403ci Ls2 Stroker Nitrous Build
 

I'm at the tail end of my Ls2 stroker build and wanted to put together a little build thread for everyone to enjoy. I have a lot of time and research in the build and wouldn't necessarily call it a "Max effort" build, but pretty darn close given there was a budget in mind.

Old setup was a HCI Ls1 in my 2002 Trans Am. Motor had 45k original miles and was running strong on a 225 (.82 jet) shot through a 4l80e. Went a best of 10.56 at 128mph at full weight

I came across a great deal on a Ls2 bare block and couldn't pass it up! From there, I spent the past 3 months piecing together the parts to build a bottom end that would hold anything I threw at it. I came across a vendor called Pro Power performance who offers a great line of stroker kits featuring cranks and rods from PEP. Per my machine shop who assembled the bottom end, the machine work was near flawless on the rods and crank and no clearancing was needed for final assembly. It all balanced out great with the the Wiseco pistons.

Below are the build specs:

Bottom End
2005 Ls2 Block (honed .005" over)
Precision Engine Parts forged 4" crank-24x
Precision Engine Parts forged H-beam rods
King Race main&rod bearings
ARP 2000 Rod bolts
ARP main studs
Wiseco -8cc 4.005" pistons
Upgraded tool steel pins
Steel top ring/nappier second (.028/.030 ring gaps for heavy nitrous)
GM Ls2 head gaskets
Powerbond balancer
Turn one power steering pump w/pulley
11.2:1 compression

Valve-train
BTR stroker nitrous cam (251/266 .632"/.596" 112+4)
BTR Platinum .660" springs
BTR titanium retainers
BTR seals/locators/locks
BTR Trunion rockers
Morel 5315 lifters
LS2 trays
Manton 11/32 push rods
GM timing gear/cam sprocket with ARP bolts
New HD GM Timing chain with dampener
Melling oil pump
Improved Racing pickup girdle (awesome product)
NGK -9 plugs

Top End
Advanced Inductions 226cc (243) heads (resurfaced for the swap)
63cc chambers
Siemens Deka 60lb injectors
Edelbrock Pro Flo manifold
Edelbrock 90mm TB
PCV delete with catch can
Speed Engineering 1 7/8 headers
TSP ORY with Flowmaster merge & 4" cutout

Drive Train
Level 3 4L80e with Trans-Brake
CAT SFI Flexplate with ARP bolts
BMR crossmember
Viking front coilovers
CE rear shocks 50/50
PA Racing Kmember w/solid aluminum mounts
UMI lower A arms
Stock upper A arms
Founders: SFC, LCA, Relocators, TA

I had the machine shop assemble the bottom end minus the oil pan and covers. From reading, i knew I was going to have to space out the windage tray using washers in order to gain the needed clearance of the 4" stroke. Two washers on each stud did the trick and the motor spun freely with the pan off. Now for the tricky part of getting the oil pan to clear...

We test fit the oil pan without the gasket and spun the motor and sure enough the rod bolt was making contact with the front of the pan where the dimple is casted into the pan. We took a grinder and massaged the pan dimple and were able to gain the necessary clearance with the pan gasket installed to spin the motor freely. That was the only part of the pan that needed clearancing.

Below are some pics of the build progress and where it sits as of today. Major steps left are to torque down the manifold, attach all sensors along with the knock/cam conversion harness and drop into the Kmember. The goal is to have the motor back in the car tonight and do the initial startup this weekend.

Sounds like a stout build!

Hope the install went smooth. Waiting on results.

Install is going very smooth with the exception of the kmember and solid mounts not lining up quite right... Took over an hour to put the motor in the kmember as the mounts and pedistols were slightly off... But its all in the car and am finishing reconnecting the wiring harness... Will be starting it up within the next couple hours!!! Praying for no bad noises lol

UPDATE:

Finished buttoning up the car yesterday and threw in some new Bosch 13111 02's along with a new MAP sensor since the car was apart any way. After double and triple checking all the grounds, lines and connections we disconnected the coil packs and pulled the fuel pump fuse in order to crank the car over to prime the engine. We held it for 10 second intervals just to be sure the engine wouldn't stat up dry.

