It's been a few months since my last post and that's because I've been out of the country for work, but now that I'm back I've started to make some real progress.
The majority of my progress has been digital and in CAD but I've got the engine pulled out of the 86 and have started to mock up the LS swap, it's my second swap so I am no stranger to the fun of it all, but this time will be super fun since. This will definetly be a multi-year project but the basics are laid out below:
Power Train:
LQ9/ High Compression 6.0
Forged Bottom End
BTR PDS Stage 3 Cam
Lunati Link Bar Lifters
Kong X-Ported LSA Blower with ZL1 lid
Ported 821 Heads
103mm DBW Throttle Body
Gen 3 Block Converted to 58x
High Volume Oil Pump
Batwing Oil Pan
Running Full E85
Haltech Nexus R3
Infinite Limit Engineering PDM
Blue Tag ZF6 mated through T56 Bellhousing using Custom Adapter Plate


This was the first test fit before the block got sent to the machine shop, it's getting decked and bored 0.030 over, rotating assembly is getting balanced, as well as line honed for the ARP main studs and mains pins.

Other Changes:
C68 Delete or Reverse Engineer (My Display is Broken)
Bose System Delete and Upgrade
Sound Proofing
Dash Redesign/ Less Noisy Replacement
Passive Keyless Entry with Walkup and Walkaway
ABS System Upgrade
Custom Body Kit and Cowl

With the above, I should be putting about 800HP down at the wheels, but do so in a manageable and safe way.
Problem number 1 is the LSA does not fit underneath the hood, nowhere close to fitting under the hood especially at the front of the car where the nose tapers down. That led me to need to develop a hood cowl and to have to cut up the hood. A couple years back I started using photogrammetry to scan the hood of the C4 and it worked but it was not the most workable model that led to some fitment issues. I was still in school so couldn't get any new toys to build a better scan, but now that era is over and I have entered into the realm of being able to get toys but have no time to play with them.
Now that I have an actual 3D scanner, I've started scanning the whole car, its a slow and tedious process often haunted by having to pause the scan and add more markers but here's the current progress:

This is the current cowl design, but I have since scrapped this design and will start working on the next revision. It was a cool concept but I don't think it matches what I have envisioned for the car.


The last time I did a swap I ran into a bunch of fitment issues and this time around I am trying to avoid them, after I pulled the motor I got a nice detailed 3D scan of the engine bay and I've been "installing" the engine in CAD to see if I run into the same issues as last time.


Because of my trust issues, I also 3D printed a dummy block and will be getting that installed tomorrow. You can also see that I still to do this day have not disconnected the throttle body, which will also be getting removed haha. The sharp-eyed will also have noticed that the front crash bar is bent on the passenger side, the damage appears to be from a tire blow out and it wiped out alot more than just the crash bar, I have a new to me front bumper but I might be desiging a custom one, thats still TBD. This is also an auto car that I am converting to stick, I have the D44 from my last swap and that will get swapped in here eventually. But right now my main goal is to get the car torn down and cleaned up and ready for the rewiring. This is getting a motorsport adjacent harness with proper bulkheads (Sorry C100) and an almost tip to tail new harness. The only thing I probably won't touch is the interior harness as that should be protected from the elements and not deteriorated like the rest of the car. I've had some pretty long flights the last couple weeks and thats provided me a perfect opportunity to redline the schematics for the car so i will also start eliminating the circuits that are being replaced by solid state options.

There are a lot of other 3D printable LS dummies available, but I started from scratch because there's a couple of things I wanted for mine. First thing was I went through all the holes and added additional plastic so that the coarse threaded bolts would work as self-tappers and hold onto the plastic, I wanted to be able to bolt on the adapter plates and heads and work directly off of the heads for fitment reasons. The seconds thing is I wanted to be able to put the LSA blower on top and have it stand up to the weight of the heads and blower, as such the main caps are somewhat functional in that they reinforce the split line and should help resist the forces pulling the lower part of the block apart. And lastly, I wanted to make sure that the deck surface was accurate would not sag under the weight of the heads and blower. The end result is a 12lb 3d print that took roughly 60 hours to print and a couple hours to assemble, its printed out of PETG and solvent bonded using PVC cement and hot staples as additional support.

