Badmouthing the B20A

[Oyvind Ryeng]

This is quoted from http://www.huanderson.com/crvtec.html (a site dedicated to CRVTEC-engines):

What about the B20a blocks from the old Prelude Si's?

When we refer to the B20s, it's only the CRV B20b and B20z blocks and engines The B20A engines were absolutely the worst engine series that we've seen from Honda, as the loooonnnng stroke was geometrically redicilous. Notice that they never went back to it either. A B20a block should be identical to a B18a or B block, so a B16 crank would fit, but the bore would still be the same as a B16, so this isn't an experiment worth fooling with, unless you have a lot of time and all the parts are free.

Also:

The b20b/z crank will put you further below ideal. Ideal being 1.75 rod to stroke. Of course you could throw all that to the wind and get some crazy ass torque on the b20b/z (and B18a/b) crank. Course you couldn't rev it as high. Hell. Throw a B20a crank in there and get some wicked ass torque, a shitty rod to stroke ratio, and 2.1 liters. All in a B block. Mate a LS tranny up to that puppy and you're good to go. At least until you push a piston through a cylinder wall.

Is the B20A really that bad an engine? From the looks of it, it seems to be a low-down torque-monster with a limited rev. capacity, due to the humongeous stroke (95mm) and the short rod. I can definately see the rods jumping out of the block at 8000 RPM, but the B20A was never ment to rev that high?

What about the other aspects of the B20A; does it make up for the apparant "short" powerband? Is it an engine with potential? How strong are the cylinder walls? As far as I can see, this is uncharted waters, as nobody has pushed the limits with the B20A that far yet?

[pimp86LX]

Well driving a b20a5 i would say they are NOT bad engnies. Other honda engines may be better, but this one seems fine. With the prelude tranny, i have tons more pickup than the accord ever did. Ass for performance applications i have no clue, but in general i would say the "old school b20a" is definitly not a band engine. ohya, i get nearly 640KM per tank and my motor has nearly 325,000km on it. :P

[k-roy]

Sounds like some ignorant shit talkers. Hey its a better option than the A20 so go with it.

[thegreatdane]

I think they are talking about the 3rd gen Prelude engine and not the 3rd gen Accord engine. Although they are much alike.

[carotman]

Well, that engine has a long stroke compared to the newer B series... however, the B20A has the same stroke as the H23A which is not a bad engine....

The B20A is just not meant to be used with a VTEC head...

Those guys are just shittalkers....

[NXRacer]

they talk shit because it doesnt have VTEC and all that other 'good' stuff like the new b motors.

[Oyvind Ryeng]

Aha, I see your points. Anyway, I like the idea of a torque-monster, rather than a high-revving B16. I like low-end-torque, as there is where I spend most of my time.

As for potential - is the B20A in stock form usable in a low-pressure turbo-setup?

[Gregg86DX]

The specific issue he is refering to (rod/stroke ratio) the Accord B20A is exactly the same as the Prelude. You have to keep in mind the context: someone probably was looking for a way to get more displacement by using a 2 liter block and all the VTEC goodies.

The point about the rod/stroke ratio is valid, but it depends on what you are looking for. Most of the B16/B18 folks pray only to the God of RPM, since it's the best way to make HP with these motors. If you want to make power with the B20A series, you need to look at boost and keep the RPM reasonable.

Because of the 4 big valves, good head design and closed deck block, the B20A should be an excellent canidate for boost. Keep the boost under 12 psi, and stock internals should work well.

That's actually an advantage to building a lower RPM motor, the stress on moving parts increases exponentially with RPM, so we don't need to worry about stronger cranks and rods, unless you want to really crank up the boost!

Gregg

[AccordEpicenter]

i despise the B20A5... B20A1 and B20Z are wonderful tho.

[pimp86LX]

why "despise"? did one let you down or something?

[RobT5580]

The B21 is the bad honda engine for sure. As for the B20a some things are odd about it for example it has huge intake valves compared to the B18A and I had Ferrea make a custom intake set and used b18a1 exhaust valves. I cant wait to hit the dyno with my setup to shut some people up. The best thing about the b20a is closed deck and plenty of torque in stock form.

[HostileJava]

The B21 is the bad honda engine for sure. As for the B20a some things are odd about it for example it has huge intake valves compared to the B18A and I had Ferrea make a custom intake set and used b18a1 exhaust valves. I cant wait to hit the dyno with my setup to shut some people up. The best thing about the b20a is closed deck and plenty of torque in stock form.

Theres a man who knows what he's talking about. Of course he's got a vested interest in some of those statements. So is that beast going to be ready for the CT meet?

[RobT5580]

Yeah but i still dont see why people bag on the stock B20A because if you run the JDM ECU it should be a decent N/A non-vtec motor for its time frame. Honda's biggest problem was torque and this had a fair amount to start with.

As for mine being done for the meet thats a sadly said "no" but it will be done very very soon. Even if the machine shop could finish it before the meet i would be rushing the whole thing and it wouldnt be broken it anyway. Plus im running the AEM EMS so it has to all be set up by my tuner so i have to work around his clock too. But im still hoping to have it done before august.

[Civvy]

Well im going to stir! I dont see why the B20a cannot be a reliable candidate for a vtec head however, it does seem pointless.

One idea i had (bearing in mind the unfortunate R/S of 1.49-1.50:1) was to build the bottom end up tough enough to survive. use a vtec, and also a turbo. Have it peaking at 4thou RPM and limiting the powerband to say 8thou?

I believed the B20a1 and the B20a5 to be the same internally?

I fair that other forums will say the (A) block is problematic because it isnt (as most think) able to be a reliable V-tec. but, i also think that there are worse blocks that they're using which have similar R/S and even worst strength in the cast of the block.

