Porting an intake manifold for FI

[KeWLKaT]

Alright. I need some smart peoples' input here.

I am in the process of finding an intake manifold that I will port myself for my application. Here is what I want to do with it:

- Port TB side to 58mm to match my BBTB.
- Gasket match the runners for improved flow.
- Paint with ceramic paint, I'm thinking like 5 coats, the ceramic part of the paint will help it slightly with heat soaking, I know it's not as good as ceramic coating it, but it's the next best thing other than ceramic coating it which is quite expensive.

Now:

For the runners:

- I will be leaving the hump because the head DOES have the hump and removing it on the intake manifold will just cause further problems in flow disruption.

- What I want to do is not make it completely smooth by polishing. Remember, I have a 5th injector spraying fuel before the TB. I want to help with the fuel atomization, and I'd like to give the surface the proper texture in order to promote this. THIS IS WHERE I NEED HELP. What do you think I should do technique-wise in order to help with atomization? Strait lines, perpendicular to the flow, or parallel? Or just randomly sanding the surface with sandpaper?

I will be using my dremel, for which I bought a porting and polishing kit a little while back, I have the bits for porting in all different grits, and I also have the bits for polishing, aswell as the compound for that.

I have a dilemma though, since we're talking about fuel atomization... Should I think about texturing the manifold's inlet aswell? And since i'm in there, what about inside of the TB itself?

I'm thinking about knife-edging the butterfly of the TB aswell while i'm at it.


COMMENTS? Thoughts?

I will be putting the spare OEM tb back on the car for the time i'm doing this. Keep in mind I am buying a spare IM aswell, so downtime is no problem. I'll take a good 1-2 days to do this properly as soon as I recieve my hardware.

[slow 2K2GT]

first get something a little stronger then a Dremel, second, dont do the manifold unless you are willing to work on your head as well. That hump will need to come out even if is only on the intake side. Remember small runners help to keep boost pressure up, I would agree on the high heat coating but if you are so worried about intake temps then get a injection kit. The intake manifold isnt going to be your biggest restriction I dont think, arent the charge pipes pretty small with the alpine kit...if you can get some larger pipes then I would worry about the manifold.

[ricerrx7]

Are you sure you need to worry about atomization with your setup? I know why you need the textured manifold in carbureted/tbi cars, but in your case the fifth injector only comes on with boost right? Are you sure the texture is going to be such a big deal?

[KeWLKaT]

Slow...

As far as the porting goes, the runners will be slightly honed just for smoother flow, nothing bigger. The only thing that's going to be bigger is the TB opening really, for the BBTB. I want to make the best out of the setup I have right now, that's all. It does kind of a venturi effect if you will.

Ricer....

Yes, the 5th injector comes on in boost only. Actually, more like at 1-2 pis methinks. Yep, I'm thinking of the same concept as a carb car if you want. I know dmdicks had mentionned it at some point but I'm not sure in which thread.

[slow 2K2GT]

again even with a larger diameter TB opening, the charge pipes will cause some restriction.

[KeWLKaT]

at this point they are not restricting enough to worry about anything.

Like I said, i am creating a venturi-like effect with the small charge piping and the large IM area. We have done this with our SAE race car we built from scratch at school and it has been proven VERY helpful.

[ricerrx7]

Wouldn't it be better to have the venturi pointed directly at the valve (head porting...), than to have to venturi leading to a random point in the intake manifold? What's the used of speeding up the air if it just has to turn right away?

[KeWLKaT]

it was just a way of defending my point, haha.

I am just opening up the IM for less turbulance because of my BBTB really and to make a nicer looking manifold aswell ;)

[Jonny666]

As far as i can tell you will want to use aprox 60 grit sanding rolls to finish the runners (and anything else that comes in contact with the fuel) and you will want the roughness to be 90 Deg. from the flow. Your going to have some issues trying to gasket match tho. For some bizzare reason our gaskets are proly at least a good 1/4 inch larger than the ports on all sides. its kinda outragous. the only real way to port match on our cars would be to make a template and do the head and the intake manifold. Also, your SAE race car is likely N/A rite? that's unfortunatly a whole new ball game. Us N/a guy's rely a great deal more on the whole pressure wave tuning crud and inertia supercharging effects to better fill our cylinders. the turbo boy's can just up the boost if they can handle more air without knocking. You are flowing a great deal more air into a manifold that was designed for a dinky 2L motor. your worst enemy is restriction.

[KeWLKaT]

i know i know, it was just a thought that went through my head ;)

I will never change the piping, or else it will lag even more which is what i want to avoid. Throttle response right now isn't as good as when i was NA but i'm hoping to correct this with the mild porting and a monster intake pipe with a huge filter (ok, not that huge, lol) i'm thinking 3 inches.

so.... 90 deg to the flow eh.. thats what i thought. thanks ;)

[Rystibby04]

mine was done but ford for my turbo it seems to help...