I've come across a rather cheap LS2 intake locally ($50) and figured I could remote-mount the OPSU (tap into the little cover by the oil filter) for $40 or so, and then make a TB adapter for $20 in bar stock.

It looks like the LS1/LS6 intakes work with grinding the bottom (this doesn't scare me, I've done it in the past to fit an LS6 intake on an earlier LS1 while retaining the coolant lines), but is there enough of a gap with the LS2 to do the same, or does it have a lower floor?

I was thinking I could just cut and seal off (tap/plug or just have it welded) the OPSU bung, but it looks like that has a passage in it that feeds the DOD lifters I imagine? Is there enough room to maintain that oil flow while still capping the fitting low enough to avoid hitting the intake?

I'm not opposed to getting rid of DOD functionality by removing the sensor/solenoid (was planning on setting it to only be enabled at 60+ anyways for hwy, and we rarely take it on the highway enough to make it worth having anyways), but I definitely don't feel like taking the heads off this car just to rip the lifters out. I don't really have a desire to do that unless I feel like taking the time to throw a cam in it at some point down the line (doubt it, as much as I'd like to).

 

Additionally, why is keeping the DOD tray required? It looks like when DOD is disabled, no oil passes through to those 8 lifters anyways. What would be the harm in using a standard flat cover that removes the solenoid and passages?

 

It can be "made to fit"...

https://ls1tech.com/forums/ls4-perfo...eping-dod.html

 

Very cool, not sure how I missed that thread in my searches. Very nice work! I'd rather not cut a hole and have to patch the intake though.

I know I can remove the DOD connector and patch that hole up. I still wonder about the OPSU bung. I don't see a need to keep oil pressure flowing to the DOD stuff since those are normally-closed solenoids anyways that will never pass that oil to the lifters since the solenoid will never be powered again. I would grind them down nearly all the way, and tap them for some plugs (1/4 NPT? for the OPSU hole and 1/8 NPT for the hole that would be left over from the oil passage?).

 

After reading some more, I'm pretty confident there is no need to retain the DOD tray (or in my case, I'd likely just plug the hole in it instead of replacing the whole valley cover). Once it is de-activated, there is no need to keep the valley cover w/ the passages and solenoids.

Looks like I'd just need to clearance the bottom of the intake, seal off the DOD connector hole, cut/seal off the OPSU bung, relocate OPSU to oil filter cover area, make adapter plate for the stock throttle body, and make my fuel rails fit (whether bending, grinding, or cutting & adding hose). Seems fairly cheap and easy enough.

 

You're assessment of how DOD lifters work is correct. They function normally without oil pressure being sent to them from those extra passages, so a non-DOD valley tray works just fine. You can then block that oil passage, as all it does in the non-DOD applications is provide pressure to the sensor. If you deactivate DOD in the calibration you can get rid of the 5 pin electrical connector too. It won't check to see if they are there unless DOD is called for by the computer.

Some people use set screws to close off the oiling for DOD, but I wouldn't unless you had the engine upside down on a stand. The DOD soleniods or the gaskets in the non-DOD valley covers work fine to seal them off.

 

Picking up the intake in the morning. Not eactly sure when I'll get around to getting it all done. Going to try to get as much pre-swap work done as possible slowly over a few weeks (car is driven every day for work). Clearance the bottom, minor porting/smoothing, patch the hole in the back, move the MAP sensor, make TB adapter, add any vacuum ports, add fitting to relocate OPSU, and figure out what I'll need to do to mount the LS4 rail on the LS2 intake.

Ideally all I'll have to do at swap-time is take the valley cover off, patch it, and mod the fuel rail (hopefully will already have it planned and have any necessary parts).

For $200 ($100 for this swap, $100 for HP Tuners, already have an LC-1), I'm hoping to be quite happy with the results.

 

First steps!

Unlocked HP Tuners the other day and disabled DOD and started with a few other small changes (quickened shifts, reduced burst KR, lowered idle, etc.)

Pulled the TB today to see what I need to do as far as making an adapter. Also cleaned it while it was apart as it was very dirty at 101k miles.

Looks like most of it is going to be pretty straight-forward. Filing down a small amount of plastic around the upper left TB bolt hole gave me a lot more room for centering the TB (DBW motor placement on LS4 TB). Also cut off and JB Welded the vacuum ports on the back of the intake.

I'm going to have to extend the MAP sensor wires a few inches as the MAP sensor is mounted the opposite direction and a little further away on the LS2 intakes.

All vacuum ports near the throttle body should be fine. The one on the right side of the TB is within 1/4" of the factory EVAP solenoid bung (not sure if I'm going to keep EVAP or tune it out.. may be useful with the heat down here in FL). The one on the left side is going to end up connecting to the rear valve cover's PCV hose at least initially until I decide to do something different for the PCV system. The factory hose from the front valve cover is going to go to the factory intake tube fitting. The brake booster hose is going to go to a new bung in the TB adapter.

