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im just posting this up to help anyone out with questions about b20's... its a nice write up...

this is not my work... i found this on b20vtec.com... written by user Bambam...

link here

B20 non-vtec FAQ Guide

I created this guide for a couple reasons, but mainly for the reason that there is ALOT of misinformation on B20's. This thread should end all of that misinformation and confusion.

How to identify your B20 Motor:

Let's first start off by saying that ALL USDM motors will have a number after the last letter in it's engine code. The Engine code stamp can be found where the transmission and block mate at the front of the motor. The JDM motors do not have this number after the last letter. For example, a B20B1 is a USDM motor, whereas a B20B is a JDM motor.This is important to understand in determining which motor you have.

Next, there weren't any B20Z's in Japan. All the JDM B20's were stamped B20B, regardless of the year. You can tell the year of the motor by checking the year/month the head was cast in. The year is located just above the fourth exhaust runner. It is in a circle with a slash through it. Disregard the slash as it means nothing. For example a circle with a 9/8 is a motor that was made in 1998. Be careful though, as this is not a 100% accurate based solely on the year. You must also look at the month it was made. Again, it is right next to the year and will have the month in a circle with a slash through it. Just like the year, if it says 1/1, that means it was made in november, the eleventh month. I'll show you why the year is not 100% accurate. If a motor was made in 98, but was made in november or december of that year, it is actually a 99 motor. That is because they start making the motors early for the next years vehicles. If the head was made in september/october though, that is a tossup as it may either be the year cast on the head, or the next year, because that is the crossover where they stop making the current years vehicles and start producing the next year's vehicles.

Believe it or not, almost all B20's, regardless of year, come with the 96+ Integra LS P75 head. They are 99% identical. They have the same valves, springs, valve covers, distributors, cam gears, etc. as 96+ USDM/JDM P75 Integra LS heads. The only differences are w/ the variances in camshafts. There is one exception however. The B20 motor was equipped in MANY vehicles in Japan, mainly the SM-X, Step Wagon, CRV, and Orthia. Of the many B20 powered vehicles, three of them came with the P8R head, and only in certain model years. The Orthia, which came out in 1996 was one. The other was the Step Wagon. The orthia came with the P8R head in it's 96-98 model years and the step wagon came with the P8R equipped B20B in it's 96-98 model years. The CRV also came with either the P8R head or P75 head in it's 96-98 model years. The P8R head is a completely different casting than P75 heads which were used on all other B20's. This head came with 84mm combustion chambers and 33mm vtec sized intake valves.



All 99-00 B20's have a knock sensor, regardless of where it comes from, which signifies the high compression 9.6:1 motor. If your B20 does NOT have a knock sensor, it is not the 9.6:1 compression motor. High compression B20's use "PHK" pistons which have a less of a dish them, as the "P3f" pistons found in the low compression B20's do. All B20's have an 84mm Bore and an 89mm stroke regardless of year. They are internally and externally identical to 96+ B18B's, with the exception of the Pistons, sleeves, and in some cases, the intake manifold and cams. They all have an 81mm combustion chamber diameter as well, except for the "P8R" head, which has an 84mm diameter and larger valves, as described above.

Here is a list of the different compression ratios and Power Ratings for B20's, in regards to the year and origin of the motor:

USDM:
96-98 Honda CRV
126 HP, 133 ft/lbs TQ
compression: 8.8:1

99-00 Honda CRV
146 HP, 133 Ft/lbs TQ
compression: 9.6:1

JDM B20B's (taken from Japan's Honda website):
96-98 Honda Orthia
143 HP, 132 ft/lbs TQ
9.2:1 compression

96-98 Honda Step Wagon
123 HP,133 ft/lbs TQ
9.2:1 compression

99-00 Honda Step Wagon
134 HP, 136 ft/lbs TQ
9.6:1 compression

96-98 Honda CRV (two variants)
128 HP, 136 ft/lbs TQ
8.8:1 compression
143 HP, 132 ft/lbs TQ
9.2:1 compression

