The LS bandwagon is almost as bad as the corvette tax, making power isn't as cheap as it used to be. I've heard that the dormans have had leaking problems as of late but honestly have no idea if that argument has any merit to it. It seems as long as you keep it together and don't port it, its all good.

Thanks DMITTZ, it's killing me that I've been so busy with work to make progress on it.
For me the cowl is a no-brainer since the hood was trashed from sitting outdoors for a decade. I've scoped out a replacement last week just in case this little experiment fails.
I've been hesitant to say anything but I've been looking at what it would take to make this a bolt on cowl that would just need to be 3D printed, sealed and stabilized with resin and possibly reinforced with fiberglass or CF. Issue is I'm an engineer with no aesthetic sense, ive always cared more for what was under the hood than the hood itself so there's going to be a few revisions.
I have a CAD model of the hood using the previous scans and all the templates I've printed are a bit too small so I'm waiting for a good weekend where I can head out and get the hood setup for a proper scan. I know where my errors came from so that'll be resolved in the next scan.

 

Well, back from crawling under the car, and dang was it ever so darn close to fitting, hood to center of motor mount came in at 19" give or take 0.125, and the TBSS sans intake gasket came in 19.75 also give or take an 0.125. The center of the hood is a wee bit higher so a shaved intake might just squeeze under there without needing a cowl, but no way to know for sure until this weekend when I hopefully get the motor back in the car. If it is close enough, it could be possible that slotting the engine cradle so the engine and mounts sit lower in the car would work. The intake plumbing is also gonna be a bit difficult to route.

 

It's been a good while but I'm finally able to work on this project again, and I have some good news!
I finally have a scan of the hood that is promisingly accurate. It wasn't easy and required me to vandalize my own car, corrupted my Windows PC multiple times, and caused said PC to overwhelm the air conditioning of the room it's in and make it 80* for 14 continuous hours. But I can finally smooth it out and start working on finalizing my cowl.
The paint lends itself to the process as it provided unique points and shapes that conformed to the shape of the hood, the primer on the car was shot anyway from being exposed to rain so I had nothing to lose.
I've put in a sneak peek of what it looks like plus what it took to get it done.
More to come very soon and hopefully a nice CAD model too.

Out of curiosity, should I move the hood fab content to a new thread to make it more accessible?

 

Awesome. Did you use baby powder + water for the surface? I've read that works well.

I started a thread for 3d print files, so maybe you should start one for 3d scan files?

 

High build primer from when she ran well enough for me to start the bodywork, the baby powder trick does work though, its best for high gloss surfaces like painted body panels.
I'll start the 3D scan thread as soon as I get a cleaned up model put together.

EDIT:
I got a bit excited and mocked up the cowl I designed, it turns out it's not as obtrusive as I thought it would be but still needs a decent amount of work.
Enjoy!

 

A somewhat success!
I had my printer going non-stop the last couple of days and the end result is a 43" long quarter print that I got to test fit today. It didn't exactly have the clearance I wanted and I need to make a few adjustments to how it fits the curvature of the hood in 2 places, but I'm happy with the overall fit and shape.
So the clearance issues I mentioned, the cowl raises the area where the intake is closest to the hood about an inch to an inch and a quarter, which is enough for it to just barely clear the intake with the motor at rest, as soon as the motor mounts flex though, that clearance puts the intake through the hood. All of this is based on rough measurements with string so there could be more or less clearance than I mentioned, but I won't know until the motor is in and the hood is cut. Currently, the total cowl height in the back is just under three inches and upfront it is just under 2 inches. it's back to the drawing board for me, I want to try and have the motor back in the car this weekend to finally figure out my heights and clearances.
But first, the Vette needs a thorough cleaning, apparently, the car cover got torn while I was out of the country and I just noticed today.

