Uprated cam need uprated springs?

[PeteE30Tourer]

I'm considering buying a 282Ԛ°/272Ԛ° - BMW M20 - DBilas cam from a company on German ebay. My head will be coming off shortly anyway to be replaced and so i'd like to take the opportunity to improve things a little.

Anyway, the company are obviously trying to sell uprated springs too as they quote: "With this degree number strengthened valve springs necessarily if it to be continuous durable is" according to the Babelfish translator.

So, do i really need uprated springs? What would be the consequence of re-using my existing ones? Do springs really break?

The cam is 299 Euros and the springs are 150 Euros, which amounts to just over Ԛ£300 all in.

[Boots_Walker]

i'd be interested to hear some opinions on this too.

also do the springs deteriorate much over time? ie, would a fresh set of OE springs be a big improvement over a set with say 150k miles?

lastly, i was think that instead of purchasing expensive uprated spring kits it would be possible to use the outer spring from an earlier m20 head (eg, the 323i's rev 6k+ on a single spring) combined with the standard inner spring? surely this would get similar results for much less money

[PeteE30Tourer]

No other takers for this one?

Does Ԛ£300 sound a good deal for this cam plus the springs?

[E30Adam]

We put this very cam in Jim's car for his 2.7. It's quite lumpy at idle but sounds gorgeous. Definately fine for the street and I would recommend uprated springs although not entirely necessary.

[Karan]

do them...... u may as well while its open....just a thought

[PeteE30Tourer]

Thanks for the comments guys.

Adam, forgive my ignorance, but why would a cam make the engine sound different and in what way?

I just had a response from the company selling these in Germany stating:

"you need absolutly this springs. they have 105 kp. The original spring 85 kp"

That's nearly a 25% increase in "kp" - whatever that is!

I also asked DBilas by email too, but they haven't responded yet.

[M5pilot]

The cam changes the sound of the engine. Think about it, its allowing the engine to breath differently by drawing in more air.

Jim's car defo sounds excellent.

I think it was a very good cam indeed.

[Karan]

as i said before..... just doi them ...would be silly not to while shes apart

[Jos]

Thanks for the comments guys.

Adam, forgive my ignorance, but why would a cam make the engine sound different and in what way?

I just had a response from the company selling these in Germany stating:

"you need absolutly this springs. they have 105 kp. The original spring 85 kp"

That's nearly a 25% increase in "kp" - whatever that is!

I also asked DBilas by email too, but they haven't responded yet.

kp I assume is 'kilo pascals' It's a pressure measurement relating to the amount of force the spring can exert on the valve when fully compressed.

If the returning force isn't high enough the valves will not return to their closed position at the correct time, high lift cams normally need much stronger springs as the valves have to be able to close very quickly to match the profile on the lobe.

When they can't close fast enough you get what is called 'valve bounce' and it's not a good thing:)

[PeteE30Tourer]

Cheers Jos - just the sort of info i've been looking for!