Port and Polish Head

osargeant · Post by **osargeant** » June 16th, 2005, 7:54 am

Is everyone running a port and polished head on a 1.6 DOHC turbo setup or B6T/BPT setup? I am considering taking my turbo MX3 off the road to get the head port and polished and was wondering what are the gains like to determine if it is a worthwhile mod or not.

Any opinions on this are welcome.

Also looking to do some new 1/4mile times in the next month or so and I am shooting for 14s this time around, car feels much better than before.

BuGS · Post by **BuGS** » June 16th, 2005, 10:51 am

Josh has one I think. He also has the bottom end built for boost. I would find his sig and go to his website. But his car gets up and goes.

nos92mx3 · Post by **nos92mx3** » June 16th, 2005, 12:34 pm

i remember reading an article awhile ago about a turbo miata putting down some nice numbers on a unported head. After it was ported and put back on it made more power on less boost, reason being less boost is because the injectors were maxing out, so id say find another head and port that while still driving the mx3 around :

Shades · Post by **Shades** » June 16th, 2005, 5:13 pm

I think you'll be lucky to get 10hp.

Porting and polishing mostly is to get rid of the casting lines in the ports and making the A/F mixture and exhaust gas flow better.

You wanna take off the short radius in the ports and remember to port match your manifolds.

Don't take too much off cause if you break into the coolant chambers, your head is garbage.

It's a very time consuming project and requires a lot of patience. With the right tools it can be done.

forcedairram · Post by **forcedairram** » June 16th, 2005, 8:09 pm

Well id say 10 hp is a reasonable gain for a so-so port and polish job, but thats on a n/a engine, porting and polishing is going to make a huge difference on a force inducted engine. The cleaner you can get your runners the more the volume and velocity of your intake charge increases. If you want to maximize your gains, remove the valves and poish all the way through the runners in your head, polish the combution chambers, and go with some 1 mm oversized valves. This will result in signifigant gains in either a N/A engine or a turbo engine. So if you do all of this it is definatly worthwhile, keep in mind by removing all the casting marks in the cumbustion chambers you will ever so slightly lower your compression, and i do mean slightly.

What · Post by **What** » June 17th, 2005, 5:41 pm

If you want bigger gains, put in a BP.

I would expect larger gains with a turbo, although these heads flow fairly nice to begin with... I have a modified BP head (mild chamber work that got rid of sharp edges that promote detonation, deshroud valves, back-cut on valves, etc..) if you're going to such a route...

JWMotorsports · Post by **JWMotorsports** » June 18th, 2005, 3:17 am

You want to focus most of your time in the bowl area and where the valve seats meet the bowl. Basically you want to turn the port into a velocity stack finished off with a multi angle valve job on the inake and a smooth radius on the exhaust side. The multi angle on the intake side helps keep the air\fuel mix atomized for a more controlled burn in the combustion chamber. The radiused exhaust side allows the gases to come out smoother and faster. Air doesnt' like sharp angles or bends. Sharp angles cause the air to shear (will result in turbulance). Air will actually follow a radius. Polishing the combustion chambers will most importantly cut down on detination by removing surface imperfections that supply hot spots which aid in causing detination. The BP and B6 DOHC heads I've seen all have excellent port positioning from the factory. You want the port to shoot the valve face as straight on as possible. Many racers will actually weld the stock ports closed and mill new ports that start out higher up on the head to accomplish this. You can also have your head and pistons ceramic coated, Jet Hot has a lot of options there. Don't go crazy thinking monster ports are the answer. You want your port velocities as high as you can get them and our stock ports have enough volume for an easy 300+ hp untouched (forced induction). Open your intake port up a hair bigger than the intake manifold runner and open your exhaust port up keeping it a hair smaller than the exhaust manifolds. This will help control reversion and back pressure. I've done a LOT of prying knowlegable sources and studing to get this info over the last 7+ years. The head is where you get the winning edge in racing and the mods are the highest guarded secerets in the industry for that reason.

Too much Time · Post by **Too much Time** » June 27th, 2005, 9:09 am

I had a compleate street port on my eclipse GS-T head and it dynoed like 35 Hp more at the flywheel.

it makes a huge diffrence, but it you are doing that, I recomened that you see if you need your lower end built up too.

nope-mx3 · Post by **nope-mx3** » June 27th, 2005, 10:39 am

A friend of mine is building a Miata now. Should be ready to drive on saturday.

About 330WHP, should be pretty fun I think

Add to this, polybushings all around, KYB AGX, Flyinmiata springs, whiteline front & rear swaybar (adjustable), Link engine management, etc etc.

Cant wait for him to come visit

Hopefully I got a dv-cam then

nope-mx3

osargeant · Post by **osargeant** » January 18th, 2006, 10:14 pm

Well folks, I have finally decided to go ahead with this mod, the car is in the shop right now getting the head removed. I am also taking the opportunity to change all the relevant gaskets and seals while I am at it.

I hope to get some pics of the port and polished head once I get it back to post up as well as to let you know the results.

Juans_93_MX3 · Post by **Juans_93_MX3** » January 18th, 2006, 10:55 pm

Wait, dont the Ford Escorts use the same engines?
Why not just go to the junkyard, get a BP head off a Escort and have them port that?

Shades · Post by **Shades** » January 19th, 2006, 1:21 am

People he's talking about the 1.6 DOHC, which is not a BP engine.

Yeah I've done some mild porting on my spare B6 head from the last engine I blew up.

I've stripped the BP head I have from the Escort and it looks to be less work than the B6 head, less casting lines to get rid of.

Josh · Post by **Josh** » January 19th, 2006, 1:49 am

on a B6 definatly port and pollish that sucker. its definatly noticable. i probably lost 30 or so HP when i had to swap a N/A head back on.
but for turbo motor im told you dont want to polish the intake side just port and clean it up. because it can flow too well. i guess you want the air to come in rather sharply but leave smoothly (threw the exhaust side). if it were a BP then i would say dont bother. as the B6DE has alot of grinding to do to even Port match it to the gaskets. but the BP there is only like a 1/6" to grind off to port match it. so its almost not worth it, other than to just clean up the casting marks. well on my EGT BP that im buildign thats the way it is.

osargeant · Post by **osargeant** » January 19th, 2006, 6:47 pm

Hey Josh,

Since you seem to be building a BP engine, what are you going to do with the current built B6 engine, I might be interested in taking the cams and cam gears off your hands.

Josh · Post by **Josh** » January 19th, 2006, 9:28 pm

osargeant wrote:Hey Josh,

Since you seem to be building a BP engine, what are you going to do with the current built B6 engine, I might be interested in taking the cams and cam gears off your hands.

well the cam gears are JUN performance gears and only so many were produced from what i understand, but they are going onto the BP. but the cams are up for grabs. they are as big as one could go with stock valve train. origionally intended for N/A use, but for forced induction they are sweet, power ban kicks in at about 4500 and goes all the way to 7200. the more psi you push from your turbo, the more it feels like a V-Tec power ban. i like them alot. i will be taking them out of the motor soon. i was looking to get somewhere around 300 but i could work out a price. PM me if your still intrested.

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