Sifting through the bay, like you do, and I came upon this.
I like to look at different ways to achieve that 150bhp target without the usual FI route. What do people think. Is this feasible? 35bhp just from a set of Piper cams?
I would want to see dyno sheet before buying
Paul H on here that achieved (almost) 150 BHP from a simple port-polish with the aid of Tim at TR Lane.
The piper cams seem very popular with the Ma5da racing boys, to the point that Piper sponsored the Mk 3 Cup!!!
Cleaning up the head, playing with the timing with a decent set of vernier pulleys and a set of cams must all add up to some reasonable performance increases?
Hopefully Taff will be along shortly, IIRC he has a set of piper’s in his little beast…
Were before and after figures measured? My 140k miler 1.6 was measured at 125hp, with nothing done to the head, but frankly, I suspect that was a bit optimistic. I have no idea what that car was on when I brought it.
Many years ago, when I was AC in Northern Ireland, I had a fair few chats with an unusually enthusiastic Mazda salesman; he hillclimbed single seaters. He was trying to put together a deal for his local Mazda dealership to supply Kent cams for MX5s, on an exchange basis; the story went that Kent had taken on some people from Holbay, who had done something in 1990-91 with Mazda Car Imports, and had some hotter cams (so the Kent cams offered were effectively Holbay profiles. The number quoted was going to be about £250 for a pair of cams. It all sort of foundered when he couldn’t sort anything out for the ECU, and Verniers were a bit on the rare side, plus the dealership calling in the Receivers at Christmas 2001 didn’t help.
Mazda’s skunkworks allegedly put together a Cali-legal 1991 Miata with 150hp NA; changing exhaust, intake, exhaust cam, ditching the AFM in favour of a hotwire MAS from a Mazda MPV, and a hugely expensive custom ECU. I always thought to get 150hp, and keep the car driveable/streetable, NA, took a lot of modifications, that needed to be cohesive, and well thought out, and inevitably expensive.
Grassroots Motorsports are the only mob that I know of who have systematically upgraded a Miata (a 1.6) and measured each change; the changes were basically the Jackson Racing catalogue, plus a head rebuild.
Some info here:
http://grassrootsmotorsports.com/project-cars/1992-mazda-miata/updates/
In the print articles though, there was a lot more information, especially about the headwork undertaken. I don’t know if you go to the Web Archive, you can find older, more detailed writeups (rather than the blog-style articles they now use). GRM have had a few Miatas over the years, so make sure you find the right car, if looking.
Essentially, intake, exhaust mods, timing mods, cylinder head overhaul, verniers, added up to 20hp on their car. I add the emphasis, because its pretty clear from all the group dyno sessions over the years, that MX5 engines are pretty variable out of the box; some cars just feel a lot stronger than others, even though nothing has been done to them. But 35hp I don’t think is really possible just from cams; the standard ones are pretty hot. The M2-1001 was rated at 130hp, with bigger valves, hotter cams, raised compression (raised to the extent that the M2 engine is no longer a non-interference design) probably ECU mods, exhaust/intake changes, hence my skepticism at the results I got at Chesterfield.
The exintake cam mod is popular, because it appeals to the sort of person who just doesn’t want to buy a Greddy kit, and save the bother. All good fun.
You rang? If I remember, Paul H also had the exhintake mod (1.8 only) done at Tim Lanes and got very strong figures.
I have just done a head for a chap which also had ( they said it couldnt be done…so I did it) a 50 thou skim and the exhintake mod with vernier cam adjustment we have had a before and after dyno run but ran out of time to advance the exhaust cam a tooth to where it needs to be as we ran out of vernier slot and with each advance we were continually gaining power.
We are back to the dyno on 6th March for a bit more tweaking and will reveal the final horse-power gains then, but…just to get you as excited as us we have a very linear across all rev ranges torque increase of a full 10% from our original dyno run already, the power was still climbing very heathily as it reached the rev limiter, to get the best out of this mod we want to find some clever electrical chap to re-do the crystal in the ECU to allow a further 500rpm, ie. 7750rpm max.
It is also very likely the car will have a custom-made Powerflow (Caerphilly) exhaust system and 4-2-1 manifold and no catalyst by the time of the next run on dyno and as such it is not quite an apples for apples comparison but we can allow 5-7bhp for that bit of loveliness
Here it is at the moment:
Dr. Eunos
So would tuning an engine to this degree be feasible for a road car or are we talking for track use?
Yes it is perfectly feasable for the road as well as the track (skim and exhintake mod) however the engine is now an interferance if the cam belt were to break. Total cost around £550-600 including parts & allowing for labour and dyno runs (3 in our case) ideally it is best to get another head and exhaust cam so that you do not need to rush the valve lapping, replacement of valve stem seals, port cleaning skimming and testing. The engine really pulls from 6000rpm up to the redline in comparison to std.
Surprisingly we are not getting pinking (detonation) although this is effectively a super-plus perol only set-up.
You could turbocharge for a few hundred more but then to get the best out of turbocharging you need intercooling, engine managment expensive trickery, different cam profiles as you can easily end up blowing your fuel air mixture straight through and into the exhaust ports due to the over-lap on a NA engines cams, and of course one type of modding is very obvious to an insurance assessor whereas internal mods are not so obvious if you catch my drift? We can put the standard valve cover back on once it is all set-up finally and no-one need ever know, sshhh 
I claim BS, more than 25% increase by re-profiling…
On a 1600 engine it probably is a bit optimistic but on an 1840cc am pretty sure 35bhp is gettable with cam re-profiling, but you would need solid valve lash adjustment and a heavy head-skim along with port matching and proper porting, the big problem is you need to raise the rpm limit significantly as you are starting to gain horespower just as the limiter cuts in…
That means it’s BS on a 1.8 too, unless you do other stuff as you say. ( after the word “but”) You would have to add programmable ecu, but that could be worth up the 10bhp just with a tune.
So it looks like we agree that it’s not possible on it’s own.
Correct, cam re-profiling on its own whilst it can improve various way-points in the dyno-graph will probably not get you 35bhp extra in its own, we have (so far) seen a great improvement in torque output via the skim and exhintake mod and the engine is already showing a significant gain in bhp (March the 6th at the next dyno session we will find out the definative maximum gain we can expect from the mods I have done on Simons engine, and good or bad we will publish them here…) on the 1.8 remember, it still has standard valve lift and standard valve sizes.
The cam re-profiling (Piper) will give an increase in valve lift of around 1mm only (metal is removed from the heel of the cam and the cam re-profiled to an A2 equiv fast road profile) but you must use solid valve lifters to make it work effectively, the maximum valve size increase asvailable on this engine is only 1mm larger than std, cost-wise it probably isnt worth doing.
The MX5 engine is not very tuneable as N/A and I have heared about people spending £4,500 to get a mere 45bhp extra from a 1600 N/A unit, am pretty sure what we will end up with is a lot more cost-effective from a 1.8 but if you are prepared to sacrifice overall engine life then fairly sizeable power-gains can be squeezed out of it, but cost-wise a turbo is the way to go, if you have deeper pockets still then super-charging will result in a more tractable driving power increase.
If you checked-out the ebay sellers other items he (or indeed she) also had motorbike throttle bodies for the engine also available but had decided to go down a different route for his kit-car.
Dr. Eunos
Jon, I think you’re getting a little confused between Piper Cams and Pipercross Filters.
It’s Pipercross who sponsored last season’s MX-5 Cup.
I think the scrutineers would take a dim view of any Ma5da racer using non-standard camshafts in their engine.