I would not want to give away a better, cost effective way to do the job. It could be handed over to other contractors. Unless it is a repeat customer, why do value engineering for free? Perhaps wait to get the contract and then offer alternatives?
if a GC is going to take your ideas to their preferred contractor, you were never going to win the bid anyway, and that certainly happens. Its common to see in the ITB to "please include your VE proposals".
The architect/engineer will have a budget before the job hits the street, and you want to be coaxing that information out of them. the only thing that matters is that you land in the bang zone, and negotiate from there. in true competitive bidding situations its tougher to find the bullseye but in negotiated contracts this should be a walk in the park.
as far as the time spent on VE options.... I don't have a multiplier to give you, but the time spent should be negligible. Everyone is working in software now, its just a few clicks of a button to come up with an alternative assembly. And every manufacturer rep out there is more than willing to put a competitive package together.
another thing to add.... on a large project, everyone in your supply chain knew about the job before you did, and they've already done the legwork to put a competitive material package together. From there its all about which contractor is willing to give up the most money.
happy to answer any questions here, looks like a good learning opportunity to get us all on the same page.
