You can actually manage a portfolio of projects pretty simply using earned value management. It might take some training of your engineers and it will require a disciplined and honest approach from you and them.
Simply treat each project as a WBS element of a master project.
Do you have any project management software in your organisation? If not, in an MS Excel table, set up:
[ul]
[li]Project list down the left hand column[/li]
[li]EVM settings across the top row[/li]
[ul circle]
[li]Original Budget[/li]
[li]Approved Variations[/li]
[li]Budget at Completion (BAC), BAC = Original Budget + Approved Variations[/li]
[li]Pending Changes[/li]
[li]Planned Value (PV)[/li]
[li]Actual Cost (AC)[/li]
[li]Percentage Complete (PC)[/li]
[li]Earned Value (EV), EV = AC x PC[/li]
[li]Cost Variance (CV), CV = EV - AC[/li]
[li]Percent Cost Variance (CV%), CV% = (CV/EV)%[/li]
[li]Cost Performance Index (CPI), CPI = EV/AC[/li]
[li]Schedule Variance (SV), SV = EV - PV[/li]
[li]Percent Schedule Variance (SV%), SV% = (SV/PV)%[/li]
[li]Schedule Performance Index (SPI), SPI = EV/PV[/li]
[li]Estimate to Complete (ETC)[/li]
[li]Estimate at Completion (EAC), EAC = AC + ETC[/li]
[li]Variance at Completion (VAC), VAC = BAC - EAC[/li]
[li]Percent Variance at Completion (VAC%), VAC% = (VAC/BAC)%[/li]
[/ul circle]
[/ul]
You can then monitor progress by checking the cost and schedule performance measures on a periodic basis.
There are various ways of independently establsihing the ETC based on performance data (CPI and SPI). You then also monitor the VAC.
I'd also suggest establishing a master project schedule in MS Project.