IIPA recipe and batch size calculation question

[Spartan300man]

A few questions about my plans for an Imperial IPA.
I have a 5 gallon carboy for a primary fermenter and a 5 gallon stainless boil pot, so my plan is to make a 4 gallon final batch. Likely a 4.5 gallon boil. That gives me some headspace in both. I have a 4 gallon secondary fermenter.
1. When I plug in the information regarding final batch size, I assume I use 4 gallons. After boil and then transfer to the primary I'll plan to top it at 4 gallons. I know that when I move the 4 gallon primary batch over to the secondary, I will have some loss due to the trub and absorption by the dry-hops. When I finally bottle, I'm guessing I’ll be down to 3.5 gallons by then. However, the final batch size should be entered in the calculator as 4 gallons?
2. I am scaling down some of the IIPA recipes I have seen to my batch size. My goal is to get close to something like a Dogfishhead 90 minute IPA, not an exact clone, but a heavy big fat IPA. So most of the recipes I have seen use a lot more 2-row than a typical IPA or APA of that batch size, and a lengthy hop addition. I'm comfortable with the hops additions and dry-hop schedule part of the recipe. What else makes it a distinctive IIPA? I am starting out this recipe with somewhere in the 10 lb range of 2-row for this 4 gallon batch. I’ll likely use a small addition of carapils for head, and I have some 40L crystal and a small leftover of Amber dried extract. I am calculating an OG of 1.075 and a FG of 1.019. The ABV so far has worked out to 7.4%, which is apparently on the low end or under the style. So what are the tweaks that I need to work on here? Is it simply adding more 2-row? Will this have the malty balance to stand up to 90+ IBUs? Do i need a Dextrose addition?

 

[Toga]

I would calculate it a 4 gallons.

You will want some crystal malt and perhaps some Munich malt to lend a bit of sweetness and malty backbone. I would omit the sugar unless you want to dry it out a bit.

Something like this may work for you.

12lbs 2 row
1lb crystal 40
Your amber extract
1lb Munich

Then hops of choice. First Wort Hop your bittering charge. It will take some of the harsh edge off the bittering hops.

 

[m00ps]

I'd sub in some dextrose and mash low for an IIPA. 1.019 is a pretty high FG for something you want to be crisp like an IIPA. I've never had one of mine finish above 1.015

 

[Spartan300man]

Toga, I do want some malty backbone. The IIPA's I've had that I enjoy have that offset of malt that stands up to the huge IBUs. I'll plug in that suggestion of yours and see what the calculator gives me.

m00ps, is the dextrose suggestion meant to lend some sweetness? But will that raise the FG even more if Dextrose is unfermentable? Last batch of pale ale, I mashed at 154 degrees for 60 minutes. Do you normally go lower than that?

Is there a yeast that is recommended? I had the Wyeast Ale yeast in mind, not sure what else my local HBS has in stock but will see what alternatives are there.

 

[Yooper]

Toga, I do want some malty backbone. The IIPA's I've had that I enjoy have that offset of malt that stands up to the huge IBUs. I'll plug in that suggestion of yours and see what the calculator gives me.

m00ps, is the dextrose suggestion meant to lend some sweetness? But will that raise the FG even more if Dextrose is unfermentable? Last batch of pale ale, I mashed at 154 degrees for 60 minutes. Do you normally go lower than that?

Is there a yeast that is recommended? I had the Wyeast Ale yeast in mind, not sure what else my local HBS has in stock but will see what alternatives are there.

Dextrose is completely fermentable, and is used in bigger beers to avoid being "heavy" like can happen with 100% malt beers. It has no sweetening power; in fact, the opposite is true. Since it's completely fermentable, the beer will be a bit thinner bodied and a bit drier (finishing at a lower FG) than the same beer made with 100% malt.

I mash my IPAs at 150-152 as a rule. You don't want it "thick" and cloying, and you want it to finish crisp and thin to medium bodied. Some will even mash much cooler, at 147-149 to make sure that the wort has maximum fermentability.

 

[Spartan300man]

Dextrose is completely fermentable,

Ah, yes, Thank You, was thinking of MaltoDextrin.
OK, I think I am on the right track, just need to double check the availability of yeasts at the LHBS and the current inventory of hops, and I am ready to brew.

Thanks for the suggestions, I appreciate the help.
It's going to be hard to wait for the final results so I will be 'collecting more bottles' during the meantime.

 

[Spartan300man]

So I have access to a larger BIAB pot/boil pot, it measures to be about a 6.5 gallon stainless (lobster?) pot. For a primary fermenter, I have a new food-grade bucket that can hold 5 gallons, with enough headspace for some foam and blow-off. So my recipe will be for a finished volume of 5 gallons. I have 10 lbs 2row, and 1 lb Munich, plus odds and ends like the leftover 40L Crystal and some Amber DME, and some Dextrose. TBD if I add that.

As for hops, I have access to Citra pellet (13.2), Simcoe pellet(13.8), Amarillo leaf (7.1), and Cascade pellet (7.0). Still working on the amount and timing, but the Amarillo will be dry-hopped. Using 1 oz Citra and 1 oz Simcoe for 60 min boil brings the IBUs up to 107. That seems to be within limits for the style, the software added some IBUs coming from the late addition hops. I need to get the late addition hops finalized, it is very confusing and subjective, and I don't want to spend a fortune on 90minute DFH hops schedule.

So far, the OG I am coming up with is 1.082, and the FG is at 1.017. On another calculator, I am getting 1.079 and 1.014. But I don't think this takes into account the mash temp, since I changed it several times and the numbers stayed the same. I'm using the SA-05 Ale yeast.

The consensus advice I have read on this forum appears to be:
Mash temp will be around the 148-150 F mark. Sparge at 168F. (I'll probably dunk-sparge)
Dry hop after the initial fermentation (What is the benefit of delaying til then?)
Try to keep it relatively dry to accentuate the hops.
The bittering hops can be added at the mash stage prior to the boil.

Any other input greatly appreciated.