Performance Cams

[mardi j]

I'm thinking of upgrading my Cams. I've been looking at the K-Tec performance Cams and the Schrick Billet Camshafts off Yozzasport. Has anyone got these and can you tell me why the Shrick cams are £200 more expensive? They both claim to retain good idle etc. but do you know of any issues regarding these?

Cheers

 

[shiftspark]

Have a search of george k 's posts he seems to have the most experience of engine mods and knows what he's talking about!

 

[hoolio]

I think only a couple of people on here have gone down that route and not really got the results they were expecting, basically they are a lot of money to fit with almost no gain. i know ASIM was less than impressed. I think to get much they would have to be so aggressive as to make the car virtually undriveable day to day.

Don't believe the hype

 

[George K]

The problem is that the type of AFM used by the Trophy and many other modern cars can not handle much overlap without the idle becoming unstable, and the algorithms in the stabilisation routine try to shut the engine down rather than speed it up. There are ways around this, but they are all expensive. Angleworks tried to compensate by only making marginal changes to the duration/overlap, but by increasing lift - this did not seem to produce much gain in the 182 - may be with head work and possibly a revised inlet manifold it might - but all getting costly and experimental. I intend to have a good look at the 197 installaion over the next few days, as I would guess that is why it went ot a different set up for the inlet cam advance and a shorter/fatter inlet manifold.

 

[mardi j]

cheers guys

After reading your advice I think I'll skip them and spend my money elsewhere

 

[shiftspark]

The problem is that the type of AFM used by the Trophy and many other modern cars can not handle much overlap without the idle becoming unstable, and the algorithms in the stabilisation routine try to shut the engine down rather than speed it up. There are ways around this, but they are all expensive. Angleworks tried to compensate by only making marginal changes to the duration/overlap, but by increasing lift - this did not seem to produce much gain in the 182 - may be with head work and possibly a revised inlet manifold it might - but all getting costly and experimental. I intend to have a good look at the 197 installaion over the next few days, as I would guess that is why it went ot a different set up for the inlet cam advance and a shorter/fatter inlet manifold.

Told you he new what he was talking about

Hows the Honda coming along?

 

[George K]

It arrived on concrete tyres - for some reason despite the low mileage and being a reputable tyre (RE040) they had gone rock hard and gripless - recent tests of 215/45x17 have shown Goodyear F1As and Hankook K110 well ahead of everything else including PE2, the Goodyear is not offically available in this size in the UK until the previous F1 GSDS3 runs out and the Hankooks were on a boat somewhere - they have arrived at last, so am doing some geometry tweaks and after a few miles bedding in will be ready for the next Wiscombe. In the meantime I have done two events on the old tyres, slightly better than I expected, albeit harder to drive and the diff requires a more aggressive style than is my norm, also the back comes out quite easily, which is not ideal between walls or trees - am looking at different springs/dampers (finding anything softer than standard is not in the Japaense after market vocabulary!!).

 

[Cue]

George - iirc Ben at angleworks earns his corn mainly in the Japanese market. He's contacts all over the place. Maybe worth a quick call....

 

[George K]

Cue - You are quite right, I did have a conversation with Ben a while ago - I should follow it up.

On a more general note, whilst mowing (4 boring hours, but good thinking time) it occured to me that the best way to describe the problem with 'performance' cams. i.e those with more overlap is that the older ones amongst us may recall the difficulty in getting a Mini to idle on a full race cam at much under 1,200 rpm. What was really interesting is that it was even more dificult on SU's and often it was possible to see the dashpot pistons fluttering up and down as they struggled to cope with the reverse pressure pulses - with modern emission requirements it is almost impossible to get stability without Vtec or more variable cam timing than the Triophy has. There are many other stories, such as on downdraft 48 IDAs there was often a mist of fuel mixture above the inlet trumpets, the modern equivalent is that some race engines actually run a deflector plate above the trumpet or even inject away from the engine.

I suppose the nub of the matter is that for competition it is very attractive to run pre 1992 cars in the production class as their MOT emissions test is so much more relaxed, let alone they are generally much lighter.

 

[shiftspark]

older ones amongst us may recall the difficulty in getting a Mini to idle on a full race cam at much under 1,200 rpm. What was really interesting is that it was even more dificult on SU's and often it was possible to see the dashpot pistons fluttering up and down as they struggled to cope with the reverse pressure pulses

Ah happy days driving around with the smell of petrol in the nostrils and the then girlfriends wondering when it would set on fire!! :lol: