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DIY: LS2 Intake Porting

80K views 188 replies 59 participants last post by  QuiksilverGTO 
#1 · (Edited)
Tools Needed:
Painters tape
Shop towels
3/8" Ratchet
3" Extension
6" Extension
8mm socket
10mm socket
13mm socket
needle nose pliers
fuel line dis-connect (or a couple picks)
Flat-head screwdriver
Dust remover can
Intake Cleaner
Drill/Dremel with grinding bits


1. Disconnect battery
2. Remove the intake tube connecting to the mass airflow and the throttle body

3. with painters tape cover the open side of the mass airflow and the throttle body to ensure dirt doesn't get inside the motor/air box

4. Unplug the connector on the passenger side of the throttle body (you will have to remove the gray clip first) and then remove the 4 10mm bolts

5. After removing the throttle body wipe it clean and for good measure put painters tape on the other side as well to keep crap from getting inside there while you're tearing the rest of the car down. make sure to also cover the opening to the intake manifold as well

6. To make it easier for removal/installation, unplug all the connectors on the passenger side wiring harness (fuel injectors/ac compressor/ground on cylinder head, etc etc) and pull it all the way back out of your way. the fuel injectors and fuel rail will be left on top of the intake for now
7. Do the same thing on the driver side as well, except you don't have to pull all the connectors off (still disconnect injectors) you can just pull it out of the way when installing/removing the intake manifold
8. disconnect the vacuum lines running to the front of the intake manifold
9. take the black cap off the fuel rail and with a pick push in the valve and release all fuel pressure (hold rag over the valve when doing so)
10. using your fuel line disconnect tool (or if you don't have one, picks) disconnect the fuel line where it connects to the fuel rail (get ready for fuel to pour out)
11. using the dust off can, spray all the dirt and dust you can away from the intake manifold area before you pull it off
12. with the 8mm socket you now remove the 5 bolts on each side that hold the intake down
13. double check to make sure you have removed everything from the intake manifold and all the wires are out of the way
14. remove the strut tower brace with a 13mm socket
15. lift the intake manifold off the motor slightly, you now will be able to access the vacuum lines on the rear of the intake manifold and disconnect them more easily.

16. wipe away all dirt from the intake ports on the cylinder heads and then cover with painters tape to ensure dirt doesn't get down in them
17. to remove the injectors and fuel rail from the manifold, simply twist the fuel injector back and fourth and it will "pop" out of the manifold (you will be leaving them connected to the fuel rail, leave the clips on the injectors)
18. wipe the injectors down and make sure the o-rings and nice and clean
19. with shop towels cram one in each intake runner to ensure a bunch of plastic residue won't end up inside the manifold

20. using a drill or dremel and grinding bits, grind away as much plastic material as you feel necessary, mainly concentrating on the parts where you can physically feel a lip. you don't need to grind more than 1" into the manifold on each runner to get it to how wide the rest of the runner is
21. after porting the manifold to your liking, remove the shop rags with needle nose pliers and remove as much plastic residue as possible
22. using the intake cleaner, clean the intake out as best as you possibly can. make sure to clean where the injectors plug back into the manifold as best you can
23. re lubricate the o-rings on the injectors, twist and push into the manifold and they will "pop" right back in place

24. go back and clean the valve covers, cylinders heads and all around where the intake manifold is going to set back onto the motor

25. (optional) go back and clean out with intake ports in the cylinder heads with a rag and intake cleaner

26. reassemble the way you took it apart! just make sure you get the vacuum lines back on the rear of the manifold and to the front, and plug all the connectors back in!

total time: approx 6-7+ hours taking your time, being a neat freak

results: car pulls alot stronger in the upper rpms!

EDIT: finally got to dyno my car, it is running really rich right now so there is still at least 10rwhp on the table! made for a nice gain across the whole board (ported intake manifold, ported throttle body, modified stock air intake, descreened maf, tune)
 
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#116 ·
I worked on this a little more tonight. I have all the ports opened to about 1.035" at the opening of the runner. I don't plan on touching the throttle body opening or the inside of the plenum. I have a lot more time into this than I thought I would lol. Kind of chilled out to drink a few beers and work on it though.

I attached pictures of the progress I made. I might work them a little more to make all the walls real smooth, but it is probably not worth it at this point. I think the next step is to wet sand, clean thoroughly and install.
 

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#117 ·
This may be a fluke as it has only been two days that I have been commuting after doing this mod, but I have been getting 20.5 mpg on my commute where I used to get 17.5-18.5. It's mixed driving and if I can hit all green lights to work, that really helps, but I can't fathom this actually helps 2-3 mpg. What is everyone else noticing?
 
#119 ·
I put my ported manifold on last night. I had originally thought I did not remove much material from the piece I was porting. Well after i removed the stock manifold and compared them side by side, I removed quite a bit of material.

I decided to start working on the car about 10:45 last night lol. I was driving it by about 12:45. First impressions are that throttle response feels greatly improved. Also, mid-top pull feels stronger. I am going to drive the car for a day or two. Then I will do a bit of logging with my Predator to see if my fuel trims have changed.

For anyone curious, the stock intake port opening on the cylinder heads is about 1.04-1.05 inches wide on my car. You can use this as a reference when deciding how much to open up your intake manifold (if you care enough).
 
#126 ·
Continuing with my cheap-assed-ness, has anyone took off the exhaust manifolds and ported those? Wondering if it would even be worth it.
 
#127 ·
the gain wouldn't be very much.... but technically it would make a difference.

depends if you really think ~5 hp would be worth the effort
 
#129 ·
I'm definitely going to port the inside of my pacesetters. Quality is crap.

Porting intake next weekend.
 
