Rookie brewer here.. I willl be brewing a wort with OG around 1.080. I have 2 Wyeast smack paks..London Ale 111 and Northwestern Ale. I really don't have time to do yeast starter. Need to know if I'll have poor results using the yeast as is.. Thanks
Those are fairly different styles of yeast. They may work well together or they may not. Even with 2 packs you would still be underpitching. At 1.080 for 5.25 gallons into the fermenter you will want 288 billion cells. Each pack contains about 100 billion on the day it is packaged. The viability starts dropping from then on.
The yeast will ferment the wort. There would be off flavors created while the yeast reproduces. How bad it would be is the big question.
If it were me I would either get more yeast or make a starter and if necessary delay brew day accordingly.
You would be better off with a starter, but either one will work fine. There will be an increase in the lag time as the yeast multiplies, but either will ferment your brew fine. Make sure that you are practicing very good sanitization and keep your wort as close to a constant 64*F as possible until it starts. Once fermentation starts the temperature will rise between 5*F and 10*F, so make sure that you keep your temperature below 66*F, if possible, for optimal fermentation.
Assuming a 5gal batch:
Brew/boil/chill as normal.
Transfer to your fermenter and aerate as normal.
Take half a gallon or so (in a sanitised container/flask) to use as a starter.
Add your yeast to the starter.
Either put it on a stir plate or shake every 15mins or so.
The remaining wort in the fermenter needs to stay sealed, but the risk of contamination in that short time is low if everything was well sanitised.
After about 4 hours you should see solid signs of krausen/fermentation in the starter. Pitch it into the fermenter.
Although still technically underpitching (in terms of number of cells) the advantage of this is that you are pitching yeast that are already awake and ready to go to work. Also, you are pitching starter wort that is the same as the rest of your beer. Fermentation starts off really quickly.
While I am not a starter fanatic, a 1.080 beer is big and needs more yeast for optimum fermentation. I think it is strain dependent, but yeasts will do different things when they get stressed. Could be good or bad but it will make beer. Never pushed these strains before but honestly, either look doable IMO. I would prolly go with NW ale but if you are anything like me and brew sessions pop up at a moments notice, build a cache of dry yeast packets so this sort of thing is a non issue next time.