24 replies to this topic

[X-man006]

Hey guys I had this in a topic in the General forum..but I didnt get the rite info...I need to know if Anyone on this site has done the b20a5 swap...And if they have can you plz give me info....

[boman]

This motor is the "bastard child" of Honda's B Series motors. Apparently the motor
has a different mount positioning over the other B's and doesn't produce that
much power. I believe it comes out of a late 80s Prelude. Also, I have read that
the motor sits wierd (on an angle) which is a head-ache and a half.

If you do a search on Honda-Tech.com, you will conclude that for
all of the fabrication that will be involved you might as well do it right with a B18B.

Hope this helps.

JAKOB

[Disco Stu]

This motor is junk for a lot of different reasons.
First is that it does sit at a different angle than the other B series motors. It sits more tilted towards the firewall, while the majority of them sit more tilted towards the radiator. Moot point though, there are more important reasons why not to use it.

The B20A is set up with 81mm pistons, same as the B16. So how does it get that extra .4l displacement? A long stroke. 95mm or so, whereas the B16 has 77mm. That, in combination ith the length of the rod, leads to a bad rod to stroke ratio. This causes plenty of problems. First, a long stroke limits how hard you can rev the motor. The piston has to travel that full 95mm twice before it completes a revolution. There's only so fast it can go.
Next, the R/S ratio directly impacts the angle at which the piston goes up and down the cylinder. As the ratio moves farther from the 'ideal' 1.75, the worse the angle. And because of that angle, the ammount of pressure exerted on the cylinder wall changes. If there is a bad ratio, the piston is pushed more against the cylinder than it is up the cylinder. This leads to oblonging of the cylinder walls, and oil control/ring sealing problems.

In short, they're junk.

[5150CRX]

junk.com

[opt1k]

i would also like to add that the b20z and b20b also have a shitty r/s since they were not designed to be performance motors the cost of turning them into a high revving beast is rather expensive

[Disco Stu]

Now, there's a very big difference between the B20B/Z and the B20A. The B/Z has the same stroke and r/s ratio as the B18A/B. So wait... if its got that same stroke, how does it get the extra displacement? Piston size. The B20B/Z has an 84mm piston which makes up the extra displacement. Now, this does lead to teh B/Z's major problem, which is cylinder wall cracking, but resleeving, posting, or other methods can solve that. I won't deny that they're not high revving beasts, but they can be made to rev much higher than the B20A's, and are very comprable to the B18A/B.

And I sure as hell won't deny it costs alot toget them to rev high. My CRVtec will be revving high as a friggin' kite, but between a B17 crank, custom rods and pistons, block girdle and golden eagle resleeving, it's a heck of a price.

Edited by Disco Stu, 02 December 2004 - 10:08 PM.

[opt1k]

Now, there's a very big difference between the B20B/Z and the B20A. The B/Z has the same stroke and r/s ratio as the B18A/B. So wait... if its got that same stroke, how does it get the extra displacement? Piston size. The B20B/Z has an 84mm piston which makes up the extra displacement. Now, this does lead to teh B/Z's major problem, which is cylinder wall cracking, but resleeving, posting, or other methods can solve that. I won't deny that they're not high revving beasts, but they can be made to rev much higher than the B20A's, and are very comprable to the B18A/B.

And I sure as hell won't deny it costs alot toget them to rev high. My CRVtec will be revving high as a friggin' kite, but between a B17 crank, custom rods and pistons, block girdle and golden eagle resleeving, it's a heck of a price.

i knew those 2 were similar, but i thought the r/s was worse on the b20b/z than the b18b/a? and you have thinner sleeves. you are a bigger expert than me.

too bad i didnt have the camera when i landed a rod through the oil pan on an improperly built crv-tec... i had an oil fire going

i dont suppose it was meant to be revved to 8500 rpm

[Old School CRX Swap]

question for Disco Stu

b17 crank in a b20 good idea, how big will the engine be, when you have it sleeved are you going to have a bigger bore to make up for the shorter stroke so you can still call it a b20, oh ya and how long of stroke is a b17

[QUOTE]
i knew those 2 were similar, but i thought the r/s was worse on the b20b/z than the b18b/a? and you have thinner sleeves. you are a bigger expert than me.

too bad i didnt have the camera when i landed a rod through the oil pan on an improperly built crv-tec... i had an oil fire going

i dont suppose it was meant to be revved to 8500 rpm

the b18a/b has the same stroke as the b20b/z and ya 8500rpm is a bit high i think with arp rod bolts they are supposed to handle 7500 to 8000 i think

[Disco Stu]

Ok, lowdown on my car...
B20B block, resleeved at 85mm by golden eagle. Rods are 140.1mm long, combines with the 81.4mm stroke of the B17 crank gives ita 1.72 R/S ratio (compared to the B16's 1.74, B18A/B 1.54, B17 1.62, B18C's 1.58 and the B20A's 1.5). This does impact the displacement, as I'm effectively going to be running on 1.84l of displacement, give or take. However, it's not just an overglorified B18 because the B20B/Z has a taller deck that allows me to use the longer rods without any interference with the head. I can't go with any longer rods than the 140mm ones, otherwise there would be pistons slapping the valves. Also, the extra mm of bore only adds to about 10cc's of displacement per piston. Not a whole lot, but since I had to have the block machined anyway, I figured I might as well give the bigger pistons a try.

[mayhem019]

B20A is the japanese version of the B20A5/B21A1 and is supposedly more durable so its a common swap for 3rd gen preludes (not much else swaps into those cars). The longer stroke of these motors gives you more torque than most hondas with similar displacement. B21A1 is like 140HP and 135ft/lbs which = more power than a stock B20B? The JDM B20A is slightly more power than that even.

Definately not worth the time though. Its not fun tracking down random parts that will fit these motors. N/A build up is a waste of time. Redline wont be able to increase much because of the R/S so most people go turbo if they want to go fast. Rod bearings fail quite often due to serious oil circulation problems. The prelude owners who build these motors do it because they love the car - not because its a good motor lol

Edited by mayhem019, 03 December 2004 - 05:47 PM.

[X-man006]

please ignore me, I am ignorant.

[mayhem019]

Wow. Boman replied immediately after you and told you it sits at a weird angle, and that you'd have better luck with a B18 swap. The newer B series swaps have been done with these cars many times.

The rest of us also pointed out the engine is not really worth putting into a performance car at all.

If you can't even try to understand what was said, then maybe you should consider something else to do with your time

In the meantime cryaboutit

Edited by mayhem019, 03 December 2004 - 08:32 PM.

[crxhybrid85]

Nothing to see here, please move on

<{POST_SNAPBACK}>

Someone please BAN this idiot.

[87MugenProCR-X]

I think you need to calm down. If you cant handle peoples opinions then mayb you shouldnt ask any more questions or something. geezzzz...

Julian

[X-man006]

I am a loser, please ignore me.

Edited by Masta, 05 December 2004 - 09:17 AM.