ECU remap, nitrous, & supercharger

[longassname]

I don't know about 0-60 times but I did use a drag calculator and the expectation for stage 2 is right around 13 seconds flat. 1/4 mile times will most likely be between 12.9 and 13.1 seconds.

[Chiketkd]

That's flying. You should call that your "STI/EVO Killer Package"!

Originally posted by longassname
I don't know about 0-60 times but I did use a drag calculator and the expectation for stage 2 is right around 13 seconds flat. 1/4 mile times will most likely be between 12.9 and 13.1 seconds.

[TomsSVX]

and some idiot told me i would never be able to compete w/ my bro's 300zxtt. HAHAHAH wait till i get my 5 speed in my fwd with stage 2, i will have the fastest svx around

[Sonar]

Originally posted by tomssvx
and some idiot told me i would never be able to compete w/ my bro's 300zxtt. HAHAHAH wait till i get my 5 speed in my fwd with stage 2, i will have the fastest svx around

[longassname]

I know the details of electronics design are beyond the understanding of probably everyone reading the thread but I think I can lay everything out so that everone can at least get the basics of what I'm saying.

As you all know the core technology that allows us to run this big nitrous oxide kit on the svx is our ECUtune stage 2 chip with nitrous control. The chip plugs into the rom socket of the svx ecu allowing us to replace the code which runs the engine with a new version. We use large enough memory to fit two complete versions of the code and provide a circuit to allow the switching between the two versions. Which of the two versions of code runs is determined by either a "high" or "low" state at a particular address line. To set the default either a "pull up" circuit is used to set the address line to high or a "pull down" circuit to set the address line to low. A pull up circuit provides a very week connection to Vcc (power) a pull down circuit provides a very week connection to ground. Connecting a pull up to ground overrides the high state to a low. Connecting a pull down to power overrides the low state to high. We were orginally using a pull up circuit and switching to the version of code run by connecting to ground.

I hooked up our emulator today which allows a laptop to pretend to be the memory and can monitor the functioning of the "target"--the ecu. I set the software to mark accesses to the memory section which holds one version of the code in red and accesses to the memory section that holds the second version of code in yellow. Monitoring the function of the ecu I saw that the ecu was accessing the wrong version of code without the nitrous switches being engaged. I broke out the fancy fluke multimeter to diagnose what was going on. I determined that the nitrous relay leaks ground back onto the circuit. While it's a tiny amount of ground not capable of activing normal dc electronics it is enough ground to overcome the miniscule connection to vcc which the full up circuit on the ecutune stage 2 chip provides. I hadn't expected this but hey that's why I test these things. The solution is to switch to using power to switch versions of code on the chip instead of ground. I had the compents available to make the changes to the chip and soldered one up with a pull down circuit and a voltage regulator to convert the 12V-14.4V (it will actually handle up to 24V) from the ignition power source the nitrous wiring uses into 5V (the propper voltage for the chip).

I haven't rewired the nitrous system yet but I had a convenient place to take the ignition power from the wiring I did the other day--the back of the arming switch. I made the conection to the chip there and was able to use the arming switch to switch it on and off. I then hooked the emulator back up and retested. It now functioned propperly. With the arming switch off all accesses were to the default version of code set by the pull down circuit. With the arming switch on sending power to the nitrous solenoid and to the chip all accesses were to the second version of code.

Ok now for pictures. Here's the emulator.



Here's what I see on the laptop screen. Notice in the little window to the lower left the traces of memory access are red.



Another picture of the laptop screen but this time the arming switch is on so the ecu is accessing the second version of code and the traces are in yellow.



Here's a close up of the ECUtune stage 2 chip with the pull down circuit and voltage regulator. Fortunately when I originally did the pcb design for this prototype board I hadn't decided on the pull up version and included a spot for a voltage regulator. Now that we're tested I can do the final pcb (printed circuit board) design and go into production on them. I have 10 of these boards and will go ahead and sell as is with the understanding they can be exchanged for the production version.



Tomorrow I'll rewire the nitrous system to put the throttle switch onto the power output of the arming switch and the input for the chip onto the ouput of the throttle switch. Then I'll do a test 1/4 mile run before making my dyno appointment. I have use of a "gtech" to measure our 1/4 mile time. So look for that tomorrow.

[Phast SVX]

[Chicane]

VERY cool. I can't wait to see the results of all your hard work.

- Rob

[immortal_suby]

I think I am in love.

[Chiketkd]

Very, very cool! Look forward to seeing the results... It'll be interesting to see how fast you can make these SVX's go!

[FlagstaffSVX]

Wholly crap! Here's looking forward to tomorrow!

So how compatible are stages 2 & 3 gonna be?

[TomsSVX]

Originally posted by FlagstaffSVX
Wholly crap! Here's looking forward to tomorrow!

So how compatible are stages 2 & 3 gonna be?

exposively compatible

Stock AWD SVX - 230hp: 0-60 in 7.40 seconds (close enough to actual).

AWD SVX w/ stage 2 (assuming a 130hp gain at the flywheel with NOS) - 360hp: 0-60 in 4.73 seconds (obviously a little extreme).

AWD SVX w/ stage 3 (assuming a 40% power gain at the flywheel, as discussed earlier in this thread) - 322hp: 0-60 in 5.29 seconds (perhaps slightly extreme, but feasible).

I believe I may already be in the 5.1-5.3 0-60 times with exhaust and intake....I have to get out to cobb and dyno and to the track and see what its doing for times....But, if you add in the ****ty from a stop launch that the automatic does, it could be hurting the 0-60 times, with a good 5 speed i could chirp the tires and have that thing *POOF* B-Gone....

[Chiketkd]

Hey tancred, what kinda times did your g-tech say you were doing 0-60 before the exhaust mod?

Also, have you used the g-tech yet to run a 1/4?

-Chike

Originally posted by tancred
I believe I may already be in the 5.1-5.3 0-60 times with exhaust and intake....I have to get out to cobb and dyno and to the track and see what its doing for times....But, if you add in the ****ty from a stop launch that the automatic does, it could be hurting the 0-60 times, with a good 5 speed i could chirp the tires and have that thing *POOF* B-Gone....

Originally posted by mranderson


does this calculation take into acount gear ratios and if it does could you do it with 4.44? thanks.

By the way those numbers make me want to scream out like a little school girl with excitement.

Unfortunately, it does not take final drive gearing into account.

Can't wait for the results later!

The g-tech says the SVX with cold air intake was doing a 6.3 w/ shift kit. 0-60. W/ 2 people in the car. 1 being about 275lbs...

the g-tech now says the SVX with exhaust and shift kit cranked to as tight as it will go, at a 5.4 I believe its faster then that.

According to modern garage the local TUNING gods for SLC, gtech has a .3 sec error margin, in either direction...