According to some YouTubers, you can pull any beer (anything, including time?) through a beer engine, even hazies.
In reality, of course, you can. It’s your beer engine. Pull whatever you like through it. Whether it does the beer or the beer engine any justice is another matter. Personal preferences, etc. If you enjoy, that’s all that matters. You can definitely pull English ales and English ciders through an English beer engine to get a very nice result in the glass. They coevolved and work well enough to survive extinction.
Beer casks are just traditional kegs really. They’re actually designed to hold significant pressure. It’s actually good practice to promote higher carbonation levels in cask ales to help increase shelf life in storage. When a cask - even one containing a traditional English ale - gets tapped, the beer is often quite lively and requires some ‘cellarmanship’ to condition it ‘down’ for serving through a beer engine. This is the bit home brewers seem to overlook. Letting it ‘breathe’ for hours to a day or so, to bring the carbonation level down to serving levels. But higher than what ends up in the glass, right? Because a lot of CO2 gets knocked out of the beer (becomes head) by the turbulence promoted by the force pushing the beer out of the pump and into the bottom of the glass. A common schoolboy error most home brewers armed with beer engines make is trying to condition beer in cask or keg to levels we’d expect in the glass. A decent traditional English ale is not warm, flat horse p*ss at all. It should be served at cool cellar temperature (~11C) with a decent head and, my personal preference, a low level effervescence, which tells me it’s freshly tapped and likely at its best, for me.
I have pulled a lager through my beer engine, after conditioning some ‘down’ in a mini keg and raising its temperature to about 11C. It was definitely what I
imagine flat horse p*ss tastes like. It’s surprising how much CO2 adds to the quality of a lager. It’s undeniably a key component, in a lager. Why lagers can be served cooler, because they have no desirable flavours to dull. Best served chilled. Just a refreshing cold one to neck down in the summer really, rather than savour the finer qualities of, like an English ale necked down all year round.
But, to be fair, I think an Altbier has a good chance of working fine, better than a typical lager, served through a beer engine. My advice is condition it down, but not necessarily as low as claimed ‘cask’ level. I’d aim for about 1.6-1.8 vol CO2 in the cask/keg. It can be conditioned down further, if necessary. And serve at cellar temperature (10-13C). Note Angram beer engines have precision-engineered glass beer cylinders and plungers designed to operate optimally at cellar temperature. If the beer being pulled is much cooler, it risks altering the geometry and causing some judder in the pull.