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3737 Views 20 Replies 5 Participants Last post by  PD939C1
I bought my '93 9C1 in '98 with less than 50k on it. Not sure why it was sold then but I bought it from someone who bought it from their local PD as a chief's car. I did what I could for the L05 but was never satisified with it. After market heads, headers, 210/216 cam, dual exhaust conversion, the usual B body suspension mods - real F-body front bar and bushings, Bilsteins all around, SS rear springs, cut front springs, homemade solid rear control arms with poly bushings. Swapped over to 19" wheels with 235/50 fronts, 245/45 rears. Wheels and tires made a big difference.
Tried many things with the TBI without satisfactory results, BB TBI, higher pressure in regulator, vac modulation. Tried all suggestions. But accepted and endured it for the last 15 years or so.
The steering had always been sloppy which was finally narrowed down to the steering box after replacing most everything else in the front end. I installed a Lee steering box with the intention of seeing if it was worthwhile to add more power. There was so much play in the steering wheel, high speed highway cruising was unsettling. If the steering had remained sloppy after the new box, I'd have scrapped any transplant plans. Fortunately, the Lee box made a world of difference so I proceeded with the new powertrain.

Fast forward.... I contacted a local builder in fall 2020 about doing an LS conversion then set out to research what to get. I'd gotten a 2017 Impala with the 3.6 VVT engine and was very pleased with the VVT power curve so I decided on the L96 version of the 6.0.

No AFM components
9.7 CR so premium fuel is not a requirement
50# injectors
#821 LS3 rectangular port heads
360 HP/ 380 ft.lbs stock form
Kept the 3.42 posi

I found a suitable motor and 6L90 trans on Ebay winter of 2020/2021. <20,000 miles. Everything included. And started making a list on what to include in the car during transplant. 6L90 on the list.

BRP motor/tranny mounts
BRP headers, ceramic coated. Very nice, well fitting pieces. Full duals.
APEUSA fuel supply

Went with a Fitech intake 'cause the truck manifold is too high. Probably could have gotten away with an LS3 manifold but without knowing for sure, looked for the lowest manifold available. I'd have liked to have a BRP manifold but they were out of stock and BRP did not know when they would be available. Remote mounted the passenger side coils onto the inner fender. All the required updates were included, radiator, electric fans, trans cooler, floor shifter, driveshaft and U-joint upgrades. The oil pan was a rear sump and fit right in. It does hang below the frame but not by a lot. A skid plate is being installed anyway.

After install, had it tuned to 312 [email protected], 350 ft.lbs @2700 thru 3500 at the wheels so pretty much following factory spec with a slight boost in torque.
The car is a blast to drive. So, so, so much better than what the L05 could do. My intention with the build was pretty much 0-100 mph quickly, decent economy to drive and it meets my goals. Throttle response is incredible. Takes so little throttle to move right along. Flooring it will effortlessy spin the tires into the 3rd gear.

To do remains putting Hotchkiss springs in so I FINALLY have a matched set of springs again, fabbing a cover/console for the floor shifter. The Fitech manifold is loud. If one puts a hand on it to dampen vibration, it quiets right down. The LS3 manifold would be quieter but I'm not willing to drop more dime on another manifold.

The builder took care of all the electronics to get everything to work. Not my strength. I've got a bunch of original parts that I can sell now that I know what I won't be using and I'd be glad to answer any questions I can about the new build.

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I'll try to get some pics up.

Tranny did not fit horribly. There was some hammer work required inside the tunnel but no major surgery. I used a x-member by BRP,

All the parts I bought from them were of very good quality and fit. I would easily recommend them.

The tuner was able to adjust some of the tranny characteristics such as when shifts occurred and their firmness if that's the kind of thing you mean.
SO glad you came back!
AND a special thanks for you willingness to measure!
Let me encourage you to install the front springs soonest. Matched bounce frequency with all four Hotchkis springs will be great. Cut front springs is always a negative. Big one on a B body.
If with the Lee the steering is still not like a Miata, it can be. Get someone to sit behind the wheel and start the car. Watch the steering box as they turn the wheel. See it dance? A front frame brace will put an end to that dancing and you will not believe the steering precision once the frame is all welded together. Pro-Touring F- body sells the brace for a little more that $100. Bolt in but weld it anyway.
Makes your front sway bar about 30% stiffer too. (feels like 30%) LS engine is lighter so the Hotchkis springs won't drop the front as much as with an IRON monster. GREAT handling awaits you.Your 93 can benefit from everything about the 94-96.
Also, an LS1 or LS2 manifold often for sale cheap used.

