APA extract recipe bitterness question

I've ordered a kit from Midwest for the Superior Strong Ale. In the instructions, it estimates the IBU's at ~52.0. As a reference, I checked the IBU of Sierra Nevada's Pale Ale, which I like. According to BeerTools.com, the IBU of SN Pale Ale is ~38.
Two questions:
1) How big is the difference between 38 and 52 IBU? Huge?
2) Given these original instructions...

When the extract is fully dissolved, return the kettle to the burner. As soon as you see a boiling bubble add 2 oz Mt. Hood bittering hops and boil 60 minutes for optimal hop utilization and bittering. Add 1 oz Tettnang aroma hops for the last two minutes and remove the pot from the burner.

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...can Beer Smith or any other program tell me what my predicted IBU would be if I boiled only 1oz Mt Hood at 60 minutes, then added the other 1oz at 30 minutes (keeping everything else the same), or used the full 2oz at 30 minutes instead of 60?
I suppose that leads to another question. If you don't intend to boil the hops for a full 60 minutes, do you need to boil the extract for 30 minutes without hops in it (should you just boil for 30 total minutes vs. 60 minutes)?
Thanks.

I like this calculator:
http://www.rooftopbrew.net/ibu.php

I am new here as well, so others will probably jump in, but I don't believe you need to boil the extract for 60 min if your first hop addition is at 30.

the difference in 38 and 52 ibu's isn't big at all. You don't necessarily need to do the 60 min boil if you aren't adding the hops until 30 min , but i would recommend to go ahead and do the 60 min boil and add all 2 oz at the beginning, because those are your bittering hops, adding them at 30 would, well, cut their effeciency in half (in other words, the bittering hops is where most of your ibu's are going to come from in this case, that late addition at 2 minutes will add hardly any ibu's. Mt. Hood. is very low in alpha acid (i think around 6% usually), so i wouldnt worry about over hopping your beer or it being too bitter. How much extract did you use?

I haven't made it yet but it's 9.3lbs LME total. It will be a decently big beer.

Thanks for the input.

SpaceportBP said:

I like this calculator:
http://www.rooftopbrew.net/ibu.php

I am new here as well, so others will probably jump in, but I don't believe you need to boil the extract for 60 min if your first hop addition is at 30.

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According to that program, the IBU for the original recipe would be 39.3, not 52.

I may try 1oz Mt Hood at 60 minutes then add the other oz at 45 minutes.

What formula are you using to calculate hop utilization on beertools? In the version I have you have to select your utilization from a drop down menu. The default "Basic" seems to under estimate IBUS by a long shot. Every time I plugged a recipe I got online into it, it said the IBUs were way less than what the recipe predicted. When I switched the utilization formula from Basic to Rager formula the calculated IBUs all went up and the recipes started to match. Maybe if you switch your utilization to the Rager formula it will jump from the estimated 38 to be closer to the target 52.

It's also possible that the kit instructions didnt use either of these formulas to calculate the bitterness, so neither will hit it right on the head...

Rager's formula was the one I (randomly) picked to use.

SoonerDoc said:

According to that program, the IBU for the original recipe would be 39.3, not 52.

I may try 1oz Mt Hood at 60 minutes then add the other oz at 45 minutes.

Click to expand...

I ran this thru another calculator @hopville.com and the original 2 oz of Mt. Hood @ 60 and 1 oz of Tettnang @ 2 min using four different formulas and came up with under 35 IBU each time. I am surprised at the kit's claim of 52 IBU from the Mt. Hood @4% AA; but then, as I said, I am a noob and am confused as well.

SpaceportBP said:

I ran this thru another calculator @hopville.com and the original 2 oz of Mt. Hood @ 60 and 1 oz of Tettnang @ 2 min using four different formulas and came up with under 35 IBU each time. I am surprised at the kit's claim of 52 IBU from the Mt. Hood @4% AA; but then, as I said, I am a noob and am confused as well.

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The reference I used show Mt Hood to be anywhere from 4-6%AA, so if you bump to 6%, that accounts for some (but not all) of the difference.

If you use Hopville's calculator make sure you specify how many gallons you are boiling... (it's in the hop section towards the bottom in light gray letters)...

It's not 100% accurate but pretty close... what's your hop's AAU and your O.G.?

BeerJorge said:

If you use Hopville's calculator make sure you specify how many gallons you are boiling... (it's in the hop section towards the bottom in light gray letters)...

It's not 100% accurate but pretty close... what's your hop's AAU and your O.G.?

Click to expand...

I estimated Mt Hood at 5% and Tettnang at 4.5%.
OG should be 1.063-1.067.

I have no idea if this matters or not, but the Midwest site shows their Mt. Hood at 4% and Tettnang at 4.4% if purhcased separately. Is it a good assumption that the same hops they sell are the same ones they put into their kits?