Hello All,

I lurk here a lot even though i own a v2500 suburban and not a third gen. ( a lot of good info on the site). I read a lot of stickys and searched and wanted to get some advice from people that may have already down the same.

Currently 5.7, Lunati .437"/.454" 207/213(flat tap), edlebrock intake and modified TBI, long tube headers, 2.5 to 3" and a moates burner. 4.56 gears with 34" tire. All is well but it is still a dog in the mountains.
I am considering;
AFR 180s
larger hyd roller
maybe the ELB flash system and a larger TBI.

All said, reliability is paramount. I get far from home and knock on wood, i have never been stranded. The OEM TBI is great because parts are everywhere.
My short block has ~40k miles so it would be nice to run it but I have considered another Dart 406. Has anyone changed to Aluminum heads? was there a noticeable improvement?. Unlike my other build, this motor will operated 2-4,000 and live under 5,000 RPM. I always liked better heads with a smaller cam but if the swap to AFR does nothing to my low end it is wasted money..


I know there are a 1,000 variable but if anyone has gone down this road already, please share.

Thank,
Chris

 

What transmission is in that rig? I have a 4L85E in my Express van. I run a 5.13 gear with IIRC a 31.5" tall tire. It cruises about 2,850 rpm @ 70. Gears are the best bang for the buck for a heavy brick of a vehicle. Your 4.56s probably only get you back to the equivalent of a 3.42 or 3.73 with factory sized tires. Gears made more of a difference than my cammed 350 Vortec to 383 Aluminum head engine swap despite the 383 making another 150 hp and a sizeable tq jump across the whole rpm range. The 383 + gears made for a huge improvement in hill climbing, especially with my 6,000 lbs travel trailer hanging on the hitch out back.

I am trying to convince myself not to buy a Gear Vendors to put behind the 4L85E. Would be nice to have the gear vendors as it splits the gears, adding gears between each gear and would give me double overdrive for running empty on flat roads.

Instead of 2.48/1.48/1.00 and 0.75 of the 4L85E the gear vendors gives these ratios. The engine rpm will drop roughly half for each gear and I will have more torque multiplication through the additional lower gear ratios.
1st of 2.48
1st over of 1.93
2nd of 1.48
2nd over 1.15
3rd of 1.00
3rd over 0.78
4th of 0.75
4th over 0.59

The gear vendors is a stronger overdrive for towing than the 4L85Es factory overdrive as well. I would tow in 3rd with the gear vendors engaged on flat land.

I have considered the TCI 2.96 1st gear planetary set that gives a 1.75 second gear as well.

Option 2 for you would be to find an 8.1 and swap in some EFI fed big block muscle. I have one in my 99 Tahoe. It has the factory GM 425 HP high output marine cam, headers and tune. With a 3.42 gear and 32" tall tires it has no problem climbing hills at 1,800 rpm @ 70.

 

With the 456s i get back to about 3.91s. I also thought of the gear vendor but it is $$$$.

 

Lower mileage 8.1 is sounding like the cheapest option to me. Probably snag one complete and running for less than those aluminum heads. Gave $1,000 for one dully dressed with 80K on it and gave $800 for another fully dressed with 120K on it. Those are 300k capable engines with good maintainence.

 

Fast, do you think some ported swirl port heads would be good here?

 

Depends on where you want to make your power.