LS3 Tremec 6 speed and 1LE diff

Drivetrain discussion including Transmission, Differential, Driveshaft, and related items.
Skyhighsami
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LS3 Tremec 6 speed and 1LE diff

Post by Skyhighsami » Tue Oct 27, 2020 8:32 pm

Would a LS3 and Tremec 6 speed with a 5th gen rear end like the 1LE 3.91 I know people have done the Tremec swap has been done but don't recall anyone running the 3.91 rear diff. Since so many parts from other chassis can easily be swapped between I was going to start looking for one with higher mileage since I would be getting one with the intention of swapping the drive train suspension brakes wheels and other parts. I was looking for a PPV earlier this year but the one I was going to purchase fell through. So now I'm in the market again especially after a friend got one and I drove and rode in it. My PPV fever has gotten worse.

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kevink
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Re: LS3 Tremec 6 speed and 1LE diff

Post by kevink » Tue Oct 27, 2020 9:07 pm

The 1LE diff will bolt right in. You can also buy GM 3.91 gears for a couple hundred bucks and put them into a 5th gen Camaro rear that never came with 3.91s and bolt that right in. That is probably easier than locating a 1LE diff.
2011 9C3: 11.48 @118.

s/c'd cav
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Re: LS3 Tremec 6 speed and 1LE diff

Post by s/c'd cav » Tue Oct 27, 2020 9:23 pm

just stick to a V8 , swapping in the manual requires the most work , the ls3 and camaro diffs are direct swaps unless its a ZL1 diff

Skyhighsami
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Re: LS3 Tremec 6 speed and 1LE diff

Post by Skyhighsami » Thu Oct 29, 2020 1:36 am

Only reason I want to swap in a LS3 is because I think putting heads designed for a 4.065" bore on a 4" bore engine. So I would either swap on a cathedral port top end or a LS3 short block with the L77 on the car or LS3 heads ported and polished with a LSA cam with a 6 speed and 1LE or 5th gen diff and get the bugs worked out before a LSA goes on.

s/c'd cav
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Re: LS3 Tremec 6 speed and 1LE diff

Post by s/c'd cav » Thu Oct 29, 2020 8:55 am

the L77 has the LS3 style heads already , and they were designed before the LS3's came out , and based on the 6.0 bores , if i remember correctly on a LS2 with 243 heads and 10.9 compression , the heads made 30-40hp more , while the compression dropped to 10.4

but yes having the 6.2 bore will help the heads flow alot better , and make more ponies

so not really worth swapping on cathedral port heads , even more so since the LS2 intake flows alot worse than the stock/LS3 intake does

Skyhighsami
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Joined: Wed Aug 14, 2019 12:29 am

Re: LS3 Tremec 6 speed and 1LE diff

Post by Skyhighsami » Thu Oct 29, 2020 2:32 pm

I helped a friend build a .030 over LS2 with a 11.0 CR and a cam that was 226-238 I believe. Anyway he a set of CNC LS3 heads and a Cadillac L92 intake. It was a dog and low on power. The bearings ended up letting go so he bought a LSX-B8. An engine with lower compression than the LS2. With the same cam, heads, intake, exhaust and everything was exactly the same except the short block. Even with less compression it was must faster with much more power. I can only attribute it to the valve being shrouded by the cylinder wall. I think with a set of worked 5.3 or LS6 heads with a cam and Fast intake would make more power than a Caprice with worked L77 heads. I had a LS1 with Stage 2 5.3 heads a Fast intake and Futral cam and it was absolutely nasty and it made so much torque low and through the midrange. It really shocked menon how quick the car was. It made 450ish whp Imagine what it would be like on a L77 shortblock.

s/c'd cav
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Re: LS3 Tremec 6 speed and 1LE diff

Post by s/c'd cav » Thu Oct 29, 2020 4:30 pm

a .030 bored 6.0 is half way to the 6.2 bore , being he had the bottom end let go , im guessing some of his problems started there

a cam only L77 can make north of 450 , and most cam only LS2's made 410-425

LS6 and LS2 heads are the same , the early 5.3 heads had smaller ports and smaller combustion chambers , they were good because they raised the compression up , and they needed port work to flow like a stock ls2/6

Skyhighsami
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Re: LS3 Tremec 6 speed and 1LE diff

Post by Skyhighsami » Thu Oct 29, 2020 4:58 pm

The motor let go because of an oil issue. He and I used the Corvette because the LS2 in the Trailblazer sucks. On the 376 B-8 had the Corvette install. The LS2 ran fine the bearings lost oil distribution for some reason. A LS2 makes 395hp in a Trailblazer and 400hp in cars. So putting a cam in a LS2 will gain more than 10-20 hp more. Guys on TBSSowners.com that go with ported LS3 heads and a cam make the same as people that use ported 243s and cam make identical power but the 243 heads make more power downlw where heavy SUVs need it. My Trailblazer has an 11.8 CR 416ci LS3 with WCCH Stage 2 LS3 heads and 240/250 can with a stock intake from a L92 Cadillac because I might gain 20hp but I'd lose 20-30 in the mid range so it's not worth it.

Skyhighsami
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Re: LS3 Tremec 6 speed and 1LE diff

Post by Skyhighsami » Thu Oct 29, 2020 5:01 pm

s/c'd cav wrote:
Thu Oct 29, 2020 4:30 pm
a .030 bored 6.0 is half way to the 6.2 bore , being he had the bottom end let go , im guessing some of his problems started there

a cam only L77 can make north of 450 , and most cam only LS2's made 410-425

LS6 and LS2 heads are the same , the early 5.3 heads had smaller ports and smaller combustion chambers , they were good because they raised the compression up , and they needed port work to flow like a stock ls2/6
I'm sorry but I had to quote the cam only LS2 make 410-420. It made me LOL. None of the performance vehicles came with a 4" bore and rectangular port heads. Corvette, Camaros, and the SS sedan all had 4.065" bore engines. If the L77 gains 75hp with a cam and a LS2 picked up the same 470 in a Trailblazer and r75 in Corvette GTO CTS-V and other LS2 vehicles.

s/c'd cav
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Re: LS3 Tremec 6 speed and 1LE diff

Post by s/c'd cav » Thu Oct 29, 2020 5:18 pm

my cam only G8 made over 450 , and my friends cam only LS2's made between 410-420

the compression ratios in the L76/77 is 10.4 , LS3 10.7 , LS6 10.5 and LS2 10.9 , so other than bore and having a very conservative cam , the L76/77 isnt that far off from the LS3

people have put LS3 cams into their L77's as part of the DOD deletion , and make close to the same whp as a stock SS sedan

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