Getting close to completing LS3 refresh. BTR Red Hot, Dual Springs, Titanium Retainers, Melling HV Pump, Rollmaster IWIS, LS7 lifters, BTR Rockers, Holley oil pan, Holley Terminator X Max, 1000HP 4l85E. I could use pointers from those that have gone before me. With headers and a good tune I'm hoping for at least 500hp. Hearing i may hit more than that. Thoughts?

 

Very cool!

A stock LS3 with optimized fuel and timing already makes 500 on a dyno, I would imagine you’ve got at least 100 more than that. Should be a blast to drive.

What year car is it going in? Do you have the accessories, fuel system, and electronics set up? Lastly I would be concerned about the differential, for whichever year it’s going in.

 

Awesome! Yea, when I split the body and frame off the 1970 I plan to change out what appears to be a 3.08 to a 3.55 or 3.70 thanks to the relief she'll get from the OD in the new tranny.

 

That is a bunch of power all right! Should be a lot of fun when it is finally set up and back on the roads again.

Higher HP C3's can be quite expensive to own, if you repair as you go. The differential and half shafts will most likely be the starting points for breaking. The best way would probably be going with a sold axle or a more modern rear suspension designed for the HP that you are going to see.

I have a C3 with a 427 and I built it like the L88 engines with the compression. My HP will likely be lower than yours but the problems similar. The first time I dumped the clutch with good sticky tires my left half-shaft's Outer U-Joint blew apart into a lot of pieces. I had new axles with new U-Joints without grease fittings and they were a step up in the right direction. On your C3 the half-shafts will have to be dramatically stronger than what they used at the factory. I would suggest that you speak with Gary about your differential because he would know which direction you need to go.

You have many of the bases covered but beware that something will stick it's ugly head up at the last moment. I have a M21 and want to change the gears over to a Rock Crusher. The bevel cut gears were done to make it quieter but the straight cut gears don't push the cases apart under high HP/Torque conditions. I will tolerate the whine from the gear box just to be sure it holds together.

With the kind of power your engine makes the trick is to learn to drive the car gently at take off and "let it rip" once moving. Hard Starts seem to be tougher on the C3 Corvettes and they can really make a mess out of the car. The rear axle "ratio" might play an important role here as well. My C3 has a 3.36 rear axle ratio and it works great. At a race track the car wants to spin the tires off the rims. It will spin for 1/8 mile or more at the racetrack with the 3.36, I often wonder why Comp Cams wanted me to go with a 3.70 at a minimum or a 4.11 . Between the gearing and the torque a BB makes it is fun to drive it and I get some gas mileage where my
buddies with 4.11's were looking for gas stations.

Please let us know how your Corvette works after your conversion. There are plenty of guys here on this forum who look at the LS engine and dream about doing what you are up to.

 

Awesome! Yea, when I split the body and frame off the 1970 I plan to change out what appears to be a 3.08 to a 3.55 or 3.70 thanks to the relief she'll get from the OD in the new tranny. Appears I need to upgrade the half shafts with HD caps, etc. It's my understanding this whole part of the train is susceptible to torque overload. I'm also planning to flare the fenders and add wheels and 335s on rear and 295s on front to keep it stuck to the asphalt. Welding in gussets and brackets as recommended for known weak spots on the frame.

 

Thanks for the rich feedback! Sorry for the duplicate posts. Been a reader up to this point and getting used to becoming a contributor. As for the fuel system it appears the stock injectors are sufficient unless anyone recommends a 'might as well do it now' condition although they appear easy to swap later on. Gotta get the high pressure pump, reg and accessories figured out so looking for advice. Drilled and tapped the water pump for the known a-arm interference issue.

 

ICT billet makes brackets for the alternator, power steering, and air conditioning compressor. These are their part numbers.

551577-3-182
551474-3-300

They use the truck/Camaro LS3 pulley spacing, and were used in this thread.

 

Nice! A blue LS is the correct engine for these cars.

Have a look at this thread. I ditched my ICT billet stuff, and will use the Holley Midmount for my LS6.

https://www.corvetteforum.com/forums...d-mount-2.html

 

With an automatic trans, properly rebuilt differential, Spicer solid U joints (all 6), street tires, on the street (as opposed to a prepped drag strip), you shouldn't have any drivetrain problems, no matter how much power you're making.

 

So my goal on the LS3 swap was to do no fabrication to the car. So I can return to OEM as it started.

Here is my swap into a 1978 C3. What ECU are you planning to use ? I used the factory GM ECU & Harness for the LS3 480 Crate engine (rated for 495 HP). Very easy install and use HP Tuners for any programming or DIAG.

As for Diff ratio's I chose to match the C6 corvette design. Driver many C6 corvette's at the race track at SpringMountain and found the combo great for street / Track driving. Since I have a T56 speed = C6 Z06 corvette and with a 3.42 diff. I selected for my C3 diff as 3.36 diff. But drove the car for a good 2 years with the factory 3.08 diff. the 3.08 diff is much better for street / highway driving giving me a great 33.1 MPG. You having auto trans, check the gear ratio and see what C6 / C7 car it matches and test drive them to see if you like it.

1978 LS3 Swap Completed. - CorvetteForum - Chevrolet Corvette Forum Discussion

 

I have an LS3 with 4L60E in my C3. 4L85 will be tight, may require some massaging of the tunnel. I opted for the Holley Mid Mount LS belt drive. Its a bit pricey but it fits and makes the swap easy. I went with Aces efi, plug and play, 4 wires to connect and it’s running.