In other news, I went ahead and ordered an R4 compressor high mount that looks like it will clear the upper control arm, the summer is drawing to a close but I'd rather put it in now and just get it done rather than worry about it in the future. I was considering switching to a Sanden compressor, but it seemed too much of a hassle and expensive. It seems that just the hoses I would need would cost more than a parallel flow compressor.

 

Hello ThatOneKid!

I believe that they make hood scoops like the one you are trying to build from scratch. It might be easier to get a good fiberglass hood scoop to avoid the damage from all the heat that will come up through the hood. PLA does not like heat and there is a LOT of heat under these hoods.

You live in Fairfax as well I see. Where are you located in our area? I live off rt 50 near Cedar Lane just outside the beltway. Fairfax is trying to make it harder on us to be able to work on our own cars, fortunately I have a back yard.

I have a 1968 C3 that started life as an L71 Corvette with it's 427. Many years ago I went to Corvettes@Carlisle (PA) and I wanted to get a big block hood to replace the one on my Corvette. I found a guy selling a Factory L88 Hood for the 1968 model Corvette. It turns out he and a Buddy ordered an L88 from the factory. They used it specifically for drag racing so right away they pulled the original intake system and replaced it with a high rise manifold. Now the Hood would not close so they took it off and made another fit. A few years later the car rolled and was destroyed. He wanted $2500 for the hood on Friday, on Sunday I bought it for $250 at 4:30 pm. two weeks after I bought the hood the gentleman who sold it to me mailed me the remaining Hood parts. The parts go on the carburetor and seal it to the hood. It was painted and installed on my 1968. Now it needs paint again as the hood gets exposed to a lot of heat after shutdown. The paint started cracking due to the excessive heat.

What you are building looks a lot like the factory L88 Hood. In my C3 you are looking down this big opening that is supplying cold air to the carburetor intake. This hood "makes" power if you do it right. At speeds there is a high pressure at the base of the windshield that forces more air into the engine. The L88 style hood has been copied and used on cars with taller intakes or EFI equipment. Most of the time you will not see the parts on the carburetor.

The temperature of the air going in is really important if you want to make power. My C3 has 12.25-1 Compression ratio and runs a "bit" warm so I employ several tricks to try to make it stay under control. I have over 25 years of experience with the C4 and my older C3. If I were doing what you are doing I would find a way to get ambient air into your engine's intake system and use your hood design to help. My C4 has some higher temperature air getting into the combustion process and I would like a good cold air intake.

On the L88 Hood they have supports inside so it doesn't collapse very easily. This is important to have down the center line.

I don't know if you have been to a Corvettes@Carlisle yet but it is a little over 103 miles from my door to theirs. It is well worth going from our spot here in NOVA. They have tons of parts for Corvettes, I still see C4 stuff there and have saved a lot of money buying the parts there, used and new.

 

I don't think I've mentioned it yet, but the cowl is printed in PETG and will be resin stabilized and fiberglassed for strength and heat resistance, I thought that the cowl was somewhat aggressive so I designed in several places for carbon fiber spars but figured I'd wait and see if it actually needs it or if they even fit with the motor in. I'm also thinking of only cuting the hood where the motor needs clearance, which means the hood retains much of its rigidity. Without the spars, the total cost for this cowl is $40-$60 and a few hours time which IMO beats the added value of any of the commercially available cowls.
I was in Fairfax, now in Manassas right off Libreria, the cops around here are pretty strict, even though my Vette is registered and insured, I can't have it on the driveway without a cover because it does not have a valid inspection. And the neighbors suck, anytime I move it into the backyard by my shed someone calls and reports a parked vehicle.
I wish I could take advantage of the cowl induction but I don't think think the top of my cowl is close enough to the windshield to fully utilize the high pressure zone, there will definely be air coming in form the bottom though so I'm going to extend the cowls top so its hooded and matches the angle of the windshield. For now, the cowl will primarily be used for blowing cool air down at the motor and out the fender vents, if I have the room under the hood for it I could design up a set of ducts to duct that air into the airbox, but I'll have to wait and see what it looks like with the motor in.
I googled the L88 hood and that's a massive hood for sure, but I like it, it fits the cars body lines very well.

