Modernizing the C4, Another LS Swap with Goodies
In my head I am calling this the ultimate C4 build, so this engine swap is just the first step of the project.
My project timeline is something like this:
Phase 1: Engine Swap, Interior Revamp, Body Work
*Where I currently am, there is a lot going on in the background, including research for the later phases and budgeting
Phase 1.5: Engine Tune and Firmware Development
*There are some electronics I am currently developing like the PDM, Digital Dash and DIC, as well as the ABS controller, this is also intended to be the point where I lay low and save money for Phase 2, hopefully without breaking anything too badly, I hope to be at this point by July so I can have some fun gently tracking the car, potentially road trip to tail of the dragon later this year.
Phase 2: Suspension Revamp
*The two weak points I have at the moment are the half shafts and transmission, looking at the bottom of the car I think there is enough space in there to swap in the Camaro alpha chassis rear suspension (easiest but tallest and does not fix trans issue), or the C6/C7 rear cradle (transaxle so no trans issue, but much more complicated) for the front, I am looking at a custom pushrod suspension because I am a glutton for punishment,I want to track the car first though and see how it performs this is also why I am keeping cooling packaging so tight. Part of this may mean doing a tubular K member or similar but thats way down the line.
In my head I am calling this the ultimate C4 build, so this engine swap is just the first step of the project.
My project timeline is something like this:
Phase 1: Engine Swap, Interior Revamp, Body Work
*Where I currently am, there is a lot going on in the background, including research for the later phases and budgeting
Phase 1.5: Engine Tune and Firmware Development
*There are some electronics I am currently developing like the PDM, Digital Dash and DIC, as well as the ABS controller, this is also intended to be the point where I lay low and save money for Phase 2, hopefully without breaking anything too badly, I hope to be at this point by July so I can have some fun gently tracking the car, potentially road trip to tail of the dragon later this year.
Phase 2: Suspension Revamp
*The two weak points I have at the moment are the half shafts and transmission, looking at the bottom of the car I think there is enough space in there to swap in the Camaro alpha chassis rear suspension (easiest but tallest and does not fix trans issue), or the C6/C7 rear cradle (transaxle so no trans issue, but much more complicated) for the front, I am looking at a custom pushrod suspension because I am a glutton for punishment,I want to track the car first though and see how it performs this is also why I am keeping cooling packaging so tight. Part of this may mean doing a tubular K member or similar but thats way down the line.
I have seen the Deepmotor intake manifold that is basically a BTR clone. It should be low profile enough to fit under a stock hood should you be inclined. If the aftermarket hoods were reasonable, I would go that route. But I have no confidence in my fiberglassing skills to attempt doing something different. Plus, I am going for sleeper look anyway.
Nivlac57 on youtube has used one on his Nissan VK56 swap into a Ford Fairmont and he had nothing but good things to say about it. Good enough endorsement for me.
At any rate, I like your game plan and look forward to the updates!
I am using an old timer trick and not using the fancy spray on enamels. I've had some pretty terrible luck getting that to bond to used blocks due to the high oil and moisture content from the porosity of the casting. This time, I went with the Rustoleum Rusty Metal Primer for the base layer, Rustoleum Bar-B-Q Flat Black for the color, and then a thin layer of spray-on 2K matte clear coat for the oil and gasoline protection. On my last build, I used Krylon Metal Primer and VHT engine enamel, and even after going through the same prep steps, it was bubbling up after a little of run time, so I am hoping that this method works better. One thing I will say is that the spray-on stuff is way easier to get on evenly and and consitiently. I have had to buy 4 different types of brushes to get all the nooks and crannies on the block.
Yes, I did paint the mount bosses, but I will be wire brushing their faces before installation. I just wanted there to be a thin layer of paint to keep them from rusting while in storage and during the build process. The head gasket surface was masked off when I was priming and I removed the mask so I could relubricate the deck to keep it from flash rusting.
Now this weekends adventures will have to be cut short because I have to work tomorrow, but I did make a little progress on the most meaningless thing.
As I wanted this to feel like a modern car with the passive keyless entry, I gutted the steering column and rebuillt and lubricated it. This has turned out to be quite the process, and I was not expecting it so spiral so far but it has and now I have to deal with it haha.
So first things first, I removed the ignition lock cylinder from the column and redesigned the shroud to eliminate the lock cylinder bump and hole, but as I went through that process I got tired of the grease turned rubber getting stuck to me so I stripped down the column the rest of the way and ultrasoniced all the parts to get rid of the old schmoo. From there, I made the decision to delete a couple of things, first on the list was the locking pin, lock plate and the horn contact plate, but as the latter of those set the pre-load for the angular contact bearings in the column, I replaced them with a 3D printed spacer, I also increased the preload by thickening the spacer by 2mm from stock. The spring still has 1.5mm of travel, even with the increased preload, which should be enough to protect the bearings from shock loads. The picture below was with the "stock" replacement of the spacer, I still had a little bit of wobble in the shaft so I reprinted it with the additional 2mm. The ratchet strap in the background was how I had to get the c-clip back in. I used the old wheel ratchet strapped to the old ECU mount to pull the wheel down and compress the spring, with no lock plate, you can't use a lock plate compressor anymore. You cannot imagine how creative I got with my words as the ratchet strap was only found in the last hour of a 4-hour attempt. Two quick notes, you cannot believe how different the relube has made everything feel, alot of the notchiness in the steering and telescoping is gone now and everything is way smoother, I used SuperLube grease for this and it did a really good job. Note two is if anyone is rebuilding their column or replacing their wheel, for the love of God, check the four E-Torx bolts that hold the entire tilt mechanism to the column. Mine were not even hand-tight, I am not sure what would possess GM to not use some kind of threadlocker here but that was scary to find.
