93 mustang convertible 331 and turbo

I ran Marshall blueprint engines through Bing and you will not be happy with the complaints that came up. The engine I bought had poorly knurled valve guides, and used a lot of oil, producing smoke in that pattern. They blamed it on the carb (the oil was not diluted!) and had the mechanic put new rings in. The carb was not flooding, it still smoked oil, and I did not get my money back. Then the oil pump shaft twisted like a piece of licorice on the way home from the re ring. Here is another complaint of many. I do not know how they have a good BBB rating.

https://www.ripoffreport.com/report...ty-engine-twice-and-inspection-dept-co-325061

It's a hypereutectic piston. Probably with a ring set gapped for a N/A configuration.

Hyper eutectic pistons are used because they grow very little in the bore when they get hot. Consequently, that allows the builder to set the piston skirt clearances fairly tight when they finish hone the engine. The benefit to you is the piston is much more quiet in its normal day to day operation, and less piston rock in the bores......which equates to longer cylinder life/less overall wear. So in the application they are spec'd in, a good fit.

When a power adder enters the picture, ( nitrous/turbo/sc) that all goes to hell in a hand basket.

The piston is brittle. It doesn't tolerate pinging or detonation.......at all.

The ring set won't tolerate the additional heat either. As you add boost, the piston gets exposed to more heat ( the byproduct of more power) if there isn't sufficient ring end gap to allow for the commensurate expansion that will happen to the ring when exposed to that heat,......the ring ends butt.

And can literally cut the top ring land right off of that hypereutectic piston.

When you look for an engine suitable for boost, the piston is what matters most. It is what gets exposed to the additional cylinder pressure and heat that comes with a boosted engine. You'll want a forged piston.

And all forged pistons are not created equal. There is a true forged 2618 alloy piston, and a 4031 alloy piston. A 4031 alloy is what you'll typically find in most crate engines listing the piston as forged. A 2618 alloy is what you'll typically get when you order a custom "race" piston. It's typically the strongest and most forgiving alloy with regard to how well it will tolerate heat and the abuses that may occur as you tune the engine for boost.

But it grows a lot in the bore, and that requires a lot of cylinder wall clearance, and that excessive clearance means a noisy piston.

( ask me how I know that)

Don't be afraid of the 4031 alloy. It runs tighter,..it's quieter,...and more than adequate for all but the highest power builds.

If you're planning on anything near 500 rwhp, the stock blocks are sketchy. That's about their limit before they split. A stock 351 block can handle more like 750. An aftermarket Dart block would be a good start too.

Another thing. If your plans include boost, chill out on the ridiculous high lift cams. Boost don’t care about high lift. It’s jamming the air in there anyway.