417 ci LSx stroker out of a OEM 6 liter iron block??l

**B'klyn9C1** · 06-18-2012, 02:40 PM

Anyone has a 417 ci LSx stroker out of a OEM 6 liter iron block(LQ9 or LY6)??

I was reading in the July 2012 issue of "Super Chevy" magazine in their article "LS3 vs 418 stroker". They stated that in building their LSx stroker they couldn't use a iron block, LQ4/LQ9, because you are limited to only going to a 4.030" bore size!!!! What?!?!?So they went with the LS3 block with its 4.065" bore. !! I know that this is not true and I know we shouldn't believe everything that we see in magazines anyway.

But all the same I want to build my LSx stroker out of the OEM 6 liter iron block because I know that they are way stronger, cheaper and more plentful than the aluminum block (LS2 and LS3). I know that guys out there have bored these babies beyond 4.030".

A few years ago I know that at first 402 ci strokers(with the 4.00" bore) were all the rage then they were followed by the 408 ci (with the 4.030" bore). Remember those SLP short and long block packages? But there has got to be quite a few of those big bore big inch LSx strokers in the 415 ci to 417 ci range out there running around by now.

If you have one of these 415+ ci iron block babies withthe 4.00" stroke, please post your experiences here?? How big did bore out your iron block???

**Firebirdjones** · 06-19-2012, 10:50 AM

Alot of variables here that come into play. Sonic testing is the only way to know for sure how far any particular block can be bored. Most engine builders rely on a .200 wall thickness minimum spec, and this depends on how the engine will be used. If power adders are in the cards they could prefer a thicker wall than .200". Thicker walls are more desirable as they hold their shape better under extreme loads, especially on the thrust side.

In the case of the cast iron 6.0 they have been bored .060 in many cases but I doubt those are power adder applications. However they go 4.030" easily with room to spare. I believe they are still on a 4.4" bore spacing which is alot of room providing you don't run into a water jacket. Again sonic testing is the only way to know.

Works okay for a budget build but for anyone looking for serious power I don't think the max bore diameter just to gain 9 cubic inches is worth pushing the limits. If looking for larger displacement and big power I'd probably look at something with more bore spacing like the LSx block or something similar. I prefer thicker walls with room to build again down the road, not much of a fan of taking it to the maximum bore just for a few cubes. In that case it would make more sense to start with a larger bore to begin with and have some wiggle room. Sounds like the LS3 fit the bill in this instance which is probably why the magazine chose it.

**Jay37** · 06-20-2012, 02:49 PM

Go .060 it will pass the sonic test. Magazines have to much money.

**Jay37** · 06-20-2012, 05:31 PM

[QUOTE=Firebirdjones;2785387].

Works okay for a budget build but for anyone looking for serious power I don't think the max bore diameter just to gain 9 cubic inches is worth pushing the limits. If looking for larger displacement and big power I'd probably look at something with more bore spacing like the LSx block or something similar. QUOTE]

I think the Screaming Chicken meant to say siamesed cylinders.

**B'klyn9C1** · 06-21-2012, 07:47 AM

I am glad that you guys brought the 4.4" bore centers

One thing I want know is why everyone or least alot of people are saying that for the OEM iron block the maximum bore 4.030" while they bore out the LS3/L92 block from 4.065" to 4.071"??? Why the 4.030" limit??? They both have 4.4" bore centers. The LQ4/LQ9 block is made of all cast iron and the LS3/L92 cylinder is made of soft aluminum and ductile iron. But it is safe to go with the bigger bore with the block that is made of the softer material and the the harder stuff is somehoe forbodden???

I don't get??

Please some explain why the "hard" limit 4.030" bore for the OEM LSx iron block???

**Jay37** · 06-21-2012, 02:43 PM

The stock bore of an LQ9/4 is 4.00" The stock bore of an ls3 is 4.060. what that means is that the LS3 has bigger cylinder walls so the OUTSIDE diamater on the LS3 would be bigger than an LQ4. The LSX block is has siamesed cylinders meaning the OUTSIDE diameters are so big they actually are one piece of steel with no gap between the cylinders for coolant, this greatly increases the amount you could bore it to. Which is 4.250.... HUGE. The only reason I can say a "max" bore for that block is because I'm quoting GM, they built the block for performance and designed it to have a huge bore for guys like us

On the other hand, the "hard" limit your looking for depends on a multitude of different things. I personally wouldn't go past .030 on the first biuld of a virgin block, not because I don't trust it, because I want to be able to freshen it up and punch out to .060 down the road. On the other hand I also would not have an ounce of worry about running a .060 over LQ4 either that is n/a and doesn't have to compete in the baja 1000.

Plus unless your planning on putting down serious serious power for a competition only motor the lsx block is HEAVIER than the stock OEM iron blocks.

just to clear up the bore center thing. ALL LS blocks have 4.4 bore centers. How much steel is around them that matters. Also with a siamesed block I.E. LSX it's more likely to overheat due to coolant not being able to flow to around the cylinder.... I'll try to get picks.