Tuning tips: Fast road cams (Sports camshafts)

obi_waynne

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What is the camshaft, what does it do and how can it be modified. The camshaft is located at the top of an engine. Is is a long shaft with a series of lobes along it and it rotates relative to engine speed. The lobes push close the valves in the head and allow the [...]
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What do you think of this tip then, read the article and post your comments in here.
 
Article is VERY basic and of no use to anyone wishing to repace a cam and of little use to those looking to upgrade. Much better to actually talk to a cam manufacturer/specialist supplier.

Cams are also buried in the engine of older OHV types and most American V8s.

IMO the worst article I have read in this series :-(
 
Yup, time for a rewrite then.

What topics would you want to see it covering then og? How to replace a cam? Choosing durations?
 
I think so, this is a very complex subject, much like tyre design and technology. It's not really possible to cover it in a short article such as this.
 
I'd like to offer more than a "this is what a camshaft is children" approach. I'm sure we can cover it in a bit more depth without overcomplicating the issue.
 
Possibly. But it's important not to over simplify this either. When we consider variable cam timing which is pretty common now then yet another set of variables appears in the mix.
 
This is very true. My long term aim with TC and all the other sites is to offer an in depth set of articles that cover every aspect in a number of different technical depths from beginner to DIY tuner to professional motorsport setup.

I know a lot more now than I did when I started out and sometimes cringe at some of the earlier articles I wrote.

I am still very conscious of the fact that there is a lot I don't know as well. "The more you know the more you realise you don't know!".
 
hmmm i think fast cams are over rated, they dont give lots of power increase as they say without more modifications to go with them to give there true potential so that means more money and they are bloody expensive as it is, plus dont they give you a rough idle? that would do my head in always feeling like a miss fire
 
hmmm i think fast cams are over rated, they dont give lots of power increase as they say without more modifications to go with them to give there true potential so that means more money and they are bloody expensive as it is, plus dont they give you a rough idle? that would do my head in always feeling like a miss fire

Agreed - 'Fast' cams are pointless in cars for road use. Not only is the idle rough and lumpy, the general running and torque delivery below about 4000 ish rpm is spineless.

It's one of the worst ways by which to tune a road car.
 
Agreed - 'Fast' cams are pointless in cars for road use. Not only is the idle rough and lumpy, the general running and torque delivery below about 4000 ish rpm is spineless.

It's one of the worst ways by which to tune a road car.

AT LAST, something to argue about! :)

I was running Newman L1 racing cams in my Elan way back when. 168bhp at the wheels and 9000rpm limit. Cams came in around 4000 and just kept giving.

As the engine was set up well and the cams were timed properly using offset dowels (no vernier pulleys for twin cams back then) the car wasn't lumpy on tickover and was docile when pootling around. Only problem was as I was using cold plugs they tended to foul up unless they got a regular thrash (honest officer, I was just cleaning the plugs).

However, I was young and happy to accept that the car wasn't as smooth as standard
 
AT LAST, something to argue about! :)

I was running Newman L1 racing cams in my Elan way back when. 168bhp at the wheels and 9000rpm limit. Cams came in around 4000 and just kept giving.

As the engine was set up well and the cams were timed properly using offset dowels (no vernier pulleys for twin cams back then) the car wasn't lumpy on tickover and was docile when pootling around. Only problem was as I was using cold plugs they tended to foul up unless they got a regular thrash (honest officer, I was just cleaning the plugs).

However, I was young and happy to accept that the car wasn't as smooth as standard

yes but you are talking about a lotus elan that was had a lot of tuning to it anyway, for a day to day car or on a boy races saxo corsa etc, they arenty going to do much, they need other mods to go with them and are pointless without the proper set or if your just using the car for a daily driver without taking to the track, on there own uprated cams are useless
 
yes but you are talking about a lotus elan that was had a lot of tuning to it anyway, for a day to day car or on a boy races saxo corsa etc, they arenty going to do much, they need other mods to go with them and are pointless without the proper set or if your just using the car for a daily driver without taking to the track, on there own uprated cams are useless

Oh, agree. But no single mod works properly in isolation. As so say, simply fitting a high lift cam into a standard car (assuming the valves still miss the pistons) is useless and will probably result in a reduction in perfomance, although to the novice the rough idling and spikey power band may feel faster :)
 
I do think cams are the most misunderstood mod around. It is possible to ruin a car if you get it wrong.

Worst ever combination I've found is a super light flywheel and 280 degree cam!

So what is more important Lift or Duration?
 
:lol: I was hoping someone would have a go at that one!

Trust me, if I had the answer I would supply it directly. The answer is both, or neither. Factors such as valve acceleration, spring rates, bounce, harmonic resonance all come into this. These are all limiting factors and were they not present then we could go further with the performance benefits of high lift and long duration cams. Sharp lift profiles will exacerbate cam and follower wear, and can also batter the valve seats and stems themselves.

It really is a very involved subject. Turbocharged cars, for example, will have different requirements to NASP ones. High levels of overlap will generally increase top end power, but at the expense of low end flexibility and economy. But shorter overlaps can allow for a fine degree of internal EGR control, especially when combined with variable valve timing.

And so on, ad nauseum et infinitum.
 

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