After reconnecting the coils and putting the fuse back in the moment of truth came for the first start up... The car turned over almost instantly and oil pressure went sky high as it should and no knocking or ticking was heard!:rock: We started adding distilled water a little at a time as the motor heated up and went through the burping process until there were no more air pockets in the cooling system. We ran the car for about 30 minutes on the lift at different loads to aide in seating the rings and once it cooled down a bit we drained the oil and it looked nice and clean. Filled it back up with conventional and plan to drive it around this weekend and get it nice and broken in before dumping the oil and going synthetic.

I am hoping to throw it on the dyno for the tune on Monday night and just waiting to hear back from the tuner if its available. I will put up a couple pics and videos tonight of the car running. The cam doesnt sound too radical either but has a nice chop to it.

Any vids?

Will take a video tonight and post

I'm building almost the same motor with a Lunati crank and Scat rods, Did your machine shop have to clearance the block at all for the rods to clear?

Yes, the machine shop said they had to just lightly clearance the block at the bottom of the cylinder. They said other rod/crank setups required much more clearancing of the block. They were very happy with the fit and finish of the rotating assembly

Hope everything is still going good. Waiting on results as I have this cam and 2 others trying to decide which I'm going to run. Good luck with her.

Hey guys, a little update about the build. The motor runs great but I am having an issue with the trans being in limp mode and the car misfiring while driving. Mind you, I only have 2nd gear right now when trying to drive the car.

From reading, it looks like i need to do a CASE relearn (crank position sensor relearn) as the entire motor has been changed and that could be my issue as to why the trans is in limp and the motor misfires when driving... My misfire tables are zeroed out in the tune because of the stall so no codes are being thrown for it, but you can hear it misfire when cruising.

Anyone help on this?

Awesome build man!! Hope you get it figured out quick.

any pics of where you had to clearance the oil pan for the rotating assembly?

I'm really kicking myself for not taking pictures for everyone of the clearancing that was done... I was kind of caught up in the excitement of buttoning up everything and completely forgot!:(

But the picture attached is of an Fbody oil pan and shows the area in which you need to "massage". We took a grinder and just went in slow circles to deepen the dimple that is cast into the pan. Maybe 45 seconds of actual grinding. After adding the gasket without bolts and spun the motor over there was no longer any contact with the front rod bolts. So it was a success. The reason we knew that was the area to "massage" was because the rod bolt put a light line through the contact area.

Is it me or did u go with head studs instead of head bolts? Btw where are those vids lol jk.. anyways are u gonna have any clearence issues with that manifold?

Yes sir, I went with ARP head studs as well as ARP main studs. And I am trying to get this trans/misfire issue sorted before I take some vids so it will be worthwhile. I posted in the tuning section asking if a CASE relearn will fix the issue as my trans wiring hasn't changed at all since doing the swap.

In regards to the Proflo manifold: Yes, there are major clearance issues and you must be willing to do some cutting of the metal and plastic cowl as well as the hood. You have to remove the wipers as well because when you cut the center of the metal cowl you lose the bracket that holds the wipers down. We had to cut all the way back to the firewall for the manifold to clear. However, when putting back the plastic cowl pieces you cant see any of the cutting and looks really clean.

The Ws6 hood had to be cut in the center and below is a pic of where we had to cut. I really wish I didnt have to cut up the car but as we all know its "because racecar".

Hehe yea i thought so.. i was just unsure cause im thinkin about doing the same thing with the trans am i picked up.. debating whether a vic jr or pro flow..i have somewhat of a similar set up that im going to rebuild soon.

Did you try switching the outer cam sensor wires (If your using the ls1 wire harness)? Check grounds first.

Not sure what you mean about the outer cam sensor wires? I am running the casper knock/cam sensor adapter harness with the pigtail on the front cover so it plugs in at the bottom of the timing cover... I will try the case relearn procedure tonight and see what happens.

Update

So I finally figured out the issue with the trans being in limp mode... The damn harness plug was in upside down!! It can plug in either way and never realized it was in wrong until i read a thread on here where a few guys had the same problem... Flipped the plug over, fired up the car and Boom! Shifts perfect and car runs great for being untuned!

I will be getting it tuned in 2 weeks when the tuner gets the pro version upgrade back in the mail. Ill try and get a video posted tomorrow of the car running now that I'm not pissed off at the pos lol