B18C5-EH2

I was looking at the 1990 Honda Service manual today and I noticed the D15B1 STD engine is rated at 70hp, while the D15B2 Dx/LX engine is rated at 93hp. This is according to page 1-2 on the same page as chassis and paint codes under "General Information."

I've always known that the two engine were rated about 2ohp apart, but lately I've really been wondering:

What exactly makes the engines 20hp apart?

They are both 1.5L and dual-point fuel injected.

I'm looking in the manual, but I cannot see anything to distinguish the 93hp engine from the 70hp version.

Anybody know for sure?

I have theories that it's probably the cam and maybe port sizing?

Thoughts?

Caleb V

There is a restrictor plate underneath the downdraft TB, the TB is the same diameter as the DX, the cam is different, the ecu is different.

blackZC (W)

i always thought it was just a rating thing. Ive run DXs off of STD ECUs..
I know a honda jedi master that restores 4 gens for a living. he said every number of every part is identical. ???
plus when you put a DX motor in a STD with a 4 speed it does feel like it has 70 hp lol..

StorminMatt

Also, the STD gets a close-coupled cat with a shorty exhaust manifold. This certainly hurts power.

91civicDXdude

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Also, the STD gets a close-coupled cat with a shorty exhaust manifold. This certainly hurts power</TD></TR></TABLE>

only the 88-89 has the HF style manifold. 90-91 STD has the normal 88-91 4-1 manifold.

89dxhunchback

I gave my old DX ecu to a guy at work and he slapped it in his 91' STD. and he said it made a huge difference !!!

20HP in a civic is more power gained than stock vs I/H/E !!! Wonder what a DPFI with a Si head, and DX ecu would put ?? hehe..

Makes you wonder why and the hell honda didn't just build a HF, DX, and Si...

jlicrx

the biggest difference is that the B1 is an 8-valve engine and the B2 is a 16-valve

Caleb V

The D15B6 is the only 8 valve motor in the lineup with 8valves on the CRX hf, the STD motor which can be either a D15B1, D15B2(mine is a B2) has 16 valves and is identical to the DX internally, I need to verify if the cams are actually different sometime. The ecu is definetely different I installed it in mine without changing the restrictor plate yet and noticed a mediocre difference, fuel cutoff is a little higher as well.

B18C5-EH2

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jlicrx &raquo;</TD></TR><TR><TD CLASS="quote">the biggest difference is that the B1 is an 8-valve engine and the B2 is a 16-valve</TD></TR></TABLE>

Wrong.

You're thinking of 1992-1995 Cx engines, which were 70hp and 8 valves.