B20A vs B20A5 Confusion

[Randy Rourke]

Hello

I am hoping to gain a better understanding of the differences between the JDM B20A from the second gen preludes and third gen accords and the B20A5 from the third gen preludes. I havew a third gen prelude, so I hope no one minds me posting here.

I saw Yasu's excellent website and articles describing the JDMB20A that he put in his accord, I also noted the difference in the block.

I am wondering if anyone knows why the B20A (like yasu's) is rated at 160hp and the B20A5 (USDM) in rated at 130hp.
Could it be the Cam/ECU/Fuel Injection. I think the compression is a tad higher.

Also, is there a JDMB20A5??, for the 3rd gen lude?? I would like to start building an engineand now am wanting to be very careful to get the right one.

Thanks for any help
Randy

[dXsquared]

im betting there is a JDM B20A5 for the 3rd gen lude... call an engine imorter, or reserach online... this is an accord site, and we dont know much about 3rd gen ludes, although, you might be lucky
Travis

[AccordEXI]

Like you mentioned the increase in power is due to the cams, ECU and compression ratio(9.4:1 vs 9.1:1)

There is a JDM B20A for the 3rd gen Prelude. It's rated at 145hp@6000rpm vs the 135hp@6200rpm of the B20A5. The main difference is probably the compression ratio, again 9.4:1 for the JDM version. The JDM engine will be stamped B20A without the 5 at the end. Other than that it should look identical to a B20A5.
Just make sure it's not the Accord B20A because this engine will not fit in your Prelude.

[cruznz]

try here for some 'lude resources.... http://www.pdu.co.nz/resources/

[toxicshock92]

i just started here and im trying to find out what makes the accord b20a more powerful than the 3g prelude b20a. i was told the accord cams are more aggresive but what parts make the accord b20a more powerful than the 3g prelude b20a i need an answer like cams, pistons, crank, head, block, valves, etc i have an accord b20a and want to see if i can make my b20a5 as powerful accord b20a because im using all the accord internals thanks

[2ndGenGuy]

I thought that the JDM version of the B20A5 Prelude motor was also 160hp?

[toxicshock92]

no the accord b20a is rated at 160 the 3g prelude b20a is rated at 143 and the b20a5 is rated at 135. so if someone can tell me what makes the power difference that would be great and btw i have no use for the accord b20a head anymore so if someone wants it let me know it also has the intake mani the valves are still in it and the pistons. no block or crank or cams. but first i need my ?? answered

[2ndGenGuy]

Lots of skepticism whether or not the goldtop actually makes 160hp. I don't think I've ever seen an actual dyno of a stock one. I think Thegreatdane has a dyno but there was a bunch of mods to it. Tuning and all that. Looking at the B20A5 and B21 dynos on Prelude Power, it looks like the cams really die off round 5000RPM, so maybe the Gold Top cams carry the torque up higher in the rev range.

[toxicshock92]

Lots of skepticism whether or not the goldtop actually makes 160hp. I don't think I've ever seen an actual dyno of a stock one. I think Thegreatdane has a dyno but there was a bunch of mods to it. Tuning and all that. Looking at the B20A5 and B21 dynos on Prelude Power, it looks like the cams really die off round 5000RPM, so maybe the Gold Top cams carry the torque up higher in the rev range.

well the accord b20a gold top makes 160 hp at 6300 rpm and 137 lb.ft at 4000 rpm and the accord black top makes 160 hp at 6200 rpm and 137 lb.ft at 4000 rpm but the 3g prelude b20a makes 143 hp at 6000 rpm and 128 lb.ft at 4500 rpm but the b20a5 makes 135 at 6200 rpm and 127 lb.ft 4000 rpm
so the only one that makes the most torque at a higher rpm is the 3g b20a but all i need to know is what they did different to all these motors to make the power difference.

[carotman]

The valves are bigger on the Accord engine. The cam profile is also different.

[toxicshock92]

The valves are bigger on the Accord engine. The cam profile is also different.

so me using the cams in my b20a5 did help. will it be alright to use the vavles as long as i port first

[Rendon LX-i]

yes but the volume in valve size will effect it as well.

an NO you cant . valves are bigger there for valves will not seat.

[2oodoor]

The question that crosses my mind whenever this topic comes up is what about the black top having the 88-9 vac controled 2 stage runners intake or does it?
Does the A20a3 in the 88-9 have more hp than the 86-7?

[Rendon LX-i]

yes. i took apart both. only thing that was different was the intake couple sensors but block was and pistons crank. so on so front. im not going to say that used extreme measures to get down to the specs but visual wise the same. the 88-89 pre vtec i call it made a different in runner design. the 86-87 had a j type of intake. was all intake and exhaust designs and ecu.

[carotman]

The question that crosses my mind whenever this topic comes up is what about the black top having the 88-9 vac controled 2 stage runners intake or does it?
Does the A20a3 in the 88-9 have more hp than the 86-7?
The compression ratio on the 88-89 A20A3 is higher than in 86-87

This is why it makes more peak power. The dual stage intake will help lower end power only. This won't show as peak numbers but would make a difference on a dyno graph.

[toxicshock92]

yes but the volume in valve size will effect it as well.

an NO you cant . valves are bigger there for valves will not seat.

thats why i would port it i already have bigger valves in the head so i dont need to put these ones in

[bullard123]

I love these kind of threads. Maybe I can contribute to the 20+ year old mystery when I finally get around to dyno'ing my B20A. For those of you who don't know I have a blacktop B20A (rated at 145hp) with the gold top B20A cams (rated at 160 hp). Only mods I have are the goldtop cams and a short ram intake. So mine is pretty much stock

[2ndGenGuy]

Dang. Get it on the dyno. I'll send you $80. :) Which ECU is running it though? Any other mods on it?

[carotman]

On the stock ECU, I dynoed the same thing as an ITR with my B20A.

I have ITR pistons, reground cams DC header, Edelbrock intake, Integra TB, Port and polished head

I should just do the OBD1 switch since I already have the ECU and get that thing tuned.

[2ndGenGuy]

What's an ITR put down on a dyno? I saw on your site you have Colt cams, but it doesn't say what grind?

[bullard123]

Dang. Get it on the dyno. I'll send you $80. :) Which ECU is running it though? Any other mods on it?

Im running the stock blacktop PH3 ecu. I'll say this, it definitely feels like it has more than 145 hp. No other mods

[MessyHonda]

yeah we need someone to dyno a stock b20a

[carotman]

What's an ITR put down on a dyno? I saw on your site you have Colt cams, but it doesn't say what grind?

I was at around 145 wheel HP on this dyno

The cams I have are from Mike Lee's project. I don't remember what's the exact grind on those but I was told it's close to a regular "stage 1" grind for regular B18's

[2ndGenGuy]

Cool, thanks for the info. :)

[AccordB20A]

nobody around here has a stock b20 with low kms to dyno lol

my modified one i bought off trademe made about stock power untuned haha

[carotman]

nobody around here has a stock b20 with low kms to dyno lol

my modified one i bought off trademe made about stock power untuned haha

I have one but it's out of a 2nd gen prelude and it's not in a car. LOL

[honda-hardy]

yeah we need someone to dyno a stock b20a

im a newby here, i have a stock b20a jdm engine and mine was dyno'd and measured 127.6bhp, stock they were only 137.

[2ndGenGuy]

But that's the later B20A, from the 3g Prelude I assume, based on your sig? Basically the same as the B20A5.