Library : 1st Gen CRX CA Legal Engine Swaps
1st Gen CRX legal engine swaps
By Scott Harris, copyright 2002
cbstd@hotmail.com
Current California law states that you may change
engines and remain legal. The catch is that the engine going into
a car must be from the same model year or newer as the recipient
car. And all of the engine's pollution control devises (including
the ECU) must be used in the car. As with any car, swapped engine
or not, any replacement parts in the ignition, intake, or exhaust
must have a CARB tag. Headers and intakes without the CARB tag will
create an instant failure at the inspection station. Adjustable
cam sprockets are not allowed in California, so I reset my adjustable
sprocket to stock settings and replace the plastic timing belt cover
when I need to smog-check my car. And your ignition timing must
be at factory settings to pass.
JDM engines are cheap and plentiful. But they generally
are not clean enough to pass California emission tests. Installing
a JDM engine is a risk if you want to pass emission testing.
Now that the legal stuff is out of the way, lets
examine what engine/transmission combination can be swapped into
the 1984-1987 CRX: Anything engine/transmission that Honda makes
will go into the early CRX. End of article.
Oh, what is that you say? What goes in easily? Ah,
that is a very different story.
The very first thing to remember about the 1st Generation
(1984-1987) CRX is that the USDM engine and transmissions are very
different from all subsequent (1988 and later) Hondas. Consequently,
if you are changing to a newer motor, you will have to also change
to a newer transmission, axles and knuckles that match the new engine.
If money and engineering skill is no object, you
could shoe-horn a NSX engine into a CRX. Back in the 80's, somebody
stuffed two Accord engines into a CRX. If you do not mind your engine
sticking up above the hood, I suppose you could put a tall CRV B
series block and transmission into the CRX. But for practical purposes,
the B16 engine/transmission is the strongest stock combination that
can be made to fit with the hood closed.
Outside of engine size, the most important factor
to consider when swapping engines is engine mounts. As I said, the
B16 will bolt right to the CRX.. But you will either have to fabricate
your own motor mounts or buy an expensive set of motor mounts from
www.hasport.com. And you will have to figure out how to adapt the
car's wiring harness to the B series engine management system or
you will have to source a B series wiring harness. Sport Compact
Car did a series of interesting articles in early 2002 about a guy
in Arizona who put a B16 into his '87 CRX Si and all the specific
details are in those articles.
The cheapest and easiest swap to make into the early
CRX is to use the 1986-1989 Integra DOHC D16 engine and transmission.
This combination was available in the CRX in Japan and Europe and
it is engineered to go right in. Here is a brief overview of these
engines.
At the top of the family tree for the D Series, DOHC
1600cc, 16-valve engine is the JDM spec ZC engine of 135 hp. Next
in line was the Euro-spec D16A8 which makes about 120 hp. In the
US, we got the D16A1 Black Valve Cover version in the 1988-89 Integra,
with 118 hp. And at the end of the line is the D16A1 Brown Valve
Cover version in the 1986-87 Integra with 113hp. Many people refer
to all 1986-89 Integra engines as being a ZC, but this is not technically
correct. ZC is Honda's term for the top rated version of its engine.
If you can find all of the JDM parts, you could build a USDM D16
into a ZC because all D16 blocks are exactly the same.
The 88-89 Integra engine (black valve cover) is slightly
more powerful than the 86-87 models because it has a better intake
manifold, domed higher compression pistons, and lighter connecting
rods. The 86-87 D16 uses a distributor and ECU that are similar
to the stock 1985-1987 CRX Si so
if you use a 88-89 engine, you could either use the 86-87 distributor
and ECU (easy) or change over to the later wiring harness and ECU
(harder). The transmission gear ratios got changed in the 88-89
model and most performance people prefer the 86-87 gear ratios.
Parts are interchangeable between all versions of
the D16 so you could build an engine that uses the best parts of
all versions. For motor mounts, you should use the CRX motor mounts
for the timing belt side and rear of the engine, at the transmission
you must use the Integra transmission mount. Use a complete set
of 86-89 Integra axles including the intermediate shaft. and you
have to use the 86-89 Integra knuckle/spindle assembly so that you
can utilize the Integra 3-piece axles. The 86-89 Integra axles DO
NOT plug into 84-87 Civic/CRX knuckle/spindle's. Also, use a complete
86-89 Integra's shift linkage.
If your CRX does not have fuel injection you have
two options. You can retro fit your CRX to a pressurized fuel system
and wiring harness necessary for fuel injection. Or you can adapt
your engine to run on carburetors which will not pass California
smog control laws. A twin carb set-up is expensive and difficult
to balance. But it will also make more horsepower than a fuel injected
car once you get the mixture correct. Theoretically, it is possible
to put a D16 head on a stock EW block. I have never seen such a
beast and I do not know if there is any material available on making
this monster work. Now that you have that bigger engine in, you
are home free, right? Well no, because you have to help your suspension
deal with an engine that weighs almost 100 pounds more than the
stock engine. Thicker torsion bars (I suggest the 23mm size for
street cars, 27 or 29mm for race only cars), thicker rear springs
and a rear sway bar are all good upgrades. I also highly recommend
replacing at least the front lower control arm bushings, the sway
bar bushings and end links. And upgrading the stiffness of your
engine mounts by filling them with polyurethane glue (let them dry
24 hours before reinstalling them) is a cheap, easy and useful upgrade.
Of course all that extra hp will require extra stopping
power. I strongly recommend installing Integra front brakes as a
minimum upgrade. The Integra rear disks are cosmetically interesting,
but are heavier and not any more effective in daily driving than
the stock drums. I have HF aluminum drums on the rear of my '87
Si which are lighter than disks or iron drums, dissipate heat almost
as well as disks, and are much cheaper and easier to install than
disks. Steel braided brake lines, fresh brake fluid and quality
brake pads ( I prefer Porterfield or Hawk) complete the brake upgrades.
Avoid installing cheap cross drilled rotors, OEM disks are plenty
fine for 99.99% of the driving you will do. If you must get fancy
disks, PowerSlot rotors are good. What kind of performance can you
expect from this swap? 1/4 mile times, top speed and mileage will
vary according to differences in tire compound, transmission type
(LSD, gear ratio) and driver skill. Installing an engine with 25%
more horsepower than stock should make a significant difference
in speed and make a corresponding negative impact impact on mileage.
But you knew that already.
So what kind of swap do I have in my car? As I am
most interested in Autocross and track racing, I have elected to
keep the stock D15A3 engine that came with my '87 CRX Si. 1st Gen
CRX's that have been hybrided get classified out competitive classes.
Plus, I have increased horsepower in my stock engine and reduced
weight in my car to the point that my power to weight ratio is pretty
close to a hybrid car's. And the Mugen LSD that I have installed
in my transmission makes my power train much more efficient than
stock.
The 1st Gen CRX Si's stock D15A3 is an OK engine
(very strong bottom end with a so-so head design) that can be built
in racing trim to make upwards of 180hp. A street legal D15A3 can
be built to make almost 120hp without the weight penalty of the
D16.
If you see any errors or omissions in this
article please contact me and I will make corrections immediately.
cbstd@hotmail.com
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