Stock everything apart from 440cc injectors,CAI & ECU - 213 hp / 148 ftlbs
As above plus a dry nitrous shot using a 0.47 jet - 285 hp / 233 ftlbs
The vehicle was dyno'd on a DynoPack so the figures are 10-15 hp higher than
what you will see on a DynoJet. The torque a little bumpy down because I had
the nitrous operating a little early on that run, plus the engine receives
fuel slightly before it receives nitrous and so runs rich for a little while.
The recommended nitrous jets were 0.24 (which made such a small amount of hp I
did not bother to dyno it) and 0.32 (which made 40 hp).
We also found that there was no difference in hp between having the nitrous
spraying into the intake and backwards (spraying up the intake). We opted to
spray the nitrous so that we got maximum mixing of the nitrous and air, as
spraying straight past the throttle body looked unhealthy for cylinder #1.
Note that this is different vehicle than the supercharged / nitrous vehicle of
which dyno charts were posted yesterday. We've been testing how nitrous works
with the programmable ECU...
(the good thing about nitrous is when something goes wrong you can also see
the funny side of it)
As long as you have bigger injectors to deliver the fuel and...
As long as it is tuned with safe ignition and fuel values.
The Programmable ECU does several things
1) Switch the nitrous on
2) Retard the timing
3) Add fuel
4) Switch the nitrous off beore the redline
The nitrous delivery is programmable for :
- vehicle speed (so it doesn't activate in 1st or 2nd gear for example)
- Air pressure (so it comes on only in boost for example)
- Throttle position
Injectors don't make any difference to power. Plus bigger injectors are of
no use without tuning. The car made 212.5 on stock injectors, 213 hp on 440 cc
injectors. The 0.5 hp was probably from a slightly colder run. The car made
283 hp @ 7000 rpm (with nitrous) on stock injectors at about 94% duty cycle,
which was about the same power as with 440cc injectors. By putting in bigger
injectors and running the nitrous to higher rpm I hoped to make more power,
but the power falls of after 7000 rpm with nitrous (at a guess the stock
exhaust system is too restrictive).
We're seeing more variation in power with the K20 engine than the B-Series.
The normal range on a dynopack for a K20A2 with reflash + CAI is 195-205 hp.
My car made more power even when 100% stock (180 hp vs average of 165-175 hp),
so lucky me.
So, this is nitrous done safely.