i found a 90 or 91 lude with a b21a1. I own a 91 civic hatchback. the crx/ef forum keeps trying to sell me a b16 like they get some sort of kickback from it.

I DO NOT WANT TO HEAR ABOUT ( NOOOO put this motor in instead)
i am not affraid of a little hard work,. has anyone ever heard of this being done? any ideas on what parts i might be able to use, or what parts ide have to buy aftermarket (if avail) or do i have to buy a block of aluminum and start filing myself a spindle?

 

You want to put the B21 into your Civic? Not really worth the effort. B20Z would yeild similar power, and be much easier to swap

 

Hey Bud,

I own a 91 Prelude SR (Si in USA I think.) b21a1

Anyways, the person who sold her to me in 2006 warned me about burning oil. Oh man and did she burn oil. I mean maybe a quart liter EVERYDAY.

Anyways, finally after about a year, one of the cylinders Blew up on me.

I found an engine direct from Japan with only 50 K Miles. Something about emissions in Japan, I don't know the story but you can get engines here in Toronto, with lot less miles. I paid $500 for engine, $500 labor.

Now this new engine is B20a. First I was unhappy thinking its 2.0 and not 2.1.

But honestly man I don't feel the difference. Also the engine burns not a single drop between oil changes.

I recommend against b21a1. Thats my honest opinion. You make the call, good luck.

 

I don't think of myself as an expert on this topic at all, but I've read on and off a little bit about them. So here's what I remember...

B21A1s came in the '90-'91 Prelude Si. They have FRM cylinder walls and are known for burning a LOT of oil and eventually putting a nice hole in the side of the block. I actually have a souvenir from a local wrecking yard because of such a problem. The "donor" car had the stock B21 in it (and matching empty quart of oil in the backseat). Behind the header there's a hole about the size of my hand. I managed to squeeze my hand in and grab the biggest chunk of block left.

From what I understand rings can usually be done (repeatedly, I imagine, since the FRM parts are so strong the other parts wear prematurely), but it just usually isn't done.

The other thing to take into consideration is that the B21A1 (and other '88-'91 Prelude engines, like the B20A3 carb and the B20A5 FI) is NOT like other B-series engines. They mount funny in the cars (lean back 18 degrees - it's noticeable) and the parts are in different locations, such as the alternator being up front on top instead of down at the bottom backside on the driver side.

They really look more like F-series or H-series from the next generation Prelude more than a B-series imo.

The reason those people are telling you to get a B16 (or really any other B-series) is because those engines are tried and true swaps for your car.

Most people who find a 3G Prelude engine and want to swap that in just think that it's neat that they found it, it's cheap or it's unique. It might be all those things, but it doesn't mean it's a good idea to swap it into your car. Plus swapping it in might be more difficult or expensive than the standard engines.

I have a B20A5 in my '88 Prelude and while it's great in the Prelude... I don't think I'd even even consider it in a Civic. You can get the same power or better cheap and easy in other ways.

https://honda-tech.com/forums/hybrid-engine-swaps-18/prelude-b20s-same-crvs-1179304/

Here's proof that you can swap a B20A (or B21) into an '88-'00 Civic engine bay. You can see what I was talking about how the engine leans back.
http://hondaprelude.to/forums/showthread.php?t=112675

On Prelude Power at least one guy pointed out that these engines can't end up pushing too much horsepower out because of a lack of headgasket options. The '88-'91 Prelude has very, very few aftermarket parts available for it out there. Some of the parts people in the 3G community like to use are made for other cars. Those parts even sometimes need modification.

 

^^^Pretty much, right on.

I have a 89 Prelude SI that I use as a drag car with the b20a5. There is a MLS headgasket available now and there are few parts available. A lot of custom fabrication is required and makes it expensive. At the end of the day it still doesnt make any impressive power numbers.

Its not a bad engine, if you are willing to do the extra work. I wouldnt waste my time with the b21a1. Much better of with a b20a, if you really want to do it.

I am planning on swapping to a different engine/trans setup after this year. Much more potential with a H or B.

 

thank you for real info, the douches over on the EF forum just want to hear about jdm front lips and grs leathers. a bunch of clowns that couldnt beat my qtr mile time on my huffy.

haha i had just found the stuff real cheap so i figured i could build the bottom end drop in a turbo and sicne i got a 2.1 letre motor it would make more power than a turbo 1.8 due to size alone.

 

i own a rare 91 se sr and it got that darn b21a1 last summer i ad my valve seal all the gasket and the piston ring done i ever get here a 1000km break in and i still burn a little bit of oil its not cool to put that much money and not fixing the problem now i am looking to swap anything in no more b21a1 for me iam done

i really think a two stroke engine burn less oil than a b21 but the final decision is up to you