how much hp does matching/porting intake/heads add?

[cp2295]

i saw in the tech section showing how to match the size of the intake, throttle body, heads, and exhaust ports. how much hp/torque does this legitemately add and is it worth the time? i got everything out already so thats not an issue. does this decrease mpgs in anyway?

makes sense it would add hp since the transition of air flow is smoother, just don't know if its worth the gains.

if anyone has done this can you give me some pointers? tools to use?
thanks!

 

[swynx]

Dremel type tool. If you've got the time I would do it. They dont p&p race cars for shits and giggles

 

[RonD]

The gain would depend on how the ports are now vs after, rough guess would be approx. 5%-10% gain.

Anytime you make an engine more efficient you get better MPG....IF driven the same way.
The port and polish means there will be less fuel staying on the walls and obstructions during entry so O2 sensor will report rich and computer will close injectors sooner, so better MPG.
Also less carbon build up.

 

[cp2295]

I'm doing it, is the plastic intake manifold too sensitive to touch or can I match those surfaces as well?

Why don't they do this from the factory just out of curiousity?

 

[stmitch]

The gains from porting and polishing vary widely. It really depends how restrictive the stock castings are, and how far you go. People have gone to far and gotten worse power/economy before, but generally it's not going to hurt, and in most cases will help. Every port job is a bit different.

The most important tip I can give you is to be patient, and let the tool do the cutting. Don't apply lots of pressure. Slow and steady is the key so that you don't remove too much material, or go to far. Gasket match the openings, and then focus on smoothing and blending any sharp corners into rounder, straighter paths for the air.

 

[cp2295]

Okay I'm just kind of confused about how I'll know the surfaces will mate equally. When you say gasket match do you mean take the gasket onto each surface and see if it's the same on both sides? It just seems like the only way I could tell is if I mated them together and had x ray vision or something!

 

[cp2295]

A tape measure would work but I doesn't seem as effective as seeing them together

 

[RonD]

I'm doing it, is the plastic intake manifold too sensitive to touch or can I match those surfaces as well?

Why don't they do this from the factory just out of curiousity?

Never done a plastic intake so can't say.


When you are done............then you will understand why factory doesn't do this to every engine.
General cost for V6 to port and polish runs from $700-$1,700, another reason factory doesn't do this.

Factory could also increase compression, better MPG and horse power, BUT..........., also a better chance of regular gas pinging so higher octane needed, or sparking timing has to be retarded so much that any gain in either MPG or HP is negated.

 

[cp2295]

Okay I read into that tech article a little more, still kind of confused about the gasket matching. From what I understand, you place the gasket on your piece of work (intake for example) and then you scribe around the gasket onto the intake, then you take off the gasket and proceed to sand away all metal until you reach the point where you scribed at. Also go down 1.5" and smooth that transition. Then do this to the opposite side of the gasket (the head in this case). Is this correct?

Also no gasket matching the exhaust manifold unless the manifold ports are smaller than the head, just polish them really good. Is this correct?

 

[stmitch]

To gasket match:
1. position the gasket where it would be located once the install is done, and tape it down.
2. Secure the gasket so that it can't move. Tape is fine.
3. Trace the areas that you want to enlarge. You can use a scribe, but I'd suggest using a colored dye, paint, or marker. That way, it will be easier to see what material needs to be removed. They make special machinists dyes, but I've used a fine tip marker before too.
4. Remove the gasket carefully so that it doesn't get damaged
5. Start grinding, and keep grinding until the colored dye/paint is gone.

For the rest of the porting, the idea is to give the air the easiest path into and out of whatever piece you're porting, so smooth out and soften any sharp bends as much as possible. Get rid of casting roughness and mold marks as much as possible.
A lot of people leave intake runners a little rough, like 150grit sandpaper. They say it helps the air and fuel swirl around and gives you a better mixture.
You are correct about the exhaust ports.

 

[cp2295]

Okay one last question, is 16000 rpms enough? At harbor freight and they got two options, one for $10 at 16000 rpms, and one for $25 at 35000 rpms.

Thank you all for the prompt responses!

 

[RonD]

Also MARK the gasket for which side goes where

 

[kimcrwbr1]

I watched a video one on port and polish and they used water to determine how much material they removed. Put the valve in and fill it with water using a large syringe. You want the intake or the exhaust to hold the same volume of water just put a light coat of grease on the valve seat and stem to hold liquid and protect from rust.

 

[kimcrwbr1]

http://www.powerblocktv.com/episodes/HP2011-02/horsepowers-port-and-polish-for-power-how-to
Here they used alcohol to measure the volume good video answers most of your Qs.

 

[UrbanRedneckKid]

My quick .02...
Mine were done a long ways back. It just seemed like a really good running 4.0. Then I put headers, y-pipe, high-flow converter, Accel coil, NGK iridium plugs gapped to 0.055... It came alive.

My conclusion was, more flow in one area is pointless without more flow thoughout everything, and with a better air charge in the cylinder the hotter spark was put to use.

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