VS Eco series II advice

[Banj789]

Looking to get as much as I can out of my old 6. From looking around mace mods all same to be small gain for large money, I just want something that will be atleast decently effective without the car being entirely illegal. Yes I’m a young P plater, the car is a project that currently has a turbo ecotec being built in the shed with forged con rods, pistons and a stroker kit. I’m looking to get what I can from the quote on quote “chassis” of the car. It’s running a built 4L60E and has a series I diff. I’m looking at diff gear modifications and anything else I can to get a stronger driveline with the capability of handling more power down the line and of course getting the best I can now.

I’m looking at 3.4, .7, or .9 gears for the diff as I know they’ll make a noticeable difference in the Low end whilst affecting top end much worse. The questions I have with diff gears are from peoples experience how much worse will the fuel economy be from its stock configuration? I know it’ll be worse but not to what extent. I’m open to suggestions and I’d love to here what the community has to say.

I’m sure there will be critics in the comments but that’s fine and that’s life. Just let me know what y’all think without just saying “throw an LS in it ayeee” because that’s not what I’m looking to do. I want the best from an eco because it’s something unique. If everyone threw their motor in the bin and went LS, god it’d be boring!

 

[Pollushon]

There's not that much of a difference in economy between them. Sure the revs go up but you don't start using 10 more litres per hundred because your cruising. On my boosted Eco with 3.9 Truetrac up from 3.08 stock I added about 300rpm at 100km from memory. Totally worth it for the pickup and responsiveness. I would have gone 4.11 but the 3.9 was a wicked deal I couldn't pass up. Boost is going to cost you way more juice anyway

 

[losh1971]

It might come down to what you can actually buy. Assuming you have the stock M75, 3.45s are plentiful, 3.7s and 3.9s might or might not be a challenge to get. They used to be impossible to find when I did a regear in my VR old ute.