ok sooo it would appear that stock bore on a b18a/b is 81MM.. same as a B16.. stroke varies from 77.4MM on a b16 to 89 MM on a b18/b20.. the .2L difference between the b20 and the b18a/b comes from enlarging the bore on the b18 block to 84MM which yields a 2L motor

my question is this.. since the b20 has the same stroke as the b18 i see no reason that you couldnt rev the b20 to ~9K ( assuming cams make power that far) with the proper rod bolts etc.. like every other ls/vtec on the planet am i correct in assuming this?


now.. my OTHER questions is this.. am i retarded.. or am i correct in assuming that to build a high compression B20 block you have no coice but to use aftermatket pistons due to the fact that the b20 is an 84MM bore versus the 81MM bore of all the other stock honda piston options for high comp ( ie b16a/b type R blah blah etc).. honda doesnt make a 3MM oversize opem pistons i wouldnt think.. thats 120 thousandths (?? i think)overbore.. thats rediculous


is there some magical mystery piston ( ie same principle as vitaras) that happens to be 84MM bore and yield a decent compression number on the b20 block?


if it matters

PR-3 head
GSR cams
b20 block is the setup

 

Apparantly the thin sidewalls come into play at high rpm, but you hear about that more often in F/I setups.

 

I cracked the cylinder walls on my all motor b20. F/I has nothing to do with it. The b20 block is cast diffrently than the b18. The cylinder walls are not quite as strong and crack fairly easy. However depending on how high your compression is I would throw a block guard in and some better rod bolts in and you should be good. Make sure to get a tune and only run premium gas. Detonation will destroy that motor.

 

high compression b20vtecs are very popular in augusta, it seems. anyway my room mates motor finally gave out at the strip a few months back. it lived about 3 years of daily driving and him beating the **** out of it to almost 10k fairly often. i would have never believed someone if they had just told me, this motor was daily driven and has seen over 9k rpm. but i watched him do it for almost a year before it poped. b20b4 with 11.8 cr pistons on new oem shot peened rods. using all arp hardware. milled pr3 head. finale compression was 12:1

if i posted a pic of the car, i'll bet you would recognize it

 

As long as you built it the right way and tune it good you can rev that high with no block guard but who knows how long it will last

 

Rocket has built cams for B20V motors running stock sleeves at 13.xx+ compression and 10k rpm drag motors. As long as the motor is <U>properly</U> built with <U>quality</U> parts and carefully tuned, I don't have a problem with stock b20 sleeves.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by clean rice &raquo;</TD></TR><TR><TD CLASS="quote">Rocket has built cams for B20V motors running stock sleeves at 13.xx+ compression and 10k rpm drag motors. As long as the motor is <U>properly</U> built with <U>quality</U> parts and carefully tuned, I don't have a problem with stock b20 sleeves.</TD></TR></TABLE>


Thats how I see it too.... but most chumps around here think they are complete junk. Ok by me.. I get complete, mint used motors for 500 bucks!

 

my old B series set up was stock rod & sleeve b20 85mm bore and 13.9:1 comp.....tuned to a 12.0:1 afr..... i made over 100 passes on that motor until it dropped a valve.....the sleeves never cracked.....it went 11.52 @ 118.8 in street trim....since then ive built about 10 85mm bore stock sleeve b20 setups like this but with comp around 11.5:1 for pump gas and have yet to have one crack sleeves....i do belive the b20 sleeve is weaker than the b18 but if you dont get greedy with timing or a lean afr you will be fine....detonation cracks the sleeves not a certain compression ratio or HP level.....i beleive its all in the tuning

 

I have a b20 vtec and love it. Problem is most people think they can just get away with a half *** build. You might be able to do that with other B series motors, but it will not work with a b20.

 

How about block posts..

http://www.theoldone.com

Seems like a good idea.


http://www.theoldone.com/articles/badtothebone/

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Here's that old B20 block, exhibiting it's acid-eaten finish. Note the posts on the intake side (major thrust axis) of the block. These will support the cylinders under the high loads this engine will be seeing. When we prepare blocks, all the water, oil gallery, and crankcase access plugs are removed. </TD></TR></TABLE>

