so i have been researching a lot about b20's vs LS and boost.
one common thing i read is that the b20 has a thinner factory cylinder than the LS. I also read how the b20 cracks due to this.

As luck has it, i have both bare blocks sitting in my garage. so i busted out the trusty caliper and gathered a few measurements.

the top 2 are of a LS that had a head gasket failure. but i took bunch of measure emits from around the block and averaged them, .250-.265 is the range.... the b20 never went smaller than what is pictured which is .314. so that is a considerable difference in thicknesses.

so does the b20 have thinner walls that are prone to cracking? NO, at least not on my 2 blocks. what it does have is between where any 2 cylinders meet on the b20 its all steel. and on the LS you can see aluminum in-between the cylinders.

what does that say? to me it says that the b20 will retain more heat in-between the 2 cylinders, and be prone to failure there. while the LS has aluminum that will dissipate heat quicker into the coolant.


any questions? comments? concerns with my method?
Yes, i am building b20 vtec turbo... im hoping cooling will be a huge help to the longevity of the engine, along with a good tune.

time will tell.

 

IMO the LS is a better platform to build on. B18 is stronger and thicker. All you're getting with the b20 is a .20 liter difference with thinner walls. Boost go with the b18. Ls vtec go with the b20

 

They both have the 81 mm bore but there is still a .20 of space difference in the block. This means less metal.

 

the b20 actually has a 84mm bore, and has thicker cylinders....

 

B20s are more prone to cracking because of the material to make the sleeve not the thickness .

 

The problem is the b20 has siamesed liners... this causes a weak point between the cylinders, given their lack of aluminum supporting the sleeve.

 

+1 cosigned

 

But will it hold 300whp like the stock block LS??
Longevity seems to be an issue imo

 

Eh... one good pressure spike (detonation) event and the sleeve is done for.. b20 sleeves tend to crack before a ring land breaks, which is the total opposite from other Honda motors (normally)

I mean if you have a perfect tune and good gas you should be fine... however one bad tank of gas and you're screwed.

Honestly if it were me I'd stay with the LS... the torque gain provided by the extra displacement is really negated if you keep breaking motors... if you want a 2 liter motor, sleeve an ls or b20 and bore it to 84 or 84.5, however if something damages a cylinder wall at 84.5 you're basically going to need new sleeves. 85mm doesn't really leave much between the cylinders for headgasket sealing.. its not an issue for an all motor car but the extra cylinder pressures and heat from forced induction will pop headgaskets like mad

 

I was contemplating the B20, but you brought up a good point about pressure spike.
I am aiming for reliability with this build, the extra displacement I was hoping for would be pointless if I break motors.

I was thinking a stock block with a fully built head and turbo cams. Cast Ironmanifold and a t28, 550 ccs injectors and walboro 255 fuel pump tuned on chrome a 3 inch exhaust

I want a wide power band with boost pulling consistently as as far as it can till boost drops off.

 

Im not sold on the b20 either, but I already have one. Its machined and ready to go. so unless someone here wants to buy my b20 for a NA setup i will use it till it blows. And in the meantime I will be saving for a GSR or LS to be sleeved.

Side note, what are stock cranks good to HP wise? Its either hasn't been covered here (which i doubt) or I am searching incorrectly.

 

if you look at the 2nd pic from the bottom you and compare it to the top one u will see the difference in the cylinders and the siamese-ness in the b20

 

The stock crank will handle what your throwing at it

 

I know the stock crank will hold what I am currently going to be throwing at it, but the plan is to upgrade and build more power once I become a competent tuner with FI.

 

900+whp

 

I've seen 1000hp drag Hondas that still use the stock crank... they are beefy,

The only advantage to an aftermarket crank is altering the stroke and maybe some weight reduction... buteagle cranks are meh... I had an ls crank bull nosed and knife edged, as well as had the oil passages in the crank cleaned, honed and lightly polished... then we removed the pressed in ***** where the passages were cross drilled (they can come out, rare, but it happens and will cause an immediate loss of oil pressure and flow) and tapped them for hex plugs that were loctited and safety wired.

