The Honda D Series motor was in production and put into a
ton of cars from 1984 to 2005. They have
varying power levels and trims but the basic motor is the same. You can check out this Wikipedia article on
the web for all the different variations of the engine.
What I am more interested in is increasing the power levels
of this lower end engine. Achieving
cheap speed and not spending a ton of money to accomplish this is my goal. This engine is found in tons of cheap Honda’s
all over the internet and can be a nice little project for someone, me
Keep in mind that adding power to any motor is fun. Increasing the power even a little bit can
improve the driving experience of a vehicle by leap and bounds. Even more so if there is some suspension
tuning and other items involved.
Let’s start by going over what kind of modifications you can
do keeping the motor in a naturally aspirated configuration. Basic bolt-ons come to mind like and intake
system and exhaust. It seems that a
basic header can improve drivability and increase mid range torque quite a bit
to give the engine a little bit more grunt.
It is also possible that the header can give you up to 5 HP more at
You can put on a Cold Air Intake or a Short Ram intake and
maybe see 1-2 HP gain, but putting a K&N filter in the stock air box may
accomplish the same thing.
They make intake manifolds for these motor a plenty. This seems to be where you can actually gain
some power so there are a couple of options from many different companies. I was able to find a dyno sheet on the
Edelbrock Performer X for the D-Series that showed a 5+HP gain using their
intake manifold. I am going to make the
assumption that the others will gain around the same.
At this point, you’ve put the easy bolt-ons to the D-series
motor and you’ve bumped up HP to maybe 12 more than you had before. That is not too bad, considering they don’t
make much power to begin with, if you are looking at percentages, it would be
in line with doing those same mods on any other motor. If you started with 100HP and now have 112HP,
which would be a 12% gain. Not too bad!
If you are interested in keeping the car Naturally
Aspirated, there is more you can do to increase power some more. A nice camshaft will gain you some more power
as well. Bisimoto and Crower both make
camshafts of varying capabilities both offering street and race performance
cams. I have not found any dyno sheets
that show what the gains might be but a stage 1 cam would seem to net you about
10% more HP and a stage 2 around 15%.
Adding another 10-20 HP to the naturally aspirated motor is not too bad. If you had all of the items listed above you
might have that little D pushing around 120-130 HP. Keep in mind; by percentage increase all
these modifications are worthwhile.
There is some more you can do if your goal is a Naturally
Aspirated D Motor. You can change out
the pistons to increase the compression ratio.
If this is a route that you want to go in, you can pretty much exchange
any D-Series piston into any motor since all D-Series are 75mm bore. There is power to be found here but not much
and is probably not worth the money. The
general rule of thumb is that for every point of compression, you gain
approximately 4% more power. Making such
little power there is really no need to strengthen the internals when staying
Naturally Aspirated. If you went from
the average of 9:1 to 11:1 you would only gain another 10HP. If you had all the money in the world, this
may be worth the cost, but I know I’m not doing it…..
That is my D-Series All Motor post, and I would probably go
as far as putting in the Cam to get to that 120 HP number in my stock
d-series. I would definitely pass on
changing the pistons for higher compression ones as that would not be very cost