I know the LS7 block has 6.86" liners (which are significantly longer than LS2/LS3 liners)

Because of this is it feasible to run a 4.25" stroke crank in a LS7 case?

What rods/pistons would you use for a naturally aspirated engine?

Also what dry sump pan would I have to use for a C6 corvette. ( I plan on installing coilovers so clearance of the leaf spring is not an issue)

 

I believe you meant 5.86 long, not 6.86"?
Is this a street engine and always staying N.A. (no nitrous or F.I.)? What are planning on doing with the engine as far as fuel,C/R, heads etc. ? If your planning for nitrous the ring pack would be too tight to be reliable and for FI it would be hard to get enough dish volume. The R/S ratio isn't that good at 1.44, but depending on what your use is would be a factor. I would contact ARE about a dry sump set-up.
I tried to talk you out of it, so we have a new 4.250 stroke X 2.0" rod journal crank with a std. snout (not longer for the LS7 dry sump) if your interested. The rods would have to be 6.125" long minimum and the pistons a custom with a .980" C.H., tight ring pack, etc. Allow for reluctor ring clearance!! Of coarse the assy would have to be balanced after all the components are determined.

 

pm'ing you with some information. It is an upper level complex build that you really need to be on top of your game to build. My 457 has a 4.250 stroke in it, we can build it for you.

 

Yes as Blanco said that is a fairly difficult deal but they work and I have done several of them and they all work just fine. It isn't a simple drop in deal though and everything has to be right. The bigger heads like the bigger stroke as well. The oil pan matters as well as some are much better than others.

 

^ Using 6.125 rods that leaves very little room for compression height. I'm guessing you use pistons with rail supports in them?

 

Any of the 1.1xx compression height stuff uses a rail support

with 4.250" stroke, compression height be around 1.000"

 

I think the reason 6.125" rods are specified is because the oil ring location at BDC is going to be critical (otherwise oil consumption might be too high I am guessing).

 

Yep the CH is around an inch and it isn't a power adder setup anymore.

 

9.240 Deck height - 2.125" (1/2 stroke)- 6.125" rod = .990" Compression height

A 6" rod increases the rod angle requiring deeper clearance notches in the cylinder which must stay below the oil ring @ BDC, reduces the counterweight radius to balance, reduced pin boss material, piston thrust wall loading.......

6.125 rod-2.125"(1/2 stroke)-3.625" (1/2 reluctor dia)= .375" pin cnter above the reluctor
ring. Narrow pin bosses and short pin is a must.

6.125"-2.125-.433(half pin dia)- .150" (min. pin boss and clearance) = 3.417" max C-weight radius at BDC. Alot of mallory required!

.990-.433-.2 (rod pin end thickness)= .357" for dome thickness and clearance assuming flat top piston and H-beam rods so the pin gets oiled

I looked at this for a customer and decided against it even with our 5.8" sleeve length. The stock deck height just doesn't leave enough strength in the ring lands, piston dome thickness, valve relief's,etc. even with a .866 pin and 043",043",3mm ring pack for my comfort for what he was doing. Big valve reliefs for large diameter valves and high lift cams are out, piston dish volume for a 454 CI and FI are out with 70cc heads, a safe top ring land thickness for nitrous is out. And yes an oil rail support is required with < .350" for 3 ring lands and valve reliefs . That's why I asked what your plans are and like the others have said it's not an easy build even if you had all of the right parts spec'd for you. A lot of details to deal with after you have the parts, so take their advice.

 

http://www.worldcastings.com/prods_p...ks/warhawk.htm

How about one of these blocks in 9.800" deck height for a 4.25" stroke?

I am assuming the cylinder liners on these are much better than a LS7 block right? (Do they use Darton Liners?)

Also what rod length would be advisable with a 9.8" deck height to get a good ring package. (I will probably be considering FI on race gas at some point)

 

What are you doing for headers? I also gather you'd use the intake spacers from world castings to get the intake to match up?

 

The liners are about the same length but there is more room for a longer rod and more CH so it's nice. I have one of these here right now and the piston is very comfortable with a 6.460 rod.

 

You can run the pistons a lil more out of the hole for more CH but you are right that you can not really run big power adders anymore. We have done some 400 shot 1.000 CH stuff that was very fast and lasted but the tuneup had to stay very conservative.