C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Considering a C4, LS Swap?

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Old 02-23-2020, 01:49 PM
  #21  
Mike Holmen
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Mine is an 85 vette, took me about a week to do the swap. I'm running LQ9/700R. The hardest part was the C-beam mods (I just welded two pieces of aluminum), as I moved my engine ahead some. Mine was cheap probably $5k canadian all in. I did my swap four years ago, zero issues yet with the car.


Last edited by Mike Holmen; 02-23-2020 at 01:50 PM.
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Old 02-23-2020, 03:37 PM
  #22  
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Originally Posted by 84 4+3
Hey, it has seatbelts!
Bahahaha
Old 02-23-2020, 03:55 PM
  #23  
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Originally Posted by mike2977
Anything can be done, the question is what is the end result that you want? I chose to go the full resto-mod route, and so wound up spending $$$ and taking over a year for the swap to be done "right."

My basic package was an LS-1 build along with a 4L65e automatic transmission from Turnkey Engine Supply of Oceanside, CA. They provided a kit of sorts that included the engine, motor mounts (which had to be shimmed), wiring harness, Howell computer, shorty headers, all accessories with a serpentine mount including a/c compressor. I also opted for their premium package which included "big block" chrome coil pack covers, a hydro-dipped manifold and trim for the power steering reservoir.

I retained Corvette Masters of Maitland, FL to do the conversion for me. It took a lot of time, but there was a lot of work to do. Given the larger transmission, the cross-frame had to be notched and reinforced. And the longer length of the transmission including the tailshaft housing caused us to consider either shortening the driveshaft (which we didn't do) or reusing the original transmission's tail-shaft housing (which did fit.) We also found out that the early C4's had the engine and transmission custom fit during installation resulting in several millimeters of misalignment when the new transmission was mated to the included transmission adapter and the engine. That required about a 90 day delay as we sought out a machine shop to build a jig and machine the interface so it was correct.

The entire front end of the engine compartment was reworked to accommodate the swap. I purchased a new cross-flow radiator from Ecklers. A visit to Coastal Corvette (used Corvette parts) resulted in a top end radiator mount and air intake system from a '96; we reused the bottom end radiator mount from my original. A new fan box was fabricated by Corvette Masters containing two Spraul electric fans.

Lots of engineering by Corvette Masters went into making the installation look like GM had designed it that way. Cudos to Robby Hooper and his team.

The generic Howell computer came with some standard settings that were not proper for my installation. It was enough to get the C4 started and on the road, but terrible for the actual swap. I took it over to Faster Proms in Lutz, FL for a street tune by Jeremy Formato. Perfection!

Here's a video of the initial startup: https://photos.app.goo.gl/pBLWTz6Aam7UjkBQ6

And one of many shots of the completed installation


LS-1 in 1984 C4

So, yes, you can do a swap yourself in a "reasonable" period of time. My decision to go the resto-mod route has resulted in recognition from several national magazines including a 3 page article in Corvette Magazine, appearance in Vette Magazine, and 3 page article in Classic Corvettes magazine (Eckler's house publication.)
That’s beautiful and how an LS swap should be done.
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Old 02-23-2020, 04:01 PM
  #24  
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C4s brake and handle very well. I think the over all weight distribution of an 84 is 51% front and 49% rear, no wonder they could corner at 1G.

Last edited by GregMartin; 02-23-2020 at 04:02 PM.
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Old 02-23-2020, 04:45 PM
  #25  
84 4+3
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Originally Posted by GregMartin
C4s brake and handle very well. I think the over all weight distribution of an 84 is 51% front and 49% rear, no wonder they could corner at 1G.
it was 1 G as it slides into the wall lol. The one they got to 1g was a test car with suspension that made the 84 Z51 seem tame. In reality it was somewhere around .9.
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Old 02-23-2020, 06:00 PM
  #26  
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Originally Posted by 84 4+3
it was 1 G as it slides into the wall lol. The one they got to 1g was a test car with suspension that made the 84 Z51 seem tame. In reality it was somewhere around .9.
Yeah you’re 100% but that’s still very good for the tyre technology of the time. Do you remember how other **** boxes in 1984 handled?
Old 02-23-2020, 06:12 PM
  #27  
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Originally Posted by GregMartin
Yeah you’re 100% but that’s still very good for the tyre technology of the time. Do you remember how other **** boxes in 1984 handled?
At that point in time it was world class.
Old 02-23-2020, 09:27 PM
  #28  
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I put an LS in my car and I had to move because I kept getting death threats from a bunch of angry husbands because their wives loved my car so much
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Old 02-23-2020, 10:28 PM
  #29  
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Originally Posted by Pwnage1337
I put an LS in my car and I had to move because I kept getting death threats from a bunch of angry husbands because their wives loved my car so much
But did you get a letter from the chief of police saying it's illegal for a car to sound that good?
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Old 02-23-2020, 11:28 PM
  #30  
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Originally Posted by ThatOneKid
I'm not much into AC, so it is something I could do without, worst case I can pull the engine and notch the member somewhere down the line, but we're still in the cold season for atleast a couple more months.

That's an amazing car you got there, I can only be inspired by what I've seen. I'm planning on keeping the stock LQ4 PCM just because ive gotten comfortable with tuning my truck.
what kind of misalignment were you seeing, was it lateral or torsional? I'm not too sure how I'd combat that level of misalignment but I'm sure I could figure something out if need be. Was the rad the majority of the front end work, or were there other aspects that needed to be changed to get the engine to fit.


