Cross

iTrader: (10)

Ok so I am getting ready to swap the 408 Stroker I just recently had built into my GTO. However as I drive my GTO Daily right now I want to make sure this is a weekend swap project so I have been trying to read and research as much as I can.

I have found a few things I need to pay attention to and I have laid some ground work that I hope should handle most of what I need. However I am looking for some more guidance and any advice before I get started.

So far my biggest concerns remain with the GTO Drive Train handling the 408. It was in my Vette which was totaled in a Hit and Run on December 4th. I bought the GTO to replace it and it was almost stock minus a drop in K&N, Predator 91 Tune and Magnaflow rear Mufflers.
I have since made a few modifications to the LS2 (It will be going in my FRS LS Swap) and some to the GTO to lay ground work.
So far the GTO now has Headers and Full Exhaust, Rim's with 305's in the back, some cosmetic changes that I wanted along with clean up and I just ordered the One Piece Driveshaft from The Driveshaft Shop that says it takes up to 1000HP.

I am still concerned about the rear end and the transmission. I was told that the MN12 should be alright at my NA Power levels with the 408. I do go to the Drag Strip from time to time but I have never been a serious participant. I play occasionally otherwise I just like having a torquey toy.
I have a Tick Stage 2 T56 sitting here for the FRS's swap but I was not sure about swapping it into the GTO due to the shifter differences, and gear ratio differences. To be honest I don't know that it's the right idea but then I also don't want to break the MN12.

Next while I am doing the Driveshaft there seem to be many different opinions on how to handle Wheel Hop or prevent it. One is Axles from GForce, another is the Diff Cover, another is Bushings, another is Airbags... some say a combination. I just want to know which will work for me, I can't be the only one doing what I am. Do I really need axles too or would say bushings and airbags handle the problem? That Diff Cover costs so much I doubt I would do it before Axles.

I als have found mention that the LSD in the diff is well... it sucks. If this is something I should get ready to do I would like to know it now so I can look into which LSD to switch to. I am not looking to go to a Solid Axle with this car for any reason. This may limit my options but it is what I want to do.

Now for the direct motor swap needs.

I saw the Injector Connectors are different. I see ones that switch the connectors to the standard GM or perhaps considered the Older GM style but not the other way around. (My 408 currently has Injectors on it with the older style connectors) Who makes these or would you recommend just buying a new set?

I saw the Valley Covers are different and of course the Knock Sensors moved. I assume I can just put the knock sensors on the new block and switch the other's to the LS2 hopefully for the FRS...

I noticed that on the Valley cover the Oil Pressure Sensor location looked to be different. If this something I should be worried about or will it just bolt right up no issues?

So far that's most of what I have seen and I guess worst case I can just swap pigtail ends with the FRS engine harness to make the injectors work.

Thanks for any insight you guys can give me and things I should be concerned with on the GTO to make it reliable and ready to enjoy.

2QWK4RU 06 GOAT

iTrader: (1)

Stay away from GForce parts and get a harrop cover. You can find more info at gastiresoil.com or at ls1gto.com if you don't mind the bs there.

I've built many of these diffs, you can find lsd info on gastiresoil.com.

good luck

J-Rod_Almighty

There is nothing wrong with G Force axles and stub and such. As for a weekend swap I don't think so. Plus All the other stuff you want to do? Too many variables. LS2 out of your corvette? What year? Reluctor wheel will be an issue. That means you have to pull the crank.
I would worry about the motor trans swap on one weekend and then some other weekend do the rest. Your stock rear, drive shaft and everything will handle a 408 cid

Cross

iTrader: (10)

Why would swapping knock sensors, a valley cover and bell housing be more than a weekend project?
The motor is out of my 2000 Corvette, its an LQ4 Iron Block 408 Stroker and I swore I read it was not the 58x reluctor wheel on the GTO LS2. I will go check again but other than that everything else should be straight forward. Oh and I will need to swap the oil pan over as the Batwing would not work.

Is there some other piece I am missing?

blackbyrd

iTrader: (14)

I agree with J-rod you might be pressed to get the swap done in a weekend (3 day weekend maybe)

on the reluctor wheel the swap to 58x was a running change during the 05 model year i believe, may want to search that on goat forum or just for the ls2 in general. I think it even carried over to 06 making it an even further crapshoot.

you may also run inot ecm issues going from an ls1 car to an ls2 car

Cross

iTrader: (10)

I have already been playing with the PCM it is definitely different but after some time I like the changes so far. Had to account for the changes I made to the car after getting it.

I will look into the reluctor wheel issue again because that would be a pain in the ***. I mean I guess the other motor is already out and ready but now it's time to find out if the GTO has the 58x wheel over the 24x.

