gmen08

Hey guys, I was just doing a little research about boring the B18 and B20 blocks. From what I can see the B18 has a bore of 81mm and the B20 has a bore of 84mm. A B18 can either be bored safely to 81.5 or 82mm without sleeving, and the B20 can be bored safely to 84.5mm without sleeving. If a B18 block(more specifically a LS) was sleeved and bored to 84mm, would it theoretically be the same as a B20 block since both blocks have the same stroke??

Combustion Contraption

Looks like you have done some searching and found some good info.

The answer to your question is yes, for all intensive purposes they will be the same. Same crankshaft, rod length, all accessorie's bolt on yada yada. The only real reason to sleeve the B18 instead of the B20 is if emissions are a concern, the B20 will NEVER pass a LEGAL visual test in a car chassis.

vinuneuro

Dimensions aside, wouldn't the sleeved B18 be much better structurally because of the B20's issues around the sleeves?

Combustion Contraption

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vinuneuro &raquo;</TD></TR><TR><TD CLASS="quote"> the B20's issues around the sleeves? </TD></TR></TABLE>

Such as?

vinuneuro

I'm not a B-series guy, so I'll just pull a quote from Larry's 2.0L build off the Endyn site.

In inspecting the block for structural integrity, the first thing I look for on a B20 is the quality if the aluminum casting that surrounds the 4-in-1 cylinder sleeves. Viewing the block’s deck, there should be no areas where the aluminum wasn’t absolutely flush with the bore casting, especially in the fillets between the adjoining cylinders. All B20 blocks are not created equally in this important area, and if the block isn’t “perfect”, broken cylinders are a certainty.

The cylinder casting that Honda uses in these B20’s is extremely brittle when compared to more resilient “round” individual bore liners. This is simply the nature of a casting such as this where sectional thickness varies so significantly. These cylinders are easily cracked if there’s just a hint of detonation and all it takes to break one of the blocks with the small casting flaws is about 220 HP, so they can certainly be a liability.

I've read elsewhere that high compression and rpm = bad with the B20 block?

I know Kevin Helms rebuilds his H1 B20vtec fairly often compared to others.

Combustion Contraption

PM'ed

gmen08

Ok so I wanted to do a all motor application and I keep going back and forth between a B20VTEC(GSR head) and a GSR. I have searched both builds, and I did like the fact that the B20 had a larger displacement and put out a good amount of torque, but I also liked that the GSR was able to rev high without the fear of cracking a sleeve and plus I could buy a complete swap easily. I know that whenever you buy an engine and you want to rebuild it, it is always a good idea to bore it so the cylinders are all the same. So I could bore the GSR to 82mm making it just short of a 1.9 liter or I could bore the B20 to 84.5mm to make it a little over 2.0liters i believe. Lets say i went the GSR route, would there be that much of a difference in hp/torque from the B20VTEC(equal parts used for both)?? And if so, could the GSR maybe faster since the engine could rev higher than the B20VTEC?? i am just trying to really understand both builds fully so i dont wind up throwing away alot of money

all-mtr-teg

Boring the GSR to 82mm will get you some more tq, and close to 1.85L, but you're still lacking what the B20/LS has an advantage over the GSR block, and that is the stroke.
If you threw a B20/LS crank and rods in your GSR, bored it to 82mm you'd be really close to a 1.9L

As long as the bottom end is balanced, throw on some ARP rod bolts, build your head, then you should be able to rev it to 9K rpm safely assuming that all your clearances are good and you got a tune. I got a GSR block bored, with B20/LS internals so feel free to PM me if you got any questions.

gmen08

So correct me if Im wrong, but a GSR with a LS crank and rods that is bored to 82mm would be the same as a LSVTEC that is bored to 82mm, right?
and what type of numbers are you making with that setup

all-mtr-teg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gmen08 &raquo;</TD></TR><TR><TD CLASS="quote">So correct me if Im wrong, but a GSR with a LS crank and rods that is bored to 82mm would be the same as a LSVTEC that is bored to 82mm, right?
and what type of numbers are you making with that setup
</TD></TR></TABLE>

Yeah, you will essentially have an LS/Vtec without having to run oil lines or buying a conversion kit. It's a stroked GSR, great for those of us who have to worry about smog, or want that sleeper motor.

I haven't dyno'ed it yet, just got a street tune, but I've taken out my buddies ITR with bolt ons, and my buddies built GSR with S2S2 cams and drag suspension, and all I got are BC3's and stock suspension

tek9_ej2

lots of good info. Im torn in between lsvtec with p73's, and a b20vtec with rs machines itr pistons, my car will be a dd, and for circuit not drag. What do you guys recommend?