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these are things said by a few members on another forum. i felt it somewhat persuading (in a good way) to anyone thinking about the service, as these are unbiased people, simply members of another forum discussing the process. there were lots more comments & none negative towards the process. emmaculate whats up with the GB!!!???


you cannot compare a hand job PnP with EH. If you truly understand how EH works then there would be no question regarding which is better and how the processes are different.

I don't care who performs the PnP job, a human cannot reach all the same areas and remove material as accurately as EH. The only reason EH might not yield gains across the entire rev band would be due to improper port matching.

The concept of distributed forces over an area (i.e pressure) being used to refine the surface and remove material from a closed passage is superb.

The surface finish that results from EH is ideal for maintaining the boundary layer and improving flow. PnP is old school and anyone that tries to suggest polishing any surface is going to improve flow performance is just living in the past.

Pick up a fluid dynamics or thermo book in the library and get informed before wasting $500 on a PnP hand job. Save your cash and do it right.

Assuming that the abrasive media is exerting equal pressure in all directions and an equivalent amount of material is removed from the entire passage, the venturi shape or relative geometrical shape should not change dramatically.

Increasing the overall cross sectional area slightly may have less of an effect on velocity than simply reaching in with a grinding tool and removing gross amounts of material where you can gain access. From what I recall when studying this in fluids class many years ago, the valve opening was actually the throat or smallest section of the venturi where fluid (air & gas mixture) velocity was supposed to be the fastest.



Assuming that the abrasive media is exerting equal pressure in all directions and an equivalent amount of material is removed from the entire passage, the venturi shape or relative geometrical shape should not change dramatically.


They inject an abrasive paste at high pressure, into (a manifold, intake runners, heads, ect) to port the entire runner. The finish is like glass, and looks like a mirror. It cuts the entire runners at the same time, with the same pressure and same abrasive. There wont be any deviation from one runner to the next.

I had a GM TPI intake ported back in the day to match my heads (called a port match). Problem with this is.. you can only go so far into the runners of the intake or the head. usually its only about 1-2" deep.. which is enough to give you gains. But the problem with the porting by hand is.. mistakes can be made.. and sometimes the port work from one runner to the other is uneven.

I sent out my intake and heads to extrude hone.. got them back.. installed.. took it to the dyno.. made an additional 15rwhp OVER the original portwork which netted me 12rwhp to begin with.
 

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I am happy with the qulaity of the job I received from Extrude Hone. They gasket matched the openings on the intake and then from there I passed them on to my machine guy who then matched the intake on the heads. I am very excited as to what the out come will be.

I will try to start a GB for this later on, just for a heads up the price will be $400 for a minimum of 4 people.
 

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you cannot compare a hand job PnP with EH. If you truly understand how EH works then there would be no question regarding which is better and how the processes are different.

I don't care who performs the PnP job, a human cannot reach all the same areas and remove material as accurately as EH. The only reason EH might not yield gains across the entire rev band would be due to improper port matching.
+1 for extrude hone.

You should not compare a hand PnP or even a CNC job with Extrude Hone. What the OP missed mentioning (or wasn't mentioned in the quoted material) is that Extrude Hone works so well because the abrasive paste removes material where there is a restriction to the flow. A good port job is not necessarily replaced by extrude honing if there is a substantial flaw in the part being modified. If there is a lump of restrictive material inside a casting (especially common in aluminum V8 intake manifolds), the EH process will optimize flow around it, where a few minutes with a grinder will remove it completely. The point that EH maintains uniformity across all ports/runners/etc. is unfounded. EH is only as good (or bad) as the part was before you put it through. If runner to runner there is a large difference in primary flow characteristics, then there will still be that difference afterwards. Once again, EH doesn't correct or fix major flaws, it optimizes forms in their current shapes.

You can also shape venturis and velocity stacks into castings that didn't originally have them, with PnP, further optimizing the flow.

If anything the best way to use extrude honing is to replace the 'polish' step on a PnP job. Extrude hone is a great choice for people modifying cars without a wide following (because experience is key in porting for proper gains) and those who want the extra edge.

Where EH absolutely gets it right is that they don't remove too much material in easily accessible places by the hand PnP guy, a common mistake, and a sure way to destroy flow characteristics.

The surface finish that results from EH is ideal for maintaining the boundary layer and improving flow. PnP is old school and anyone that tries to suggest polishing any surface is going to improve flow performance is just living in the past.

This is a misplaced criticism on semantics. 'Port and Polish' is really only used to describe removing and shaping material and then cleaning up the tool marks. Even then, the microfinish associated with polishing or extrude honing is a good thing, either way. Rough, uneven surfaces create turbulence, which is usually a bad thing.

Pick up a fluid dynamics or thermo book in the library and get informed before wasting $500 on a PnP hand job. Save your cash and do it right.

Increasing the overall cross sectional area slightly may have less of an effect on velocity than simply reaching in with a grinding tool and removing gross amounts of material where you can gain access. From what I recall when studying this in fluids class many years ago, the valve opening was actually the throat or smallest section of the venturi where fluid (air & gas mixture) velocity was supposed to be the fastest.
This is 100% true. If you let the local machine shop who just rebuilds 'stuff' PnP your head/intake/exhaust you're tossing money away. Most people have bad results because they don't spend the money and/or the work is substandard. If the shop doesn't have a flowbench, then I wouldn't let them polish the head on my dick. Seriously.

Extrude Hone is an excellent choice, no matter what level of preparation your motor is at, from stock to full lock. It just doesn't stand alone as well as this post seems to indicate.

GSM
 

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So given the current mods available to us G2 guys, coupled with a quality EH job, you could get some decent gains for your $. I would spend my $ getting the EH over the hand pnp, but if you are more inclined to hand pnp yourself, by all means go ahead, you will save $, but for you guys that arent so diy inclined or just dont have the time, I say go with the EH. Be prepared to spend about $450-$650 for EH and have a budget to replace other parts along the way just in case. Just my $.02
I think my post was a little more anti-EH than was intended. It's great. I was just speaking against the material saying that EH replaced the PnP job altogether.

Unless you have a flow-bench and a ton of experience and patience you shouldn't touch the heads on your car, yourself. The dollar savings are false economy at best. Jesus. If anybody is thinking about taking a grinder to their heads and doing it DIY-style you need to go find a bum somewhere and pay him $5 to kick you in the nuts...then take the rest of your money and get the Extrude Hone job.

Seriously.
 

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I will try to start a GB for this later on, just for a heads up the price will be $400 for a minimum of 4 people.
$400 for heads and IM? I'll be down!

Where are they located cause I know shipping weight is going to kill me.. :(
 

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Are there any flowbench numbers for our int-manifolds, stock and EH-modded?

I found this post on another forum Why it doesn't make sense with regard to EH vs PnP.

Please know, I am always openminded and very favored to EH process(esp when I see a EH-Honda win a race or 2 on the drags), with that link I'm keeping in mind those comments may be anecdotal and 1-sided...since its just 2-3 people commenting. Which goes back to my question, flowbench numbers?
 

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That site pretty much backs up my criticism about considering EH as the 'only answer.'

You cannot improve on inherent problems present in the parts by running them through the EH process.

I would also like to see stock flow numbers.
 

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The GB has been started for the Extrude Hone service! Sorry it took so long.
 
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