extrude hone is it worth it????

[Carrera3.5L]

Originally posted by island911
This all comes down to the belief of the 911 owner.


If you believe; that the porsche engine engineeers, and all their legacy data, testing, tweaking, retesting, tweaking . . .watching highspeed combustion-chamber flow characturistics, retesting, tweaking; watching engine power output, retesting, tweaking . . ..somehow left something on the table.
And, that these guys who figured-out a way to make a hole bigger & smoother by squishing abrassive mud thru (like a big ol turd) have trumped those simpletons at porsche; Then, yeah, extrude-hone is the answer.

I dont know that E-H even gives any peakHP addvantage. But, for sure, the notion of "higher flow' sells (K&N, coffee-can mufflers ... )

If every car manufacturer got the max potential out of every motor there would be no need for any of us to mod our motors for more power. Fact is, there are fights between the accounting and engineering depts on a daily basis regarding performance improvements on production line models. The company I work for develops and builds some OEM performance parts for Daimler-Chrysler, Ford and Saab (GM).

If a performance enhancement is not selected for a production model, it is often times due to cost reasons and not because it doesn't work. This is completely out of the hands of the engineers. Contrary to the belief of many people on this forum, Porsche is just like other automakers where costs do matter for street production models. Their employees put their pants on one leg at a time just like the rest of us.

And yes, as I stated earlier, extrude honing does help at the top end (at least according to Andial's engine dyno) but doesn't really do anything in the mid-range. What is important here is that you don't LOSE anything in the low and mid-range to get that little bit of peak power because that is what affects normal drivability. Of course, displacement increases will help alleviate that issue.

Here a couple before/after pics of Extrude Honing my plenums. Sorry for the less than professional quality:

Before:



After:



Valid point on the high flow numbers though. Hopefully people don't automatically assume that huge cfm gains translate to huge horsepower gains. I don't think that has been claimed anywhere in this thread though

Ralph

[89911]

Extrudehoning is just a part of the components that, in addition, can make an engine run better. By itself, it would be a waste of money. Just like a bored throttle body would or new cams, or just headers. But add them together and they can make some nice gains.

[fastpat]

I agree completely. Doing six improvements to my 3.2 that gain 5 horsepower each, for 30 hp, at 3500 rpm would be worth around $2500-3000. Since guys are spending $8000-10,000 for a 3.6 liter engine to gain about double that figure, it might be very cost effective.

[jpahemi]

One thing that hasn't been discussed here is the ability of EH to equalize the flow #'s on each of the runners. I had my plenums done and recieved the before and after figures.
The before difference between the high and low flow #'s was 14.3 CFM (5.75%)
The after difference was 10 CFM (3.55%)
Flow done at 28 inches, pressure: 29.6.
From what I remember the full throttle growl was a bit deeper and the upper rpm range felt more elastic.
J.P.
Ps. If you check Steve Weiner's site, his high/low #'s are as low as 1-2 CFM difference between the runners. These #'s can be played with depending on when the flow #'s are taken during the flow process. Iwasn't that thrilled in my high/low difference, so I asked why they couldn't get them closer; basically it depends when they take the readings.

[Steve@Rennsport]

Great thread,....

I'd just like to step in and mention a few things.

Airflow in Carrera manifolds varies all over the spectrum; some aren't bad and some are terrible (relatively speaking). Needless to say, some sets will benefit more than others with the EH process and further engine modifications such as displacement changes and cams will enhance the effects.

For many years, we used to cut them open in a bandsaw and spend 30-40 hours of labor working inside each runner to equalize their airflow on our flowbench. The EH process has eliminated such tedium with better overall results and I'd rather spend my time doing heads or other such endeavors that EH cannot replicate.

Each and every set of manifolds gets flow tested before we send them to EH and after the EH process to measure the improvements in that particular pair. AVERAGE results are posted on our website, however they do differ from set to set.

Porsche learned all this very well and by 1992, the 3.6's came with an injection-molded plastic intake that was much better than the earlier aluminum ones (which we used to do the same things).

We have installed the plastic 3.6 manifolds on 3.2's (using some custom adapters) and that works very well.

