B20 non-vtec FAQ GuideOriginally posted by BamBam here http://web.archive.org/web/20060223224918/http://nonvtec.com/board/viewtopic.php?t=2543I 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 and intake manifolds. 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/P75 head in it's 96-98 model years, depending on it's compression ratio. 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.
***I'm still trying to find more information on this P8R head. As of now, it appears that all the B20's w/ the P8R head come with a 2 layer headgasket, which is part of the reason the compression ratio on them is 9.2:1. Another reason the compression ratio is 9.2:1 is because the valves are 33mm and not 31mm, which takes up more space in the head, giving it a higher compression ratio than w/ the P75 heads. I would still like to get accurate readings on the volume of the combustion chambers, as well as other dimensions such as the depth of the chambers. I'm hoping to post more info on the different intake manifolds as well, but not until i've done more research. Also, I am currently researching the differences between all the B20 cams. I will update accordingly.
