - the most important factor for a street unit.

Zitat von dave the rave

Camshafts...........
......... unit.

Könntest den Text auch ins Deutsche übersetzen??

.... hört sich verdächtig nach KC an ....

Hallo!

Zitat von Zwerg_Nase

Hallo,
sagt mal,
nach dem ich das ganze Forum(glaub ich) durchsucht habe wollte ich mal wissen was eine HHKHW bringt und ob das auch bei einem 1000er was her macht? Warum ja und warum nein? Ich hoffe ihr könnt mir helfen.

Auf dem 1000er Motor bringt maximal eine1,3:1 HHKHW mehr Leistung - wenn der Rest(Kopf, Nockenwelle, Auspruff, Ansaugbrücke....) auch gemacht ist.
Eine 1,5:1 wie sie bei 1300er verwendet wird bringt nur Nachteile!

ALEX!!!