[A Quiet Boom]

IMHO I don't care for EH unless it's simply to smooth out the surface. Comparing 911 heads to Al aftermarket Ford heads I can see why 911's make such good HP per liter. In the Ford aftermarket there are plenty of shops that do CNC port work based on lots of flow bench testing. A larger port is not always better, the idea is to get more airflow without losing too much velocity which is why the V8 aftermarket spends a lot of time working on particular trouble areas of the heads. Ideally you'd have a professional either hand port or CNC port your heads using a flow bench to test the results. For many 911 parts I'd simply clean them up myself and match the heads to the intake so the transition is smooth. This is called port matching and ideally the intake exactly matches the port and lines up perfectly, in the real world we often size the intake just a touch smaller than the port to help with misalignment as well as work against reversion. The exhaust side is where I get critical of Porsche, the later cars had part of the exhaust tube going through the flange up into the port which is exactly the opposite of what you'd like to see. A step up in size from the port to the header can really help build HP as long as it's only a small difference. Example I ran 2' OD headers on my drag car and sized the ports to 1.980" I was able to torque up the intake to the heads and block without valves or pistons and hand ground the intake to head transition using a flexible wand on a Dremel tool, the end result was just under 100HP/liter on a pushrod engine that occasionally saw street use. Even with large ports, intake, and exhaust, a big cam and big carb I could break the street tires loose in high gear at freeway speeds. Plenty of torque and HP on hand. I love my 911 but I sure miss the days of 600+ naturally aspirated HP, sure the cam gave the car epilepsy but when it came "on cam" very few cars could even think of keeping up.

Back on topic, EH removes material from all surfaces without concentrating on the problem areas. Use it only to smooth out the surfaces or for a minor port job.

[island911]

Interesting.

I would expect the move to plastic was more about plastics much lower thermal conductivity (keeping the in take cool) and the lighter final part.

Manufacturing a smooth aluminum casting certainly could have been done. It's all about the tooling. (btw, the tooling for the plastic will be more expensive, for sure.)

[Carrera3.5L]

Hey Steve,

Other than the obvious benefits of potentially keeping the intake charge cooler and the lighter weight, is there a significant CFM gain and/or variance or measureable horsepower difference between the plastic 964 plenums and an Extrude Honed 3.2/early 964 aluminum version? I don't remember anyone ever playing with this while at Andial. We were too busy gutting Cup Cars in '92, putting them back together and than gutting most of them again.

Ralph

[Steve@Rennsport]

Hi Ralph:

Indeed, there is a worthwhile HP gain from using the 3.6 plastic intake on a 3.2-based engine. Flow numbers are up as well as the obvious thermal benefits. We did not try a suitably modified aluminum 3.6 intake since we didn't have one here at the time.

Its a work in progress around here so I'm unable to share specifics, but all of the dyno work was well worth the efforts and the in-car performance is impressive for a mild 3.2. This one has DTA Engine Management so we could manipulate all the parameters as needed to properly evaluate everything.

[Carrera3.5L]

Originally posted by Steve@Rennsport
Hi Ralph:

Indeed, there is a worthwhile HP gain from using the 3.6 plastic intake on a 3.2-based engine. Flow numbers are up as well as the obvious thermal benefits. We did not try a suitably modified aluminum 3.6 intake since we didn't have one here at the time.

Its a work in progress around here so I'm unable to share specifics, but all of the dyno work was well worth the efforts and the in-car performance is impressive for a mild 3.2. This one has DTA Engine Management so we could manipulate all the parameters as needed to properly evaluate everything.

Thanks Steve,

This sounds like an attractive alternative for many of us 3.2L owners. I don't know how much the plastic 3.6L intakes go for on the used market, but I see used 3.2L Carrera alu plenums selling anywhere from $200-$400 for the pair.

It MAY be more economical to sell the alu plenums (thus also saving the high Extrude Hone cost) and purchase the plastic plenums with custom adaptors. As long as all the 3.2L ancillary brackets and fuel system components easily bolt right up to the plastic plenums, this sure looks like a win, win, win proposition to me.

Anyone know what 3.6L plastic plenums sell for?

Ralph

[Quicksilver]

Smooth is not the holy grail on the intake side. Texture can help keep fuel in suspension. You do not want a mirror finish. Also a little boundry layer turbulance can decrease the thickness of the boundry layer and help flow turn around the short side easier. (The thinner boundry layer is what helps with fuel dropout.)

Shape is what you are looking for not texture. If you get a good shape with a mirror finish it will kick the hell out of good texture with bad shape. Still good shape with good texture wins.

The holy grail will be found in increasing flow with the least increase in port cross-section. You are trying to keep velocity up as that leads to all sorts of good things.

A good porter should be smarter then a flow of abrasive muck. EH is going to do more removal on the long side of the port where you don't want it. It isn't going to do as much on the short side which is where the big gains are made. It certainly won't try to get a good "D" shape in the corner to help flow turn the corner.

The 911 motor was delivered with a good compromise between low-mid range driveablity and high end power. The ports were kept smaller so you have better power where you drive it most. When you decide that you want to have more power and will compromise on the lower end then of course the port you want will need to have higher flow and to get it you will need to increase the cross-section some.

And of course you will get more power...
...but there is no way that extrude hone will get the same power as a good set of hand ported heads. It will make it cheaper though. I do think it would be useful on the exhaust side as a surface treatment after the hand porting is complete. (Smooth is good on the exhaust side: no fuel in suspension)

[jyl]

Originally posted by Quicksilver
Smooth is not the holy grail on the intake side. Texture can help keep fuel in suspension. You do not want a mirror finish. Also a little boundry layer turbulance can decrease the thickness of the boundry layer and help flow turn around the short side easier. (The thinner boundry layer is what helps with fuel dropout.)

