402 vs. 408
402 vs. 408 So i just bought an LS2 block and was going to go with a 402 stroke but im debating on whether or not to bore it to a 408. Does anyone have the pros and cons, if it makes a difference or not? THANKS!!!!
The only good I can see is slightly less shrouded valves from the larger bore. You will not notice any added power from the 6 extra cubes.
However, unless it needs bored, why bore it? You're just removing the possibility of future rebuilds.
However, unless it needs bored, why bore it? You're just removing the possibility of future rebuilds.
It really depends on which cylinder head and intake valve size you're planning on running.
I would have to disagree and that the larger bore will show a gain in power, but only if using a larger valve that needs the larger bore to utilize it and not shroud the valve as you mentioned. However the gains will be slight, but the main advantage will be gains in mid-lift airflow from un-shrouding the intake valve.
It really depends on which cylinder head and intake valve size you're planning on running.
It really depends on which cylinder head and intake valve size you're planning on running.
It's like doing a stock rebuild on a 350 by making in a 355 and leaving everything else alone. All things being equal, you'll never notice the extra cubes of a .030 over bore.
Pros and Cons
Pros added power (never a bad thing)
Cons added cost (are you getting moneys worth)
Lets apply some basic old school math..
If our 402 makes say 450 HP, it makes 1.119 HP per CI. Now if we increase the CI to 408 and no other changes, our 408 should make 456.716 HP. Up a whopping 6.716 HP.
For me it comes down to cost. Is there added cost to go from 402 to 408? If not go for it, if so I would have the weigh the cost. Chances are 6-7 HP could be found somewhere else at less cost.
Pros added power (never a bad thing)
Cons added cost (are you getting moneys worth)
Lets apply some basic old school math..
If our 402 makes say 450 HP, it makes 1.119 HP per CI. Now if we increase the CI to 408 and no other changes, our 408 should make 456.716 HP. Up a whopping 6.716 HP.
For me it comes down to cost. Is there added cost to go from 402 to 408? If not go for it, if so I would have the weigh the cost. Chances are 6-7 HP could be found somewhere else at less cost.
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6-7 HP will likely never be felt and would be within the margin of error on a dyno or even the track. Unless it's going into a dedicated bracket racing car with boxes and brains doing the driving, it will never make a difference.
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Verdad Gallardo Also, there may not be an added cost other than machine work to bore it, but you're still eliminating the possibility of future rebuilds. Why go to the max bore right off the bat just to have something go wrong and all of a sudden, you're looking for a block to stuff all this expensive **** into.
I guess I didn't word that correctly. What I said was exactly what you said. Nobody will notice the added power of 6 extra cubes alone on the butt dyno. But if the valves are shrouded, you would notice it from un shrouding them.
It's like doing a stock rebuild on a 350 by making in a 355 and leaving everything else alone. All things being equal, you'll never notice the extra cubes of a .030 over bore.
It's like doing a stock rebuild on a 350 by making in a 355 and leaving everything else alone. All things being equal, you'll never notice the extra cubes of a .030 over bore.
The Ls2 can go to 4.030 but should be sonic checked. No questions or exceptions. However, like I have said, that's about it. Once it's out that far there is usually nothing left, if it can even go that far in the first place.
The most common is a 403. Which is a .005 hone on A stock Ls2. 402's have become more common recently for some reason...I guess people have come across blocks that have perfect cylinder walls or just calling their 403's, 402's. 
I guess people have come across blocks that have perfect cylinder walls or just calling their 403's, 402's
But I think most people just call 403s 402s since they don't know the details of what was done at the machine shop, or don't think that a hone will be enough of change to cause an increase in displacement.
I was also contemplating before proceeding with my build doing an ls3 build but isn't the ls3 build more expensive? I'm looking to for about a $25000 550-600hp build including in the price the ls conversion in a 3rd gen (moser 9inch)
You are gonna be hard pressed to hit 600 with ls3 heads on a smaller bore. If you want 600 youre gonna have to fork up the dough and get some nice heads, a big cam and every possible bolt on