I think I may be able to make it to Carlisle this year, it all depends on my work schedule which changes on the daily. My goal is to have the car running and reprimered by the end of July, but the car hasn't been driven since 2010 so I'm not sure it'll be roadtripabble which sucks.

 

IT FITS, OH MY GOSH!!!!!
Excuse the fan-girl moment lol, but the hood cowl finally fits and now it really looks like an L88 cowl, maybe a little bit smoother transition.
Small update on the Vette, currently making C-Beam plates, just finished slotting the beam itself, carbide burrs are amazing btw 9.99 from amazon, did 3 holes in the time it took me to do one with a Dremel and sanding rolls, sooo motor should be in its new permanent home by sundown today!
After 2 stagnant months finally progress.


Edit: Cowl will be released as soon as I get the width and front mount point verified, so excited!

 

No pictures today, but there will be plenty tomorrow, it seems pretty realistic to say that it will be running next weekend and maybe driving the one after.
The motor is finally in and it is in to stay!
It was a very busy day today, started the day slotting my C-beam plates(measure twice, cut once and all that jazz), I mixed up the center to center and center between holes distances up on the diff side. Got those slotted and moved on to welding the stover nuts on to the top plates, and then iI realized the c-beam was the wrong way around and had to redo it all, I think this proves three hours of sleep is not enough...

After the C-beam plate fiasco the real work began, my brother was helping today so things were a lot easier. We had some trimming to do on the pressure plate bolts because they were self-clearancing on the starter, from there the motor got a new starter and a test crank before the install began. At first, we had the c-beam bolted to the trans and shoehorned the whole darn thing into the car, that would have worked great if the diff wasn't angled up so we swapped the c-beam over to the trans, and the driveshaft over to the trans, the combination of these two let me pull the c-beam and diff down while guiding the trans into the beam using the driveshaft, that worked great and gave me just enough leverage to lever the LS into mounts. From there we ran into our first problem of the day, and where I will be starting from tomorrow, the c-beam even slotted 1/4 inch as it was, did not reach, I thought maybe the diff side was slid too far back, but nope. Turns out the swap plates I have moved the motor forward 7/16 of an inch and not 1/4 as I thought. No big deal as I can just pull the C-beam out and slot the diff side, but it sure as heck is frustrating.

Now the first good bit of news, the cowl should provide enough clearance for the TBSS intake, hell the TBSS intake fits under the hood like the TPI in the back, just under the rubber water seal, it does not have the angle like the TPI so it will definitely need a cowl for the front to fit under the hood, but this is great news for me. The half of the cowl I have done leaves 1/4 inch clearance at the highest point of the intake, so tommorow after the c-beam fiasco is solved, the hood's getting cut, mounted and I'm moving on to electrical work. With all that said, I will be releasing the cowl CAD file tonight for anyone who wants's it, look for it in the 3D scan, 3D print, and it's own thread.

 

For the first time, the LS is fully mounted and supported fully by the car.
Took a few tries with the C-beam slotting, but in the end there was a 1/4 slot cut in both the diff and trans side, for a total of 1/2 an inch.
Plenty of room under the hood for activities, the AC bracket I ordered clears the A-Arm mounts perfectly and is pretty close to stock position, there is lots of room under the balancer to get the belt in to and there is plenty of clearance between the balancer and the brace in front of it. All in all, a good fit that wasn't too difficult once things got moving.
A few updates on things:

