Anyone here used ExtrudeHone?

[Rot 911]

I am thinking of sending my 3.2 intake manifold off to them to have it extrude honed. Any happy or unhappy users here?

[RickM]

Kurt, I believe Steve Wong had his manifolds done. I wonder how much of a real benefit this process affords a 3.2.

[Jim Richards]

Kurt, there were a few threads on this process in the past. Here's one from a search on "extrude hone."
Extrudehone???

[Rot 911]

Originally posted by Jim Richards
Kurt, there were a few threads on this process in the past. Here's one from a search on "extrude hone."
Extrudehone???

Note to self: Remember to use search function. Thanks!

[john walker's workshop]

what about the head ports? 3.2s already have pretty large ports.

[dd74]

I've done some research on extrude hone which mirrors what's written on the board. $500 for 5-7 hp is a lot.

Say one (like me) wants early CIS (78-79): that's $500 right there, I believe. I want to optimize the CIS, so I have it extrude honed: that's another $500. I've spent $1K on CIS. That's definite Weber territory IMHO.

John - do the 3.2 heads truly work on a 3.0. I've heard of this being done before, but for very little gain from what some have told me. What's your opinion?

[Rot 911]

From what I have seen $100 per horsepower is cheap on a Porsche.

[Laura-Hergesheimer MotorS]

Kurt,

We have used these guys for few years and have been happy with their work. They are pretty busy, so be sure your time frame will work with theirs.

[Rot 911]

Laura, thanks for the info!

[Andras]

Guys, be careful and think twice before you lay out your dollars.

I have asked Orbit Racing this very question, and the answer is that the intake "pipes" on a CIS are purposefully rough on the inside, to help induce turbulence in the intake charge, thus filling the combustion chamber more thoroughly, for better flame propogation.

In short, Porsche AG designed them this way (with rough walls for turbulence), and smoothing them will not add horespower.

Would Orbit not do this if it would help them get an edge on Alex Job Racing?

[RoninLB]

Originally posted by Andras
intake "pipes" on a CIS are purposefully rough on the inside, to help induce turbulence in the intake charge, thus filling the combustion chamber more thoroughly, for better flame propogation.

Andras has a good point on this one..
a "boundary layer" is formed and, especially at mid rpms, is very efficent. very high rpms is another story ......Ron

[Steve W]

Rick is right, I did have my manifolds Extrude honed back in the day. It was based on a tech note by the old Bruce Anderson on some dyno tests they did back in the February 95 issue of Excellence. To summarize the article, I'll put the essence of the dyno runs here:

Starting with a 3.5 twin plug Carrera engine, and a mass flow sensor system, they got:

RPM HP
2500 88.8
3000 109.6
3500 132.5
4000 158.6
4500 187.8
5000 215.0
5500 234.5
6000 244.2
6500 229.1

They then changed the intake manifolds with some that had been Extrude Honed:

RPM HP
2500 88.7
3000 110.0
3500 132.2
4000 158.1
4500 188.2
5000 219.2
5500 238.6
6000 251.7
6500 235.5

You can see that the hp increase is exponentially proportional to the increase in air flow volume, and is nil at low volumes. It's pretty hard extracting hp out of a Carrera motor without spending big bucks, and a lot of some manufacturers claims out there are pretty exaggerated. Since this was independently proven, I knew what to expect, so I was satisfied. There really is no benefit to hand polishing the Carrera manifolds over Extrude Honing. My sources from guys who used to work at Andial tell me that they used to cut open manifolds and polish them as part of a performance enhancement package that consisted of this, plus a chip, and a muffler. When the Extrude Hone process came out, they measured no performance difference between doing it by hand or by Extrude Hone. I've been told that of the head guys at Extrude Hone claim that displaying even flow numbers between intake runners depends on when the guy presses the button on the air flow bench. The air flow measurments fluctuate so wildly between runners on the flow bench, that if you hit the record button at just the right moment, all the numbers can appear to match up pretty close to each other - enough for show anyways.

[Randy W]

Don't know about how it works on a CIS 2.7 or 3.0, but on a Motronic injected 3.2L the extrude honed manifold is worth 5-10hp, depending on other mods present like enlarged throttle body and injectors. There was a perceivable increase in pull above 4000 rpm and dyno tests backed this up when it was installed on my car and the fellow's car I later sold it to.

[Randy Webb]

Yes. You can definitely put the 3.2 heads on a 3L -- and they flow really well. That was done on a car owned by Randy Jones, I think. He may be on the list.

The extrude hone will not do much for you except at high rpm and see above for the other caveats.

[89911]

This is lifted from Steve's site at "RennSport":

3.2 Carrera's also respond to some intake manifold modifications due to the uneven airflow characteristics of the OEM manifolds. The stock Carrera's intake manifold runners are well known for unequal airflow and there are some great gains to be made here that translate into more power, greater smoothness and better drivability from each cylinder receiving the same quantity of air and fuel.

Airflow comparisons from 3.2 Carrera Stock vs Flowed Intake Manifolds

Cylinder Stock Airflow cfm Flowed Airflow cfm
#1 277 351
#2 280 349
#3 280 351
#4 295 351
#5 286 349
#6 289 352

I'm not sure what method he is advocating for increased airflow. The increase looks to be about a 25% increase. This in line with other modifications would help in a limiting motronic setup.