You might enjoy this new thread:
What was the design source of the '94-'96 Impala SS's great handling
Thanks for the suggestions. I'll check them out. I don't see such a brace at however. Can you direct me?
Welcome PD939C1, looking forward to photos of your swap

Was already explained to you.

LS1 - LS2 -LS6 intakes with cathedral ports do not fit LS3 - L76 and the other rectangular heads
Thanks. Yeah, I knew it had to be an LS3 but I just figured Jack was just pointing out going used rather than new.
Finally got the weather and chance to take a few pics. Motor vehicle Automotive air manifold Vehicle Auto part Automotive design
Automotive parking light Car Automotive side marker light Vehicle Vehicle registration plate
Automotive side marker light Automotive parking light Wheel Tire Car
Car Vehicle Plant Motor vehicle Car seat cover

Car Vehicle Motor vehicle Mirror Steering wheel
Car Vehicle Land vehicle Vehicle registration plate Hood
Tire Wheel Automotive side marker light Car Vehicle

Tire Wheel Car Automotive side marker light Vehicle
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Thanks. Regretfully, the ground clearance with the truck oil pan has become a headache. I'm planning on replacing the front control arms this summer and along with that putting in the Hotchkiss springs (the rears are already in). It looks like the Hotchkiss springs would lower the front a little more which I am not willing to accept. So, will be installing a 3/8" Global West spacer under the spring to raise the front by 3/4" over where the Hotchkiss would put them. I'm expecting a net raise of about 1/2". Then will have to evaluate whether anything needs to be done out back.

The console is a matter of personal preference. It just went in yesterday. I've got a 'beverage' holder to attach to the rear of the console, also made from diamond plate. Just need to get the 2 3/4" holes milled in it. I just like the no-nonsense look of diamond plate.

As mentioned, the 6L90 went in without drastic work but without putting it on a lift, I doubt I can get under far enough to get a pic that would actually show you anything. I will say I am considering GM's shorter trans oil pan as it sits about as low as the engine oil pan. The engine oil pan will be protected by a skid plate attached to the engine cross member but the trans pan just sits out there by it's lonesome. :eek:
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Thanks. My current front springs are the original 9C1 with 3/4 coil cut off (I think, it was over 20 years ago so......) and I had a set of Impala springs in the rear. Hotchkis's stated lowering heights from stock won't mean much. Someone here (sorry can't remember who this second) sent me a photo of their front end at 26 1/2" to the top of the front wheel which I've stuck on my desktop. I've got 27" now so I am hoping to gain some ground clearance between the Hotchkis and spacers.
I read , for clearance people splice Pontiac G8 80E pans together to fit the 90E .
They also use CTSV 90E pans .
HOW MUCH clearance would you gain ?
Don't know ?

1.2" ;)which would be a big gain.
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PD939C1 - Understood about tough to get pictures. If you remember the next time it's up in the air, I'd appreciate seeing it. If not, no problem.

I did a lot of looking into a shallower option for the 6L90E pan, including the mythical CTSV versions and all that - I was not able to find anything.

I also did a lot of research into shortening the 6L90E pan and changing/modifying the filter and the net result was that I would be able to gain 0.500" (at most) before running into the solenoids/valve body. It was a lot of work/risk for very little gain in my opinion.

If someone has pictures/part numbers contrary to the above, I'll gladly stand corrected. Next time I pull the pan off a 6L90E, I'll try to take some pictures/measurements
This is why I come here. Thanks for all the input- sincerely.
I was on the path of 'assuming' all that needed to be done was to replace the trans pan and put in the shorter G8 filter. But from the nature of your responses I'm getting the impression there's some piece of information I don't yet know. Does the valve body/solenoids sit lower in the L90 vs the L80? If that's a fact then I'll have to rethink my intentions regarding the trans pan. Cutting and welding the pan in some hodge podge pattern does not seem like time well spent. Bottom line, I guess, is I'll have to dig for some more info unless one of you tells me it CANNOT work with the pan I linked.

The Hotchkis springs will not end up lowering the car. That is not my intention. I've lived with cut front springs and rear Impala springs for 20 or so years. Never regretted the ride. My Dad died in 2021 and left me enough inheritance to have a little and only a little fun. That's primarily what funded the LS swap. I bought the Hotchkis' so I would finally have an engineered, matching set of springs to enjoy.

Fix, I'm hoping NOT to have to have the car back on a lift anytime soon but if it is, I'll try and get some pics.
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Well, Maybe I stand corrected?

Not at all. In my naivety, I thought the only differences between the L80 and L90 was internal and that, at least, the pan pattern and fit would be the same. This thread has, at least, opened my eyes to a pan swap being more than that.
I think someone posted a link that included a link to this pic but here's the pic directly. Shows
the 35mm length difference between L80 and L90. Puts a damper on a straight pan swap.
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