High gravity pitch, can you use too many yeast packets?

[sablesurfer]

So I am working up an imperial stout recipe. Every year I brew one, every year they are a little different.

What I am noticing is that Nottingham seems to have the best attenuation and clean ferment that I can find (and I like Notty anyway).

But at 1.105...brewer's friend is suggesting that FIVE packets would get to the target 470billion cells.

I've heard about two packets, but I'm assuming that if five is needed, then do five?

No, I do not have the time or the resources to brew a beer and then use the notty cake from that beer.
I am following the, no starters for dry yeasts philosophy, if I was going to do a starter I'd get a smack pack, but none of the common stout strains attenuate far enough.

 

[sablesurfer]

So, was this question just too dumb? Calculators giving the cell counts don't seem to match with any discussion I have found on the web, but I am assuming I should go with calculators.

Under pitching gives more esters right? Not sure I am going for that in this year's RIS. Rather go clean to get the malt roasts to balance my vanilla without fruit this time.

 

[agrazela]

Dry yeast pitch rate calculators do not all agree, depends on what you believe as far as viable cells per gram, how much dies when added to wort (when not rehydrated), etc.

You do not say what your batch volume or target pitch rates are; I'll assume 5 gallons and a "High Gravity" target 1.0 million cells / ml / degree plato pitch rate since that does yield a target 470 billion cells as per your chosen calculator:
http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/#cells_per_gram

That leaves you wanting 47g yeast, which is just over the 46g of 4 packets (at 11.5g each). So 4 packets for 5 gal at OG 1.105 added dry? I have no problem at all believing that.

 

[giraffe]

4 to 5 packets seems right. Dont underpitch, You may have problems with attenuation, its better here to err on the side of too much yeast.

 

[sablesurfer]

4 packs in a 2cup measuring cup of 85F water....YEAST VOLCANO!!!

Took my eyes off it for a while as I messed around with getting wort into the carboy. No idea how many hundreds of thousands of beasties escaped. AHHH.

Oh well, turns out my efficiency really took a hit, and that a RIS will clog even a BIAB session....so ended up with 1.095 instead of 1.105. Fermentation regular and quick by ~11hrs later when I woke up and checked.