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Discussion Starter #1
I've been looking at the Mast ls3 heads, they seem to flow real well. Not looking to spend a fortune, but want to put a good cylinder head on it. Have the Dart cathedral ports on the engine now, and I think we are going to pass their potential with this new motor.
 

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What are the details on the engine? Bore size? If you are going to an aftermarket casting and have at least 4.125 bore size available, go with the C5R (PXR) port from Mast. The castings cost the same as the LS3. You will spend more money in valvetrain, but it would be worth it if you ask me. If you aren't limited to a wedge head, there are other options too but hold on to your wallet.
 

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Curtis would say,,,,,, LS-R by RFD LOL there is a post here somewhere with them on a 430 making over 1050HP I think
 

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You need to look at RM, Morgan designed LS3. It has the best profile of any LS head I've had across my bench. I'm a dealer for them as well. GM core, 260cc and moves 375 plus.
Is that a gm LSX core with the added material to the spring pockets and a 5/8 deck? I can't see Morgan or you wasting your time on a production GM core.
 

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Is that a gm LSX core with the added material to the spring pockets and a 5/8 deck? I can't see Morgan or you wasting your time on a production GM core.
Kinda thinking the same thing. Does the LSX casting have a better valve placement than the regular production based head?
 

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Yeah the LSX castings do have some advantages... but the OEM castings aren't that bad. The LS3 casting will move almost 400cfm with a killer velocity profile and the castings don't cost anything in comparison to the LSX heads.... only drawback they have is the spring pocket diameter, but we can still put .750" lift springs in there (or more if you want to change the springs in a drag applcation). The deck thickness on the stock casting is more than enough for most applications, only on something with 20psi of boost would I worry about them.

Biggest problem I have seen on the LS3/L92 castings and work done to them is the runout, the PM of the seat inserts along with the diameter of the valve make it hard for people to get these things round... haven't checked many of them that are.

 

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Well we aren't sure yet if it will be an lsx engine, or an ls2 block. 4" arm, some slugs from my buddy mike at diamond, single dominator on gas, 2 systems from IS.
Personally I would stick with a Mast or Allpro head. Your getting a superior casting with 3/4 decks that you can mill a lot off of and still have a thick deck, more material under the spring pockets and are already machined for 1.650 springs, and more material around the shaft rocker area also. If I was building anything with a 4.125 bore or larger I wouldn't even bother with Ls3/L92 head period. The Mast Ls7, PXR, Splayed Valve, or Allpro from WCCH are much better choices. Mast might give you a package deal on a set of heads with their 2-piece 4500 carb intake.
 

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See that's the type of response I was hoping for. haha.

How much nitrous will an ls2 block with the ls3 heads hold? What's the threshold on them, I'd prefer to not find out the hard way.
Do you have that block or are you looking for one?

I wouldn't be scared of making 1000hp out of that setup... stock crank, stock block, OEM head castings.

How fast do you want to go? 8's?
 

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Discussion Starter #19
Right now it's a 5.7 block with dart heads eagle rods, diamond pistons, stock crank and a big hydraulic cam with the carb conversion..

We were wanting to build something 400+ to go 8.50's or quicker.. More so 5.20's or quicker.
 

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How fast is it going now? Might just be able to tweak what you have right there for less and hit that goal.
 
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