Thanks for the insight, my truck is currently making 350hp crank out of the 5.3, so itll definelty be a fun car to drive, glad to hear that it doesn't nose dive to bad, and that that the tail doesn't wag too much. The tail coming out is one of my largest concerns, but that seems to not be as big an issue as I thought it was.
Sorry I missed this... if it's the L83 5.3 in the 14 and up trucks... you'll have a grin from ear to ear. The 6.0 is a beast down low. The 5.3 in my experience wants to wind out but the 6.0 it's all there as soon as you mash it. I'm not a fan of the 5.3 at all honestly. No matter how good it was I always felt it was weak on the bottom.

Last edited by 84 4+3; 02-23-2020 at 11:29 PM.
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Old 02-24-2020, 07:40 AM
  #31  
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Originally Posted by 84 4+3
Sorry I missed this... if it's the L83 5.3 in the 14 and up trucks... you'll have a grin from ear to ear. The 6.0 is a beast down low. The 5.3 in my experience wants to wind out but the 6.0 it's all there as soon as you mash it. I'm not a fan of the 5.3 at all honestly. No matter how good it was I always felt it was weak on the bottom.
I completely agree, the 5.3 has to be revving over 3k before it's got any guts. I'm on the LM7, nothing that new for me lol, got it converted to flex-fuel, but havent done any e85 tuning just yet... I have a set of 862 heads sitting on my bench in the garage, I'd love to try my hand at port matching the heads and slapping those heads on a 6.0 with a decent cam, I can see that as being a very fun car to drive.

In other news, I decided to pass on the C4 I was looking at, the car was just in rougher shape than I would have liked for the price point, so the C4 hunt continues. I had originally intended to buy a running driving C4 and fix it up, and start tuning the suspension to make it handle the way I would like, jumping straight into a swap with a new to me platform is a daunting task and it is something that has to be done right and doing it right would not meet my two month time period.

Last edited by ThatOneKid; 02-24-2020 at 07:42 AM.
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Old 11-10-2022, 10:41 PM
  #32  
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Originally Posted by mike2977
Anything can be done, the question is what is the end result that you want? I chose to go the full resto-mod route, and so wound up spending $$$ and taking over a year for the swap to be done "right."

My basic package was an LS-1 build along with a 4L65e automatic transmission from Turnkey Engine Supply of Oceanside, CA. They provided a kit of sorts that included the engine, motor mounts (which had to be shimmed), wiring harness, Howell computer, shorty headers, all accessories with a serpentine mount including a/c compressor. I also opted for their premium package which included "big block" chrome coil pack covers, a hydro-dipped manifold and trim for the power steering reservoir.

I retained Corvette Masters of Maitland, FL to do the conversion for me. It took a lot of time, but there was a lot of work to do. Given the larger transmission, the cross-frame had to be notched and reinforced. And the longer length of the transmission including the tailshaft housing caused us to consider either shortening the driveshaft (which we didn't do) or reusing the original transmission's tail-shaft housing (which did fit.) We also found out that the early C4's had the engine and transmission custom fit during installation resulting in several millimeters of misalignment when the new transmission was mated to the included transmission adapter and the engine. That required about a 90 day delay as we sought out a machine shop to build a jig and machine the interface so it was correct.

The entire front end of the engine compartment was reworked to accommodate the swap. I purchased a new cross-flow radiator from Ecklers. A visit to Coastal Corvette (used Corvette parts) resulted in a top end radiator mount and air intake system from a '96; we reused the bottom end radiator mount from my original. A new fan box was fabricated by Corvette Masters containing two Spraul electric fans.

Lots of engineering by Corvette Masters went into making the installation look like GM had designed it that way. Cudos to Robby Hooper and his team.

The generic Howell computer came with some standard settings that were not proper for my installation. It was enough to get the C4 started and on the road, but terrible for the actual swap. I took it over to Faster Proms in Lutz, FL for a street tune by Jeremy Formato. Perfection!

Here's a video of the initial startup: https://photos.app.goo.gl/pBLWTz6Aam7UjkBQ6

And one of many shots of the completed installation

85
LS-1 in 1984 C4

So, yes, you can do a swap yourself in a "reasonable" period of time. My decision to go the resto-mod route has resulted in recognition from several national magazines including a 3 page article in Corvette Magazine, appearance in Vette Magazine, and 3 page article in Classic Corvettes magazine (Eckler's house publication.)
I am very impressed with the result of your swap. I am putting a plan together to do a LS7 swap in my 85. So far, I have gathered the block, heads, and intake. Everything else I have to piece together. I would like to know what headers you used and what a/c bracket you used?
Old 11-11-2022, 06:20 AM
  #33  
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Originally Posted by rssshen vette
I am very impressed with the result of your swap. I am putting a plan together to do a LS7 swap in my 85. So far, I have gathered the block, heads, and intake. Everything else I have to piece together. I would like to know what headers you used and what a/c bracket you used?
On these old posts that are brought back from the dead, you need to check the profile of the person that you are asking a question of. That person hasn't been active on the forum since:

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Old 03-10-2023, 05:54 PM
  #34  
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Originally Posted by Mike Holmen
Mine is an 85 vette, took me about a week to do the swap. I'm running LQ9/700R. The hardest part was the C-beam mods (I just welded two pieces of aluminum), as I moved my engine ahead some. Mine was cheap probably $5k canadian all in. I did my swap four years ago, zero issues yet with the car.
what power steering, alternator and harmonic balancer setup did you use? I'm having a lot of trouble finding one that will work
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Old 03-14-2023, 10:26 AM
  #35  
Mike Holmen
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I'm running the C6 accessory kit and the C6 vette harmonic balancer.
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