Thinking about a b20b swap on my db1.

Recently decided to scrape the cash together to get a b20 from tigerjap, since my b18a1 is about to hit 300k and is burning mad amounts of oil. Did a quick search and didn’t seem to find what I’m looking for.

First question; I see that some of the jdm b20b’s are better than others. On tigerjapanese you can either get the short manifold b20b or the long manifold b20b, one is about 35 dollars more than the other. I’d obviously like to have the better one.

Second question; Is it true that I can use my obd-0 harness, intake manifold, injectors, throttle body, ecu, all the sensors, and anything else I may need on the b20? If so, that would be awesome because I have my b18a1 to butcher for parts if needed. Or would it be better to spend the extra cash and go obd-1? If retaining my LS stuff is easier, cheaper and works fine…I’d rather do that.

Third question; Someone told me I could use my LS cams in the new motor, that they would be better than the b20b cams. True or false? If true, explain please.

Fourth question; Can I re-use my LS transmission, and all my trans/engine mounts(and prothane mount inserts)? I’m actually wanting to buy a lower mile LS trans, since mine has 300k…wouldn’t make sense to put in a fresh motor and keep the worn out trans. The new one would still be cable, not a fan of hydro transmissions.

I checked out the link posted below that explains the b20, but that didn’t help me much since tigerjap only offers two b20bs and the only difference that I can see is the IM being short or long…the years/models are the same on the details pages which I’m assuming is wrong.


Any other tips/advice/links are more than welcome. Thanks for reading!

i too am putting a b20 into my 90 db1 this summer and i’ve done some research…

1st question… buy the cheaper one and use your b18 manifold… the long style doesn’t fit under our hoods though…

2nd question… apparently there’s no issue with using your obd-0 sensors… in fact when i picked up my b20 there was already an obd-0 harness attached and included (private sale, not tiger) it seems honda was nice and made almost everything interchangeable for the b-series :slight_smile:

3rd question… haven’t looked into this… great question and i’d love to know that myself :slight_smile:

4th question… going back to the b-series thing mentioned in 2nd question… b-series are typically straight swap (same mounts, no issues etc) just do a bit of research before… but yes, buying a new(er) tranny would definitely be a wise choice if you’re tossing the engine as well!

hope this helps, and if anyone could answer question 3 i’d love to know as well…

Thanks for the reply.

I’m still trying to find out the following…

-What are the complete list of differences between short IM and long IM, and a list of correct specs for each.

-Which ones have the Pxx head, which have higher compression and 20ish more HP. This is a big question to me as I want the Pxx head version, not the P75 normal version. Tigerjap has long IM or short IM, both motor pages have the same model years and engine specs on them(most likely wrong info) so there’s no way to tell which head version I’m getting. Definitely need the answer to this much more than the others.

-Is it possible to utilize b18a1 cams in the b20b, and if so…what are the pros/cons.

-Can I use all my obd-0 LS stuff on the b20b, but keep the b20b intake manifold since the LS manifold will result in a power loss…if so, do I also use the b20b throttle-body and b20b injecters and will it all connect up to my harness/car.

it would depend if u had b18b cams… if u have a good ole’ b18a just use the b20 stuff. now that i think about it, i thought the b20b cams were the same as the b18b. not totally sure. but u can look into that. but don’t bother switching them. i’m sure that the b20b internals have less wear n stuff. and yes use ur old engine/tranny mounts. u can use ur tranny if u want or buy another. ur choice.

and no just use ur ls intake manifold n stuff. just take the longblock. i highly suggest just following the b20 swap guide. u’ll need ur ls thermostat housing, extend ur ECT connector wiring… u might need to do a dipstick modification, but i haven’t ran into that issue. my b20b is in there and is purring like a kitten =P

if u do decide to use ur ls intake manifold (with TB)… then change ALL of ur coolant lines hoses that are on the intake manifold. change the vacuum lines too.