Somewhere in the disassembly process, my mind began to wander, and I decided to also delete the multifunction switch and high beam rod, I have now committed myself to doing steering wheel controls and getting all of the steering column functions moved over to digital control because nothing says modern car more than CAN bus
. Now I say committed because the only way to remove the high beam rod without removing the column and dismantling it further is to cut it. I was ok with this because I have a spare pristine column I picked up a couple of years ago because my 85 suffers from floppy wheel syndrome. But moving on, with those features removed that left only the telescope rod on the side of the column and I got a pretty neat minimalistic column.
With the need for the multifunction switch gone, that let me open up the insides of the cover up so I actually have a lot of space in here. If I were to do this again, I would remove the column and fully disassemble it and downsize all the covers to the bare minimum.
That brings us to the next project which is already underway, a clean and useful digital hub on the steering wheel. Just a quick note, these are all prototype parts shown here, I will be reprinting them in PPA-CF with hidden seams.
On the steering wheel at the most accesible locations I have my turn signals, head light control, fog light control, 2 horn buttons with one on each side, those are the 6 button locations up top, at the bottom of the wheel I have the less comonly used stuff, there are 3 total *****, 1 for engine map, 1 for traction control strength, and the last one can be used for a couple of things by pressing on it like ABS mode, wiper interval, interior light and display brightness, and if I can figure it out, media control for the head unit, and that kind of stuff. The bottom 2 buttons will be mappable buttons depending on engine mode. In normal mode they will act as a wiper toggle and exhaust cutout toggle, in "sport" or map 1 they will act as flat shift enable and a scramble button, map 2 is meant to be a track day map and will mostly disable traction control and the buttons will be used for a cooling system override and rotational idle enable, I haven't planned much beyond that because I have to dig into what haltech will let me do. The last button is on the bottom right and that will be the engine start/stop button, thankfully haltech allows this to be a crank while pressed and doesn't try to do some smart stuff behind the scenes like modern cars so I don't have to program that myself.
The above model was just to start trying the ergonomics of the hub and make sure it fit the wheel and my hands nicely but I am now working on the full version.
Now for some engine updates, I decided to switch over to shaft rockers for the valve train stability side of things, this is paired with BTR platinum .660 springs and titanium retainers, while I can't rev past 6500 with the current pulley setup, if I were to go with a larger pulley on the blower and shift my rev-range up higher that gives me the necessary space to do so.
I also will be ceramic coating my piston tops and doing an abradable dry film coating on the skirts as well as the blower rotors, I finally found an abradable coating that is fuel resistant so I can now add staged injectors on the blower to get some more evaporative cooling from the E85. I am also switching over to gas ported rings just to help with blow by and get that little bit more of efficency out of the engine. I have also started designing my fuel system, I now have a fuel cell surge tank that I will be installing in the top of the factory C4 tank, that surge tank will be fed by a single 525LPH hellcat pump, and inside the surge tank will be a fuel lab 500LPH pump for steady state and another 525LPH hellcat pump that will kick in at ~7PSI of boost. From a thermal managment standpoint, the lift pump will be PWM controlled with 3 or 4 states to match the engines fuel consumption, the brushless pump will be running in closed loop to maintain rail pressure. Cooling system-wise, I have also decided to ditch the dual CWA400s I was planning on using in favor of a single EMP WP32, while it flows less than the dual CWA400s, it can handle more head pressure which will let me run a restrictor at the block to keep block pressure high and prevent flash steam pockets during a run.
For example the 2026 Z06 LT6 makes 600hp in naturally aspirated form and has a 12.5 CR. They dropped the CR to about 9.5:1 when they put turbos on it for the ZR1 LT7 and make over 1000hp. They could have kept the same 12.5CR but then they would have ran lower boost and not got 400hp+ out of the turbos.
It was just a recommendation, the OP seems like he has it all dialed in.
Now engine-wise I have made some progress and gotten it fully painted and ready for assembly, as well as had several back and forths on bearing clearances and decided to go with 25 thou main and rod clearance and running 5w40 oil.
I've been cleaning the engine out and getting it ready for assembly from all the wirebrushing, all cam bearings except cam bearing 1 have been installed because I have to take it off the stand to get that one in.
Cooling update wise:
The primary rad has finally come in and dear lord is it big. I think I mentioned it before but in case I did not, the front part of the frame will be cut off and replaced with round tube or I will notch it out to fit the rad, not quite sure which just yet and I need to get some more measurements and scans to see what works best. This is a 31"*19" core which believe it or not is still undersized for the engine if you use the 1 square inch per horsepower rule. The build updates are going to slow down for a little bit while I get everything sorted out, so far i've been planning everything on a whim based on experience but now the real engineering begins.











