I have a 90 ls with a b18a with 130 hp. The later b18a's and b18b's produce more power and torque. Does anyone know what the difference between these #'s are. Is the cam profile, ecu programming, IM design, head design. I was just thinking that if it's something simple, like swapping the head, it'd be a good cheap mod for 12 hp. Also, if it's only cam profile then the crower 403's should give me like 30 hp if they're good for almost 20 in the b18b.

 

you just answered your own question. B18B's, yes, have a better intake manifold design, better ecu programming, exhaust manifold design, and I believe a better cam profile.....all of these things combined make it have a bit more power than the B18A engines.

 

i think it's a combination of the cams/intake manifold and exhaust manifold which made up the diffrence between the two.

 

better flowing head as well.

 

Both Cylinder Heads flow the same.
It is the cam profiles introduced in 92' that made the 10 extra "rated" hp (increase from 130hp to 140hp).
In 94' the B18b's started, which had the same cam profiles as the B18a's in 92-93', but a better intake manifold which made the 2 hp increase in the rated hp (140hp to 142hp).
All cam profiles from 92' and up are the same (in all the 1.8 non-vtec's).

 

So by swapping cams from a 92 or 93 into the 91, you can get the 10 extra hp? Is that possible?

 

So there's no difference in actual head design, it's just what bolts on to it (ie. IM, exhaust manifold, cams). So a b18a and b18b with skunk IM, crower 403's, and same header would produce the same flywheel hp? At least in theory? Well, that's good to hear.

 

Doing that, you get 5-8 untuned whp.


No need for aftermarket cams to produce whp equal to rated flywheel hp. A B18a, with 92 and up cams, i/h/e, FPR, Adj. Cam Gears, & Timing tuned on the dyno can get up near 140 whp with 20% more tq than B16a.

 

I always thought it was a slight redesign of the quench area that increased this 2 hp....?

 

What I meant was that a b18b with all those bolt-ons would not have an advantage over a equally modded b18a.

 

quench combust area is the same. The heads are exactly the same, except for the Valve Cover.

I see. The difference in power gains would be close, except for whenever you get into the newer B18B's OBDII it produces less. *Transmission is also a factor. 94' and up hydro trannies have the longest gearing out of all the B-series trannies. Fastest setup would be an OBD-0 or OBD-I with the 90-93' Cable tranny. BTW, Tranny parts are interchangable.

 

Don't forget the ECU. You can add better cams and a better intake manifold. But the ECU also needs to be tuned to take advantage of them. So if you add the later stuff to an earlier engine and keep the earlier ECU OR if you run a later motor with earlier electronics (as is often does to simplify wiring when doing, say, a 1994-1995 B18B swap into 1988-1991 Civics), you will not realize the full power gains.

As far as the head, I am still somewhat unclear on this. Alot of people have said that the 1994-1995 head is better. But it is still just a PR4 head. The B20Z, on the other hand, uses a P75 head, which indicates it is an updated head compared to the B18B head.