Hi All,

I've hit the tipping point and sick of chasing oil leaks in my SBC400 24x motor and finally got around to lodging some late tax returns so it's LS1 time for the TransAM.

Luckily most of the rest of the car has been converted already with a later model 4l60E, VY commodore dash, gauges, BCM and the rest of it wired in, 4th gen plastic fuel tank with Walbro 460 pump, and other bits and pieces, so a good chunk of the hard work is already done.

I'm going LS1 from a 2000 commodore, rebuild it, put a better intake, bigger injectors, and mafless tune in, put something along the lines of the V4 Torquer cam in and bolt it up to a stage 2 4L60E with 3600 stall.

As I see it now I have the following to work on, other than stripping down the LS1 donor motor and freshening it up:

* Engine Mounts - already purchased the 4 position adapter plates to boltup to the existing clamshell SBC mounts and set to 1" backspaced to line everything esle up
* 4l60E trans member - Already modified the original one to allow the polyurethane mount to sit properly and got the 6 bolt tailshaft housing with the torque arm mount installed
* Notch the K member to clear the LS1 firebird sump that is on its way from the states (no need for ac notch, will use the top mount relocation bracket)
* Exhaust headers... this is probably the big one for me.

I've already installed the VY steering column along with some mods that give me a little bit more clearance than the usual RHD header clearance from the steering column, but that's still where it'll be a tight fit.
LX_SS had a great thread going here about doing a similar build (except a lot better, higher quality, and thought out than mine) but hasn't had any updates for a few years now, but from what I gathered he was making his own headers from scratch.

I'm hoping to be able to find something that can be used as is, as the commodores would surely have plenty of options for headers for these motors.

The other option I'm toying with is bypassing the steering column area all together and setting the motor up for a low boost single turbo setup. This would allow me to use turbo headers which would head up instead of down and I could reroute the exhaust back under without much issue, and I can always put the turbo on later if needed.

Any aussies have any experience with the ls1 swap they'd be able to offer on the header selection? Worst case scenario i can use the stock ls1 manifolds which i've heard are still decent as is.

I'm aiming for around 400rwhp max and using it as a daily so extractors are preferred but not critical.

Here's the beast at the moment:

 

sump has arrived, just waiting for the weekend now to start pulling the old motor out and get to work on the k-member notching.
I'm going to also remove the brake lines and replace them at the same time, and see what I can do about dropping the car over the engine as other have done instead of lowering the engine into the car.
So once it's out I can properly measure up the clearances for the motor.

Still up in the air about whether to cam or turbo the motor instead.

Current advice I have is the cam selection is too big for the rear end ratio and that with the low ratio rear end leaving the motor stock and changing the valve springs and pushrods and running 4lb of boost will yield a better daily and overall motor and reliability.

I'm just not sure if the turbo headers would clear the steering column on a right hand drive conversion steering shaft.

 

So I've found out the 97 10 bolt diff I have which is series 2 carrier and 2.73 can actually have 3.46 gears installed without having to change the carrier which is good news.

With that the Torquer V4 cam would work better, but the 224/224 is the top recommendation at the moment.

I'm not looking to do too much more to the motor other than cam, intake, injectors and exhaust, reliability is the key metric here.

I bought a 102mm throttle body and intake combo off ebay to help it breathe a bit better, not sure how good they are, but at a 1/4 of the price of a fast intake I'll take my chances.

 

Small Update:
Got a 2002 VY SV8 Holden Commodore as a donor car so I have some spare parts if needed.
The motor has 220,000km on it, but after an oil test looks to be in really good condition. Compression was around 150psi on each cylinder, but I'm going to do a full rebuild anyway.
Bought the rebuild kit, along with a VCM710 cam package with new timing chain, chromoly pushrods, new ls7 lifters and trays, and waiting to get a new oil pump and water pump.

The 3.42 gears arrived for the bolt set up for series 2 carrier, so I'll drop that off at the diff shop to get installed in a week or 2.
I also got a cheap set of 241 heads that I'm gonna have a go at porting and see how they turn out, otherwise I'll match port the existing heads before they get put back on the motor.

So in the end I should end up with a fresh new motor, freshly rebuild 4l60e, and not have to worry about oil leaks anymore.


Also the intake while good quality had a few high spots in the intake tunnels, so I just had to deburr the weld spots and smooth them out a bit, but a quick hit with the dremel fixed that up.

 

So motor has been stripped down and everything cleaned.
Pistons and bores all looked good, bearings could have kept going but will replace them all out anyway, not much sludge or deposits and crank is in good condition as well.

I have the cylinder a quick flex hone to take off the gloss, but was a little too gentle and need to have a another go to finish it off. First time using a flex hone and was worried the surface wasn't smooth but since found it needs to be a bit rough to seat the rings. Its a 240grit flex hone so should be good after another pass.

Everything else should be ready to assemble, but for now the hold up is the heads.

The set I have are 241s and I've decided to give porting a go.
Nothing too drastic, but I'll attempt to open the exhaust roof a touch to match the top half of the gaskets, smooth everything and trim the guide bosses, and for intake straighten the walls, lessen the rocker bulge, again tidy up the valve guide bosses, and remove some of the swirl ramp.
I haven't done it before but there's a first time for everything. The VCM710 apparently benefits a fair bit from some porting so I'll give a go, worst case scenario I buy another set of junk 241 heads and let the professionals do it.

 

How's the build coming along?
I love seeing other Aussie LS swaps. I'm always trying to work out what commodore bits will work for us to avoid getting stung by the exchange rate.

 

Haha, yeah a lot of it will fit if you're willing to do enough work.

The motor bottom end is assembled but I'm still waiting for some seal install tools from the states to do the front and rear mean seals. Also my Higgins ported heads are stuck in Victoria somewhere with COVID so not sure when they'll arrive.

I've got the headers I'm going to try and see if they need any work to fit, but I'm not quite at the point for the 400 motor to come out yet.

For my build it has the following implants from a VY commodore:

Dash including gauges
Body Harness
BCM
PCM
engine harness
wiper motor
Sterring wheel
Steering column
4L60E (from a VT series 1)