You can also see the adapter plate in the above picture bolted onto the block, its still a plastic thread but man is it strong.
Lastly the ZF adapter plate, I am using the T56 bellhousing as I plan on upgrading to the T56 magnum later down the road, they are also plentiful and easy to find and pretty affordable. ZFDoc also went down that road but the thing I cannot for the life of me understand is why he made his adapter plate so thick and made it require the ZR1 input shaft. My adapter plate is only 0.6" and with that thickness I can get away with just a standard pilot bearing extension with the standard shaft. Please excuse the rough 3D scan, it was literally a 30 second scan to get the pickup points I needed and the tip of the input shaft for scaling purposes.

My bellhousing should arrive in the next couple of weeks, and I should be able to try a test fit then. I would appreciate any insight into why ZFDoc would have gone with the thicker plate. I had initially thought of using the C5 bellhousing(Cheap, small, and uber available) but its a little deeper than the T56 bellhousing, its not so deep to not have any aftermarket options, however.

I think thats a pretty good wrap for a kick-off post, for the long weekend I am working on getting the interior torn down and dash pulled so I can start my integration and wiring runs.

 

Good stuff… the detailed engine work and engine build is by far my favorite part of a car project. And maybe the tuning.

 

I agree, this is the most fun part for sure.


As promised, today was the interior tear down, I was able to get the dash pulled out and found some burnt-up wires on the passenger side wiring by the seat, nothing too critical but some severe damage nonetheless since it had burned through the plastics and carpet and finally compromised the seat belt. I know I had originally said that I was not going to touch the interior harness, but looking at the harness behind the dash and reviewing the schematics, I am going to leverage the Haltech as much as I can to simplify the wiring inside the car as much as possible. Looking at the schematics, theres a lot of room for improvement here.

Also got the dummy block and some scrap heads bolted in so I could start getting the harness layout finalized and start taking measurements and figuring out connector clearance.

On my last swap, the factory LS PCM stayed in the engine bay as they are somewhat weatherproof, but the Haltech VCUs are not, so the passthrough behind the heads becomes critical for getting the harness through so the ECU can stay nice and dry, assuming the weatherseals don't leak. I've ordered up my replacement connectors for the C100 and have the new engine bay harness figured out and ready to go. Theres still a couple of things I have to figure out, but the easiest solution right now is to plan for expansion. The list isn't so long but heres what I have to figure out:
First on the list is AC and Heat, I am hoping to make this modernized C4 my daily which means proper air conditioning is a necessity, heat is the easy part because there will be a lot of it under the hood, but the cooling side of things are not so simple. The LSA blower won't be very efficient at the performance level I am pushing it to, which means lots and lots of heat. In order to fit the heat exchanger I have to sacrifice the condensor, that's not so bad since the 86's condensor isn't the most efficient with R134a anyway. Because of the packaging limitations with the heat exchanger I am pulling a page out of the EV book and using a liquid condenser.

With how prevalent EVs are now, these are pretty cheap and are actually way more efficient than the condensers found on the early C4s, the other cool part is with a little extra work, I can also use it as an interchiller by installing another one and being smart with the EXVs and plumbing.
Second on the list is lighting fixtures. I am not going to be using any traditional bulbs and will be switching to LEDs, these will either be LED conversions in the factory housings(depends on how they look) or custom LED boards and lenses but until I get that figured out, I don't know my wiring requiremtnes
Third and this is a big one, is the total heat load, in traffic I am looking at 50-95K BTU/hr, that is a lot to deal with and the C4 was never designed to handle that. The bumper "cheeks" are great empty space for tossing some more rads in but the issue becomes feeding them all air. I have a lot of homework to do on that front and this will take the most time to figure out. The easy part is building the car, the hard part is making sure it stays cool so it can keep making power.
Lastly is the accessory drive, I tried my fair share of off-the-shelf options for my last swap and was able to kind of get it to work the way I wanted, I went through 3 or 4 options and some worked for this and not for that. This is a highly custom build so I don't think anything will work with my setup and my goals and with services like sendcutsend, its trivial to do.

 

Don't worry about heat. Be like the C7 Z06.

I'd imagine you would be considering hood ventilation too. I don't know even if you could get enough heat exchanger that you'd be able to evacuate the air properly in mostly stock trim.

 

Thats an active design element, but it's not so simple with the cowl required to fit the LSA. I didn't mention it in my previous post to keep things relatively short but i am planning on laying down the cooling stack compared to how its currently done with the vertical or tilted rads.