As far as im concerned There can be a relaiable V-TEC B20A but we cant rev it - so whats the point?

I think bolt ons are perhaps the best way with this engine, adding to the torque isnt to be ashamed of! stick to the original head and use a turbocharger! then race the v-tec 1600cc's up a hill! :kekeke:

[RobT5580]

I already tried to place a vtec head on my B20A and there is a lot of machine work involed and would not be worth it imo. I just did it because i had a head lying around and was curious but i never had plans to use one it was more or less to help other people.

[Civvy]

I already tried to place a vtec head on my B20A and there is a lot of machine work involed and would not be worth it imo. I just did it because i had a head lying around and was curious but i never had plans to use one it was more or less to help other people.

This isnt just for you rob!
There is a website in england www.jakan.co.uk pay for shipping and he will make it fit for you if you get stuck. If you still see point.
I really thought there was a lot more knowlegde of what could be done with the B20a engine here.
Anyways, this guy put the last engine in Honda's F1 car.
Listen to him he knows a lot about these B20's including our B20A1

[SteveDX89]

You might as well give it up. You have to take into account the power band of VTEC motors. All of them except the B18C1 start making power at 5500 rpm. That's the VTEC crossover point. If you put it on a block that will only handle 6250 rpm, what's the point? You have VTEC for 750 rpm. If you use the C1 cams, you start making power at 4400. This is a little better but you still only have it for 1850 rpm. All the machine work required to make it work would be worthless, IMO. Use the stock head and get some aggressive cams.

[Civvy]

I agree with the machining being an a$$ but, to the people who want to spend real cash on this particular engine (B20A) it can be done and the results can be similar to these engines:-
B20b VTEC SIRII cams, 48mm ITB's, and AEM ECU gave 197bhp @ 6500rpm Naturally aspirated
B20v VTEC VTi cams, B16 throttle and intake, T25 Turbo AEM ECU 215bhp @ 3300rpm and no lag @ 4psi
Many have done it!
To me its not worth the money! to others it is! Im using this forum for advise too!

[Civvy]

You might as well give it up. You have to take into account the power band of VTEC motors. All of them except the B18C1 start making power at 5500 rpm. That's the VTEC crossover point. If you put it on a block that will only handle 6250 rpm, what's the point? You have VTEC for 750 rpm. If you use the C1 cams, you start making power at 4400. This is a little better but you still only have it for 1850 rpm. All the machine work required to make it work would be worthless, IMO. Use the stock head and get some aggressive cams.

I said 8000rpm not 6200rpm?

[SteveDX89]

You have to build the bottom end for 8K. If you do that, great. But for some budget consious person who just trys getting the head to work and doesn't beef up the bottom will be sorry.

[RobT5580]

I think if you want to spend a lot of money on machine work go turbo. I dont think you will be happy with a vtec head slapped on the B20A. To me its just a bad combo and not worth the effort at all. B18A1 cams fit our head if you get the sensor groove cut in the exh cam so if i were in your shoes i would do a turbo setup or go high compression with a good set of cams and all the bolt ons. Just all the bolt on stuff will set you back a pretty penny nevermind custom machine work on that level.

And on another note tom@ludespeed did this to a B21 or B20A5 and did not have good results from what i recall. If you want a lot of hp with the B20A then turbo is the best route. If it were a b16 or b18 i would say its all up to you because they make decent numbers n/a and turbo.

[Oyvind Ryeng]

Will the JDM B20A's MAP-sensor read boost?

[AccordEpicenter]

only to like 9-10 psi max, but the computer throws a cel when you get any positive pressure.

[Civvy]

I agree Rob, totally. as I said it is a pointless mission.

I think since we are limited in RPM we could just as well use a higher duration
and in effect weve got the V-tec switched on all the time!

My point is for the people who still want V-tec it can be done and can be reliable if u dont rev it.

Check out www.B20vtec.com

I want to go the Turbo route so i'll start a new Thread.

[SteveDX89]

I agree Rob, totally. as I said it is a pointless mission.

I think since we are limited in RPM we could just as well use a higher duration
and in effect weve got the V-tec switched on all the time!

My point is for the people who still want V-tec it can be done and can be reliable if u dont rev it.

Check out www.B20vtec.com

I want to go the Turbo route so i'll start a new Thread.

That website is not for the B20A. It is for the B20B/Z from the CR-V. You're getting confused on what B20 you're talking about.

[Oyvind Ryeng]

only to like 9-10 psi max, but the computer throws a cel when you get any positive pressure.
I see. Is there a simple, effective and cheap solution to this problem?

[RobT5580]

Yeah the GM 3.5 bar map sensor this is what im going to use on my setup. AEM sells this setup or you can find them online elsewhere and it still has the same 3 wire hookup. Im not sure if it will work the same since on the AEM EMS you have to scale the values a bit when you do this.

If you dont want to do that there is another method of check valves that seems to work fine as Justin used this on his car with over 20 PSI. This would be the cheapest method im guessing.

[Civvy]

That website is not for the B20A. It is for the B20B/Z from the CR-V. You're getting confused on what B20 you're talking about.

Do u only half read what I've talked about?

How can u possibly comment if u dont read?

'B20 (A)' is all over each thread Ive made.

Civvy

[SteveDX89]

Do u only half read what I've talked about?

How can u possibly comment if u dont read?

'B20 (A)' is all over each thread Ive made.

Civvy

Why did you post that link? It serves no purpose for the B20A.

[AccordEpicenter]

you could use a different map sensor, but youd have to run stand alone engine management because a GM map sensor no worky w/honda computer