My version of a 90 min clone...sparge water questions

[Lando]

Here is what I plan to brew.
The problem is that if I go by the old standard calculation I have been using of 1.33 quarts per pond for strike water and .5 gallons per pound of grain for sparge I end up with more sparge water/grain than my mash tun can hold. Plus that is a lot of wort that I would have to condense down into my 8 gallon pot.
Suggestions for sparge amounts would be helpful. Thanks
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IIPA My 90 clone 8-30-10
14-C Imperial IPA

Size: 5.0 gal
Efficiency: 75.0%
Attenuation: 75.0%
Calories: 309.3 kcal per 12.0 fl oz

Original Gravity: 1.092 (1.070 - 1.090)
Terminal Gravity: 1.023 (1.010 - 1.020)
Color: 13.75 (8.0 - 15.0)
Alcohol: 9.15% (7.5% - 10.0%)
Bitterness: 134.8 (60.0 - 120.0)

Ingredients:
16.5 lb Pilsner Malt
1.66 lb Amber Malt
2.0 oz Amarillo (7.5%) - added during boil, boiled 90 min
1.0 oz Simcoe (13.0%) - added during boil, boiled 90 min
.5 oz Warrior (16.0%) - added during boil, boiled 90 min
1.0 oz Amarillo (7.5%) - added dry to secondary fermenter
.5 oz Warrior (16.0%) - added dry to secondary fermenter
.5 oz Simcoe (13.0%) - added dry to secondary fermenter
1 ea WYeast 1187 Ringwood Ale

 

[Nateo]

I would subtract the base malt until you get your grain bill down to a feasible amount, then add malt extract to make up the difference.

 

[Lando]

I thought about that, but would like to keep it all grain.
My last single infusion mash/batch sparge barley wine ended up with a ton of wort that was almost like water. I feel like i could have gotten way with less sparge water and it had a similar grain bill.

 

[Nateo]

I re-read your first post. Are you sure you're using gallons per pound for strike water? You should be using 1-1/3 QUARTS per pound. That could be the problem right there.

this is the calculator I use:

http://www.brew365.com/mash_sparge_water_calculator.php

There are a lot of variables on there. I've found from experience that with my setup, my trub loss and equipment loss are a lot smaller than the default fields, so it's something you have to play around with to find what works for you.

I've also found that for big beers, that is, beers over 1.070 I have a hard time doing full 5 gallon batches with my equipment. I've started doing 3.3 gallon batches and have gotten a lot better results.

 

[Lando]

Yeah, I meant 1.33 quarts. Thanks for the link.
I plugged my info into it and I think something closer to 5-6 gallons for sparge water sounds a bit more reasonable. I will keep taking pre boil gravity readings when I do this one to make sure I hit my numbers.