I could get away with as thin as 3/8" aluminum for the throttle body adapter, but that wouldn't be thick enough for pockets for the intake bolts or for decent thread engagement for the TB bolts. 1/2" is enough to fix both of those problems, and the TB will be about exactly at the stock position. The downside to 1/2" is that I would *maybe* be able to tap a 1/4NPT hole, but more likely only a 1/8NPT hole which isn't enough for the brake booster ... so I'm going to go with 5/8" as that will allow me to easily tap a 1/4 NPT hole. 4.5" by 4.5" will be perfect, and then I'll cut it to shape to match the LS2 intake.

The LS4 intake's fuel rail mounting bosses look to be the exact same location and height as the LS2 fuel rail mount bosses, so that's awesome. I expect the LS4 fuel rail's crossover tube will either need to be bent a bit or cut and extended. I'm definitely not ruling out grinding the intake a bit if necessary to avoid having to cut the fuel rail.

I'm going to get rid of DOD completely, so I'm going to get rid of the connector and OPSU bungs. If I end up finding a cheap LS2 valley cover, I'll go that route for the more bolt-on approach (and ease of being able to go back to stock to sell the car if needed, etc.). OPSU is going to the cover on the oil pan above the oil filter.

Overall, it looks a bit easier than I was hoping for, so that is cool. I'm going to grind the ribs off the bottom of the intake in case I don't end up finding a cheap LS2 valley cover. Also going to port the intake a bit as it looks like this provides for some pretty decent gains on these intakes (looks like it ends up a bit better than an LS6). That really just involves a little bit of work on the TB inlet and then a decent amount of smoothing in the runners.

 

Here is a general drawing for the adapter plate to bolt the LS4 throttle body to the LS2 intake. The offset electrical connector on the LS4 throttle body forces the adapter to be slightly offset.



The general shape of the LS4 and LS2 fuel rails is very similar with the injector cups being the same distance from the fuel rail and the center rail having the same overall curvature (LS2 is on the intake in the pics):



The issue with fitment is the brackets off the fuel rail are 5/8" shorter on the LS4 fuel rail than the LS2:



So the LS4 fuel rail would need 5/8" more clearance to the center tube/runner to run the stock LS4 height injectors (which I don't think is there), or by using some 5/8" spacers between the fuel rail and intake, you can use stock LS2 height injectors without any significant interference between the fuel rail and intake.

The LS2 injectors are 34# and the LS4 ones are 28#, but they use the same injector connector... so if you go this route, you will need to change the injector size in the tune.

 

Picked up a set of FAST injector spacers to take care of the clearance issue there (they are exactly 5/8" longer). I'll just need some spacers and longer bolts to mount the fuel rail.

I've done some minor port work on the runners to clean them up a bit. Even with the little I've done so far, it should help quite a bit as there is some horrible flash/alignment issues near the ends of the runner. I'll have to get a better rotary if I want to go much further with it. I'm not sure how beneficial it'd be anyways with the stock heads/cam.

This weekend I hope to get the throttle body adapter mostly done. I went with 5/8" aluminum. This way I'll have enough meat to recess the TB-to-intake bolt heads to keep them out of the way of the TB itself, drill/tap a 1/4NPT port for brake booster into the side, route a channel for the factory LS4 TB gasket, and cut a decent transition from the factory TB to the 90mm opening.

I plan on spacing the bolt holes for the LS4 TB itself tight enough to not allow any wiggle room when tightening the TB (there's a bit of clearance/slop from the factory). This will let me grind the lip at the back of the TB down, which will open that up a bit. The factory TB on these motors is a joke. There's a bit of a lip on the back side that looks like they left it there to ensure the gasket had enough room to compensate for the wiggle room the bolt holes left.

If I knew for sure what was involved in getting the truck 90mm TB working, I'd almost just go that route for $85, but I can't risk the car being down a few days if something doesn't work right with that. Maybe that will end up getting done down the road if I clean up the heads and put a cam in it. At that point, I'd probably do like I saw another member do for the 8/6pin stuff and just add the new connector in parallel to the existing one so I could swap between them before I am confident the 90mm one works.

Just ordered the OPSU relocation pieces. Ended up being about $25 using some 4AN line I already had. The OPSU fitting itself (Russell 640830 ... M16x1.5 female to 6AN male) is $14 by itself anywhere I looked. I'm going to mount the OPSU very near the stock location using a metal strap and bolting it to the one bolt on the back of the head. This way I don't have to modify any wires.

OPSU bung is going to get cut down and drilled/tapped for a 1/4NPT hex plug. I'm probably going to cannibalize the DOD connector by entirely removing the top part of it, but leaving enough of it to seal the hole in the cover.

Aside from tools, I'm going to have ~$130 into it total, not bad. Might even have enough aluminum left over to finally make some brackets to mount my rear strut tower brace that I bought a year and a half ago. Bonus!