LS376/480 Build Questions

[TomH33]

I am getting my ducks in a row for a LS376/480 create motor with T56 Magnum 6 speed trans and 9” Ford rear end with 3:50 gears and TrueTrack posi and 3 link.

Being a newbie I have lots of questions. I was told there are others that have done this build so I have searched 40 threads out of 70 so far with no LS builds. I will continue to search, but would appreciate some direction. Is there a spot on the forum for Chevy motor builds.

I have questions concerning LS3 oil pan, long tube headers, hydraulic clutch (not mentioned in the manual), drive shaft specs. and drive by wire or wireless peddle.

I would like to find someone that has done this type of build and pick their brains about the problems and concerns they had.

Thanks Tom H

[GoDadGo]

TomH33,

There are other Chevy guys out there, myself included, but I'm building an MK-4 Roadster.
Please know that I am using a 3/4" master for my ZF-6 Speed (Corvette C-4 Transmission).
I hard lined the transmission and clutch pedal, but used a short 8" braded brake line to link the two to deal with vibrations.
By The Way, I Love Those 33 Hot Rods & Almost Went Down That Path!

Steve

https://youtu.be/3f1Q4aS5SG4

[Mountain-Metalworks]

I'm not far enough along to offer you any real-world advice, but I've been doing research for 9+ years. My MKIV Roadster was delivered before Thanksgiving and I've started with all the suspension pieces. It will start life with a LS376/525 with LS7 flywheel/clutch, and T56 Magnum as well. Different than your '33 build for sure, but some issues will still be the same.

Oil pan decisions will be based on both your intended driving and the actual fitment. I'm planning lots of laps on the track and will be going with a baffled batwing pan while I'm building a dry-sump LS2/427 for later installation. If you're planning on the LS "connect and cruise" package, there's no reason to not use the drive-by-wire gas pedal and electronics. It will also come with the same LS7 aluminum flywheel, bellhousing, and internal throwout bearing that I'm using. Some don't like the internal throwout bearing based on lack of access to service it, but I'm not concerned. Your long-tube header problems will be different than mine based on MKIV sidepipes vs. your expected routing.

My build thread has some additional info, check out this link to view engine mount options which might be usable for the '33. There might be specific LS mounts available for the '33 though, which weren't available for the Roadster. I'm essentially using Mustang 4.6L to LS conversion mounts.

On a side note, if you didn't see it, GM has a $500 rebate until Dec 31st for the Connect and Cruise packages. I'm purchasing mine WAY earlier than needed to get the deal. Let me know if you want more info on the rebate. You can buy from Dealers or Summit/Jegs and get the deal.

-TJ

[TomH33]

Thanks for the insight. Good for you putting a chevy LS3 into a Cobra. I was going to build the same but I don't race and the 33 has mounts and has been designed for an LS also. Are you using the street or track(lower gears) version of the T56 magnum. I am concerned about handling so I'm going 3 link. Are you going IRS or 3 link. I might be concerned about the rear end if your putting 525HP to an 8.8 pumpkin. If your going 3 link I would have Moser build an 9" Ford with all mounting brackets and a Detroit TruTrac posi and 4 piston calipers Wilwoods for $3500. Just a thought especially if there is an LS7 in you future.

Well congrats on your new project. I will keep up on your thread to see how it goes.

Thanks for the help.
TomH33

[Mountain-Metalworks]

Thanks for the insight. Good for you putting a chevy LS3 into a Cobra. I was going to build the same but I don't race and the 33 has mounts and has been designed for an LS also. Are you using the street or track(lower gears) version of the T56 magnum. I am concerned about handling so I'm going 3 link. Are you going IRS or 3 link. I might be concerned about the rear end if your putting 525HP to an 8.8 pumpkin. If your going 3 link I would have Moser build an 9" Ford with all mounting brackets and a Detroit TruTrac posi and 4 piston calipers Wilwoods for $3500. Just a thought especially if there is an LS7 in you future.

Well congrats on your new project. I will keep up on your thread to see how it goes.

Thanks for the help.
TomH33

I'm planning on the T56M version with the 2.97(1st) to .63(6th) gear spread since I'm keeping the 3.55 gears that came in my diff. I'm using the '15 IRS since drag racing(and a live axle to handle it) isn't my thing. The HP I'm hoping for is why I stuck with an iron diff instead of the lighter aluminum though. These cars are so light, and with no dragging, I expect the diff to handle things pretty well.

-TJ

[TomH33]

Here are the ratios from Tremic. 2.97 2.10 1.46 1.00 .74 .50 2.90
2.66 1.78 1.30 1.00 .80 .63 2.90

I selected the 266 mainly because the overdrive ratio and car weight. Double check but I believe you have the 2.66 Trans overdrive lsited as the 2.97 trans. I am using 3:50 gears and 26.5 tires and found the 6th to below !800 RPM @65 and that is to high for the 480HP LS3.

Have Fun
TomH33

[Silent T]

I am using a Keisler (no longer made) 5 speed:
1- 3.37
2- 1.99
3- 1.34
4- 1.00
5- 0.67

Rear is a 3.08

My car has the stock 430hp LS3 and is only street driven. With a 26.1" rear tire size I am doing 55 at around 1500 rpm in 5th. 1750 is 65 and perfect for long cruises...

The wide ratio trans works great on the street in an overpowered light car with a broad torque curve like the LS3.

with 430 horses the thing is a ground missile - you'll have a blast!

I also have a "build Thread" on the other site...

[Mblueye33]

tom33

I used the Tremic 2.66 to .63 six speed... I am running the IRS but with the 3.77 gears and 25" tire .... six at 1900 ... fifth at 2400 and fourth at 3000 rpm... have not driven much...still at the go cart stage.

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