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Minimum cylinder wall thickness for stroker nitrous build?
I'm getting mixed opinions on this so hopefully someone here can give some better insight. Most the research i've gotten online and from talking to local machine shops have recommended a minimum of like .150. However from the 4 lq4 blocks i've had sonic tested recently, I always have atleast one wall that's less than .120, one even as low as .094, and usually half are below .150.
Plan on using a gen 3/4 6.0 iron block. 4" stroker kit with a G6x3 cam. Ported and polished Ls3 5364 heads with a 5 angle valve job. 102mm ls3 intake and a 102mm dual stage wet nitrous plate. The nitrous will be used with a dual stage progressive controller for a total of a 300 shot. Will also be running this motor on e85. I have everything for the engine except the pistons, and the block (maybe).
Was hoping to bore the block to 4.065 but from all the low number readings i've been gettin it seems impossible to bore these blocks at all. (Maybe i'm just having bad luck on good blocks)
So my question is what would you say the safest cylinder wall thickness would be for me to run?
These are my most recent sonic test numbers from an 02 lq4. Planned on using it for my build only if the thicknesses are good enough.
Unfortunately, it's one of those things based more on opinion that fact. Cast iron blocks are not all created equal, so where one should have .150" wall, another can get away with .100" wall.
The numbers you're getting are typical. Most 6.0L iron blocks I've seen can fit a 1/8" rod between the cylinders. With a 4" bore in a 4.40" bore spacing, that means there's about .140" wall left, and that's assuming its centered.
I'd just take it .005" over and run it. Going to 4.030" isn't really going to make any difference in power when you're spraying a 300 shot. The extra wall thickness might be a better advantage though.
That's what I figured, just confused how all these peopled are boring these blocks like .070 over. Maybe they're willing to take more risk.
I appreciate the reply, another opinion is always helpful.
What about gen 4 blocks? Is there any gain durability wise with them over the gen 3?
That's what I figured, just confused how all these peopled are boring these blocks like .070 over. Maybe they're willing to take more risk.
I appreciate the reply, another opinion is always helpful.
What about gen 4 blocks? Is there any gain durability wise with them over the gen 3?
I bored mine out to 4.065", but I just planned to stay NA. I wouldn't have hit it with a 300 shot.
I haven't messed with too many Gen IV iron blocks, but I doubt they're much different as far as cylinder wall thickness.
You can fill the block to the water pump holes with Moroso or RockBlok filler if you're worried about it. Then all you need is about .080 min.iron wall thickness but you would have more. All of your low number readings in that plot are non thrust areas and shouldn't be near as much a factor in taking .065 out. I have a .030 over 6.0 block and some .065 new forged LS3 stroker slugs andI am going to do it.
I personally would leave the bore size alone... just do a good aftermarket nitrous piston with hellfire rings.
You'll have a 402ci motor which you not go tell the difference between a 402 vs a 408ci motor.
You can fill the block to the water pump holes with Moroso or RockBlok filler if you're worried about it. Then all you need is about .080 min.iron wall thickness but you would have more. All of your low number readings in that plot are non thrust areas and shouldn't be near as much a factor in taking .065 out. I have a .030 over 6.0 block and some .065 new forged LS3 stroker slugs andI am going to do it.
I was thinking about filling the block, however this is going to be a daily driver so wasn't sure how much the cooling would be affected. Live in the midwest, border of Illinois and Iowa so our summers get pretty hot.
I personally would leave the bore size alone... just do a good aftermarket nitrous piston with hellfire rings.
You'll have a 402ci motor which you not go tell the difference between a 402 vs a 408ci motor.
True.. in a sense i'm not really to concerned with the HP differences from a 402 and a 408 specifically. My concern is the heads. With the such large ls3 valves I know 4" bore is a minimum, where 4.065+ is recommended (from what i'm told). This reason is why i'd like to go as big as possible, otherwise I feel like i'm not getting the full potential out of the heads. I think if I had ls2 heads i'd be completely fine sticking with a 4" bore.
Please though, correct me if i'm wrong with my reasoning on the ls3 valves and larger bore size.
just confused how all these peopled are boring these blocks like .070 over. Maybe they're willing to take more risk.
For a mild NA application that is fine on some blocks...however you plan on pushing extremely more cylinder pressure with a 300 shot so it's not the same thing.
True.. in a sense i'm not really to concerned with the HP differences from a 402 and a 408 specifically. My concern is the heads. With the such large ls3 valves I know 4" bore is a minimum, where 4.065+ is recommended (from what i'm told). This reason is why i'd like to go as big as possible, otherwise I feel like i'm not getting the full potential out of the heads. I think if I had ls2 heads i'd be completely fine sticking with a 4" bore.
Please though, correct me if i'm wrong with my reasoning on the ls3 valves and larger bore size.
64post brought up a good point on the cylinder walls. After all the LQ blocks are not as strong as people think they are. They don't have siamese bores like some of the later LS blocks have.
Otherwise I would do a 402ci as I already mention. Keep all the meat you can!! Don't worry about valve shrouding with the factory bore size. If it was a serious problem GM wouldn't had put the head on the (6.0) LY6 engine to begin with...
03-02-2017, 07:23 PM
Minimum cylinder wall thickness for stroker nitrous build? 
