Chevy L8P Crate engine & 6L80e Transmission in 71 Camaro

[72srcool]

Hey Carlo,

I just saw your post and I know it has been a while but if I can help I would like to. I put a L8T crate engine(the L8P wasn't out yet) in my 72 Camaro with a Tremec 5-speed. I put a Texas-Speed cam, springs and pushrods. I also did a CHE trunion upgrade and a LT2 Corvette intake turned around backwards with Speed Engineering mid length headers. I will tell you that this thing RIPS!! I used Speed Engineering LT mount plates to the SBC factory motor mounts. I cut the mounts down 1 inch to get the engine as low as possible to give me as much clearance in the tunnel for the transmission as possible.

Lance

[csouth]

Hey Carlo,

I just saw your post and I know it has been a while but if I can help I would like to. I put a L8T crate engine(the L8P wasn't out yet) in my 72 Camaro with a Tremec 5-speed. I put a Texas-Speed cam, springs and pushrods. I also did a CHE trunion upgrade and a LT2 Corvette intake turned around backwards with Speed Engineering mid length headers. I will tell you that this thing RIPS!! I used Speed Engineering LT mount plates to the SBC factory motor mounts. I cut the mounts down 1 inch to get the engine as low as possible to give me as much clearance in the tunnel for the transmission as possible.

Lance

6L80 is way bigger than a TKO/TKX... that trans is not going to work without cutting the tunnel. It won't even fit in an A Body without mods let alone and F Body...

[Carlo C.]

Guys,
Quick update. Car is almost finished and I decided to go with the 4L80 as it just made life a lot easier. It allowed me to keep the factory console and with the addition of a Shiftworks shifter kit for the 4L80 it looks great and has some cool new features. The Custom Built Transmission 4L80 is installed with a Circle D converter and I used the Holley Crossmember with 3" PST aluminum Driveshaft with Billet strange yoke to connect it to the 12 bolt rear. The car is currently at RCS motorsports in Fort Worth, TX getting wired. I normally do all my own wiring as it is something I enjoy, but I wanted this one over the edge nice and my work compared to Rick at RCS is like a all good high School football player compared to a Super Bowl winning all Pro. His work is just the best I have ever seen and I have been around a lot of nice cars that have been professionally wired. So I should have it back in another week and start putting all the final touches on it and getting ready for the HotRod power tour.

[Easytouring831]

What did it take to mate the 4l80 to the l8t? Are you doing a full manual 4l80? I can’t find any swap harnesses online for that combo.

[Carlo C.]

What did it take to mate the 4l80 to the l8t? Are you doing a full manual 4l80? I can’t find any swap harnesses online for that combo.

Easytouring831,

GM Performance doesn’t offer a standalone controller that will properly run a 4L80 behind this setup, so something had to give. Cutting up the floor to cram in a 6-speed wasn’t happening. I wasn’t about to lose the factory console just to row gears. Deal breaker.

So the GM ECU and harness hit the bench, and in went a Holley Terminator X (Gen V LT Direct Injection kit, 550-1631). If it was going to run, shift, and behave like it should, Holley was going to be in charge.

Of course, nothing worth doing is ever plug-and-play.

Holley doesn’t currently support the factory L8P DBW throttle body, which sent me down the rabbit hole until I got Nick Williams — the throttle body guru — on the phone. After walking through a few checks, he nailed it: ditch the L8P throttle body and run a 2019 Corvette unit. It’s physically identical to the L8P throttle body, likely with different internal electronics, but with one key difference — it actually works with the Holley system.

I would also highly recommend getting the pedal assembly from GM as well.

And here’s the important part: buy it from GM. Not the parts store. Not aftermarket. GM.

We tried a locally sourced replacement first. It failed immediately.

The genuine GM unit? Bolted on, synced up, and worked exactly like it should. No drama.

Here’s what fixed it:

Throttle Body – GM #12669871

DBW Pedal – C6 Corvette, GM #19417903

Holley DBW Pedal Bracket – #145-131 (drops right into the factory pedal location)

Once everything was mounted and calibrated, it flat-out worked. Clean throttle response, no glitches, no guessing.

Sometimes the right answer isn’t the easy one — but when it fires up and does exactly what it’s supposed to, you know you made the right call.

[Carlo C.]

Hey Carlo,

I just saw your post and I know it has been a while but if I can help I would like to. I put a L8T crate engine(the L8P wasn't out yet) in my 72 Camaro with a Tremec 5-speed. I put a Texas-Speed cam, springs and pushrods. I also did a CHE trunion upgrade and a LT2 Corvette intake turned around backwards with Speed Engineering mid length headers. I will tell you that this thing RIPS!! I used Speed Engineering LT mount plates to the SBC factory motor mounts. I cut the mounts down 1 inch to get the engine as low as possible to give me as much clearance in the tunnel for the transmission as possible.

Lance

Lance,

Sorry, I just saw your post. I’m running the full-length headers from Speed Engineering along with the Hooker Blackheart stainless exhaust. It did take a little modification to get everything to fit the way I wanted, but it turned out really well.

I took the car on the Hot Rod Power Tour and had an absolute blast. Since then, I’ve had it all over the place — even spent a full week cruising at Cruisin’ the Coast. I’m really enjoying putting miles on it.

Hot Rod did a photo shoot of the car, so now I’m just waiting to see when it finally hits print.