That block is my radiatior stand in for the moment and I am most likely going to double-stack two similar radiators, one for the low temp circuit and one for the engine coolant.
Theres a couple of challenges here, firstly the cowl is eating up prime real estate for a proper hood vent, a stock C4 rad would need ~115 to 190 in^2 vents, that's relatively easy to incorporate even with the cowl eating up the prime real estate, the second challenge is the headlights, I love the flip ups but my god do they suck to design around, they take up a lot of the usable area where hood vents would be the most efficient. I can move the hood vents back to the center of the hood and alongside the cowl, but that would mean long ducts and I am not sure there is space for that either. Heres a basic snapshot of the usable real estate for a proper hood vent, I haven't aligned this mesh yet so the sketch is a bit funky but it works haha.

I am going to a Porsche/refined aesthetic with this build and want sensible hood vents like this...

and not like this...

The side vents look great, but the main vent up front just does not do it for me, and with the cowl height (+3 or 4 inches), it will look way off. I am hoping to merge the two with vents that start from the front and end on the side that integrate into the cowls design, but that makes the cowl a very complicated piece.
Something like this for a real quick and dirty.

The center gap area between the two vents also addresses the next challenge, the air box. The air box would basically have to be in what is the best location for the hood vent, forward of the motor, which kills the majority of the area that can be used for a hood vent. This will need a proper air box, I can't just chuck an air filter on the blower inlet because the LSA is already going to be pushing the IAT boundaries, so I need to get it as cool and as fresh air as I can get. The air box will most likely be fed by the pre cooling stack air with a couple of internal ducts, but all of that is TBD still. The air box would basically sit in the valley between the two ducts for the hood vents and draw in air from just below the lowest radiator. Another really complicated piece I am soooo excited to start designing.

With how the LSA is set up, the front of the blower requires a much taller cowl than the rear of the blower, if the Vette's hood was flat and not tapered down, the LSA would fit under the hood, you only really have an issue with the taller truck intakes (same height as LSA blower) at the very front of the motor and the back tucks in pretty nicely.

This pic is from my first swap and you can see the TBSS intake is flush with hood rail, to make it fit I only had to remove a small 2*4" section of SMC that covered the metal frame in the hood and the hood closed, i did of course have to cut a hole in the hood for the front of the intake however to make that happen.

 

Last update for the long weekend, the car has, for the most part, been gutted.

I was mistaken in my original guess that there was an electrical fire/short on the passenger side. Looks like the cat got hot enough to burn the jute and melt the plastics on both sides right where the seatbelts bolt on, not an issue I'll have to worry about anymore.

I also discovered that the fiberglass in the driver's foot well is broken through and cracked in the corner.


Next order of business is to get the rear of the car stripped and peel back its harness as well. I've also got some butyl sound deadener and closed-cell foam sheets on order, and will start insulating and deadening the car. The jute mats are just coming apart every time I touch them, surprisingly no odor in them, but I am not getting too close to the carpets or jute mats until they have been thoroughly washed. I think I am also going to pull the hvac system apart and replace all the deteriorated foam, I don't want to get blinded by a spec of foam flying at me when this is all said and done.
I am also going to try dyeing the red carpets black. I know, I know, plastic-based carpets like the ones found in cars never dye well, but I have another set of carpet from the donor car, and I am a glutton for punishment and I have nothing but time, I can keep the carpet in the dye solution for a week on end because I am not in a rush. Also, not sure if anyone would want the different electrical components I removed, but I sure as heck don't need them anymore.

 

Lots going on! The liquid ac condenser is an idea that's very interesting how does that all work?

 

Subscribed.

 

Well, to be completely honest, it doesn't make sense for a whole lot of people, while it is more efficient than the tube and fin condenser that came with the early C4s, it is not more thermally efficient than a modern parallel flow condenser, but this approach lets me move the condenser's heat load out of the cooling stack and package things much tighter.
If I didn't go this route, I would have to stack the condenser, the intercooler heat exchanger, and the radiator, thats a really thick cooling stack and I would need massive fans to get any air flow out of it which means the radiator is at a severe disadvantage, and my engine and head gaskets would most likely go kaput very quickly in the summer heat. Doing this also increases the efficiency of the radiator in the summer since it wouldn't be dealing with the heat load of the condenser in front of it anymore. Because thermodynamics suck, even though water is a better thermal conductor and coolant, and the liquid condenser can be way more efficient than an air cooled condenser, getting the energy back out of the water is actually less efficient and you typically need 15-20% more surface area to reject the same heat energy because of the lower temperature delta between the water and the air.
But with this approach, I can put the condenser heat exchanger or exchangers anywhere I can fit them, my current thought is to do wheel well exhaust with and some nice looking wheel well vents, but I have to start the body kit design and start nailing this down first. The other benefit is the packaging, one of the reasons I removed the blower motor assembly from the car was because I wanted to see if I could tweak the evaporator position (headers will hit the evaporator box) and incorporate the liquid condensor into the box so that the AC lines are basically all self contained in the passenger side fender, the only thing external from here would be the 4 coolant lines (2x heater core and 2x liquid condenser) and the 2 AC lines for the compressor.