 

Hello and good afternoon to everyone. I am new to this thread and recently acquired a 1972 Corvette stingray coupe. I bought the car with an LS3 from a 2015 Camaro SS, manual shift, Engine -that’s bolted in to the front K-member. It appears to have the correct oil pan on it. I’ll start by saying that I have never completed an LS swap before and all of this is new to me.

Furthermore, the Muncie four-speed transmission is sitting on my garage floor. I’ve done some limited research and am lucky to have found this thread. I am greatly appreciative to all the work you have described here. I am in need of some help.

Here’s my plan and where I’m at:

My plan

firstly, the engine is complete with the factory Camaro harness. Accessories etc. As I’m doing this on a budget, I do not plan to change the transmission to a Tremec TKX or alternate. The plan is to keep the Muncie four-speed and get the vehicle running and driving firstly. After that I would like to consider replacing the air conditioning condenser/evaporator. Change the mechanical brakes by adding a hydraulic brake booster. Research options for the steering, Detroit speed or other type of steering drive boxes.

Questions

Regarding the Muncie what bell housing is best for this application? I have researched the housing number 621 will bolt to the LS3? Will the factory Camaro starter bolt in? Alternately if not, which starter?

What clutch, flywheel and pressure plate set up will work for this 425HP LS3? Should I modify the mechanical clutch assembly to a hydraulic assembly? If so, what kit should I use and or how should I construct this?

Regarding the accessory drive system on the front of the motor, what have you guys researched and used outside of just buying a kit from Holly or other manufactures? Can I use any of the Camaro accessories and or modify them?

Should I consider modifying the Camaro harness and wiring it into the cars stock existing wiring? I’ve been told that this can be quite time-consuming and frustrating. Others, have advised me to remove all of that and simply put in a fuel tech FT550.

The car appears to have a new fuel tank, should I put a external electric fuel pump or an internal pump? What brand/style?

The car has mechanical brakes. What is the budget method to put a hydraulic master cylinder set up on this vehicle?

I understand that the steering with these cars aren’t that desirable. What steering gearbox and or set up, on a budget, would be the best choice for this build?

The previous owner of the car has told me that he put big box springs in the front, cutting off one ring, henceforth lowering the car. I’d like any input on the suspension modifications that are recommended for my application.

thank you all advance for any comments and/or input for my little project. I greatly appreciate it. Thank you, Craig Z.

 

Welcome to the forum!

I would make a new thread asking these questions, you should get more and better responses that way.

 

I went with Billy Boat headers with side pipes.

 

On my 71 C3 LS1/4L60E swap I used the stock 2002 Camaro ECM for engine and trans control. 2002 Camaro front accessory drive/water pump. Had to mod the e-brake wheel a bit for trans clearance. Generic LS swap radiator. Single 16" Spal fan run by the ECM. Modded the water pump heater hose inlet/outlet for right a-arm clearance. Walbro 255 fuel pump. C5 FFR.
My LS1 was a new crate engine completely stock. 3.70 gears. It was not slow.
All new solid u joints.
Autometer gauges.
18" wheels all around.
Fun car.

 

I'll reply to a couple of your questions.

What bellhousing? The stock 621 will work. I went with Silver Sport because they advertised a better alloy but otherwise no dimensional differences. The LS has one less mounting bolt! Seems OK so far. A word of caution. SAE bolts will sort of fit but they need to be metric. I was horrified when I put my motor on an engine stand using the original bolts. They held, but. ... I thought it over and discovered that was a mistake.

What clutch, flywheel and pressure plate set up will work. I went with a "light metal clutch". I think the acronym is LMC from Centerforce. I have a 515 HP motor and no problem handling the torque. I shied away from hydraulic. I managed to adapt my z-bar with some adjustments due to the motor's exhaust manifolds. Details if you want them

I understand that the steering with these cars aren’t that desirable. A lot of people are happy with Borgeson including me. The OE steering is essential that of the 50's Chevy's and just plain leaks.

The car has mechanical brakes. I don't think this is what you really mean

 

@ignatz thank you very much for providing some information. I appreciate it. When I say mechanical brakes, I’m referring to that does not have a vacuum booster or any brake assist. I assumed that makes them manual/mechanical.

 

A long long time ago cars had mechanical brakes. Usually for brakes and steering the distinction is manual vs. power.

I wouldn't go anywhere given the apparent state of your rag joint.

 

I have a question for ignatz. Do you have any pics of your zbar setup?

I am putting a 6.0 in my '65 and some sort of zbar bracket is next on my list.
Not sure of the differences between c2 and c3 setups. But, there are a lot more engine swaps in the c3 forum.

 

A couple of comments:

The 4L80E will fit without tunnel modifications and will be trouble free at your HP levels.

One of the premier LS tuners is very active on the LS forums and he can remote tune your LS3.

I had the same concerns as you about the strength of components beyond the 4L80E transmission yoke. I decided to address these before anything broke. I went with a 4 Link suspension and a Ford rear. Trouble free since day one. If you go with a 4 Link you will however need to make some mods to make some more room for the movement of the pumpkin, since it's no longer stationary. Also the 4 Link gives you more room for a wider tire. See my Turbo LS C3 build