Seem a the 06's might have had some 58x ones but most GTO's are the 24x. Mine is an 05 GTO so it should be safe but I will check into the build date to confirm.
http://www.ls1gto.com/forums/showthread.php?t=193230

blackbyrd

iTrader: (14)

yeah the ls2's ecm had a few changes from the ls1's. I admitidly do not know much about the c5 setups, did they have a drive by wire setup or no?

I hope you post pics during the process i love these kind of builds and i did one with my firebird (went from a v6 to a iron block 414). while Im not as familiar with the GTO as i just got mine in march. I was really familiar with the bird by the time i did the swap and physically swapping out the motor took me a day with a 2 post lift and dropping it out the bottom. It took me a week to get it running though as i kept running into little things after the motor was in and hooked up. So thats what you need to keep in mind the stuff outside of the whats obvious will get you.

good luck

Cross

iTrader: (10)

Gotcha, yeah this will not be the first time between F-Bodies and Vette's I have done this a few times and having a few helping hands always makes life easier. I expect to find a few issues but right now I see the biggest one as the fuel injector connectors and I am about to just buy new OEM one's of the old style to fix the problem. (Lazy, it's easier to solder than find different injectors then all the tuning information that would be needed)

The C5's all did use DBW they had a different version of the TB itself but mine was changed to the LS2 90mm style.

I always say I am going to take pictures and then I forget. Lets see if I remember this time.

blackbyrd

iTrader: (14)

I have no info for you on the harness as i knew I had a long road to try and make the v6 crap work with the ls1 stuff. I went for a stand alone harness from street n performance as that seemed like the easier choice for my setup.

curious as a random off thought, what spark plugs were you running in the 408?

2QWK4RU 06 GOAT

iTrader: (1)

His parts fail to meet proper spec and have had to be returned and replaced on many builds I've done. So, unless you've had this happen to you often, how did you arrive to that conclusion? That company also just stopped building diffs because they can't get them to work right. I know another such unit now, it's in the Q now on another forum. There's even problems with their 9" conversion.

J-Rod_Almighty

The "Rumor" of there being a 58 tooth reluctor wheel in a GTO is just that. It NEVER happened. ALL 2005-2006 Pontiac GTO's are 24 tooth.

svede1212

iTrader: (3)

As far as wheel hop I can say what has worked for some has not worked for others. Driveshaft Shop anti-hop axles are good and drag bags add cheap insurance at the drag strip. With me it's taken everything: axles, bags, Harrop cover, all bushings, sways, tires, wheels and one piece driveshaft The rear ends although not the best seem to hold up with a lot of hard driven goats. The Wavetrack is a good improvement.

dw456post

Here is a pic of the 58x plug. If yours is a different color, it is the 24x.

Cross

iTrader: (10)

The car is not the 52x so were good to go.

Now on to the trans, everything I find on the MN12 it seems like it should hold and I would hate to lose the gearing changes it has but with the Built Tick Stage 2.5 sitting here I would hate to not put it in then break it. The FRS doesn't need it.

A_VAS

iTrader: (16)

you're putting a gen III 408 into a Gen IV 2005 GTO I take it.

Keep the 408 knock sensors and valley cover on the engine. Just don't hook the sensors up (simply to keep the holes sealed)
Keep the old cam sensor in the rear block hole, unplugged, just to seal the hole

out of the 4 mounting bracket holes on each side of the block, there is one bolt hole unused with the GTO engine mount brackets.
You can helicoil insert this hole down to the smaller bolt size, and swap over your 05/06 knock sensors to this newly threaded hole.

You'll need a cam sprocket and front cover / cam sensor for the LS2 (cam sprocket will have one raised 180* bump)
One of the alternator mounting bolt holes will be missing on your 408, you will need to drill and tap this hole to get a solid GTO alt mounting.

For the injectors, personally I would swap them out to a later USCAR type injector. they will plug/play with your GTO harness and no adapters needed. Not knowing what rail/intake you are using so not sure what length you have. A factory type LS2 injector at 60# would be plenty for a 408

personally I think your stock GTO trans will be fine w/ a n/a 408
you will want a better clutch in there

Cross

iTrader: (10)

I have a question on the cam position sensor, can I just use the one on the back of the 408 instead of putting it on the front?

Cross

iTrader: (10)

Ok how about the dip stick hole, on the 408 it was in the block and with the gto it's in the pan and the block hole has a cap in it I cannot remove. What is that cap or what do you normally use?

A_VAS

iTrader: (16)

I normally tap the block hole with 1/8-27 NPT and screw in a small brass plug. You can also get the small cup plugs like GM uses and drive in there.
Also a round steel ball if you can find the right size, drive it in there.

For the cam sensor, can't say I've tried to run an LS2 with the rear cam sensor LS1 style. The camshaft should have the ring on it at the rear that the sensor will read. But you'd have to extend the LS2 cam harness from the front of engine to the back. I'd think it much cleaner to just get and LS2 front cover and the correct cam sprocket. That's what I have always done