Ever sence I have been into the honda scene, I've always wanted to do a swap, and that would be the b20vtec swap. I've heard good and bad about this swap, but it seems like everywhere I go I get a new opinion, and a new horror story. Some things seems a little extreme, but others seems somewhat legit. So, the truth be told; lets get some experienced input on this situation.

Rumor #1: The cyliner walls on the b20 are very thin, and when they get too hot, and then are allowed to cool to quickly they will warp or crack.

Rumor #2: The b20 bottom is very unsafe in combination with a vtec head.

Rumor #3: The b20 is very unsafe when revved above 7k rpm.

The one that seems to be the most beliebeable to me is #3. The reason I say this is the b20 comes out of a CRV whos redline is around 6,500 rpm I believe, so this seems to have some truth to it. 1 & 2 seem possible, but not likely unless you live at redline on a daily basis. I'm looking for some good solid information about this topic because I just bought a b20vtec setup.

 

Buy first and ask questions later, huh? Interesting methodology. Perhaps you should ask this question in the "Hybrid" forum where people will be more apt to answer you with something other than "SEARCH NOOB ZOMG!"

In my experience, the B20 isn't the strongest B-series engine Honda ever made, but - like everything else - if it's built with exacting patience and taken care of properly, it can make tremendous power without so much as a hiccup. Does that mean you can do an oil change and rev to 9500? No, no it doesn't If you're interested in a high-revving engine, you'll want to strongly consider checking the bearing tolerances and looking into rods that are better suited to abuse.

 

I own a b20b, I rev it to 6700. Works fine. I've personally had friends that have done B20Vtec swaps, and beaten the **** out of them, held up fine. I've also had friends that have done B20Vtec turbo, same deal.

It all comes down to how you treat it, how its tuned, and how its put togeher. I love my b20 :-D

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Archidictus &raquo;</TD></TR><TR><TD CLASS="quote">Buy first and ask questions later, huh? Interesting methodology.</TD></TR></TABLE>

i got the entire setup put together with a nice ls tranny, act stage 2 clutch, built gsr head, and a b20z bottom for $900. would you pass that up?

sorry about posting in the wrong section

 

THe B20 is basically an 84mm version of a sleeved LS block.

The b20 and LS crank is the same. LS 84mm with VTEC head is very common and we take them to 10,500 RPM all the time with no issues.

So pretty much all of your 3 rumors are False.

 

Long time B20 user here. My first B20/Vtec back in 02, and I am impressed with what they can do. But like anything, build quality, maintenance, and how its treated play an important role.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by djmatix &raquo;</TD></TR><TR><TD CLASS="quote"> I've personally had friends that have done B20Vtec swaps, and beaten the **** out of them, held up fine. I've also had friends that have done B20Vtec turbo, same deal. </TD></TR></TABLE>

it doesnt seem logical to me that a b20b will beat the **** out of a b20vtec and b20vtec turbo. Maybe it shows that you have to build the b20 vtec properly in order for it to be fast and reliable, or else it will be as slow as a normal b20.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 97spooncivic &raquo;</TD></TR><TR><TD CLASS="quote">it doesnt seem logical to me that a b20b will beat the **** out of a b20vtec and b20vtec turbo. Maybe it shows that you have to build the b20 vtec properly in order for it to be fast and reliable, or else it will be as slow as a normal b20.</TD></TR></TABLE>


no man, you read it wrong.

i've personally had friends that have done B20VTEC swaps, that have beaten the **** out of their B20VTEC swaps, and the B20VTEC swaps that they have beaten the **** out of held up fine.

no way my b20b is faster then theirs. They even took their setups to the track and really leaned on them.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by my_slow_civic &raquo;</TD></TR><TR><TD CLASS="quote">Long time B20 user here. My first B20/Vtec back in 02, and I am impressed with what they can do. But like anything, build quality, maintenance, and how its treated play an important role.</TD></TR></TABLE>

im rather **** about my car, so maintenence will be no issue. I change my oil on or before 3k if i dont think ill have the time the week of the crossover. however i do like to drive my car. i dont beat the crap out of it on a daily basis, but i plan on it seeing 5-6k atleat once a week.

 

https://honda-tech.com/zerothread/1676914

That's your new Bible. Go baptize yourself.

 

Thats a nice setup. B20Z bottom. I wanted a b20z and ordered one, but Tiger Japanese lied and sent me the ******* low compression b20b .

If you change your mind, i'll buy just the motor from you

 

haha no way. i was offered the motor for $1200 at first, and i said no becuase i JUST swapped an ls in like 3 weeks ago, so i didnt need it. 2 days later this dude called me back and was really upset cause he could get hiss kids christmas presents and said take it for $900. i was on his door steps with $900 10min later

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Archidictus &raquo;</TD></TR><TR><TD CLASS="quote">https://honda-tech.com/zerothread/1676914

That's your new Bible. Go baptize yourself.</TD></TR></TABLE>

hahahahahaha you know Jordan the kid who made that post? remember the samba del sol he sold? im the kid who bought it!! how funny.


Modified by 93eg2james at 7:14 PM 12/20/2006

 

aww man. haha you sound like me, i'd have done the same thing. Bump for helping bring some kids some presents!

