It's not so expensive that I think it's not worth experimenting on when I know that I have plans to go to FI at some point. I can get a used manifold for a couple hundred bucks, and EH is $400. I plan to work with a local tuner on a block of dyno time, so this is just one of many mods I plan to measure.

Maybe chalk it up as my costs to the greater cause lol.

https://www.extrudehoneafm.com

They are the only ones that do this type of work that I'm aware of. If others are interested, I can ask them about a group buy.

Yes, though once you start stacking other mods the effect seems to be less noticable.

This is one of those mods that all the evidence out there is anecdotal so people are always going to take it with a grain of salt or treat it as confirmation bias. The only real thing you can do is post a baseline dyno and a post install dyno to show real results. That is a lot of money to prove something to people on the internet. If you do this and are happy with it, cool.

You have to remember there are a lot of people that tout the difference they feel running lightweight pulleys, flywheels, driveshafts, and Pilot Sport 5's so we get a little jaded when someone says I did "X" and notice this difference but have not other information to provide other than what they feel.

I agree with you on that. I'm almost 50 and built a lot cars over the years, and I've always wanted to try extrude honing. Money is much less of an issue for me than it used to be building cars in my 20s and 30s, so it's worth a try.

I'm 100% certain there's value in doing it, but the question is how much value. If nothing else, we'll have a nice cool red manifold that I can say made this tin can 992 Turbo S fast.

Basically, yes, which then puts the power in a more usable RPM band. As I said, I will get my car back on the dyno later this summer to verify the difference both with the stock tune and my self-tune on ECUTEK with the power blocks, so we'll have another real data point for them on an otherwise-stock motor. ;)

What is your experience for concluding there would be a lack of gains?

Note: I ran E85 and a 2mm overbore OEM TB while NA using this IM and adjusted the cam angles for optimization later on.


Best representation:
Red-MY13 IM,

Blue-MY17 ExHn.


https://i.imgur.com/scYgfDO.jpg
I data logged on the same road and conditions several times. The logs indicate more MAF usage (g/s, Vs) as well as running a bit leaner. The pulls also took less time.
I don't imagine you can feel any gain under 5hp. From the research I did on the subject before initiating the project 3-5%hp increase was common on NA motors. No data on FI. Ford used the process on the SVT 2.5 Contour SVT back in the day and it was good for 5-10hp.

2013 IM vs MY17 extrude honed. I never bother bolting the MY17 up before the processing.

Oh yeah, I ran the BPBs before with a tune calibrated for them as well. OFT offered it years ago. The more bolts on you add the less they made a difference. I ended up removing them to run E85 which was the best bang for the buck NA.

Where I've seen folks get decent gains in the past with Extrude Honing, it's either been on parts that had pretty poor castings to begin with (E.G. some older watercooled VW intake or exhaust manifolds) and the process in combination with some manual grinding/porting cleaned things up a lot, or where it was used to pretty aggressively increase the volume of the intake runners (E.G. on a Hyundai Tiburon V6 upper and lower intake manifold, which was then also port-matched to the heads - ultimately, with that car, fabricating an entirely new upper manifold was a better option because the plenum also needed to be much larger for better top end).

The casting on the stock 2017+ manifold looks pretty clean already, so I'd be surprised if Extrude Honing improved flow that much. I absolutely could be wrong though.


That would make a bit more sense, since it was shown that there are gains with the 2017+ manifold swap alone at the very top end of the power band because it seems to fall off less after the peak than the pre-2017 plastic manifold. Pretty sure there was a Drift Office dyno on it somewhere. Peak HP gains were minimal (1-2 hp at best), but it didn't drop off as badly at the very top.

People seemed to talk all kinds of crap about the manifold just "being pretty" and not doing anything because the dyno only showed a 1-2 hp peak gain, and conveniently ignored the HUGE difference in the post-HP-peak RPM range.

It's kind of like the argument some people have about the BPB's being a waste of money because they don't add a bunch of peak HP (which they don't), but there are substantial gains in "non-peak" areas that make them worthwhile for me because I don't particularly care about the peak numbers, and more about fattening the middle of the curve.


I've seen Shiv's posts on what the suggested changes are to his tunes for the BPB's, and have been bearing those in mind while working on my tune. Still early days with that yet, though.

Only other engine mods I'm likely to make will be the ACE A350 headers I have sitting in my attic, a Fluidampr to smooth things out a bit, and *maybe* a Grimmspeed intake. Any further money will be spent either on dialing in the suspension a bit more, or on track time to improve the nut behind the wheel...LOL.

Unfortunately, E85 isn't an option where I live, so I'm stuck with optimizing for Shell 93 octane. ;)