Headers:
The C5 headers fit on the pass side, I couldn't get them fully into position because of my head studs, but after trimming the flange I think they'll fit without needing to be bashed. I will be header wrapping them to keep temps down up until the collector flange. Speaking of collector, From the rough placement tests I did today I don't even think I need to cut the collector off, that, of course, being because I do not have an auto oil pan to deal with, more on this next weekend I hope.
Electrical:
I'll be working on this throughout the week, I have a rough idea of wire routing and how to integrate the LS into the C4 chassis harness without needing the LS fuse box.
Hood Cowl:
If I get off work early enough one of these days; I'll be cutting the hood, I realized I never took the fuel rail into account height wise but I think the cowl is still big enough to fit it. I'm holding off on releasing it until I do have that all finalized.
AC Bracket:
Like I said earlier, the ebay bracket works great, for some reason the ones that all fit the 85's R4 are called cadilac swap brackets... picture attached, but it looks like all the chinese 3 piece brackets will clear the C4's larger pulley.
Rear Composit Spring:
This one was a gotcha today, I have a cracked spring with a broken chuck of it missing on the leading edge of the pass side half of the spring. I'm not too worried about this right now but will have to evaluate things after the car is running.

Still in the works:
C5 Brake Conversion:
I started this project a while back and had to abandon it because of time commitments, this is now getting moved way the hell up in priority to keep me and other safe on the road. The bracket dxf I used is already out there, I made a thread about it earlier this year.
C-Beam Brackets:
I designed a set of C-beam brackets and had them laser cut, the dxf files will be released pretty soon, I need to make two tweaks to the diff side bracket. These aren't as fancy as ZFDocs, but they do the job and cost me a grand total of $35 bucks with replacement stover nuts.

Here are some intake fitment photos I took, It's pretty interesting to see a truck intake on a car, the TPI intake made it possible. Also attached is the photo of the AC brackets that I found to work, the thick one-piece ones will not clear the stock R4 pulley.

 

Would it be cheaper to just put a Dorman LS2 manifold on it versus cutting, glassing in and painting a raised cowl?

It is virtually identical in performance to the tbss intake but a lot more clearance.

 

Accessory costs come into play here, I still need to cowl the hood for the truck accessories, namely the large case alternator to fit under the hood, to get away from that I would need a whole new accessory bracket + intake + water pump + fuel rail + injectors etc...
The cowl, in the end, leaves me ahead, considering the whole car needs to be painted, the hood in the bump is all checked and cracked, if my car had good paint and glass then yeah, I'd look at maintaining the stock appearance. But the car is in need of extensive bodywork since the PO half-installed a C5 body kit, and so my C4.5 has a C5 rear and C4 front and it looks pretty darn good if not very unique. Another option I've been looking at is a carbon fiber top layer and keeping the raw carbon look, it adds $60-80 to the cost of the cowl, which is currently $30 in filament for the printer with about 60% of the cowl printed.

 

Here's today's progress update, the L98 harness is completely out, and yikes no wonder I had a misfire I couldn't track down. In the parts of the harness up top, the wire was very crumbly and stiff, meanwhile everything down low was soft, almost as if it was silicone high flex wire. Now the FSM is just downright inaccurate when it comes to the wiring diagrams at the back of the book which made what I thought was gonna be a few hours of finding the wires in the harness and removing them take all day.

Apart from that, I've got a close to final idea on how to integrate the harnesses and there may be a chance depending in when the rain let's up that I'll get to do a power on check and maybe even crank test tommorow. After that it's fuel system, clutch hydraulics, intake ducting, finishing the C5 brake conversion and rear brake rebuild before she's ready for a test drive.

 

Documentation time,
Here is where I stand on the swap wiring so far. It seems pretty simple to be honest, just connecting the dots, but we'll see next weekend when I have to hook it all up lol.
Just a reminder, I'm looking to integrate the two harnesses together, which will be accomplished using connectors where the two harnesses meet, but the only fuse box in the car will be the original C4 one, no bulky LS fuse box in tow. The downside of this is I am adding in an additional relay, there are MANY 12V ignitions switched inputs in the LS harness that must be properly fused, I also don't know of any fused ignition switched sources in the C4 harness so elected to may my own and add a master relay. I'm using a 40A automotive type with a 5A fuse, that should protect the wire and be sufficient for all the sensors on that bus, the injectors will still use the C4's fused outputs. The benefit of a truck harness here is LOTS of extra lengths since the truck places the stock fuse box about 2 feet away from the top of the intake where the harness then splits. That gives you two free feet of length that lets you position the PCM as you like, I'm going to try and squeeze it in the pass footwell where the old PCM went.
Attached is the current pinout doc I'm using, I thought I posted this earlier but I guess I didn't.