#130 · (Edited)
I found this and thought it was a good thing to DIY if your porting the intake manifold.

http://www.ls1gto.com/forums/showthread.php?t=332483l

If you look and compare they widened the mouth of the opening up (end that bolts to TB) from the stock 90mm to around 93mm or so. Then they took out the center pillars and smoothed the floor of the manifold out all the way to the back. Going to plan on doing this sometime in the near future and I will post back on it. The writeup by high performance pontiac talked about widening the mouth of but didnt take many close up pics. This thread shows great detailed pics of the work done to the inside also... and if you dont feel like screwing with doing this yourself they do offer a great deal. I am sure they do great work and are prompt about getting it back to you as fast as they can. Best thing to do is keep the one thats on your car and pick another stock one up off a member and send them that one. Then sell yours later on or keep it for your pile of Stock parts...
 
#132 ·
I read that the pillars are for sound beleive it or not. They help baffle the intake noise.
 
#133 ·
Some of the "professional" port jobs don't look so smooth to me. I have found a few pictures here and there. None of them ever show any real close up pictures of their final work. Some of them even appear to be opened up more than I think is necessary.

For the people that DIY, you just have to use some judgment. I posted the approximate widths of the cylinder head intake ports earlier in this thread. Open the stock intake manifold up to that approximate value. Start with the basics and don't hack it up. It is easy and free to take the manifold back off to do more work if you feel like it.
 
#138 ·
Ported mine last week. All in all took me about 6 hours, including a lunch break and I took my sweet time with the job.
I started with the grinding stone, but ended up using the sanding drums, which work a lot quicker.

After I got done rough sanding, I took some 100 grit sand paper and hand smoothed them.





And I had to try out the etching bit. Giving thanks where its due!!:rules:


Car defenitely feels healthier up top.
 
#145 ·
And I had to try out the etching bit. Giving thanks where its due!!:rules:


Car defenitely feels healthier up top.
:thumbs:

free power is good power







and yet ANOTHER person with positive results.... you can go fuck yourself jpvulpes with your BS about it harming performance
 
#141 ·
did you feel any difference going from stage 1 to stage 2? I was pondering on doing mine like that but didn't know if it'd be worth it...
 
#142 ·
I have not installed it yet, I am making a template atm for the stage 1 portion that still needs to be finished. I have some long shank carbide burs and some better things to sand with on the way in the mail. I have another intake sitting to the side with the pillars already knocked out and part of the floor done. I am going to finish the first one today though and put it on the car.

Ile post up some results...

Faster Proms says stage 1 to stage 2 is good for 6rwhp 7rwtq, seems worth it to me considering how crappy the stock LS2 manifold is. So around 15rwHP 18rwTQ from stock to stage 2...
 
#144 ·
I got to do a test it out tonight and it feels a little stronger. Seems as though its chirping 1st to 2nd and 2nd to 3rd a little harder. I need to get it tuned correctly for it, but until then ile just adjust my a/f with my diablosport.

As for reinforcing the the bottom with fiberglass...

I dont think its needed... I was going to fill the hole bottom with epoxy like I did for the patch spots. But once I felt how thick the floor was, I think its pointless. Faster Proms actually takes the ridges out on the bottom of the intake as well to create an air gap between the valley cover and the bottom of the intake. That takes away even more structural integrity and they dont seem to have any problems. They take the floor down to the same area that I did. I technically never moved the floor itself down any (other then minor sanding to smooth everything in) the only thing your actually taking down are those ridges in there to bring everything down to the true floor level.
 
#146 ·
you did a very very nice job! i was actually thinking about cracking the intake open and doing that but id really want a second intake manifold to do it... since i know id be really anal about it and take forever doing so. i was looking for a quicker route and still get a noticeable gain.

again, nice work
 
#147 · (Edited)
Thank you Lonestar! Owe it to you though, wouldnt have started screwing with it if I didnt find this great post.

You must have a second intake to do this unless you want to have your car down for 24 hours + while the epoxy sets and you do the finishing work after. I have picked up 2 used ls2 intakes for $150 a piece. Seems to be pretty easy to find them in that range...

I am sure your more then capable of doing this, it just takes some time and alot of patience. I cant tell you how hard it is to see inside while smoothing the floor out. I literally had to take a 1/4" x 24" wood rod and duck tape it to the 36" dremel extension so I could get the rest of it from about 1/2 way back. If your smart you will invest in a small little led flashlight that you can stick inside the intake while your working, cause its retarded to try and hold the flashlight and the dremel head on the extended wood rod (that makes it very hard to control).

I have ordered about $200 worth of abrasives, carbide burs, long shank mandrels and stuff like that to make this much easier and faster. I plan on doing these and starting a little business on the side for people locally or other people that are will to do the whole shipping process with a core exchange or paying for the intake itself and just selling theirs later on.

Also picked up a nice dremel because my old regular one is starting to crap out on me after this job. I can hear the bearings grinding and it is starting to overheat easily. It doesnt have the power it had when I started and you can tell its on its last leg. I will be using air tools on the runners..., but some kind of rotary grinder with a slim extension is a must for the stage 2 area.

If you need any information at all on how to do this, what tools I used, tips anything at all just ask me and I will give you what I have learned so far to help others out.
 
#148 ·
Thank you Lonestar! Owe it to you though, wouldnt have started screwing with it if I didnt find this great post.
Same here :D Glad I found it though. Free power is good power indeed
 
#151 ·
Yeah I am slowly getting the train rolling, once I have it established and going at a steady pace ile hit you up so we can stock knocking them out faster.

I am doing someones LS3 TB sometime soon and hes going to sell me his ls3 intake manifold for me to port out.
 
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