Home brew head work
 

I can get a complete 1.6 head for a song. Don't need it, and I don't expect to be running a 1.6 after this winter. However, FM's before/after headwork dyno comparison chart is haunting me in my dreams. Being that I'm not going to drop several hundred bucks, let alone $1000 or more into this motor, I was considering something DIY. Would like to attempt a p&p of the intake and exhaust ports, try to match the intake mani, and unshroud the valves.

Would love to hear from you guys who were brave enough to attempt DIY headwork. What tools did you use, what leasons can you teach. Thanks

This is the dyno chart--both plots are a 1.6 FMII at 12psi
http://www.flyinmiata.com/tech/dyno_...comparison.pdf

here look at mine:

unshrouded valves, lapped valves, polished chamber
https://www.miataturbo.net/~web1_bra...on_chamber.jpg


port-matched, ported & "polished" intake runners
https://www.miataturbo.net/~web1_bra...ntake_port.jpg

https://www.miataturbo.net/~web1_bra...take_port1.jpg


"polished" exhaust runners

https://www.miataturbo.net/~web1_bra...ust_polish.jpg


blended seat

https://www.miataturbo.net/~web1_bra...work/blend.jpg

https://www.miataturbo.net/~web1_bra...ork/blend1.jpg


No valvetrain work, but this should improve flow enough to see dyno results.....said results to follow soon (soon as in a few weeks)

^you fail at posting pics!

he lacks permissions

I did the heads on my wife's 626 v6 5spd. I bought the port/polishing kit from eastwood and a carbide rotary cutter. Used that with the compressor and a die grinder. I wasn't to aggressive- did port matching, clean up and port radius smooth, deshrouding. Never checked to see the difference and the wife didn't report any :gay:. But it was something I wanted to do. I enjoyed it. Why not, I say.

If you do it, I just might have to buy it from you when you ditch the 1.6

On scott's, the intake isn't "polished", it was finished with a 180grit scotchbrite buff. The exhaust side was finished with a 320grit scotchbrite buff. Also what he didnt take a pic of was the seat blended into the bowl to make a seamless transition.

close enough, it's shiny and smoother than the casting.

I'll get a pic of the blend in a few minutes.



If you can't tell, Brian did the work for me :bowdown:

That was an absolute atrocity on one of the KL v6 heads! The other was very smooth. The ledge on the seat must have stuck into the port by 1/32" at it's worst point and nearly all the intake seats were that way.

the usdm 1.6 heads that I've seen so far have all looked pretty respectable, but the 1.6 head off of my blown jdm motor was completely atrocious. The seats protruded above the chamber surface, the seat machining into the bowl left it sticking out at least 1/32" (minimum), and the casting lines on all the ports made the ports all offset from top to bottom by like 1/16"

For the majority of the work I used a speed adjustable dremel with the snake attachment. Making a place where you can hang the dremel up high is the best because it lets you move around the snake more easily. I used one of the carbide grinding things, its skinny and has a very slight taper to a rounded tip. That I used to take off the majority of the metal for the deshrouding, and also to take off the little step lip that surrounds the seat in the chamber.

Next I used an orange grinding stone, the one that rounds slightly down to a tip. This stone you will see has a little edge thing like 1/8" from the tip that you have to grind off before using. I used that to do all the chamber work after the carbide. It smooths things out really fast. I also used it to blend the seat and the bowl, the bowl itself, and the short side radius.

The intake and exhaust ports I used a mikita electric die grinder with a sweet ass toggle switch and a standard abrasives porting kit. They have these huge 1/2 cylinder scrolls that make quick work of the majority of the port.

Ideally you would have a valve job done after the seat-bowl blend. You can see in Scott's pic that the blend does encroach into the very first angle cut into the seat.

Also, very important, I used ALOT of wd40 while porting. It will make it so you have to use a minimum of expensive dremel bits because it keeps them from loading up.

Your best bet would be to practice on a scrap head and then do the real thing. some tips would include: always hold grinding tool of choice with 2 hands firmly (if it catches on something it will minimize the jump), use 2 spare intake and 2 spare exh valves when doing the chamber work (they will get basically destroyed)


disclaimer: I take no responsibility for destroyed heads.

Without a flow bench, you just really do not know if you are messing the heads up. Too much comes into play. I would just get rid of the casting imperfections, then polish the chambers, and get a good valve job. The valve job usually accounts for 60% of flow increase in a port and polish. Just what I am going to do. Also, with the intake tracks, from what I have always been told and from the books that I use to own, don't polish those all the way. If you look at most PnP'd heads, the intake will almost have steps in it, very small, but increase the turbulence at low air speeds therefore creating better low speed mixing.

While true that you won't know the gains, deshrouding the valves and blending the bowls to the seat will simply not hurt the flow when done properly. If you look at the pics you'll see that really all I did do to the ports was to smooth them and get rid of the casting lines. Same with the chambers other than deshrouding.

I also think a valve job is a must, and recommended it to scott (especially after the seat blending), he wants to get it but has opted not to for now. He is going to later when he is ready to strap it to a built bottom end.

yep ill do a valve job along with stiffer springs and aggresive cams when ive built my bottom end.


I'll be taking the thign to a dyno shortly, soon in a few weeks we can really see the results, ive down plenty of datalogs and dynos to compare stuff, so I expect to see gains down low along with a faster spooling turbo.

For example <bench racing mode on>-
One year I was racing an ultra low budget ITA Miata (owner was in college at the time). Car had its original 160k engine and was getting weaker and weaker each race. Though the owner was getting quicker, his lap times remained constant. At the year-end "championship" race we opted to get the (spare) head decked .010" and get a 3 angle valve job so we weren't embarrassed by our lap times.

Upon pulling the cam cover, I saw a head was stained a dark brown. After pulling the head, I was sadden to see oil returns in the block packed with burnt oil. I knew putting a healthy head on bottom end might upset the balance, but figured it would last the weekend.

The car was a full two seconds a lap quicker for under $300 of work. But our luck ran out with three laps to go in the enduro - running second in ITA the bottom end spun a bearing going on to the back straight and limped back to the pits. :sadwavey:

Ouch go big or go home huh. Couldn't you have cleaned out he oil ports abit better, to help the guy out? a 20-30 dollar oil cooler might have helped if that was allowed i guese.

I cleaned them out the best I could. The test day was the next day and I had to go back to work. Perhaps we should have skipped the test day - or at least one session? ;)

Speaking of this.. if anyone has a spare head I would definitely take it off your hands :)

A good quality performance valve job is worth a lot in flow, from low to high lift. Everything I've read says to open the bowl just below the valve seat to 80-90% of the valve diameter, and blend from there.

I was able to compare two logs finally in the short time I was able to drive the car (dont ask), but here you can clearly see the car makes boost faster:

https://www.miataturbo.net/~web1_bra...work_boost.jpg

It feels much improved and the turbo is in boost more easily and quicker. I used to hit 2-3psi when I would drive up my street to the stop sign, I noticed more like 5-6psi in the same situation I always see.

fwiw: This was the first time I boosted this block, so don't talk about my high boost numbers in comparison....the spoolup is all that's important here.

Nice, glad to see it was worth it.