I remember that post. They are pretty small in terms of volume. I'm not an engineer or an expert in fluid dynamics, so I have no clue whats necessary, but in my redneck mind, more is betterer.

so i have a tap removal tool coming (don't listen to the internet kids, a 5mm hole is really too tight for an m6 tap, 5.5mm is much better), but even if I can't get that out, there are 2 other mounting holes nearby and a hold down plate will serve my purposes fine if it comes to that.


A word about drilling. The aluminum is soft and drills easily. The holes are roughly 15mm deep and the bolts extend about 12.8mm into the head, so drill accordingly. A piece of tape on the drill is sufficient to mark depth.

The drill block works fine but makes it hard to find your center punch divot, so there were 1 or 2 misstarts. Call it weight savings ;) To prevent further issue, I have done the following:

line up aluminum plenum with the ports
Use a 6mm drill bit with a sharp point as a punch. This fits very tightly in the mounting bosses of the plenum so you can accurately center. It works way better than trying to use a marker or paint.
Then I enlarge hole with center punch. Check and recheck alignment here.
Then I free drill a divot in that spot. Check alignment again

Then comes full drilling.

Drilling must be fairly accurate, but at the end of the day, the plenum aluminum is soft, so you can hog out the hole a bit to perfect your alignment, so if your hole is a little off center, no big deal.

hope this helps.

Great info!

Cant wait to see the finished project

few pics just for the hell of it
http://986forum.com/forums/uploads02...1548774647.jpg
http://986forum.com/forums/uploads02...1548774743.jpg
http://986forum.com/forums/uploads02...1548774873.jpg
http://986forum.com/forums/uploads02...1548774938.jpg

Great pictures.....thought there would be more room to withdraw / install air boxes though...without lowering the engine temporarily. I never have the time , facilities, or inclination to hack away at plastic from above.

It looks like the top surface of the plenum will be at the lip of the engine bay with the addition of the metal bases.....fingers are crossed. Others have done it so...

Just hope you don’t have to take a shapping hammer and English wheel to the cover

If the height becomes an issue, i will lower the motor to get clearance but would prefer not to exceed .5"

Probably sick of my posts by now, but drilled 4th hole on drivers side. 90 degree drill made it easy but youll need a buddy to hold the drill block. I free drilled and it turned out fine.

Not in the slightest. I'm watching this thread intently!

Sent from my SM-G930T using Tapatalk

Tap extractor worked, hole and threads are fine. Got my gaskets so hopefully some progress on sunday

No way man ...Keep the pictures and posts coming

Quick update.

1. I have 7 holes. You will need to remove alternator and aos to drill pass. Side but thats easy with everything out. Unintended benefit is that woth 996 setup, its easier to get to everything by taking off upper plenum only. So no fuel lines, aos lines or similar.

2. Although im marking well, my drilling has not been brilliant. The holes are straight but frankly off the mark. This i think is partly due to not being able to see your marks when using the drill block. If i was doing it again, i would likely go freehand.

I have managed to get everything together by enlarging directionally the holes in the lower plenum. Im not proud of it but drilling in situ, its somewhat unavoidable in my head. The ports in the head are bigger than the intake so you have some margin for error. As long as there is no protruding lip at the connection, you should be ok.

3. God the center portion gets gunked up. What a mess. Im not gonna make it perfect.

4. Im not sure the extent of this work will be worth the effort, but we'll see. Not too many power adding options that are cheap so the sweat equity is the cost

I was thinking of something similar to this tool for the job.....but there may end up being too little room to set it down.

Yeah that might work on the center holes. No chance on the outside ones.

gents, If i'm honest, the juice here isn't worth the squeeze (i can't imagine). This was an awful lot of work and I'm not even done yet.

If your 3.2 is on a stand, go for it. otherwise, unless you have time to kill, i'd skip it.

anyways, my current status and my fuel rail solution. Before you ask, its rock solid, the angle to the port is excellent and I only had to cut off 3 tabs.http://986forum.com/forums/uploads02...1549319664.jpg
http://986forum.com/forums/uploads02...1549319800.jpg

just to follow up. The AOS hose that runs from side to side is an epic POS and broke in 3 spots. Right into the trash with that. I will run an-12 braided hose to the factory end fittings with an internal spring to prevent vacuum collapse in its place.

I'm not sure how people don't lower the motor, but in my case, the passenger side plenum is right up against the top lip of the front firewall. I purchased .5" spacers and longer studs to lower the motor a bit.

Lastly, when reinstalling the fuel rail, make sure you have the harness above and to the outside of the rail. Found that one out the hard way.

This has been a long drawn out project but once I get the braided hose, I should be able to finish up in an hour or so as I have all the vacuum lines run and all of the harness plugged in.

I’m looking forward to seeing your results. I have a motor arriving soon and I have all the 996 parts from my recent teardown. The job that you are completing would certainly be easier with the engine on a stand. It will be fun to see what effect this has on performance. Are you using the 996 maf and tune?

I have a softronic tune and the stock maf in a 987 maf sampling tube.

Keep it up man....we all appreciate your hard work! This stuff takes a lot of time.

Yes, I can recall wanting to build a scaffold so I could lie over top of the car to do this kind of work. Inake work is a drag on this engine.

One thing I don't understand is the difficultly surrounding the fuel rails. Why cant the Boxster ones be used?

Will this level of assembly allow the airbox to come in and out with a reasonable amount of work?

Airbox should come out easily at this stage.

The boxster fuel rail tabs are just in the wrong spot. You cut them off and buy $3 worth of clamps rubber line clamps at home depot. They get tweaked and shortened a bit. Then you put a long m6 bolt through with one clamp ear above the intake and one below. Then put a nut below. That looks the fuel rail in solid. It took a bit of thinking but the actual doing it was fast and easy

So, how is it coming along? I´m really curious of this mod.. I have thought of all kinds of mods but you all know the cost/hp is really high. The usual "breathing improvement" with plenum, tb, airbox, headers, race cats.. Seem to give a slight improvement, but not that much really.. Could it be that a 996-intake is the ticket to real improvement? :dance:

sad to say its been a waiting game for parts.

So, as anyone who has dealt with the long AOS tubes, its a fragile pain in the ass. I initially ordered some an12 braided hose to replace it, but seems that was too small, so I have an16 hose arriving today. I lowered the motor .5" with some readily available spacers. Once the hose is in, it should be quick work. I should be done by saturday.

If you had all the parts ahead of time, this wouldn't be so bad. I'm working on it in little pieces, which is making it feel much longer.