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# B20 Largest Bore?

Discussion in 'Engine Building' started by dvs_prelude, Jan 29, 2003.

1. ### dvs_preludeSenior Member

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If the B20 is stock:
bore= 84 mm
stroke= 89 mm
1972 cc

And the LS is:
bore=81 mm
stroke = 89 mm
1834 cc

If you bore out an ls to 84mm, you have a 2.0L correct? If this is true, what's the point of having a b20? From reading the FAQ, it appears the largest you can bore out a b20 is 85mm. If the two bocks are identical, then surely you can bore an ls to 85mm. Even if it's not possible, what's 1mm difference in bore anyway? Is there some other factors involved that make the displacement of the b20 more than the ls? Or is it just the factor of the stock bore? Help me, I'm confused!!

Also, how much can you bore a GSR block to safely?

Thanks guys

2. ### pissedoffsolRETIRED

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the blocks aren't identical.

in order for an ls to hit 84mm, it needs to be re-sleeved. the stock ones will be paper thin at that point.

3. ### E_SolSiMember of the 20 nut clubModeratorVIP

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ive seen bores listed up to 87mm
i have no idea how "safe" that is but ive seen it listed

4. ### dvs_preludeSenior Member

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87mm on an ls or b20?

Thanks for the response!

Anyone know how far you can go on a GSR safely?

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both

6. ### dvs_preludeSenior Member

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hmmm... So is it just the bore that gives the B20 the larger displacement, or is there something else? Are there other things that affect displacement? I'm just trying to find exactly what makes the B20 block larger and better than the LS. I plan on building one of them and I need to know if it's worth the money for the B20 and why exactly.
Thanks again!

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8. ### dvs_preludeSenior Member

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Thanks, but that doesn't really give much information.
Besides the Bore of the B20 being 84mm, what makes it bigger than the B18b? Is there anything else? If I wanted to resleave a B20, how big could I bore it? Is there more space between the B20 cylinder walls?

9. ### E_SolSiMember of the 20 nut clubModeratorVIP

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the B20 and B18 are pretty much identical... the B20 is just a B18 with a 84mm bore (thinner wall) the B18 and the B20 will be able to be bored to the same size... so once again... if you plan to resleeve and replace everything anyway start with the B18 it will cost you less money and be able to be built to the SAME specs as a b20 will... unless you NEED to have your block say "B20B" on it

i gave you that link so you could see that the difference between the two engines is the bore

B18B1
Bore (mm): 81
Stroke (mm): 89
1834cc

B20B
Bore (mm): 84
Stroke (mm): 89
1973cc

same stroke... larger bore = 139cc added displacement

10. ### dvs_preludeSenior Member

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Thanks for clearing that up!
So basically, B20=waste of money...
I thought there was something special about them. Basically, If I plan on building an engine, I could build an ls block just as strong as a B20 block and save myself around 500 bucks?!!?!
Wonder why people even bother with the b20 then?

11. ### K2e2vinSenior Member

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I dont really know why people choose to go b20vtec if they already have a extremely potential engine. For me im going turbo so i would keep it around 450cc a cylinder/1.8L engine, making power through revs and use a turbo. Larger cylinder gives you more torque. I would go with the b20 if i am going for all-motor, but your better off droping a h22 vtec instead of spending some for a hybrid engine.

12. ### B16Super ModeratorVIP

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because the b20 comes with an 84mm stock bore, if you find one for cheap, then it could end up being cheaper than the b18 resleeved to 84mm

13. ### E_SolSiMember of the 20 nut clubModeratorVIP

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yes if your building it it will be less expensive to just start with a B18

the B20 is a great choice for people who dont want/need a fully built bottom end, cuz its already 84mm

**damn B16 beat me to it

14. ### K2e2vinSenior Member

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and it may be cheaper in the long run for ive herd the b20 cylinders sleeves are garbage.

15. ### B16Super ModeratorVIP

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depends on your application, for NA the B20 sleeves are more than fine, if you plan on boosting, you should resleeve

16. ### K2e2vinSenior Member

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http://www.b20vtec.com/b20sleeves.html

17. ### B16Super ModeratorVIP

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calesta on this site runs a B20/vtec with endyn 12.6:1 CR pistons on his stock sleeves, he has put many miles on that thing, you can ask him about it

18. ### 2 litre EGSenior Member

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yes is true!!!

i coulda sworn i told you a bit about this dvs_prelude??

19. ### phunky.buddhaAdmin with a big stickAdminVIP

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GODDAMN MORE FUCKING MISINFORMATION AND BULLSHIT...

Any more of this "the B20 is weak crap and not worth a damn" and I'm going to stop answering questions on this board forever.

You do NOT need to resleeve the B20 to run NA, or even under boost. People screw up the B20 because they do a bad job building them, or they drive them like dumbasses.

A resleeved and bored B18 will NEVER be cheaper than a straight B20 block. If you're going NA, buy just the B20 and don't run the B18 resleeved unless you just have money to blow.

B20 short block = \$600-700

B18 short block = \$200-300
Resleeve and bore out to 84mm = \$1000

\$1300 > \$700, RIGHT?!

Unless your B20 block is costing you \$1300-1500, it is NOT more expensive than the B18 resleeved... not even if you got the B18 block for free. What the fuck kind of crack are you guys smoking? If you're running boost, just the B20 block on its own is ok too. If you want to go crazy, you'll want to resleeve any Honda B block- so if your goal is well over 300whp under pressure, you'll want to rebuild the block no matter what you do.

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