 

You might want to run a lower CR with the blower.

 

I can see why you would say that based on the static compression ratio, but I want to point out my dynamic and effective compression ratios. My static compression will be 10.7:1 after the block and heads get decked, but the real saver here is that my dynamic compression is pretty low at 7.8 because of my cam choice. So because of that, my effective compression ratio is pretty low and I am not pushing the edge of safe 93 octane until 10 or 12PSI. That's pretty substantial headroom and it means that should anything be detected, I can scale back on boost and fingers crossed keep my engine alive. Another note, the car will mostly be on E85 or an E85 blend, I am lucky that I have 3 E85 stations within 4 miles of my house. I am also not planning on using the standard bypass valve setup for the LSA and am working on something more like the hellcats where I would have electronically controlled variable bypass valve that will allow me to control boost, the haltech will have blend tables for ethanol content of the fuel so I should be pretty safe by bleeding off excess boost when I am not at a fuel content level safe enough to utilize it. This is of course dependent on proper tuning of the knock sensors and tables, but I will be being super conservative until I get the motor broken in and the tune pretty nailed down. My goal is always OE+ levels of integration and smoothness.

 

All that plus today's tuning tools make high compression and boost a non-issue.

 

I've seen stock engines with 11:1 last a quarter million miles with add on blowers. I wouldn't be that worried about it. Though on a boosted application high CR isn't as necessary it will help for driving outside boost... or in this case when the blower is bypassing.

 

Looking forward to this one! I’m doing an ls7 swap in my 94 hopefully starting soon once I get all this material from a job I’m working on out of the garage! Planning a lot of the same stuff as you, also a multi year project. Ls7, dry sump, t56 magnum, a lot of custom stuff. I’ll be following your build!

 

I would love to remove the condenser from the front as would a lot of people with street/track cars. I have it on my list to replace it with a smaller condenser but am wondering what is all involved in the route you are going with it. I have so far kept AC on the car I have now but have removed it on past cars.

 

It can be done really simply if you don't mind a spare tire delete and mounting the heat exchanger in the spare tire well, obviously there is some risk there but for an AC system that means you lose just your AC. The more involved way which keeps it under the hood (AKA the way I am doing it because I am a masochist )will require modifiying the bumper, the fender linders/ wheel well, and cutting up the hood to add wheel well vents, for the street/track, that is the ultimate option because you will also reduce the pressure in the wheel well which means the car stays more planted, atleast in theory that is.
We are officially snowed in and I have spent the last couple of days agonizing in CAD trying to make a hood cowl and hood vent that look good and flow enough air to keep the car cool. The best case for air flow is close to 900 square inches for hood vents for the full system, but that seems impossible to do, because the usable and accesible area of the hood is pretty limited because of the headlights. The headlights are not something I am willing to compromise on and they are staying no matter what, but... they may need to be downsized and modernized to help the cooling situation.
I can however pretty easily fit the vent area required for the main cooling stack into a 34*10" vent between the headlights, that would work great it just looks like crap. So I am currently taking a break from that design to keep my head from exploding.
In other news however, I am pretty much done with the ABS controller/translator required to get the BMW ABS working in the vette, I think I briefly mentioned the ABS aspect of it in another post but I am converting my car to use the MK60 ABS common in a lot of Euro cars, this is believe it or not a very cheap and easy upgrade to do to get quad channel ABS. The only reason I need the translator is to enable the DSC or stability control functionality of the ABS unit, but it will work as a standalone ABS unit without it.
I got my unit for $70 with a warranty off of fleabay just to put it into perspective of how cheaply this upgrade can be done. It's also tiny compared to what's behind the driver so some small weight savings there I guess.


