91parkave

iTrader: (4)

you are correct on the vacuum counts except the stock ls4 intake manifold has the top the back side and the other isnt actually a vacuum port its blocked off inside. So i guess places like cali they might have extra emissions crap that would require another vacum line.

GXP25

iTrader: (3)

Okay thanks.

What's the fitting on the right hand side? Basically, the fitting on the opposite side of the "PCV System Vacuum" in the following picture.





fieroguru?

91parkave

iTrader: (4)

probably EVAP

GXP25

iTrader: (3)

So is it okay to assume that the LS4 throttle body's fitting is used for the EVAP? (not the PCV since that's at the top of the LS4 intake manifold)

The brake booster vacuum is to the right of the LS4 intake manifold. Add that to the fitting on the LS4 throttle body (EVAP?), and the PCV on top and that makes three vacuum connectons.

As per the following picture in David's write-up, the large hose is for the brake booster (LS4 OEM location) but was moved there and the hole widened on the LS1/LS6 intake since theirs is in the rear; he left the MAP back there though. He then drilled and tapped another hole in the throttle body adapter for the PCV. Then there's the third vacuum fitting that he didn't have to touch since he's using the LS4 throttle body.



So that brings me back to the LS2. Would a throttle body spacer be needed so that a third vacuum hole could be made? Because as it stands, the left side fitting would need to be blocked off due to the OPSU. The rear will need to be blocked off and relocated since it has fitment issues with the accessory belt. So that's two fitments needing "homes" and no "homes" available.

Does the LS2 throttle body have a fitment?

Assuming that a throttle body spacer gets used, then I guess each side could be drilled and tapped. Ideally, such a spacer would be angled upward. Dom87SS? *nudge* *nudge*

fieroguru

iTrader: (1)

There are 4 vacuum fittings coming off the LS2 manifold and they all are manifold vacuum, so it really doesn't matter what you hook up to them (they all function the same).

The end has 2 fittings one large (brake booster), one very small for a vacuum line. Off the throttle body the one with the traditional barb is likely for the PCV (dirty air return) and the other side uses a quick disconnect and probably goes to the evap.

On my swap I cut and capped the two at the end. Used the barbed fitting at the neck for the brake booster and the quick disconnect side (used the LS4 disconnect fitting with the poly line removed and replaced with hose) for the PCV (not using the electronic evap).

The challenge is the clean air for the PCV. The LS4 MAF/TB rubber coupler has this port molded into it, but it won't fit the LS2 TB. I drilled a silicone coupler and bolted in a brass nipple for my swap.

GXP25

iTrader: (3)

Thank you very much. Do you happen to have any pictures?

All I see are three fittings: one nipple at the rear (brake booster) and the two up front (one on each side).

fieroguru

iTrader: (1)

Here is you can see the two holes I plugged on the end (Notice my water pump has the power steering bracket removed... not sure if these nipples would clear with the stock PS pump). Maybe there are multiple styles of car LS2 intakes, some with 3 nipples and some with 4.


Here is a picture showing both ports before cut (stole from an ebay listing):


Here is the LS4 throttle body and intake tube showing the 2 nipples. The one on the throttle body goes to the evap purge solenoid, the one on the intake tube is the clean air for the for the PCV. The LS2 throttle body does not have any vacuum ports:


Here you can see the vacuum port right above the throttle blade:


For my swap I added a nipple to the silicone coupler for the PCV. I took a brass 90, found a washer that slide over it, then another one that didn't. I threaded the one with the smaller ID so it became a low profile nut. Then when I assembled it, I used silicone on the washer faces and locktite on the threads to keep it from coming loose and being ingested.




Here is where I used the LS4 nipple quick disconnect (from the evap system I assume) and added a rubber hose to it for the dirty side of the PCV or the return from the catch can):


It is hard to see in this picture but this is the brake booster connection (with the hose clamp) to the barb nipple opposite from the quick disconnect nipple. This nipple wasn't large enough in OD for the booster hose, so I built it up with a few layers of electrical wire heat shrink.


Also, the MAP sensor on the E67 LS4's (or at least mine) didn't fit the LS2 intake, so I purchased an LS2 MAP sensor and pigtail. If you swap MAP sensors, you need to change the values in the calibration as they are calibrated different and you will set a MAP sensor code for the sensor being out of range. I originally though it was due to the 224/232 camshaft, but after some research I found it was a common issue with MAP sensors being calibrated differently across the various intakes.

