Author Topic: Ls swap th350 vs 4l65e  (Read 170 times)

Offline rcamozzi26

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Ls swap th350 vs 4l65e
« on: November 01, 2018, 10:18:51 PM »
Gonna be getting a denali Yukon in a few months for a lq4 donor motor and part the rest out so I will have full access to everything I need. Few questions I have are if Iím going to be running a 450 hp Iíd say 6.0 what are my pros and cons of the th350 and the 4l65e that comes in that vehicle besides that the 65e has overdrive. I would be rebuilding the 350 with monster trans rebuild kit rated for 550 hp and I would leave the 65e stock. I wonít be driving it to much over 60 mph cruising. I like to keep the swap as simple as possible so the 350 and transfer case would bolt straight up basically where as I would have to get an adapter for the transfer case to 65e if I go that route. Also looking for tips on doing a swap Iíll be going with the adjustable motor mount adapters as well as having my harness sent off. It will be going in a 1973 k10 with a np 203 transfer case I believe


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Offline hatzie

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Re: Ls swap th350 vs 4l65e
« Reply #1 on: November 02, 2018, 10:26:24 AM »
I believe the LQ4 6.0L should be mated to a 4L80E.  I have that driveline in a 9,600 lb GVW GMT800 2005 Silverado 2500HD.  I'd make darn sure it's really a 4L65E before you give up on the transmission.  The 4L80E is exceedingly heavy duty, on par with the TH400 it's derived from, and far better suited to the HP levels you're shooting for.
 If you have a 4L65E you can find the LS mounted 4L80E in the GMT800 2500HD pickups.
The TH350 and that generation of smallblock transmission will need adapters to bolt up to the LS motors and it will really tick the PCM off to not have a transmission to control.
In a nutshell... if it's a 4L65E or 4L80E you don't have to play "fool the PCM" and find the TurboHydramatic engine mounting adapters and the 4L80E is a heavier duty transmission than a TH350.  Even the 4L65E is heavier duty than the TH350.

400 HP sounds nice but the 300hp and 360ft/lb reliable stock power levels of the LQ4 engine is more than a serious upgrade over the old 155 hp 350 smallblocks.  The mechanical difference between the 300hp 360ft/lb LQ4 & the 345hp 385ft/lb LQ9 is the pistons.  Re-program the PCM and you're more than double the old engines' output.

You can adapt the LH drop transfer case bolt pattern on the transmission to mate a RH drop chain drive transfer case to the 4L80E... NP208C or RHD NP241C.  Supposedly an NP261 exists that is setup for Right Hand Drop but I think it's a mythical creature...  if you can find one and prove me wrong... that would be an ideal transfer case for a squarebody. 

You can likely bolt an NP205 to the 4L80E as well but the NP241 & NP208 are lighter and have a much lower Low range...  2.71:1 in the 208/241 vs the 205 with 1.96:1.  Contrary to popular opinion they will put up with a fair amount of abuse as long as you keep them filled with clean Delco 10-4033 oil or Dexron III compatible ATF.  I plowed snow with an NP208 for years that was coupled to a 460 and C6 in an F250.

You could also research the LH pumpkin Dana front axles and possibly keep the whole Denali drivetrain as is...  Not sure what all would be entailed in swapping the pumkin to the LH side. and it may not be possible...  Just a thought.
« Last Edit: November 02, 2018, 11:08:42 AM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
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Offline rcamozzi26

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Re: Ls swap th350 vs 4l65e
« Reply #2 on: November 02, 2018, 01:28:01 PM »
I believe the LQ4 6.0L should be mated to a 4L80E.  I have that driveline in a 9,600 lb GVW GMT800 2005 Silverado 2500HD.  I'd make darn sure it's really a 4L65E before you give up on the transmission.  The 4L80E is exceedingly heavy duty, on par with the TH400 it's derived from, and far better suited to the HP levels you're shooting for.
 If you have a 4L65E you can find the LS mounted 4L80E in the GMT800 2500HD pickups.
The TH350 and that generation of smallblock transmission will need adapters to bolt up to the LS motors and it will really tick the PCM off to not have a transmission to control.
In a nutshell... if it's a 4L65E or 4L80E you don't have to play "fool the PCM" and find the TurboHydramatic engine mounting adapters and the 4L80E is a heavier duty transmission than a TH350.  Even the 4L65E is heavier duty than the TH350.

400 HP sounds nice but the 300hp and 360ft/lb reliable stock power levels of the LQ4 engine is more than a serious upgrade over the old 155 hp 350 smallblocks.  The mechanical difference between the 300hp 360ft/lb LQ4 & the 345hp 385ft/lb LQ9 is the pistons.  Re-program the PCM and you're more than double the old engines' output.

You can adapt the LH drop transfer case bolt pattern on the transmission to mate a RH drop chain drive transfer case to the 4L80E... NP208C or RHD NP241C.  Supposedly an NP261 exists that is setup for Right Hand Drop but I think it's a mythical creature...  if you can find one and prove me wrong... that would be an ideal transfer case for a squarebody. 

