1991 d15B1 VS d15B2

I've read the HP for a 1991 Civic STD 15b1 is 70hp, but a DX with a 15B2 has 90hp. Whats the difference? I have a STD 15b1 and I would like to add the extra HP. My understanding is both are Dual point fuel injected 16v SOHC Engines.

Get the JDM D15B twin-carb... it had 100bhp.

I never understood why Japan, Asia and Australia all got this motor and you guys didn't - it can't be fuel - ours was shit in the late '80s.

from my understanding, the main difference between the b1 and the b2 is the b1 has a little restricter plate in the intake, and the fuel maps are different inside of the ecu

Thanks for the info! I've read about the restrictor plate in the forum, actually I think there were 2, but I'm not sure I'll have to check. I looked up a few aftermarket parts suppliers, and they listed the same ECU part number for both the STD D15b1, and the DX d15b2, so I'm guessing there's no ECU change? I'm a newbie so I might be way out in left field, but I'm thinking the difference might be California vs 49 state cars? Again, just a guess, if anyone can clear this up that would be great!

I'm sticking with my D15b1 for now, and enjoying the great gas mileage. I simply felt I could take advatage of the additional 20hp the D15b2 offers, if my car is upgradeable. If anyone could detail what I need to do, please let me know.

I know, I know an engine upgrade is in the works: a ZC, or a b16 vtec with a Turbo kit etc...
But for now I'm sticking with my D15, the gas prices here in SoCal is nearing the $2.50 per gal. mark again.

prolly the easiest hp mods for you to do is to swap your d15b1 head with a d16a6(SI) head and then swap your DPFI to MPFI. you would prolly get around 100hp instead of the 70 stock hp

The ECU's are different as KoRnSaQ said. I have also wondered the same thing too. They both have diffent numbers on the outside plate above the bar code. I can't remember what they are but I'll get with you on that one. Also they are different in fuel maps. (More Fuel, More Power)

The only other differences are the restrictor plate and the throttle body. The D15B2 plate opens all the way while the D15B1 only opens 3/4. Change all this and you will get more power.

I have a 15B2 ecu if you want it $20us and Ill ship it to ya.l

I've got a d15b1, with Si MPFI & intake, and Si ECU in my 90 SI (Long story)...but the power seems to blow my STD all to hell...and the b1 is 'out' of my STD that got smushed by a dodge ram....I just wish I knew how much I was actually getting...but put MPFI on your b1 and it will make a dramatic difference that you can actually 'feel'.
What I mean by feel...is when I was at 120km/hr in my STD it felt like the car was straining...in my Si...I can still jump ahead when I press the gas...and actually feel it in my seat.

Jason

I think both have those restricter plate (i dont know why honda do that),

I keep my 89 STD Hatch and 91 LX sedan restricter plate off, except during Smog Test (quieter & less aggressive)

I notice that, on mine STD throttle butterfly do not open all the way where on my 91 4gen LX Sedan it will.

on my 89 STD, it have the Catalytic on the downpipe exhaust. (88-89 have this stlye, where 90-91 have the 4-2-1 header).

and ECU might be different. I wouldn't bother checking the camshaft.
I got SI camshaft instead :)

Dx/d15b2 = Pm5
Std/d15b1= Pm9

Thanks for all the info., I appreciate it. In the near future I'll be modifying my 91HB, but for now the SoCal gas prices are just killing me. I'm so fortunate I have a fun car to drive that doesn't suck up gas!

both have restricter plates, i took mine out and it helped out a lil. I had a thread about it a few weeks ago where i posted pics and all.

Where is the restrictor plate..for those of us that would like to remove it...don't have a clue how too...would there be a RP on my Si? Remember, D15B1...Si intake and MPFI...and Si ECU.

I guess I'm loking for a "for dummies" version of how to go about this?

Thanks.

Jason

restrictor plate is located under the throttle body. the primary choke plate is also limited on the STD; it only opens about 50% of the way. its the first "throttle plate" you'll see inside the top of the throttle body