Megasquirt II/Extra and Hilborn 8-stacks

[99_ls1]

I have a Hilborn 8-stack EFI casting and a Megasquirt II/Extra. After reading through most of the MegaManual it seems as of it would be a simple conversion to a manifold that has no IAC but can provide input to a MAP sensor. I plan for it to be used for fuel only, and I have the Innovate LM-2 wideband that I got with the MSII to sniff output.

Dieselgeek - I know you've done a ton of MS stuff, has anybody ever asked you to set up a set of stacks?

(and yes, the sharp-eyed amongst you will notice that the injector stacks are switched side-to-side - this is as it showed up via eBay. Why the injectors were pointed at the manifold casting instead of the valve, I cannot say. I do not intend to run it as shown, they are already flipped around)

[ecorl]

Scott is much better able to give you specifics than I. I am using MSII for fuel only for a blown/bugcatcher application. Strongly recommend the use of the IAT if possible. Contact Fran at Fox engineering on the web, he has set these up before and is very good.

[BigAL]

How do you plan on referencing for the MAP sensor?

[99_ls1]

Hilborn actually produces the EFI manifolds with a vacumn kit. The manifold has spacer blocks under the 4 stacks that have brass vacuum taps for each hole. Then a central block bolted in the center of the manifold provides the MAP source by joining the 8 taps together. They are not really visible in that picture because the stacks and spacers are flipped side to side and they are pointing in... but they're there. I did not get the vacuum kit with the manifold, and have to put something together.

[anotheridiot]

I know Bob Beedy used to tie all his stacks together thru an extra pipe tap each stack to equalize pressure. He just used plastic tubing with quick connects. I know its alot of plumbing to go thru, but if you can connect them somehow to an IAC at a common source it might be enough. Might need to do some reduced sizes so it draws equally..

[dieselgeek]

Dieselgeek - I know you've done a ton of MS stuff, has anybody ever asked you to set up a set of stacks?

Lots of times.

MS2-Extra allows you to do MAP sample windowing, which means "pick the crank angle your MAP signal is used for load reference" so nowadays a vacuum reservoir or signals from all 8 runners isn't even required. Although, most of the ones I have tuned, used 8 vacuum signals tied together and perhaps a small plenum. Do the 8 signals if you have the option, since that's more common IMO.

The trick with stacks has little or nothing to do with the EFI tuning - it's getting the throttle blades to stay sync'd both cold, and warm. I think the hottest ticket for EFI stacks like yours, is to upgrade to sequential EFI (you'd need a MS3 CPU and MS3X expansion card), so that you can have the throttles sync'd for a warm engine, and then use fuel trims per cylinder to compensate for the conditions when the engine is cold.