 

yeah i havent looked at endyns site in a long time.. theyre brilliant when it comes to hondas.. theyve been doing it for the better part of 10 years


apparently theres a common casting "flaw" that occours with the b20 blocks.. the way to spot it is uneven material on the block decks around/between where the cyl walls join. block posting connects the outer walls of the block to the cyl bore walls.. effective making the block all one piece.. of the cyl moves it has to move the outer walls of the block as well.. which isnt happening.. makes sense to me. the only tricky part of it seems to be that you have to install the posts on the centerline of the bore at 2 specific "Stress" or something or another points...tricky maybe..

endyn DEFINATELY knows what theyre doing.. they made 300hp on a b20vtec motor using their in house pistons and cams... and headwork

pretty badass if you ask me

 

block posting. Endyn does it so it must be a good idea right?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LSVTEC 91 Civic &raquo;</TD></TR><TR><TD CLASS="quote">

</TD></TR></TABLE>

The issue with the B20 blocks in shown in the pic above. The sleeves are all one piece where as in the B18 block they are individual pieces. Search for pictures of cracked B20 blocks. WHat you will find is in most cases the cracks run from top to bottom along the area that is shared with the adjoining cylinder.

Run them cooler than a B18, a bit more of a conservative tune and use a block guard, and you should be in better shape.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by smileycvc &raquo;</TD></TR><TR><TD CLASS="quote"> block posting. Endyn does it so it must be a good idea right?</TD></TR></TABLE>

Have you done it?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SMSP &raquo;</TD></TR><TR><TD CLASS="quote">
The sleeves are all one piece where as in the B18 block they are individual pieces. Search for pictures of cracked B20 blocks. WHat you will find is in most cases the cracks run from top to bottom along the area that is shared with the adjoining cylinder.
</TD></TR></TABLE>

Great point Dave, forgot about that!

 

hmm makes sense... whats stock thermostat temp in these motors? like 190 ?

 

i would say so.. when was the last time you designed a set of pistons.. or cams.. or an intake manifld that went on a 300hp NA b20vtec?

 

Drilling a hole in your block and putting some bolts near the cylinder walls then throwing some epoxy on there to make sure your block doesnt leak is the ghetto alternative to a block guard. Just spend the money dont drill any holes in your block and get a block guard. Im sure endyn had success with it in their track car, but for a daily I think a block guard is a lot more reliable. How blocks do you think endyn went through until they became real good at posting. If you have the money to experiment on a few blocks then by all means go for it.

 

well.. since the owner of endyn has been doing block posting since the 60's on ford v8's my guess would be... 1

its not ghetto at all...sticking a block guard in there that just "sits" in place and restricts cooling a decent bit is what i would call ghetto.. especially since we've just covered how esential proper cooling is on the b20 castings

 

cooling has absolutly nothing to do with b20 sleeves failing. Also a block guard doesnt just sit in place. If you buy a real block guard not just a shitty Ebay one, it should be pressed in place and then spot welded to keep secure. Im sure Endyn does a great job and it works great, but for someone that had never done it before to just go throw a couple holes in the block doesnt exactly sound like a great idea to me. Do you even know why b20 have problems with the sleeves?

 

To answer your question on pistons. RS Machines sells ITR cast pistons in 84/84.5mm applications. As far as your block "problem" have someone knowledgable build it with quality parts, and most importantly have an experienced tuner tune the engine and youll get good results. If you half *** the build youll get shitty results, this is nothing new...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by smileycvc &raquo;</TD></TR><TR><TD CLASS="quote">cooling has absolutly nothing to do with b20 sleeves failing. </TD></TR></TABLE>

How did you reach this conclusion? Funny how the sleeves go out of round and crack in the hottest spot. i'd like to think that cooling is most of the reason why they can fail. But if you are so sure in your answer then i'm all ears.

 

The sleeves usually crack because they are a monostep design. All the sleeves are one piece and they tend to flex and in the end, crack. The motor doesnt get any hotter because your running it with a vtec head. Detonation can also cause problems and put stress on the sleeves. As I already stated block posting is an effective way of stabilizing the cylinders, but I dont think he should try it if he only has one block and is putting alot of money into it. Block posting should only be done with someone with experience or if you have a crappy block you want mess around with.

 

do you leave the stock b20 oil pumps in or swap them out for gsr/b16 ones?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JasperDA9 &raquo;</TD></TR><TR><TD CLASS="quote">do you leave the stock b20 oil pumps in or swap them out for gsr/b16 ones?</TD></TR></TABLE>

When doing an Ls/VTEC or B20/VTEC most people swap to new VTEC oil/water pumps. Read bambam's thread on building a reliable LS/VTEC itll answer these questions.