1987RX7guy

iTrader: (3)

Well I am planning a lot this summer as far as DIY for my car. I was thinking about porting my intake manifold but there is only so far you can go with a dremel/grinder. My idea is to take a mild acid or diluted acid and run it through the intake to smooth/enlargen the runners a bit. Would this be ok or would it completely ruin the manifold? I am talking about an acid that is not strong or a diluted one so that it acts slowly so that I can stop the corrossion before too much damage occurs. Any ideas?

Liquid Anarchy

iTrader: (2)

I'm just putting a hone to mine...

Icemark

probably would make it worse, as the acid would eat all metal evenly.

1987RX7guy

iTrader: (3)

hone????

Castrol86GXL

im going to hone mine too probley pritty soon and ill tell you the diff .....probley this week

1987RX7guy

iTrader: (3)

what is hone???

1987RX7guy

iTrader: (3)

what kind of companies hone intakes? could I do it myself? how and what would I need?

silverrotor

iTrader: (1)

I believe Paul Yaw offers such services. I don't have the link handy but I'm sure someone will pull through. Also, his site, elaborates on your concerns, In regards to porting Manifolds using sophisticated techniques.

1987RX7guy

iTrader: (3)

can anyone find this link thanx

j200pruf

iTrader: (4)

I think that this is a link to his web site http://personal.riverusers.com/~yawpower/

Castrol86GXL

a hone is basically a add-on to a drill. it has like 3 sandpaper pieces or alot of .... hold on here

http://www.teamcalamari.com/pix/hone.jpg

http://www.powerbuilttools.com/cdimages/648631.jpg

and all they basically do is sandpaper the inside of a pipe, but if used properly they can be used for other things like intake manifolds

NZConvertible

Extrude Hone. Very good. Very expensive.

jeremy

iTrader: (1)

yeah, honing is a process. if you can find a competent machine shop that would do it for a decent price would be easiest.

zyounker

But dont do a mirror finish inside the intake.. it should be a little rough..


-Zach

jcina7

why should it be rough?

zyounker

because turbulnace is good


The fuel will bead up on a glossy surface.. plus turbulance is good atomizing fuel..


Just something i have always seen/read. Never polish an intake runner inside. And outside is iffy to because of heat transfer.


-Zach

Barwick

Good for exhaust manifolds, not for intake.

jeremy

iTrader: (1)

very true. think of swirling the coolade to get the sugar to mix with the water. water being the air and the sugar being the fuel.

rotarygod

iTrader: (1)

This is a very true statement on carburated cars where fuel pressure is low and fuel atomization is not very efficient. The original problem was that on these earlier manifolds if the inside of it was smooth fuel would tend to puddle in the plenum chambers (V-8s, etc.) This is why you see patterns on the bottoms of these plenums internally. The fuel droplets from a carb are much bigger. In a turn (as in bends in a manifold) everything tends to get thrown to the outside from inertia. This includes both fuel and air. The heavier fuel will get thrown to the outside moreso than the air will. If the runner walls are slightly rough there will be a small amount of turbulence which will help keep the fuel from getting thrown outwards as much helping it to remain in suspension. Remember that on most carburated cars fuel is being added before the plenum. Obviously this isn't the case with a Weber style of setup but the poor atomization still applies. On a fuel injection system roughness isn't very important even though the same physics still apply. First of all, most of the manifold is dry meaning there is no fuel running through it. Get this area as smooth as you can. Even in areas where there is fuel running through, fuel pressures are much higher and fuel injector spray patterns are much better. The atomization is much more efficient. The faster the air is going, the faster the fuel will get dispersed as well. This is really good with the staged injectors that the RX-7s have. At low speeds when veloctiy is low, the only fuel injectors running are those immediately outside of the primary ports. At higher rpms when there is much more air the secondaries come on line farther upstream which helps to disperse the fuel even better within the intake runner. The higher the rpm, the farther the injector should be for maximum atomization due to greater velocity. While a small amount of roughness may be beneficial on a fuel injected car depending on injector location, it is for the most part negligible. Get those damn things flowing better. Even mirror smooth they will still have better atomization than a carburated car with rough runners.

zyounker

Well, i have also heard it will slow the velocity down inside the runner.. Kinda like the golfball theory.. The reason it goes so far is the divits in the surface.. if it was totally smooth it would not work as well..


Which is another reason i have heard for not polishing the inside of an intake runner, EFI or not..

Care to comment on that? I don't have any proof, just something i hard from people who know what they are talking about.


-Zach

Icemark

why??? what makes you say that.

Extrude hone, smooths and cleans the intake runners to a nice clean surface (but not mirror smooth like you would want for an exhaust). In addition it can be used to widen the passenges based on flow.

So I am wondering what makes you say that it is no good for intake, when it would be better for intake than exhaust.

BTW: Primary applications are air induction components for internal combustion engines, including intake manifolds, cylinder heads and exhaust manifolds. By smoothing these rough "as cast" surfaces in the induction passages, Extrude Hone dramatically enhances air induction and combustion chamber "swirl" velocity. The increased air volume and improved fuel/air mixture result in a cleaner burning, more powerful and more fuel efficient engine.

Extrude Hone’s Powerflow processing of intake manifolds and cylinder head intake ports already has met the challenge for viability, reliability and cost effectiveness. Its value was proven in a four-year, $8 million effort supported by Ford, GM, and the Advanced Technology Program of the National Institute for Standards and Technology.

The process is applied to intake and exhaust manifolds, and cylinder heads, in order to remove rough cast surfaces that restrict horsepower efficiency. Powerflow enlarges and uniformly polishes air and fluid passages to maximize flow velocity through the component. All polishing is performed parallel to the air/fluid flow. The result is a surface finish "grain" achieved in the same direction.

Superior results are reflected in the widespread use of Extrude Hone’s Powerflow by professional race teams in NASCAR, NHRA, IRL, CART and SCCA. Production vehicles, such as the Ford Contour SVT, rely on Extrude Hone to produce the increased airflow required for the 2.5L V-6 to achieve 195 hp.

and:
Mazda Rotary Intake $ 585.00

Icemark

BTW: you want a nice smooth clean surface for intake that is not mirror smooth. The rough stuff left from cast manifolds is simply power robbing mountains in the air flow streams.

On intake, though you want mirror smooth as the ultra smooth surface resists heat better and forces the exhasut to travel at higher volocity.

This has been well known for 20 years. Go ask any engineer working on intake or exhaust manifolds for performance applications.

jeremy

iTrader: (1)

ok, be it most of my experience has been with carbs, are you saying that the injectors do not inject into the manifold, meaning that our engines have been on the forefront of direct injection, rotarygod? i can see the reason that it wouldn't need to be cast rough but do the injectors and chamber automize the fuel well enough that a mirror finish can be applied?

Icemark

actually you don't want a mirror finish on the intake tracks of the intake because there will insufficent surface tension on a mirror finish.

You want it smooth, but not glass smooth. No smoother than a good 600 grit would make it.

jcina7

i just dremmeled all openings/exits on all the intake mainfolds with the grainiest grit little wheel to match each opening to the other and removed all the little mountainous tracks that i could reach