You can likely bolt an NP205 to the 4L80E as well but the NP241 & NP208 are lighter and have a much lower Low range...  2.71:1 in the 208/241 vs the 205 with 1.96:1.  Contrary to popular opinion they will put up with a fair amount of abuse as long as you keep them filled with clean Delco 10-4033 oil or Dexron III compatible ATF.  I plowed snow with an NP208 for years that was coupled to a 460 and C6 in an F250.

You could also research the LH pumpkin Dana front axles and possibly keep the whole Denali drivetrain as is...  Not sure what all would be entailed in swapping the pumkin to the LH side. and it may not be possible...  Just a thought.
The Yukonís came with the 65e as the 2500 Silveradoís came with the 80e. One reason I donít want to go with a 80e is because they are heavy and I believe longer so it will be more work for a trans I donít need. The th350 would get a 550 hp rated rebuild kit so I am not worried about it. If I go with the 65e wouldnít it have a different kind of gear selector linkage. Iím not worried about the transfer case style as I will not be using it often ďstreet drivenĒ. I guess you could say the answers Iím looking for is what all is involved in getting the 65e to work properly and I also might be able to find a transfer case that works better if I need


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Offline rcamozzi26

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Re: Ls swap th350 vs 4l65e
« Reply #3 on: November 02, 2018, 01:30:50 PM »
Also plan on adding a aggressive cam and probably ls3 heads in the future depending on my budget at that point so Iíd say between 4-450 hp also will have it tuned and headers and some other small things


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Offline hatzie

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Re: Ls swap th350 vs 4l65e
« Reply #4 on: November 02, 2018, 09:32:33 PM »
The chain drive transfer cases will mount to the 4L65E the same as the 4L80E. 
I'd seriously consider building the 4L65 rather than a TH350.  Much easier to just go with the engine/transmission combo the PCM is already equipped to handle.  More importantly you aren't giving up any HP/torque handling by using the 4T65E.
« Last Edit: November 02, 2018, 09:34:22 PM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
GMSTG Textbooks-->http://tinyurl.com/STG-TEXTBK
Radio Manuals-->http://tinyurl.com/DELCORADSVC

Offline rcamozzi26

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Re: Ls swap th350 vs 4l65e
« Reply #5 on: November 02, 2018, 11:54:25 PM »
The chain drive transfer cases will mount to the 4L65E the same as the 4L80E. 
I'd seriously consider building the 4L65 rather than a TH350.  Much easier to just go with the engine/transmission combo the PCM is already equipped to handle.  More importantly you aren't giving up any HP/torque handling by using the 4T65E.
Decided Iím going to go with the 65e and get a np241 transfercase since itís the easiest to run according to research on the web. It also has the vss. What exactly is vss and is there anything else I should know about that swap. Will I need to have custom driveshafts made. My truck has a 4Ē suspension lift not sure if that makes a difference on driveshaft length vs stock


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Offline hatzie

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Re: Ls swap th350 vs 4l65e
« Reply #6 on: November 05, 2018, 11:52:38 PM »
Vehicle Speed Sensor.
I believe the LS motors use 8K VSS.  The RH drop NP241 was on TBI RV series trucks with either 4K or 2K VSS.  It may be as simple as snagging the reluctor and pickup from the newer transfer case and installing in the NP241.
If you're keeping the 1973 speedometer you'll need a Dakota Digital electronic speedometer to cable speedometer adapter or similar unit from someone else.
« Last Edit: November 05, 2018, 11:56:11 PM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
GMSTG Textbooks-->http://tinyurl.com/STG-TEXTBK
Radio Manuals-->http://tinyurl.com/DELCORADSVC

Offline rcamozzi26

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Re: Ls swap th350 vs 4l65e
« Reply #7 on: November 07, 2018, 10:57:56 PM »
I just bought a passenger drop 241 today Iím not sure if itís the 32 or 27 spline shaft but Iíll look it was on a nv3500 manual I think he said? Iím going to get the Dakota digital dash with the ls adapter obd2 port plug in so the dash gathers the data from the pcm so I can monitor everything. Will I need to shorten or lengthen drivelines with the 65e and 241
Transfer case? I will also be doing the blazer 25 gallon tank and getting the efi fuel sending unit with the 381 pump


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Offline hatzie

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Re: Ls swap th350 vs 4l65e
« Reply #8 on: November 10, 2018, 09:39:20 AM »
The NP231 & NP233 paired with the NV3500 in the S10 trucks is more common. 
I don't believe the NP241 was used in the S10 trucks.
If it's really an NP241 that was originally paired with an NV3500 then it came from a fullsize GMT400 CK truck with a 4.3L V6 and it'll have 32 splines.  This is a LHD transfer case.  Not what you want.
« Last Edit: November 10, 2018, 11:04:16 AM by hatzie »
SVC & wiring mans --> Here http://tinyurl.com/7387BRD-SVCMAN or My Bucket @ http://tinyurl.com/SQ-SVCMAN
Parts & Illustr Books -->http://tinyurl.com/SqParts
GMSTG Textbooks-->http://tinyurl.com/STG-TEXTBK
Radio Manuals-->http://tinyurl.com/DELCORADSVC