What simple (cheap) mods can I make to a Ford 2.8 v6 from an 86 Sierra?

Er...

Find a turbo technics XR4x4 in a scrap yard!

Failing that, a good filter and a less restrictive exhaust (which you'll have anyway) will help. You can get replacement cams, the engines can be bored out, etc, etc. They can take quite big power with relative ease. I remeber reading something somewhere about using the EFi from the 2.9.

Or you can do a DIY Nos kit for as little as £50 with an old fire extinguisher bottle and other such stuff - I'll have to dig out the website. You choose how much power you want - it's all down to how much the engine can take, and some of the turbo conversions were over 300bhp so it's pretty strong.

Just don't make your car faster than mine will be

Liam

To get more oomph out the 2.8, there are a lot of routes to follow...my XR4x4 puts out 191 bhp (corrected to flywheel from wheels figure), see Glen Tunstalls website for an unbiased opinion.....

The heads need a major rework, I have an old Fast car article written by Dave walker (now at CCC) detailing some head mods, plus the yank book on tuning this engine, its mostly cr@p but has some useful stuff in it.
The Inlet manifold is shite, you can improve it with some porting, but the route to go is the 2.9 manifold........although this is not a straight swap!
Exhaust manifold's want to be tubular with the longest primaries you can get (about 36" is optimum) want to be about 1 1/4 to 1 1/2 inch for the single cylinder branch, and a wee bit bigger for the twin branch. After that if you want to go to a single system, secondaries need to be at least 24" long.
Cam...crucial, mine is a copy of a US Crane profile but with a wider LCA for the injection, idle is a bit (read very) lumpy, but it will rev to 7,000 (although my single springs mean I now get valve float at 6,500)
Block is weak, bottom end won't take repeated use above 6,500 or the main bearing's pull out the block, solutions exist such as welding/bolting bracing across the caps so they all help each other out! 225bhp is max possible, above that a snapped crank is a certainty, unless you fit a 24V crank (giving 2.9 litre) which can cope with about 280..but to get that you'll have to rev higher than the block can cope with! If you can afford it, the 24V crank is a good option, it gives 2.9 litre, raises the CR and is better balanced, a crank will cost about £200 with machining to suite 2.8, and pistons need a light skim down to suite!
Head cooling is poor, need to drill some extra holes (as 2.9, and detailed in yank book)
Also need to skim the heads/deck block to get the CR upto about 10:1-10.5:1 (depending on cam) - this is the only mod not yet done on mine!

Forced induction is an option to which the 2.8 responds quite well, but not sure it will suite a locost!