 

Basically, IMO. If you can't beat the **** out of it all day long, it's not reliable.

I don't like the 1.54 b18b r/s ratio.

 

yeah 84x89 is a scary combination for high reving because of piston speeds, but i've witnessed many-a-b20vtec's take beatings and keep on ripping.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Bense &raquo;</TD></TR><TR><TD CLASS="quote"> I don't like the 1.54 b18b r/s ratio. </TD></TR></TABLE>

r/s ratio?

 

1

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 93eg2james &raquo;</TD></TR><TR><TD CLASS="quote">r/s ratio?</TD></TR></TABLE>


Rod to Stroke ratio.

 

Rumor #1: The cyliner walls on the b20 are very thin, and when they get too hot, and then are allowed to cool to quickly they will warp or crack. yea when u go above 9000 rpm it will do some damage , too much stress

Rumor #2: The b20 bottom is very unsafe in combination with a vtec head, well my buddy drive a b20/vtec crx and is very reliable

Rumor #3: The b20 is very unsafe when revved above 7k rpm.----- my friend take it to 8200 every weekend for about a year now

think about the R/s ratio b20 has a bigger crank there for it will take longer ,faster to make 1rpm than ,gsr's,b16 motors and if the crank is rotating faster that means piston speed increases , therefor pressure on the wall increase

 

basically, it's a combination of a lot of things.

1. a r/s ratio that's not ideal for side load on cylinder walls (it puts stress on the cylinder walls)

2. The sleeves are already weaker than b-series 81mm sleeves.

some say they're reliable, others say they aren't. In my opinion it's not reliable above 7000rpms.

But then you'll hear stories of one that's "got 80k on it for the past two years" I'm willing to bet that they rarely go past 7k rpm. I almost went with b20vtec in my old em1. I then realized that a final drive makes the engine "breathe more" B16s can rev to 8k forever lol

 

I can't believe after all this time people still whine about the 1.54 rod stroke ratio. Time and time again the ls/vtec and b20/vtec has been proven to be a long lasting reliable motor if built by somebody who has a clue. Bense, not picking on you here but 99% of the nerds who complain about r/s ratios and blown motors have no first hand experience .....and spread rumors.

Now I have never personally blown or damaged any of my motors over the years, but heres how I see it. A b20 block suffers from cooling issues in between the cylinder where they pair them together. Time and temperature cycling will cause the cylinder to go out of round. All the b-series do it but the b20 is much more prone to it. You know what I mean if you have studied cylinder walls on used motors. If it gets bad enough or there is severe heat or detonation they will crack. Always in the same spot

Now if you can keep water, oil and cylinder temperatures at reasonable levels these engines should last a very long time.

....Oh yeah I :heart: my b20/vtec

 

heres my 2 cents, stock b20b with arp head studs thats all, i had a super 16g front mount 11.2psi hondata, that was the key. made 240 something and cracked 3 sleeves from overheating it. i prob had 10k on it from me, ran flawlessly. i believe it if my stupid *** didnt overheat it she would still be goin strong. IMO very strong and reliable setup no matter what. ooh and my rev limit was set at 8400 and it seen that most of the time.

 

We are currently running 3 identical race engines for 3 of our race cars.
1 Hot Rod CRX on methanol
2 SFWD/Pro-Am Civics on C16

All 3 have LS/VTEC setups. 84mm, 10.8:1 compression, our Exospeed Race heads, Supertech Valvetrains, Carrillo Rods, Arias Pistons, Darton MID sleeves.

The Hot Rod CRX has made over 800hp and is winding up the motors at 10,500 every run.

1 of the Pro-Am Civic is taking it up to 10,000 RPM every run,
the other Pro-Am Civic is usually taking it up to 9500rpm(a little lower than the other because of the trans and tuning setup)

They are all making power and while R/S ratio is a big topic for some people, these real world results prove that its not that important for most since majority of big HP turbo setups are similar to ours. R/S ratio is an important topic, but I dont believe that "bad" R/S ratio motors shouldnt be built.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by exospeedAMcrx &raquo;</TD></TR><TR><TD CLASS="quote">THe B20 is basically an 84mm version of a sleeved LS block.

The b20 and LS crank is the same. LS 84mm with VTEC head is very common and we take them to 10,500 RPM all the time with no issues.

So pretty much all of your 3 rumors are False.</TD></TR></TABLE>

Not quite true. The cylinder walls in the B20 and The LS block are cast diffrently. In fact they are not even the same material. B20 cylinders are quite thinner than the ls. Also a stock b20 isnt to reliable past 7000 RPM.

To answer the OP questions:
1.The B20 cylinders are thinner. They do crack Ive had it happen to my b20 before. It cracks from higher revs or commpression not from cooling to quickly.
2. A vtec head on a b20 isnt a problem as long as you have a VTEC oil conversion kit. This will help run more oil thorugh the motor. However on a stock bottom end be careful how high you rev.
3. As stated before high revs kill cylinder walls. As far as the bearings and crank go they will hold up to the revs. The cylinders will for a while, but will almost definetly fail over a long time of abuse.