This makes sense for a carburated engine where fuel enters at the beginning of the manifold. In the 3.2L, fuel doesn't enter the manifold until the very end of the runner, down where the injector lives, so keeping fuel in suspension wouldn't seem to be an issue for the manifold?

I recall Bruce Anderson's book had some tests where various mods were successively done to a 3.2L with dyno runs after each, and the Extrude Honed manifold did increase HP. Not by a lot, but actually none of the mods increased HP by a lot. I don't have my book handy, or I'd post the details.

Steve, along the lines of using a 3.6L intake on a 3.2L, I would like to ask if you know whether the 3.6L heat exchangers will bolt up to a 3.2L? For a street car that needs catalytic convertor, heat, and a stock "look" that can squeak by a visual inspection, I wonder if this would provide more flow on the exhaust side. For example, if someone's converted a 3.2L to a 3.5L.

[jpahemi]

The 3.2 plenum is a dry intake, the fuel is injected into the port, so fuel suspension is not an issue with EH.
j.p.

[Quicksilver]

Originally posted by jyl
This makes sense for a carburated engine where fuel enters at the beginning of the manifold. In the 3.2L, fuel doesn't enter the manifold until the very end of the runner, down where the injector lives, so keeping fuel in suspension wouldn't seem to be an issue for the manifold?

. . .

Correct, but nothing that interesting is happening in the manifold. The real gains will be in the heads. (The real expensive gains!) The hard part of any intake system is turning the flow right before the valve. When you turn the flow more then 11° the flow will detach from the short side. Everything that a good head porter does is to recover from this fact.

The runners in the manifold are straight so all you are looking for is consistent port cross-section that is equal across the ports. This will get you the equal flow. I would flow the manifold and if it is out to lunch then I would fix it. I would work on the heads and if they dictated a larger cross-section then I would go back up into the manifold.

More velocity. Pack those cylinders!

I think there might be some possible gain in setting up a higher energy boundary layer before it gets into the head (where it is dry) but I am only guessing. Once the boundary layer gets thicker it is hard to get rid of it. Still I would worry about shape before texture. I knew a guy who said he was going to try extremely small vortex generators upstream of the short side to see if it would turn the flow better. Not sure if he tried it or if it worked.

I wonder if anyone has tried making the runners more of a "D" shape up in the manifold to directly feed a good head that is "D" shaped on the short side. It couldn't hurt and it would be fairly easy...

[Steve@Rennsport]

Originally posted by jyl
Steve, along the lines of using a 3.6L intake on a 3.2L, I would like to ask if you know whether the 3.6L heat exchangers will bolt up to a 3.2L? For a street car that needs catalytic convertor, heat, and a stock "look" that can squeak by a visual inspection, I wonder if this would provide more flow on the exhaust side. For example, if someone's converted a 3.2L to a 3.5L. [/B]

Hi John:

Assuming that you are asking about 993 heat exchangers (964 ones are not worth any effort), its definitely a LOT of work to attach those to 3.2 heads.

The studs are clocked the wrong way on one side and the outlet flanges face the wrong way to permit the cats AND a muffler system to fit these cars.

IMHO, not worth the efforts.

[Nine9six]

Originally posted by 350HP930
All the process is good for is smoothing passages by removing casting roughness. If your passages are not really rough then the results will be negligible.

To think that it can even out uneven flow through a manifold is wishful thinking.

Some think the rough passages help to atomize the AF mixture...

[fastpat]

Originally posted by Nine9six
Some think the rough passages help to atomize the AF mixture...

Not true with a dry manifold, there's no fuel in the manifold until just before the air enters the head. Virtually all atomization is handled by the injector, a major strong point of individual injector systems.

Swirl in the combustion chamber is handled by chamber shape and valve proximity to the chamber wall.

[cgarr]

Originally posted by Nine9six
Some think the rough passages help to atomize the AF mixture...

If your passing an air/fuel mix (carbs) then is always good to just ball hone the passages, if you polish them the fuel can form droplets on the sides rather than a sheeting process. Since your only flowing air it may be better to polish it? I dont know, I have only worked with carb intakes...

Craig

[350HP930]

As soon as I get done eating and perusing the internet I am planning on testing my DIY ported manifold on the home made flow bench.

DIY Flow Bench

I will make sure to link to my data when I am done.

[fastpat]

Originally posted by 350HP930
As soon as I get done eating and perusing the internet I am planning on testing my DIY ported manifold on the home made flow bench.

DIY Flow Bench

I will make sure to link to my data when I am done.

Don't forget to figure in your hours invested in the job, at around $90.00 per.