Cam Shafts

shaznandy lockyer · Post by **shaznandy lockyer** » Wed Jul 24, 2002 5:13 pm

I'm interseted in any expeience(s) with aftermarket Camshafts.

Brands, Profiles, costs and installed by...etc.

Any advice??(just need a door length on those Hondas!!)

Fletch · Post by **Fletch** » Wed Jul 24, 2002 6:37 pm

I bought some un-ground blanks from Mazda Competition in the USA (US$78
each!), and got the ground locally to specs based on my ported head-flow
numbers...

Grinding was about $220. Fitted them myself

I also have a Link ECU. (and cams worth doing, need an ECU to work properly)

Its going pretty good. I havent had it on a dyno yet, and am still finalysing
my exact cam timing (adjustable sprockets), but they've been good for 15-20
hp, I'd guess?

Fletch.

shaznandy lockyer · Post by **shaznandy lockyer** » Wed Jul 24, 2002 7:03 pm

Thanks Fletch
Q:is your engine S/C or Turboed? mine is N/A and will remain so...
ECU's...thats another issue-Link was best option for you?
I'm going in stages as cash allows;( so should really take the right steps along the way!
Cheers Andy Lockyer

MC · Post by MC » Wed Jul 24, 2002 7:43 pm

Hi
i ran HKS 256 cams in my previous N/A MX5, and they work very well especially
with a lightened flywheel, Franklin cams in Pukekohe has the profile that Ray
gave them and they cost me $500 for them to build up and reprofile the pair of
stock cams i gave them, they give about 15hp, they run very well with the
stock ECU as all of Rays supercharged cars were fitted with these cams and
they ran very well with the stock ECU even with the superchargers fitted as
there is less overlap than the stock cams, the improvement is most noticeable
around 4000rpm onwards, and as Fletch says they are worth doing if you want to
keep N/A.
MC

Fletch · Post by **Fletch** » Wed Jul 24, 2002 9:08 pm

Mine's NA, and always will be... Its also my daily driver so its got to run
well at partial throttle and around town as well as full-out.

I found the Link to be the best option for me, but there are others...

I'm surprised that the HKS 256's work ok with the stock ECU, but as I havent
tried them...

A friend in Hamilton had some stock cams re-ground by Kelford in Christchurch,
he ran them for a week on the stock ECU, and while they did run, he found them
much easier to live with once his Link was fitted...

Fletch.

Gary Morrison · Post by **Gary Morrison** » Wed Jul 24, 2002 10:26 pm

I'm surprised that the HKS 256's work ok with the stock ECU, but as I havent
tried them...

Fletch, according to my info the stock cams in the MX-5 are very close to 256
degrees - SEAT TO SEAT - so maybe the HKS cams aren't that radical. Probably
why they run OK on the standard ECU.

Gary

lou Girardin · Post by **lou Girardin** » Thu Jul 25, 2002 8:19 am

I believe the '99 on cam profiles are more aggressive and won't require
aftermarket ECU
Lou

lou Girardin · Post by **lou Girardin** » Thu Jul 25, 2002 8:22 am

What suits FI is not correct for NA. FI cams need LESS overlap otherwise the
pressurised charge is blown out the exhaust. Search the Miata.net forum for
info or talk to Fletch.
Lou

Gary Morrison · Post by **Gary Morrison** » Thu Jul 25, 2002 12:00 pm

Correcting myself and if anyone is interested...

Standard 1600 Intake Cam is 236 degrees, Exhaust is 248, Overlap is 111.

Fletch's cams are:

Intake 254 degrees, Exhaust 260 degrees.

These are from my copy of Desktop Dyno.

MC · Post by MC » Thu Jul 25, 2002 5:23 pm

Hi
your right Gary the cams aren't that radical, idle is a tad lumpy that most
people would not notice
here's the figures:
stock timing HKS timing
inlet opens 5*BTDC inlet opens
0*BTDC
inlet closes 51*ABDC inlet closes
36*ABC
exhaust opens 53*BBDC exhaust opens 31*BBDC
exhaust closes 15*ATDC exhaust closes 5*ATDC
with 8.7mm lift
i think this is correct
the auto's have different cams

so you can see why Ray put these in his cars( stock ECU), less overlap on the
exhaust, and they certainly run well in the N/A cars also,
I'm considering putting the HKS profile in my Turbo 5 ( yes I do run the Link)
as another of our neibours runs them in his Turbo 5 i think you know him Lou,
Pravin with the red and tan leather 5.

Gary Morrison · Post by **Gary Morrison** » Thu Jul 25, 2002 5:49 pm

Hi there,

I don't think those cams would work well at all on an NA car. For interest I
stuck them into Desktop Dyno. I have a model of my 1600 with the work that has
been done on it, standard cams at the moment. I took that and just stuck in
your cam figures and ran the sim. If you want to see the two sets of results I
can email you a couple of pdf files of the results.

Gary

Fletch · Post by **Fletch** » Thu Jul 25, 2002 6:18 pm

I'm surprised those cams are called "256" when the described duration is 216
(0+180+36 or 31+180+5). unless those durations are at .050" lift, which may
very well make them 256 seat to seat. Those stock timings you've listed are
seat to seat.

Gary, the stock durations are as you describe, but theres no way the overlap
is 111 degrees... looking at the figures below its 20 (which is about what I
remember).