 

Sneak Peak of things to come.
I've committed the ultimate sin...


But it was for good reason, here's the side profile. Also, I love how clearly the offset towards the passenger side shows with the LS in there, you cans see how the entire motor sits closer to the passenger to make more room for the driver.

Other things of note that got done this weekend, the motor finally spins at the turn of a key, the harness has been test fitted and now I'm figuring out placement. I lied about not having a secondary fuse box, there is an el cheapo one from Amazon that I'm using for the ancillary LS stuff that the stock harness does not have provisions for such as the heated O2, MAF, and the 2 stage fans. The secondary fuse panel is fed using a 40A relay that is triggered by the ignition switch, to prevent problems with DTCs occurring from split second differences, the PCMs ignition switch feed is also coming from that fuse panel so all LS stuff comes online at once.
There's still a LOT to do but I'm getting close, I'll be sneaking time in after work to make small bits and bites as well taking some detailed pics of the entire thing. Also a more detailed update coming soon, this is a quick one typed up during my "lunch" break even though it's dinner time.

 

Now that you have a hole in the hood, perfect time to add a blower and bug catcher :-)

 

lol, it would look sweet, while it's not a traditional blower, I've been looking at what it would take to do an LSA swap, that's for all further down the road though. This vette is too new to me still so it will be a little while before I start putting down all that much power down but this car will be going FI sooner rather than later.

 

ITS ALIVE!
Well... sort of, maybe more like it's on life support?
I kicked it into overdrive this past weekend and had a goal of having the first start on Sunday, I am happy to say that it was a success and the LS took its first fiery gulps of breath and man does she sound mean.

Fuel System
There was a lot that took place this weekend, first I started off by emptying the gas tank, now typically syphoning gas can be a pretty distateful experience. I had a couple of gallons in the tank but it wasn't gasoline, it was all water. Now obviously this would have caused problems had I pumped it into the new lines and rail, so out came the sending unit and the gas in the tank. The water was getting into the tank because of a bad sending unit gasket, I took a few steps to stop the water ingress, first, the gasket had to go and in it's place an 1/8" NBR sheet was cut to size to take it's place. Normally I would have just gone with the stock gasket replacement, but my tank had hefty corrosion on the sealing surface and I wanted to give it it's best shot of sealing, the surface was wire wheeled but still had large deep pits. Step 2 was rectifying the unequal clamping pressure problem, I've tossed the stock bolts and put in large flanged M6 ones to help with getting some even clamping force around the perimeter, the best option would be to make a reinforcement ring out of 1/8 steel or such that would evenly clamp the sending unit to the tank, but that's over engineering the problem when you can have a compliant gasket. With all that said comes the surprising part, the rust somehow managed to stay outside of the tank, the inside appears to have a black coating(POR15?) that kept all the corrosion at bay, there aren't even any bubbles in the coating, color me impressed. I skipped ahead a bit so back to emptying the tank, the tank was then wiped down in its entirety with blue shop towels so that without a doubt there was no water in the tank, this was not a pleasant experience as the hole is just large enough to fit my arm, but the deed was done, and I am glad it is over with, there was some gunk at the bottom of the tank below the plastic baffle that the fuel pump pickup sits in, but using a flat head and shoving a towel under too care of that. Next in the ordeal is the completion of the fuel system upfront, I had ran the hose but not planned the system completely out just yet so Hadn't commited, I'm glad that was the case as the original plan would have led to some HOT fuel courtesy of the header. The new solution came out pretty neat and looks pretty clean IMO, the regualtor is mounted on a 3D printed bracket that mounts where the ESC once did, this lets me route the feed to the rail with the coolant tubes(which will be insulated), the pressure and return lines run under the HVAC box, and straight into the filter/union. The end result is a regulator mounted pressure gauge that is easy to see, and just barely clears the hood mounted fender's flange, hidden fuel hosing, and a route that limits the fuels exposure to heat from the headers to the greatest possible degree while keeping the hosing safe but accesible. Other things of note, I am replacing the fuel filter once again as I am incredibly dissapointed in the amount of water that came out after blowing the system out both ways and leaving both ends of the system open to air it out as much as possible, going in will be a K&N high flow filter, I'm not sure how well that will work and the lack of fiter media size has me skeptical but everything is worth a try once right?

