IPA Recipe w/ Concord Grapes

I'd say go with Cascade. When used in large amounts, the grapefruity flavor reminds me of why its called "grape"fruit.
So far as your maltbill, I think some lighter caramel malt would work well to keep the grapes from drying out the beer too much.

 

This strikes me as a risky venture that I don't think I would pursue. Personally, I can't imagine the flavor of concord grapes going well in any IPA. Before brewing, consider adding some concord grape juice to a commercial IPA and see if you like it.

Alternatively, something simple like a blonde or cream ale might make a better backdrop for concord grapes. I would also try a Belgian style with concord grapes before adding them to an IPA.

That said, if you're completely set on brewing a concord grape IPA, here are some thoughts about hops. I have heard some people describe Nelson Sauvin as having grape-like characters (though it's more of a white wine type grape). Brewer's Gold might also be a nice fit, as it is often described as raisins or black currants.

I also wouldn't use pilsner malt in an IPA. The grain bill for many IPAs is very simple, with the vast majority coming from some form of 2-row pale base malt. Some golden promise, Munich, and crystal would all be fine, but pils seems out of place.

1-1.5 lbs of grape per gallon of wort seems about right. Just be prepared for how strong and distinctive that concord grape flavor is.

 

I've been playing around with hops and fruit for a bit. It can work, but the balance can be tricky. I'd think that something like a hoppy red would be a better vehicle, with more maltiness to play with the grapes. I'd go light on the grapes, no more than .5 lbs/gallon. You'll certainly need some dry hops if you want it to read as an IPA.

IPA is about using enough high quality hops (I start at 8 oz in 5 gallons between flame-out and dry hoppings), and serving the beer as fresh as possible (with limited oxygen exposure). I didn't have great luck until I started kegging.

Because they grow in clusters? (according to Wikipedia)

 

Cool. Learn something new everyday. I do think that beers that use a lot of cascade have a scuppernong or catawba grape flavor, but that may just be a mental association, though.

 

I would either increase the GP to 100% or drop it all together, don't see any point in 10% GP. GP has the "sweetness" you seem to be looking for, no need for Munich or Caramel malts.

I don't think I would like grapes in my IPA, so I can't offer any advice there.

 

I would just add the grape must from the crushed grapes. Blend it with the beer during fermentation. A good example of a beer working in unison with grapes:

http://www.beeradvocate.com/beer/profile/64/66507/

That being said, an IPA probably isn't a good choice for this. I would keep the same hop profile that you have, but ferment it with a saison yeast. It could be an interesting brew.

 

i'd be another one that says grapes and IPA aren't quite in sync in my mind for a collaboration brew...but that's not to say a talented brewer could probably pull it off. Also I have had IPAs that have a grape-like aroma, but i usually associate that with IPAs that have been on the shelf too long.
Heck concord is hard enough to make a drinkable wine from...let along adding to a beer. So somethings to keep in mind about concord is it's a high acid, low sugar grape and generally winemakers have to add lots of sugar to get it up to the standard European varietals. Also if you let the grape skin sit in primary, you're going to get a decent amount of tannin (& color) extraction so I wouldn't use the levels you're suggesting.
Either way, I'd more lean towards a belgian style beer (like a dubbel) if you go ahead with this...

Edit: just noticed OldSock already mentioned the amount of grape per gallon. I would listen to him if I were you.

 

Before you go too far with this brew, I suggest they you research a bit about wild yeast that might be clinging to these grapes. You could end up with a sour/infected beer that is worthless. I realize that you said that you won't use the skins, but....

 

The beer uses concords.
http://www.beeradvocate.com/beer/profile/1398/59666/
Never had it, but it is used in the production of a cheese called Ledyard, which is dope when a point.