Fletch.

Fletch · Post by **Fletch** » Thu Jul 25, 2002 6:19 pm

That's true, but they only fit in a 1.8 the bore spacing and length of the
head/block is different for the 1.6's.

Fletch.

Gary Morrison · Post by **Gary Morrison** » Thu Jul 25, 2002 6:35 pm

Sorry mate, lobe centre, overlap as you note is 20 deg. Brain was out of gear.
Those HKS when treated as seat to seat only give 5 degrees overlap.

Gary

Post by **zorruno** » Thu Jul 25, 2002 6:59 pm

could you use them on a 94-97 with the stock hydraulic lifters? or will the
solid lifters fit (not going to attempt it - just interested)

lou Girardin · Post by **lou Girardin** » Fri Jul 26, 2002 8:24 am

Hi Guys,
Unless I've missed something, I make stock overlap 104 degrees, HKS 67. Which
raises the question, why would you fit these to NA?
Extra overlap promotes cylinder scavenging, simply put, the exiting high speed
exhaust gas draws intake air into the cylinders over a limited rpm band
(usually high). Reducing overlap lessens this effect, but boosts low end
torque.
Lou

Clive Granger · Post by **Clive Granger** » Sat Jul 27, 2002 3:07 pm

Would less overlap be better for a FI engine? What would you suggest cam
wise for my JRSC fitted 1800cc?
Clive.

lou Girardin · Post by **lou Girardin** » Mon Jul 29, 2002 8:43 am

Hi Clive,
I'm thinking of trying the alternative timing set-up for stock cams that
Fletch has described so eloquently.
It reduces overlap, so in theory should give more low rpm torque. If you try
it 1st let us know how it went.
Lou

MC · Post by MC » Mon Jul 29, 2002 9:43 am

Hi
for those interested, the HKS 256 cams were designed for the 1600 N/A back in
89, spoke to Ray the weekend and he confirms they work very well in a N/A 5,
Glenn at Rotary Power was the fist to fit these cams in his 5 back in 89, Ray
followed in 91,
Lou, Ray said you drove his car at the launch of the 1800 at Pauanui in 93,
(before he fitted the supercharger) along with a lot of club members who
reported that this car ran very well, Ray said it adds 15kph to top speed with
more go from 4000rpm, which confirms the same results i had with my 5.
MC

shaznandy lockyer · Post by **shaznandy lockyer** » Sun Aug 04, 2002 6:52 pm

Gary,Fletch, Ray...
REgarding recent discussion on camshafts you all provided some interesting & usefull information for future reference, ty.You all mentioned Degrees opened and closed ,overlap, duration but no-one mentioned lift...how far the cam lobe pushes the valve into the combustion chamber.Is std. about 8mm(from memory)?
I mean duration is one thing but lift has a great affect on gas flow too.Also, Fletch is your head ported & polished?Are you sticking to 9.4:1 compression?etc...
Cheers Andrew Lockyer, Tauranga

Gary Morrison · Post by **Gary Morrison** » Sun Aug 04, 2002 9:22 pm

Hi Andrew,

Lift is restricted somewhat by the valve springs you have. Fletch is or has I
think gone for higher than normal, and was looking for stiffer valve springs.
I will stay at the stock limit. Fletch & I both have identical ported and
polished heads, and the combustion chambers were also cc'd. The head was
shaved to raise compression ratio to about 9.8:1 which is as high as the head
guy said he thought you could run it on the gas we get. I think Fletch has
logged some knock in circumstances where his ignition timing was a little too
far advanced. I'm yet to get to the cam thing, but I have been following
Fletch's progress with interest. If you look at what Bill Cardell at Flyin
Miata has got out of his 1.6 with 10.5:1, cams, and the Link ECU on a Dynojet
you can expect about 135 HP at the rear wheels as the upper limit.

Gary

Fletch · Post by **Fletch** » Mon Aug 05, 2002 7:22 am

As Gary pointed out, yes I've had port/polish work done, and slightly raised
CR.

Standard lift is about 7.8mm. My cams have 8.7mm

Apparently 9.0mm is about the limit that can be achived with the stock
valve-spring, and even if you replace the springs, its also around 9mm where
you have to start removing metal in the head so that theres room for the cam
lobes to rotate (mainly, the lifter guides need metal removed so the corners
of the can lobe will fit past).

Changing duration and overlap can have effects on idle quality, power-band
etc, but as far as I can tell from my reading, gaining lift seems to be free
of other consequences.. open the valve further and you get more air in...

Fletch.

lou Girardin · Post by **lou Girardin** » Mon Aug 05, 2002 8:40 am

Just one question Fletch, does increasing the lift as you've done change the
valve/piston relationship to interference type? Could be a concern if the
c/belt breaks.
Lou

MC · Post by MC » Mon Aug 05, 2002 12:48 pm

Hi
A valid point Lou, the valves do not touch the pistons if the belt breaks on a
stock engine, the HKS 256 cams have 8.7mm lift,
and 8.7mm valve lift,
wouldn't want to guarantee they wont touch if the belt breaks tho.
MC

Fletch · Post by **Fletch** » Mon Aug 05, 2002 8:11 pm

Yes, a valid concern.

With extra valve lift, and/or shaved head, its will definitely become an
"interference" at some point... I havent actually checked if I'm there yet.

It is something I plan to check some time.

Fletch.

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