Harness
Oh boy, this one was a real doozy, all it took was 4 hours, 1 bricked ECM and a whole lot of frustrated head banging to find a single missing ground, but it was found and that's all that matters. This is where the majority of the weekends time was spent, while the harness has been done for about a week, this was the first test and validation run that it would have so I used it to flush out all my problems, and apart from that ground SNAFU, the engine harness is all set to go. Wish I could say the same about the car harness though, I have somehow managed to disable the dash, power windows, radio and HVAC system, even though ALL assosciated wires show continuity and measure out nominally, I'll be taking a closer look at this one tommorow when I get off work, but it has me very confused and I am hoping it is as simple as a missed ground somewhere, the LS harness is back out of the car so hopefully that'll make it easier to find whatever is missing. Now, with the engine harness verified, I'll be diving into getting the vehicle side of things ready, I am removing all the critical antiquated relays and replacing them with 40A rated waterproof ones, all the ends where the pins go into the connectors are green and the insulation has dried out and fallen off which is a HUGE short circuit risk, I'd rather play it safe than sorry and if that means violating the "GM Engineers know best" rule than so be it, but those relays are old and way overpriced. Also new to this car is an 11" dual fan setup that is fully shrouded, that means it will need another relay added so I can run staged fans, not that big of a deal since this car is almost completely LED lights and has the 160A alternator, but it means less parasitic draw when it's not needed. I am still undecided about it, but I may take on the effort of having the LS ECM, and later on, the standalone, control the AC clutch, that would allow the fans to be completely controlled by the ECM and allows me to use the AC Requested higher idle. I have no clue how the C4 AC electronics work so it will take some research, the going thoughts are to have the AC Clutch feed go to the AC requested pin on the LS ECM, and ground out the ECM's low pressure input. This would allow the factory HVAC to run the operation, monitor the switches etc, but let the LS ECM do its thing on launch, and in traffic, still a fledgling idea but seems simple enough.

Drivetrain
Not much done to this one, currently pending clutch hydraulics and putting the yolk straps and bolts in, I'll be working on these this weekend hopefully and fingers crossed taking the car for its inagural drive and tune.

Dash
Not sure how everyone else has been doing their dash stuff but I went with the swap standard 3 pin CTS that lets the ECM and dash share a sensor, that means no need for adapters, just a twenty something dollar Delco 12551708 sensor, since I redid my own harness, the 3 pin connector for the AC pressure transducer became the CTS, with a single flying lead that goies into a metripack connector along with the oil temp, tach and oil pressure sensor for the dash. For VSS, I am going to try hooking up the speed sensor to the LS, and then use the LS 4kpm signal to the dash, I tried reaching out to batee about the dash being able to process a non zero crossing sqaure wave signal but never got a response, worst case is it will take a resistor and capcitor to convert the square wave to be zero crossing ala this amazing theadr(https://ls1tech.com/forums/conversio...-wire-vss.html).
That's this weekends update, I'll get some pics while I'm working on the car tommorow.

 

Damn. Just, damn.