Anyone out there tried replacing their cams in the quest for a little more power? Happened to notice that Piper offer cams for various types of vehicle and a quick phone call confirmed that they can do something for the Mx5 / Roadster. Piper don't make a specific cam for the 5, instead they re-profile the ones you have. Costs about 170 for a 2 week turnaround. When your car will be very much off the road, that is unless you have a spare set of cams about. I've no idea what this does for power / drivability, nor did the guy at Piper for that matter. So that's the reason for this e-mail has anyone got any info on cams that raise hp (say about 10 hp would be nice), don't break the bank, keep the car driveable, etc? (2/01)

I'd be more tempted by someone who could do the removal/reprofile and refit over a day or two rather than live without my car for 2 weeks. Price is cheap enough though as a set of cams would cost somewhat more than that. You could also specify what you hoping for then too.

I had some shipped from Japan for a swift Gti years back at over 500. Gave lots of power top end and made it crap low end. Very differnt car though as engine is 1.3 twin cam rev limit at 9,000.

Biggest issue is what to do if you don't like it as you've no originals to fall back on. (2/01)
Regrinding cams is fine - - - but - - - - it can stick an extra up to 2mm of valve clearance which your HLAs will have to take up. Maybe they can do this OK, I'm skeptical. With a "new" cam you would need new followers (HLA or solid(ugh-need to adjust shims every 5000miles)) anyway. Performance cams move the same amount of torque further up in revs to give more power, meaning you generally have less power in the rev band you usually use.... (2/01)

My experience only relates to an old Elan twin cam and BDA engines and following is all relative to degree of reprofiling: I would GUESS that it would work OK. You will get a real advantage as the engine revs so high. Low down you will lose something and the car will not pull as smoothly from 1800 to 3000. At the extremes you turn a smooth motor into a raving little firebreather which is a sod in town and to which you feel compelled to attach twin Webers, remove the cat etc etc. Therefore ask for a compromise profile and limit respiratory ambitions to air intake and filter mods. ECU mapping might be an issue.

I personally would be inclined to make absolutely sure I had a spare set of of cams before even thinking about it. (2/01)
To get the full benefit you would need to have the head worked as well. (2/01)
HLA would probably not take the extra clearance up .. so end up with nice lightweight solid lifters .. that would cost several times more than the cams. The Mk2 has solid lifters .. these don't need tweaking every 5k miles Bob .. I would say more like 60k miles and are very stable with no morning taps (reason why they are on Mk2s). The only trouble is that Mk2 lifters are heavy :-( HKS do cams for 1.6.... As for ECU .. off WOT (wide open throttle) the lambda sensor would do it's stuff .. on WOT should not be a problem as the power is related to air flow .. so you would just move more air and get the resultant of more fuel. (2/01)
You are missing head work .. 3 angle valves are reputed to be worth 8-10% with a quick gasket match .. or maybe 15% with a full gas flow .. first one is maybe 150 GBP .. second is 300 GBP more but there is a catch .. the head gasket bits will cost 150 GBP or so. So I would go look at this after CAI, exhaust and free spark plugs! .. it should be possible to get to 160 bhp/1.6l engine .. just takes some effort! The alternative is to love the power in the corners and get some funny gas for the overtaking (NO2)... (2/01)
Begining to wonder if there's all that much power left to be extracted out of the stock 1.6 all that easilly without getting a blower, which I'm not tempted to do. Of the ready to buy and known to work products, say exhaust, CAI, 14 degrees BTDC, maybe a ECU Interceptor then you get about another 15hp, a bit more when on the move as the CAI comes in. Not bad, say that puts you in the 130bhp at the flywheel terretory at a cost of a couple of grand, Getting any more power, i.e., skimming the head, valve job, cams and all the other good NA things is going to cost big time extra cash if it all works. Malcolm you are probably sitting there smugly thinking why's this guy making it difficult for himself? I don't know either, but as I say I don't like turbos for some reason. Anyway off to try and find some stuff about those HKS cams.(2/01)
I guess time marches on - I had a twin cam alpha with valve clearance shims and I was ALWAYS adjusting those buggers. I had the cams reground by kent & soon couldn't get shims thick enough! they had ground 2mm off the back of the cam without restoring full lift. Mind you - what a difference with full valve lift back! (2/01)
Two grand for 15 bhp! - I can see why you don't like turbo cars - 40 bhp for one grand ! or 140 bhp for 3 grand if you send your money to FM. If you really want to stay NA then get a link and have it all running right - people were quoting me 20bhp is possible with one on a NA car, and it will come in handy when you eventually decide on a turbo as well. (2/01)
..not thought about supercharging then! You could also fit a fuel pressure regulator (to boost the fuel pressure in the fuel rail) - I've got one here if you are interested. If that's not enough, you could go for a higher pressure fuel pump - as above. (2/01)
Changing the rate of rising fuel pressure on fuel pressure regulator .. some have tried and liked it.. (2/01)
Is this the product sold as a Power Boost Valve? If so as I recall they do one specifically for the MkI MX5. Although to refer back to the orignal query it is probably for the common NA engined cars. That said they do universal ones too. I never really got my head round what these did (apart from use more fuel. Any explanation would be gratefully received. (2/01)

Yes .. when you put your foot down to accelerate you distroy the vacum in the inlet manifold .. this pressure in the inlet manifold is used as a reference by the fuel pressure regulator .. so if you have your foot on the accelerator you have no vacum (equals atmospheric pressure, or regular air pressure) .. and hence more fuel pressure. At idle or low throttle openings you have plenty of vacuum and so lower fuel pressure. The fuel pressure is relevant bacause the fuel injectors are basically a hole that can be opened electronically .. more pressure with same sized hole in your bucket = more fuel. The power booster valves changes the rate at which the pressure increases so effectively giving you more fuel at maximum acceleration (foot hard on accelerator) .. this may or may not work .. if Mazda have done their home work right it should not as you are just pouring fuel in with no extra air ... and rich does not mean more power .. but a little bit richer air/fuel mixture can give more power .. and some manufacturers give up this power for emmissions/economy .. so it works.

So .. in summary .. it gives you more fuel at WOT .. which you may or may not need (but you can now adjust for added playing..) .. and at least one person had a positive review by measured results.. (2/01)