Tuned Vortec TBI to MPFI on 7427

[woody80z28]

Stock Vortec head, 207@.050 LT1 cam, Edelbrock Performer manifold combo. I think the biggest thing making it feel lazy was the steel wheels. Borrowed a set of aluminums once and I was amazed at the difference.

Got the new truck running TBI on the 7427 and drove it in the garage. Was getting excited to start playing with it...and then the wife found a truck I couldn't pass up. So this one will be getting sold as-is cause I have too much other stuff to do. Kinda disappointed because it would have been cool to do this MPFI conversion finally. But I ended up getting a Vortec 8.1/ZF6 6spd 2500HD for less than this 1500 was going to cost me. So I had to think with my head, not my heart...

[Fast355]

Stock Vortec head, 207@.050 LT1 cam, Edelbrock Performer manifold combo. I think the biggest thing making it feel lazy was the steel wheels. Borrowed a set of aluminums once and I was amazed at the difference.

Got the new truck running TBI on the 7427 and drove it in the garage. Was getting excited to start playing with it...and then the wife found a truck I couldn't pass up. So this one will be getting sold as-is cause I have too much other stuff to do. Kinda disappointed because it would have been cool to do this MPFI conversion finally. But I ended up getting a Vortec 8.1/ZF6 6spd 2500HD for less than this 1500 was going to cost me. So I had to think with my head, not my heart...

I had almost that same combo in my G20 Van years ago. I had a LT4 cam with 1.6 rockers. It was a tire smoker even with 3.08 gears.

You will enjoy the 8.1. I have one in my 99 Tahoe with a 4L80E behind it. 3.42 gears and P305/50R20s on it. Even with the low-end torque loss of the Mercruiser 496 HO cam it roasts the tires if you get on it more than about 1/2 throttle in first gear. It has a healthy dose of HP Tuners editing. I have seen 17 mpg running 70 mph running in leam cruise at 16:1 air/fuel ratio.

[woody80z28]

I had almost that same combo in my G20 Van years ago. I had a LT4 cam with 1.6 rockers. It was a tire smoker even with 3.08 gears.

You will enjoy the 8.1. I have one in my 99 Tahoe with a 4L80E behind it. 3.42 gears and P305/50R20s on it. Even with the low-end torque loss of the Mercruiser 496 HO cam it roasts the tires if you get on it more than about 1/2 throttle in first gear. It has a healthy dose of HP Tuners editing. I have seen 17 mpg running 70 mph running in leam cruise at 16:1 air/fuel ratio.

I've been researching HPTuners vs EFILive to dive into this thing. This BlackBear place has a good reputation and they use EFILive stuff. But HPTuners is cheaper and that would save me some cash vs getting a "base" tune from BlackBear.

What have you found the 8.1 responding well to? I would guess some more spark and less PE fuel. How do you keep lean cruise from activating while towing? My manual trans doesn't have a tow/haul button.