Looking to modify an already made wort before pitching yeast

[sfla]

My homebrew club is scheduling a group brew at a nearby brewery in a couple weeks, they are doing a pretty generic recipe that people can modify and pitch their own yeasts later. The base recipe will a medium gravity amber wort.

I want to modify it to make a IPA, but I am unsure how to calculate the additions. I need to boost up the IBU (they are aiming for 30), and I wouldn't mind boosting up the OG (again they are aiming for 1.050) as well.

I know that I will have to gather up some hops and some grains in some more water, but how do I calculate what effect that the addition will have to the base wort so I can plan the amounts of hops/grains to use. Anyone have any ideas how to calculate that?

 

[Six_O_Turbo]

I havent done a group brew before, but if everyone is getting their pitchable wort at the same time, it wont be too easy to make it a lot more bitter, but you do have the option to dry hop, which wont add much bitterness, but will definately increase the hop aroma. Assuming you are getting 5 gallons, I'd toss in an ounce of the hop of your choice after the fermentation is complete, then rack off after a week or so and bottle.

Of course, if you are boiling your own wort you can add your bittering hops as usual, and in that case I'd just double the additions from the recipe. Maybe a little extra added toward the end of the boil and then dry hop. Tough to give you a hop adjustment without knowing how much you want to bump the gravity, but if it's not too much you should be fine as stated.

 

[COLObrewer]

Any way you can separate your portion of wort and boil it separately? Then you have more options.

 

[sfla]

I won't be able to separate my wort, we are doing about 500 gallons

So there is no way to calculate what the effects of mixing two different worts together? Basically that's what I would have to do before pitching. Boil up some water with some additional grains and hops to change the wort.

 

[david_42]

Trying to boost a 30 IBU, 1.050 wort into the IPA range won't be easy without re-boiling or mixing in so much additional wort that you may as well have started from scratch. It would be really tough to do with grain.

If you are willing to re-boil and use LME, you can calculate a bittering addition for 30-40 IBUs, add 1-2 pounds of LME and make flavor and aroma adds.

Why not accept it for what it is and try a new yeast?

 

[sfla]

Well i am not opposed to reboiling but I would rather avoid it.

I wouldn't mind boiling up another 1 - 2.5 gal of water to make it a smaller batch of the base amber ale and a 5 gal IPA. I was figuring I would have to make another small wort to add in to significantly change the beer. Just trying to figure out the numbers on the small wort to make the changes i want

I will 100% happy w/whatever it turns out to be, just looking at experimenting.

 

[david_42]

I've participated in group brews before and comparing the results of different yeasts/fermentation conditions is the big payoff for me.