mx5cartalk.com

Hi all,
So I need alittle help in deciding if I should get some headwork done to my car. I have researched about headwork and what it can do, but so far I am finding it hard to grasp why anyone would do it for a Daily driver that wants a little bit more out of their car. I have some cams (252 IN/EX) that will be installed when I do my timing belt and I had a thought why not get my head port and polish? My car currently has an Intake and a full exhaust including high flow cat, so it would make sense to maximize the benefit of my cams with a port and polish theoretically ? I understand I will require an ECU (which i plan to get regardless of this) if I choose to get a port and polish but wouldn’t getting an ECU alone outweigh the benefit of a port and polish? Will I even see any realistic gains if I got an ECU + port and polish?

Looking for some experiences and info from users that had head work done to their cars.

I cannot be blunt enough when I say this, and I dont know how many times I need to repeat myself.

You can take a na6 at 100 HP and add intake and exhaust.
You take your now 120 HP na6 and add a high compression bottom end.
You take your now 130hp na6 and work the head and tune to suit the headwork and get anywhere up to 200rwhp.

So what Im saying is that you can gain 100% more power, of which only 30% is found outside the head/ecu.

Yes.

Headwork works.

YES.

I repeat myself all the time.

Exhaust and intake adds 20hp maybe, but headwork and a tune to suit can add 80 more.

Yes.

Thats where 80% of the performance is.

OK.

Hopefully this is the last time this winter Ill need to drill this in.

Also people do this to their daily because headwork (specifically cams) are such easy power.

Want more power? Bigger cams.
Want MORE power? BIGGER cams.
Want EXTRA MORE power? EXTRA BIGGER cams.

Get it?

Dann

Heres a section out of billzilla's excellent 4age page.

This info is all 100% spot on and includes all mods needed for each goal all laid out. Google it if interested in seeing a typical stock->240rwhp 1.6L modification path.

Heres some of it.

"170hp - 180hp
Still not any huge differences between the big and small port engines here. Not a lot more work required to get the extra 10hp from the engine now; just slightly bigger cams really. I'd recommend 288 to 304° duration.

180hp - 190hp
Definitely 304° cams, and you'll have to start paying attention to tuning the inlet manifold length, if you haven't done so already. This is also getting to the limit of what a lightly ported small port head can manage.

190hp - 200hp
Getting towards the upper limit of 304° cams, and you'll also need to have the compression up to a good 11:1. 200hp is about the limit for a small port head, no matter what the porting, so from here on the big port is the way to go. Another area that has pretty much reached its limit is the stock valves - Past 200hp you'll be needing the big valve kit. More on that next paragraph.
The standard exhaust manifold has also reached its limit, so 200hp is about as far as you can go with an engine that still retains a large amount of standard parts. It will need to be revved to around 9,000rpm to get 200hp, though if built properly the engine will still be able to be dríven on the road. "

Get the idea?

More compression, bigger cams, bigger cams. and then bigger cams.

Dann

i was waiting for you to say "go Turbo" Dann

i remember when i had my ED falcon a few years ago. Head gasket went on it, so decided to get some head/cam work done. It went from 105rwkw to 165rwkw just from a good head/cam combo

thanks regie.

And Im absolutely all for the supercharger/ aspirated crowd. My last setup was an alcohol fueled, cammed, ported na6.

I just dont believe in a blower/na for the average joe blo who wants 200rwhp NA/NB like everyone else.

A T25 on a log mani with 2.5" exhaust and megasquirt is just so cheap reliable and easy.

Dann

thanks that Dann i knew i could count on you to reply. I have actually seen many of your post regarding this topic but was hoping other users which dont take their car the the absolute limit like you do could chime in. So would a port and polish be suffice for my cams? Should i get the shaved also to bump the compression just abit? I understand bigger cams = more power (thanks for drilling that in ), but I got my cams cheap and i don't want to sacrifice to much stability in the car for more power.

Stability?

Look, PM wozzah1975, tell him what you have and your budget and he will tell you how much power he can give you.

Easy.

Also, warren is the man.

Dann

Just PM'd wozzah will wait to see what he has to say.
What i meant from stability previously was going to far from factory.

You can have a perfectly reliable daily driveable 140rwhp na6.

I had one.

It was better in stock in EVERY way to drive.

More power everywhere and no big surge of power or anything. And LOADS of torque.

Dann

NitroDann wrote:You can have a perfectly reliable daily driveable 140rwhp na6.

I only hope i can obtain the same thing you once had.

You want 11:1 compression.

270* cams with a fair bit of lift.

Solid lifters.

Good condition head.

Light port job.

Ecu and tune.

Intake.

Exhaust.

Recipe for bliss. And a hell of a lot cheaper than an S2000 haha

Dann

You also forgot 830kgs too Dann. Got that was awesome to drive

Off topic now... But yes. It really was something special somehow.

Dann

You can do without solid lifters in most non race applications (reference woz, garry Stewart and others).

Sent from my GT-I9100 using Tapatalk 2

Without them you have to run duration rather than lift and steep ramps to make power, which means that high rpm power people seem to be afraid of in a street car.
Solids means you can run smaller duration and make up for it with aggressive lift, and then make huge torque at reasonable rpm.

EDIT (rewrote for clarity)

People are afraid of a car that makes power up top, god knows why. These people have also probably never been in a car with a nice little pair of 270*s and some compression..
But basically solid lifters let you run cams that retain 99% of the stock powerband but just make it feel stronger and bigger everywhere, like a bigger engine.

Dann