A company does a cool process to inline four cranks where they remove as ,much material fro, the counter weights as possible, basically makes them square, they lay flt on a table lol... then they bullnose the leading edge and knife edge the rest, reducing windage losses and oil splashback.

I know what you're thinking, removing that much weight will cause issues... well they have 1000hp + DSM motors using them with no issues, I'll probably have it done to my ls crank.., I think the whole procedure is like 550 dollars, which includes them balancing the rotating assembly, micro polishing the journals and chamfering the oil outlets on the journals, which promotes more oil flow as well as an even oil film.

http://www.ffwdconnection.com/butchercrank.shtml

They can remove 5-9lbs from a crank which is a huge loss of reciprocating weight. You'll make more horsepower and torque just by swapping cranks... not to mention how fast the motor will respond.

They can take 8lbs off an sr20 crank, which are over built 41-42lb pigs... I know because I have 4 of them.. I'll also be having it done to my sr20 cranks when it comes time to motor build

There's so much you can do to a crank... shot peen it, nitride it, harden it, have an oil shedding coating applied to reduce windage losses from oil dragging on the crank, have the journals coated with a layer that promotes oil adhesion and friction loss, increasing power/response as well as an added layer of protection should you have an oil starvation event.

The sky is the limit as long as your wallet follows

 

yeah the oem crank can make over 1000 hp i know its in a few very prominent drag cars currently.

another issue with the b20 style sleeves is that they are more susceptible to cracking from torsional forces in the block. being one solid piece the iron liner is possibly too rigid for its own good.

i would just use that b20 on a moderate boost 200 something hp with a conservative tune and all safeguards like boost cut and lean protection if offered by your management. i can tell you this from personal experience: with the sleeved block on a boosted application i went right from 81mm to 84mm and it was ridiculously night and day difference

 

Use the B20, and get a CSS insert installed, i personally think it will make a world of difference in controlling the movement of the siamese sleeves.

 

The B20 sleeves have proven to be weaker due to their monolithic design. Hasn't stopped a lot of people, including myself from making some decent DD #s with them.

https://honda-tech.com/forums/showth...dyno&t=1556817

Sold the car with 15,000 boosted miles on the engine.

Good luck.

 

blaze did u ever run it?

 

My own personal first hand experience.

Rod knock in my gsr, swapped it out for 99' b20z that i got for dirt cheap.Went STOCK b20vtec with my gsr head. About a year or two later i bent a valve, block was fine. put a semi built LS head on it. crower valve train & crower 403's, daily driven seeing 8k. drove that for another 6months or so, decided i needed vtec in my life so i swapped the semi built ls head for a b16a head. drove that for awhile, got bored so i boosted it. put about 10k miles on it. still running.

I dont know if i got some crazy factory motor but my b20z has taken a beatin for the past 2 1/2 years. Has also seen 9,000RPM on occasions.

*cliff notes
-b20vtec
-built LS head/ stock B20z block
-b20vtec agian
-b20vtec turbo NOW with two different turbo setups.

now over 10k miles my BONE STOCK b20z block is STILL running. Hopefully for even longer now that im adding meth injection. =]

 

The question is how much power you making?

 

power wise, probably not much. boosted probably 275-300hp. all my setups were all street tunes no dyno, plugs checked after every run, little to no timing added. but with this new setup, I think I'm going to try and push its limits with methanol. goal is 350whp/400whp on meth. well see how that goes. lol


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I'm looking for a ls crank rods and pistons I spun a rod bearing and scarred the crank and broke a rod.I was wanting to go with the eagle crank and rods And new pistons but can't find those in factory L's specs the block is rdy to built just need a new crank and rods with bearing.

 

I have to say I was a skeptic until I read your post.
B20 is cheap for a long block that's why I was thinking about it to be honest.
I was saving for a B16A sir swap for my DA but idk now.
Definitely want to boost though, I have had all the B series VTEC motors already (aside from a Type R) and B20, B18 .. I'm tired off all motor.
Being this is my 1st boosted car in doing I thought why not a B20.
But it's good to be informed and know as much as possible before making a decision.
Good info guys.