99-00 Honda CRV
148 HP, 136 ft/lbs TQ
9.6:1 compression

96-98 Honda SM-X
128 HP, 135 ft/lbs TQ
8.8:1 compression

99-00 Honda SM-X
138 HP, 137 ft/lbs TQ
9.6:1 compression

These power figures are worthless for you and me, in the sense that these numbers are for these motors in their respective stock vehicles. Take into account that these numbers are with the restrictive CRV header/exhaust, extremely restrictive CRV ECU with it's conservative fuel/ignition tables, restrictive CRV Intake, etc. I've seen multiple B20's dyno in the 125-140 HP range with nothing more than an intake, header, and exhaust, with torque numbers in the 130-140 FT/LBS region. Which is more torque than they are rated at to the flywheel. Based on the factory numbers, these kind of gains shouldn't be made just with an intake and exhaust upgrade. This just goes to show you how underated these motors are from the factory. There is a Rule of thumb that says whp numbers should be about 15-20% lower than flywheel rated horsepower. By using that formula, High compression B20 motors should be rated closer to 160 Hp and low compression B20 motors should be rated closer to 145 wheel horsepower.

BEWARE!! Do NOT let engine importers fool you. Many of them knowingly try to sell you a "JDM" B20B and tell you that ALL JDM B20B's are high compression. As many of you have just learned, this is not true. They tell you this because demand for the low compression motors is alot less than the higher compression B20's. Possibly, many importers just don't know the difference. But don't take that chance. The only REAL way to tell is if the motor has a knock sensor. Also if it is a USDM "B20Z", it is no doubt the 9.6:1 compression motor. So, it may be safer just to find a "B20Z".

I hope this has been a helpful guide for you. If there's anything I've missed at all, please feel free to let me know.
 

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Yeah man you completely left out the fact that the 2nd and 3rd Generation Preludes came with B20 non VTEC engines.

I don't know much about them because I was a 4th gen Lude nut before I got into tegs but we should add those engines (USDM and JDM) to the list in the OP.
 

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Heres some of the specs on those engines

The JDM B20A produced 160 hp (120 kW) at 6300 rpm, while the EDM B20A1 produced only 137 hp


Engine list for all 3rd Gen preludes

Quote: Engine List Honda Prelude:
B20A/B20A1 - 2.0L DOHC PGM-FI 137/160 hp (Europe/Japan)
B20A3 - 2.0L SOHC carb(12v) 104 hp Canada/US
B20A4 - 2.0L SOHC carb(12v) Non US
B20A5 - 2.0L DOHC PGM-FI 135 hp (101 kW) US
B20A6 - 2.0L DOHC PGM-FI 142 hp (106 kW) Australia/New Zealand
B20A7 - 2.0L DOHC PGM-FI 150 hp (110 kW) Europe
B20A8 - 2.0L DOHC PGM-FI 133 hp (99 kW) Europe
B20A9 - 2.0L DOHC PGM-FI 140 hp (100 kW) Europe
B21A - 2.1L DOHC PGM-FI 145 hp (108 kW) Japan (SI States)
B21A1 - 2.1L DOHC PGM-FI 140 hp (100 kW) Canada/US
 

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shore96teg on Apr/29/09 said:
Yeah man you completely left out the fact that the 2nd and 3rd Generation Preludes came with B20 non VTEC engines.

I don't know much about them because I was a 4th gen Lude nut before I got into tegs but we should add those engines (USDM and JDM) to the list in the OP.
There's really no sense adding them to this list as the only thing shared between the engines is the "B20" in the name. They are totally different than other B20's, no parts are interchangeable.
 

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^nothing. and 91? are you referring to year? the b20b(usdm) head is almost exact to the ls head. the b20z(usdm) has a bit different head charecteristics. i forget the specifics, but this would possibly yield a gain. b20b and b20z being way post 1991 though
 

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dude the info was awesome. glad i stumbled upon it considering i will be going to a motor importer next week to pick a b20 up and now i know what to look for but i do have a few question. ill be putting this into a 95 integra ls that started knocking so i planned on using the intake manifold from my b18b to convert the sensors over. i want to look for the high compression P8R motor, but is there any way to tell if it has a knock sensor other than taking the valve cover off? will using the original ecu from the integra affect the performance of the motor. and lastly, would putting the cams from my b18b in the b20 benefit me in any way? all help is appreciated
 
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