I'm sorry to be the one to tell you this shayne but u will not be running pump gas at 8-10lbs at sea level on a pro or any other 2 stroke for that matter
wrong
I highly doubt u would be able to run half those boost numbers at sea level
completely wrong
A low comp turbo head and a 3* timing key might allow u to run 5-6 lbs on pump, maybe a little more if your lucky
wrong
No matter what though you'll be playing with fire as there is never any guarantee of the octane level of the fuel u buy at the pump
well, with an agressive knock calibration and no too much timing you will be safe, very safe(proven already)
Long story short, if you're going to turbo your sled, please put quality fuel in it
same as previous.
for reference`in another post.
First of all, i would like to introduce myself, my name is sebastien and i am the tuner and developper of this vipec plug in ecu. I have never posted on this forum before but now i think it is time for me to clarify some things
like you, i do believe in math for 2 strokes or 4 strokes, a engine is an air pump, thats it!
for the injectors duty cycle, let me explain..
i decided to go to 43 psi because with the rising 1 to 1 fuel pressure regulator, we will have room for 15 psi with the stock fuel pump..
the stock fuel pump runs @ 58 psi, by dropping the fuel pressure to 43 psi, i know i will be able to use the good effects of the fpr without overloading the stock fuel pump and the charging system.
if you are not using a rising 1 to 1 fuel pressure regulator here is what happens
lets say you have 500ccm injectors at 58 psi end you are running 8 psi without fpr, that meens you get 58 psi - 8 psi = 50 psi real fuel pressure
now you got only 464,24 ccm injectors, that is way probably you are running out of fuel... as much you increase the boost, as much you decrease the injectors size if you are not running fpr
at high altitude, 7000 and over, you get around 75 kpa of absolute pressure, with a 6 psi spring in the hm turbo kit (aerocharger air to water intercooler), i was getting 115 kpa asolute at full boost, and i was using only 80% duty cycle to achieve the same air fuel ratio.
if you get the engine running perfectly normaly aspirated, then when it gets in boost, you wont have to increase the pulse width to get the same amount of fuel in the engine..
now i am at see level and with the same 6 psi spring, i get to 160 kpa absolute and i am still using the same injectors but i am close of 90% duty cycle, with the 2011 injectors that are smaller the 2012..
let me explain
here is the formula to calculate how much boost you will be able to run at high altitude with stock injectors..
160 kpa absolute @ see level - 75 kpa absolute at 7000 feets = 85 kpa of boost available
85 kpa x 0.14504 = 12,33 psi
that meens that you can run 12,33 psi at high altitude with no problems,
here is the REAL maximum for stock 2012 injectors
12.33 psi @ high altutude
8 psi @ sea level
i don't believe in using fuel to cool down the reeds valves, having a good intercooler system will save them, not fuel....
fuel requirement for a given horsepower is always directly related to brake specific fuel consumption, by getting the engine running efficient, you can drop the bsfc from .65 to .58 no problem even maybe .55, that meens that you can use less fuel for the same horsepower.
I am not telling i make a 350 jet a 500 jet, i am just using every drop of fuel efficiently
why our ecu is the best solution for turbo charged application
1. first of all, when installing the air box and the turbocharger, you will change the volumetric efficienty of the engine even when it runs normaly aspirated, i found that a 2 strokes engine is really responsive on exhaust back pressure and intake back pressure. that is why i had to re-tune the entire fuel map with no charge tube before thinking about boost..
the stock rmk was pulling 130 hp on the dyno, when we installed the turbo kit, without charge tube, the engine was pulling only 105 to 110 hp, this is why you have to get the engine running perfect without boost first, i don't see how it can be done with a piggyback.... everything is possible, but probably takes a lot more time...
2. the ignition as to be perfect on boost, that is why you need to retard the ignition when boost comes in, a piggy back usually only controls fuel, what about ignition???????
of curse you can rely on the knock control from the stock ecu, but everything changes when knock happens, the stock ecu will add fuel and back off the timing, you will reajust your piggyback and you have just started chasing your tale....again and again.
3. will it be hard to get it running with the vipec...
yes it is hard to get a 2 strokes turbocharged engine running perfeclty. that is why i am putting a lot of time on getting the base map as close as possible from perfection.
boost will be always boost, we all ready have some real good running turbocharged sled using our products, i don't think i will see a big difference between any turbo kit manufacturers, boost will always be boost, 6 psi is 6 psi.. the big difference between all turbo kits will be air charged temperture,
4. barometric compensation, we included the barometric pressure to the fuel equation, that meens that an engine running 8200 rpm per minute will have 8200 baro update a minute, if you go up or down a hill
i'm sure fueling will stay on target
5. we have the possibility to run staged injection, but i think it is best to maximize the stock injectors and then use the stagged injectors to help with the fueling. i think it is the best way to get the engine running clean,
i am not a great sled ridder for sure but i don't see how i could handle more power then 12 psi on those machines
my arms are dead right now lol
hope this post help and was not to long!!!!
sebastien
precision efi