The translator I am designing is pretty small, about the size of a credit card, and converts the VR signals of the C4s wheel speed sensors to DF11i, of course it being a BMW part it uses a non-standard signalling protocol. Not all the BMW ABS modules use that protocol but the cheapest ones do and that's why they are cheap, haha, this one is specifically the MK60E5 out of a 335i, I think.
I am not the first to do this and there is a great product with great support available, but it didn't meet my requirements for flexibility and features so I am making my own, plus another cool feature I am going to try working on is to get the diagnostic capabilities like the bleeding cycles programmed into my module so I can easily cycle the ABS and bleed the brakes from my phone on track days. I am also curious to see if I can have an ABS based linelock, since the translator is actively generating the pulse train for the ABS module, I should be able to kill the emulated signals for the rears and stand on the brakes and see what happens...
There's still a lot of improvement to be made here but I can atleast get a couple boards on order and start testing now. I think I will spend some time tomorrow finalizing that board and getting it squeezed down as much as possible, the empty space bothers me and it wouldn't fly at work haha.

In other news, my replacement for the C100 connector came in before the storm hit and man am I excited to get this installed. Going from the C100s 38 positions to 60 total with 48 pins rated at 7.5A and 12 rated at 13A, and with a chill IP68 and IP6K9K rating. Oh and they are basically the same size as the C100 and not impossible to pin (looking at you milspec connectors).

I never got the chance to strip back the rear harness in person, but I have spent a lot of time redlining the schematics in the FSM to eliminate any of the extraneous stuff that I won't need moving forward. I have to head back out of the country the weekend after next, so I am going to try to get the rest of the car stripped down next weekend so that when I get back I can get started on the engine harness and start getting the car wired back up.

 

For me it is not the durability, but the power. The blower is generally more efficient at compressing air, so for max power you usually want higher boost and lower CR and let the blower do more of the work instead of the pistons.

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.

 

Well it has been a couple of weeks, and progress has been slow, but I was able to work a bit more on the cooling system design. I also heard back from the machine shop that my block will be ready Monday which sucks because I have to leave the country for a business trip Monday morning. Anyway, there were a couple of design elements that were gnawing at me so I sat down and did some math.
I have settled down for a 31"*19" dual row, single pass radiator as the main radiator and I am still messing around with the math for the intercooler heat exchanger.
I may use the aluminum rad/stock C4 replacement I had bought for my last swap as the heat exchanger. However, I am still not sure how I feel about blocking that much area of the main radiator. To make this fit, I am planning on cutting the frame forward of the fender mounts and replacing it with tubular members up to the bumper support, its a high effort action but it gives me the most effective way of mounting the rads without compromising the frames stiffness and affecting the hood while driving. Theres a couple of other things I have decided on that affect the design of things, firstly, I am defintely getting rid of the factory hood release and will be using aerocatches, that should also help simplify and reduce the massive hood support that were provided but I also am trying to understand why those were made so hefty in the first place. Second decision was I won't be able to rely on the cooling from the main radiator alone for keeping the engine cool, based on the heat load estimates I am looking at almost 700in^2 to keep the engine cool enough from derating, which means I may have to sacrifice some of the condenser performance for engine cooling. Lastly, I am ditching the stock front bumper for sure to add the necessary mounting and cooling features I will need to keep this beast cool and reliable, the cheek/aux coolers may get sledgehammer-like features to get the air into them, but the main cooling will remain bottom-fed just with a more robust cooling solution. All in all, the biggest challenge for this car seems to be the cooling and once I get that figured out I am sure I will find another big problem .

 

Being on the other side of the world from my car puts a damper on progress but I took the opportunity to make more progress on the hood design. Unfortunately for me, the Porsche hood design is a no-go for me, and the only way I can fit the right-sized hood vent and make it look good with the cowl is to merge the two. I'm all ears for how to make this look any better, but this is my 4th or 5th go at it and looking for some more inspiration on other hood vent ideas. Crunching the math, this hood vent gets me the correct vent area for the radiator, I will be fully ducting the radiator so this was one of the critical aspects of the design.


A couple of other things I settled on was the cooling system, I am now comitted to two CWA400 pumps and will be going remote mount pumps, my cooling system will be pretty restrictive and the factory pump does not like that at all. One nicety of this is I will not need a thermostat for this amd can regulate engine temp by varying flow through the engine, when temps are low, the pumps will run at full speed in short bursts to make sure that no steam pockets form and that the engine can warm up properly, a cold engine and E85 is a recipe for disaster.
To accomplish the remote mount I started designing my own coolant manifold, the manifold uses -16 hoses and will help me get the parallel cooling circuits.

It's still a work in progress but rough cost estimates put this at about ~$170 which is almost a quarter the cost of the other options online. Hopefully more updates soon and a better idea pops into my head for the hood cowl

 

Have you considered throwing in the towel on the hood and just finding an LS2 intake or using a low profile intake? I am looking at the Deepcool intakes. Being fiberglass, it just complicates the hell out of things.