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Discussion Starter · #1 ·
a friend of mine just gave me a b20 block but i found out it is a b20a block the one off the prelude i was wondering if it is any good, am i able to put a vtec head on it or should i just pass on the block?
 

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Discussion Starter · #3 ·
dont really know much bout the motor, just know its a b20 and is the ones that comes in the earlier year prelude,
 

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well the B20 that everyone talks about now comes out of the Honda crv. Yes it is a torque monster if this is the one you are talking about. My friends JDM B20 with i/h/e dynoed at 166ft/lb at 3600 rpm. I dont know if it is a B20a and you might be right that it came out of a prelude but then one ppl are doing swaps with now come out of the Honda CRV.
 

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You guys are not hearing the man. He said B20 block from the earlier ludes meaning 88-91 ludes. Yes I have seen them having a VTEC head thrown on them customed made for turbo, but I have not seened first hand what the thing can do both in the 1/4 mile and on the dyno.

My cousin use to own a shop and they had a few of these things hanging around. I wish I had taken pictures of them back then.

Honda has got to do something about mixing up these engines names. I mean its this scenario is like saying D16 and not knowing whether the person is talking about the D16 in the first gen teg or the D16 in the civics which are also two different things.

Quite honestly though, you'll probably be better of using that thing in an older accord instead of your teggy. Your teggy deserves the newer B20 block which is the ones that came off from the CRV's.
 

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yea i agree with "sak" u guys are getting all mixed up, the B20B, B20Z are from the CRV. the B20A is from the old preludes. actually DoNT vtec the thing, from wat i read the b20a is a bad engine, one reason y honda didnt go back to it. if ur gonna vtec a 2.0L B series do it wiht the CRV, B20B or the new CRV B20Z.

i had an article somewhere about how horrible the B20A is, but i think i lost it or cant find it.
 

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B20B/Z block has a crank whose stroke is 89 mm. The bore is 84mm. The rod ratio is 1.59.

B20A block from the 1988-89 Prelude Si and 1990-1991 Prelude 2.0Si (not the 1990-1991 Prelude Si alone) has a crank whose stroke is 95mm. The bore is 81mm. The rod ratio is 1.48.

The B20A crank is used on a lot of stroker kits for the B18C to turn it into a 2L (eg. Crower's kit). Now think about what that does to the rod ratio (the B18B rod is 137mm, B18C rod length is 137.9 mm). Now think about the effects of a lower rod ratio....

here it is in black and white already written out for you:

http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=20

Unfortunately the B20A had an 81mm bore not an 84mm bore and it's rod ratio is a puny 1.48 (141.5 mm/95 mm). The displacement is 1958 cc.

A B21A off the 1990-1991 Prelude Si had an 83mm bore instead. Same 1.48 rod ratio but has 2056 cc displacement.

Anyway, the B20A ain't exactly a high revving animal. It has a rod ratio worst than the B20B/Z. It will give you 2L but at what performance price?

Before you get all excited about swapping the crank into your B18C1 or B18B, remember what it does to your rod ratio and you would need to notch the block to allow the crank journals to clear the inside of the block without hitting it. Some of the engine builders can get around not removing the block oil squirters but most just remove them to get more clearance for that B20A crank. Gee, that really helps the cylinder walls and piston rings/skirt: lower the rod ratio, increase cylinder wall sideloading, and remove lubication of the walls at the same time....nice.


why not write the whole article again Tuan to answer this question? ...I anticipated the question BEFORE YOU EVEN THOUGHT OF IT AND PUT IT IN THE ARTICLE. LOL.

makes you wonder why your "friend" gave you the block...
 

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and you wonder why I get pissed off having to ask people to read the articles...my fingers are killing me...LOL

BTW I have the most posts in TI...yes...that's higher than anyone here....including SurferX and MorningZ (what a postwhore eh?) and any member here....all from retyping (cut & pasting) my answers that are already in the articles...all tech and some joking around...like this one.

BTW for the Articles: please don't expect to get it all in one reading. The more you work on your engine, the more the article will make sense. It took me years to sort outthe info and so why should you expect to "get it" in one reading. They were meant to be used. They aren't meant for contemplation or virtual-reality engine building. Book learning without doing it is useless. You may have to refer back to them and read parts of it again as you understand more. And if you don't understand a part, just ask here or in MD Tech Corner. This is the only place where you can actually interact with the author...try doing that with a Sport Compact Car or Superstreet article. Take advantage of the opportunity...please don't waste it though. I'm not here to be your info booth. If the question is about the article, I'll be happy to answer them. However, please don't send me endless PM about how to build your engine, LIKE SOME MEMBERS HERE ARE ENDLESSLY PM ME. Get your thoughts together in 1-2 questions please. Be organized and to the point. thanks.
 

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i'm just throwing this out there, what about using a b18b/b20b crank with some custom 145mm rods? that should clear the b20a deck, right? 1.63:1 r/s ratio is not too bad? bore and resleeve to 85mm, and you have displacement like a b20b, and the revvability of a b17a...

how would a setup like that compare to a dart big bore, tall block?
 

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isn't the b20a a closed deck also which will compromise the reliability of the engine.
 

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ugh. the rod ratio will comprimise it much sooner if you insist on revving it
 

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Okay I'm gonna put this out here:
the way to use a b20a block to it's maximum potential is as follows (and it costs a LOT of money)
B20A
Bore: 81mm
Rod length: 141.5 mm
Crank stroke: 95 mm
Rod Ratio: 1.48
Displacement: 1958


Frankenstein B20A:
Custom sleeves running 84.5 mm bores:
Pistons: Endyn roller-waves with piston pin moved up 3.48mm (0.137”)
Rods: custom rods with to compensate for the loss in stroke:
Bore: 84.5 mm
#1 #2#3
Rod length:147.98 mm148.88mm151.78mm
Crank stroke: 89mm87.2 mm81.4 mm
Rod Ratio:1.66271.70731.865
Displacement:1996.4261956049.21041825.945

#1 B18A/B and B20B/Z 89mm
#2 B18C 87.2 mm
#3 B17A 81.4 mm

Sure you can run larger bores, you do the math for them.
The moral of the story: you can achieve the same displacement as a b20b/z with a better rod ratio. You just have to pay out the ass. If you plan on re-doing the internals on a b20b completely it may be more cost effective to get the b20a block (cheaper) and spend the same $$$ on the internals.
 
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