You can get the LS2 low compression 402 from SLP and run with a small pulley to get high boost with the Radix. I am sure with a stock set of heads you can get 500 RWHP and be able to run high boost. The package is all forged too.

http://www.slponline.com/view_product.asp?P=12413

Crate-Engine-Assembly, "ZL402" LS2 Aluminum Short Block (Low Compression)

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The ZL402 LS2-based aluminum short block builds on the success of our original ZL402 iron short block. This new package uses the same race- proven internals as its iron block predecessor but features the all- new LS2 block for weight savings of over 100 pounds compared to an LQ4/LQ9-based engine.

Although designed primarily for use in late-model F-Bodies and Corvettes, the aluminum ZL402 also makes a great choice for most late-model GTOs, street rods, muscle cars, and trucks. Best of all, it’s sold outright, without core charges.

You won’t find a higher quality, better value LS2 stroker short block anywhere!

Includes:
Built entirely from brand-new parts.
Sold outright, no cores required!
402 CID displacement
GM LS2 aluminum 6.0-liter block (includes block plugs)
4.000" Eagle 4340 forged steel crankshaft, balanced to rotating assembly
4.000" Ross 2618 forged alloy pistons with -28.50cc dish (includes new rings and full-float pins)
9:1 compression ratio (nominal; ultimate compression ratio will depend upon heads and gaskets used)
6.125" Eagle H-beam rods
Includes new, factory-installed cam, rod and main bearings.
Comes with everything required to retrofit into an LS1-equipped car or truck
Designed for naturally aspirated use.
Assembled to OEM tolerances and specifications.
Capable of supporting over 700 hp.
Oil pump, camshaft, pans, and plates not included.
ZL402 badges (pair).

 

If you go with an LS1/LS6 block, you will need to have it re-sleeved (as already mentioned). There are many vendors that sell the blocks, and yes some have had their issues (cooling, leaking, etc). I would check with SDPC for a 402. This is utilizing an LS2 block with a 4" stroke. I know they will build to suit, and they post a lot on ls1tech. IMO, I don't believe there are really very many NA 500rwhp cars out there. However, with 400+ cubes, a radix, and an intercooler, you should be able to get there. Also consider the drivetrain, and it's impact on your dyno #'s. After working with a really kick-*** load dyno, I have come really care less about DynoJet #'s. Just go hold a heat gun next to the dyno's thermometer and see what happens.

 

Thinking in terms of $$$$ I'm wondering what I can get out of a 408 with maybe Dart heads and a compatable strong street cam with the Radix and about 8 pds boost. Any guess-timates?

 

8psi from a 112 on a 408 will equall lots of hot air.

 

You can alky mist before the supercharger or even nitrous to drop IAT.

 

have you talked with whitt1? he has just about this exact setup, I think he is making 6lbs of boost, don't quote me though. I think 500-550rwhp would be a realistic number not knowing your backround.
You will enjoy gobs of power under the curve!

 

I have a radix on my LQ9 (SS Silverado). With various bolt-ons I did 473RWHP and 491RWTQ. I feel that with meth, more timing, more freeflowing exhaust and a more blower friendly cam...500 is attainable. The current internal mod is only a mild cam.

If you want a sure bet, go with the 408. If my engine ever takes a dump, you can bet I will do the same

 

have a link to your dyno charts? what are your mods?

 

Do you have aftermarket cam and heads, or stock heads w/some work? What other bolt on's?

I sent a request out over the salvage yard network yesterday and got a hit.

Guy with a long rep in business has a 6.0 w/trans, 2004 with 24k and wants $2750 shipped, guaranteed for 90 days (or maybe it was 30 days... forgot).

Sounds like this may be a good deal but needs to be checked out.

Bore it .030 over, do a cam, work the heads or do the Dart heads and I should have a pretty strong piece. Then have the trans "built". Sounds like I'd be able to have a pretty strong combination for somewhere around $6k.

 

if you're going to do a 408 with a radix, try and keep the compression around 10.0:1. you're only going to be able to get around 8psi or so which means there is absolutly no point at all in going low compression. i'd also recomend sticking with stock heads and keeping the cam small. keep the duration below 225@.050.