McMaster.com part # 92510A801 are aluminum spacers 5/8" in length, 3/4" OD and with a 5/16" hole. These work great to mount the LS4 fuel rail to the LS2 intake and cost $2.30 each or less than $10 + shipping. Then you can either run the LS4 injectors with the injector spacers or the longer LS2 injectors w/o spacers.

GXP25

iTrader: (3)

Thanks for those pictures!

I was going to post the following picture showing the fourth vacuum line which is actually sealed with a T-shaped cap. But good thing you replied.

DavidGXP

iTrader: (14)

Nice work everyone!

GXP25

iTrader: (3)

So I understand that you increased the outer diameter (OD) of the nipple on the left hand side of the LS2 intake manifold with the heat shrink so that the brake booster hose would fit. My question to you: does the brake booster hose not need a certain diameter to function properly? Does there need to be a certain amount of air flow for the vacuum for it to function properly? Would using that smaller nipple affect the brake system/pedal feel? Of course, you were able to use that nipple because you blocked off the OPSU in that area and tapped the block for your new OPSU location.

Here's a [nasty] drawing I made in paint outlining the swap. Of course, you would need to grind down the OPSU and weld it at an angle along with modifying the DoD/AFM connector.

With the thinner DoD/AFM VLOMs out there, hopefully the intake fits. Or maybe someone can get those intake spacers going it might even be a better fit.

GXP25

iTrader: (3)

Nice! So I'd only need four of these then? What about the bolts (I know you have a button head obsession)? I'm assuming I'd need longer ones. Would the LS2 intake manifold bolts then work with spacers?

EDIT: It looks like the OEM bolt studs are long enough.

91parkave

iTrader: (4)

The rear vacum piece on any ls__ intake swap will never clear because of trhe power steering resovoir

91parkave

iTrader: (4)

One more question regarding placement it seems like since my map sensor is mounted at the neck of the intake shouldn't I do the same for the swap instead of the rear mount ? Just pondering the logic

GXP25

iTrader: (3)

That's just the sensor for the absolute pressure in the manifold. Mount it where you have the space but make sure there's no leak.

91parkave

iTrader: (4)

**** my life **** gm **** this car OK down ranting almost done with the swap ended up slicing the alternator bracket on the car to much of a pain in the *** to take off broke the spare dod conmector trying to solder it so oh well its like I use dod anyway and the damn heater lines hit the throttle body adapter so have to grind the corner off an unbolt the heater hose lines to bend them down out the way I'll post pics later and a video of what David Gxp was saying about the fuel limes pivoting over

BTW there is no need to buy any kind of extension harness all you need to do is pull the wires from the loom there is more than enough there to support any location on the manifold

91parkave

iTrader: (4)

The fuel line pivot in case anyone wanted to know is in the video I made

x11 nut

iTrader: (3)

How'd the start up go? Just got an LS6 intake for my Turbo GXP - looking to get my ducks in a row...

Cheers

91parkave

iTrader: (4)

First start up was flawless however I ran into some minor bugs with the ls2 tb blade getting stuck causing a reduced power mode the fuel rail inlet I heated up and used a tubing bender to move it up and to the right just slightly to clear the coil pack everything else was smooth and if you have the means to do so I'd recommend cutting the alternator bracket on the car just be careful to lay a towel or something to cover everything else from sparks and debris. And you might have to grind the back right portion of the manifold to clear the coolant crossover and grind the back left webbing between the intake bolt hole and intake so that bastard power steering line can easily clear it.

Dom87SS

iTrader: (3)

I had a little stumble along the way of getting mine installed but the new part is now done. The guys at my work were a little concerned with the previous material I had used to make the TB adapter in that over time it may sag which would obviously cause a huge vacuum leak. So I modified the file a little added more thickness to it, added larger radius edges for strength and then made it in a high temp material. This stuff has a heat deflection of 335 F and we decided since its being used for air flow we tumble polished the part to smooth it all out then coated it with a high temp (350F) epoxy to seal it up and give it a super smooth finish. So Im back on track to get this done. Im going to be busy the next few weekends doing automotive photoshoots and drag race coverage (my side gig ) then ill be able to jump on this. Im really excited to get this and few other items on the car to wake it up.

91parkave

iTrader: (4)

I don't get why you made it thicker rather than just shortening the length. Regardless awesome idea especially if you were to go in business I know I would want a better material for a adapter for the ls2 throttle body