ECUtune Stage III development

[SVXtasy]

[QUOTE]Actual measurements with the wideband 02 meter of effects on afr due to adjustments to the constant verify that the constant and it's mathmatical properties were correctly identified. With this verfied we can go ahead and make the sofware adjustments for the 740cc injectors and install them.

This by the way is the biggie. Lest it escape anyone's attention, today the last step necessary to unleash major horsepower from the svx was taken. The rest is just engine building, forced injection, the usual stuff the performance industry excells at. So drop the ballons and crank up the music the SVX is now officially in the same league as the skyline....if you build it we can tune it.QUOTE]

Now this is exciting!!!!!

[mbtoloczko]

Originally posted by longassname
We've acquired our set of Nismo 740cc injectors which have become annoyingly difficult to source recently....

Manifold looks cool, but 740 cc/min injectors? According to my turbo calculator, even at 15 psi of boost, 11:1 afr, the stock 36 psi fpr, and a BSFC of 0.5, only 550 cc/min injectors are necessary. I'm sure the 740 cc/min injectors will work fine when the gas pedal is pressed to the floor, but from what I've read, its very difficult to make an engine idle or run smoothly at low fuel delivery situations with way oversized fuel injectors. From what I've ready, the old Legacy Turbo injectors are a direct fit onto the SVX fuel rail and flow at around 400-420 cc/min. If you install an adjustable fpr and set it to 55 psi base pressure, those injectors ought to be enough for 8 psi of boost. Someone at NASIOC also suggested that the new STi injectors may fit. Haven't checked that out yet though. Anyhow, you might have better luck tuning the motor with a smaller injector.

[mikecg]

Originally posted by Jimsbaby
ok new idea to get more $$ for this project sell tickets to sleep near the car while getting worked on...1. more money coming in is always good...2. who else would protect the svx better then a fellow svx that wants to have that much power...3. i want to be first to sleep near it so i can be first to hear this baby scream and purr hmmm power (homer simpson voice)

Keep up the GREAT work man its coming along alot faster than i would have though

PS glad i got that second job now jimmys getting a new svx toy

Jim

You mean you want to be the first to scavange the parts off it while noones looking

[Guard-TL-]

87 Octane is for girly men

[svxsubaru1]

Originally posted by Earthworm
It also looks like a large 6 legged spider

Thats the first thing one of my friends said when he saw the stock SVX intake with out any thing on it . I think it look more like a ant tho .

I also heard the difrence between semi large injectors and large ones is not that gig. Ive rode in a 3rd gen Supra with around 740 injectors and it idled like what seemened normal.

[Subafreak]

Originally posted by longassname
We got the wide band o2 meter functioning today. This allowed us to hook up the emulator to the ecu and verify our ability to adjust the constant used to calculate the base fuel injection quantity. This is the constant that we adjust to match the size of the fuel injectors. As usual our understanding of the sofware and calculations based on it were dead on. Actual measurements with the wideband 02 meter of effects on afr due to adjustments to the constant verify that the constant and it's mathmatical properties were correctly identified. With this verfied we can go ahead and make the sofware adjustments for the 740cc injectors and install them.

This by the way is the biggie. Lest it escape anyone's attention, today the last step necessary to unleash major horsepower from the svx was taken. The rest is just engine building, forced injection, the usual stuff the performance industry excells at. So drop the ballons and crank up the music the SVX is now officially in the same league as the skyline....if you build it we can tune it.

I have no idea what you just said....but WOOHOO!!!!!!!

[EddieSVX]

Originally posted by Subafreak




I have no idea what you just said....but WOOHOO!!!!!!!

LOL...I second that!

[oab_au]

Originally posted by mbtoloczko


Manifold looks cool, but 740 cc/min injectors? According to my turbo calculator, even at 15 psi of boost, 11:1 afr, the stock 36 psi fpr, and a BSFC of 0.5, only 550 cc/min injectors are necessary. I'm sure the 740 cc/min injectors will work fine when the gas pedal is pressed to the floor, but from what I've read, its very difficult to make an engine idle or run smoothly at low fuel delivery situations with way oversized fuel injectors. From what I've ready, the old Legacy Turbo injectors are a direct fit onto the SVX fuel rail and flow at around 400-420 cc/min. If you install an adjustable fpr and set it to 55 psi base pressure, those injectors ought to be enough for 8 psi of boost. Someone at NASIOC also suggested that the new STi injectors may fit. Haven't checked that out yet though. Anyhow, you might have better luck tuning the motor with a smaller injector.

I tend to agree with you on this. Why so big?. It's very hard to get big injectors to function well at idle. the amount of fuel injected is the same amount as a NA engine, but the larger nozzel size, means that the 'on time' is almost cancelled out by the 'pick & release time' of the injector.

As the fuel pressure rises, as the boost increases, there is not a lot of extra fuel, needed to be added. We have seen No2 set ups adding the same amount of HP, through the std injectors, with added pressure.

Cost of the project can be a major factor in its up take, the lower the cost the more you sell.

Harvey.

[longassname]

Today's pictures are of the fuel rails and the installation of the 740cc Nismo injectors into the fuel rails. Our injectors, both the old and new, are what are called side feed injectors. As the name indicates, side feed injectors get their fuel feed from the side. This means they must seal at the top of the fuel rail and the bottome of the fuel rail and have open access in the fuel rail for the fuel to flow to the next injector and into the inlet ports on the side of each injector. You'll notice in the pictures that the new injectors are an exact fit. They are actually made by the same manufacturer that made the factory injectors. The old fuel injectors as pretty much all of the engine management hardware on our cars are labeled JECS. The Nismo fuel injectors are labeled UJ, for unisia jecs (JECS has merged with Unisia). There are differences in the design of the body of the injector between the top and bottom orings; however this does not apear to be any problem. The ports on the old injectors were towards the top side of the openings into the chambers the fuel injectors are held in while the ports on the new injectors are towards the bottom side. I can't speak for certain about why the change on the larger injectors but it seems likely to me that the height of the ports is made closer to the tip in order to reduce "latency." Latency is the measure of the time it takes between first energizing the injector and the actual release of fuel. Although the 740cc Nismo injectors can flow two and a half times the fuel as the old injectors their latencies are very similar. Back to the differences in the body of the injectors. Again, this is just a perception of mine and not known for certain, but it appears that they change the body design along with the port location in order to keep the open space inside of the cyllinders where the injectors are housed the same. I'm guessing they match the volume of the space around the injectors to the volume of the same length of fuel rail between the injectos so that there are no fluctuations in pressure accross the rails.

[svxsubaru1]

Originally posted by oab_au


I tend to agree with you on this. Why so big?.

Harvey.

Maybe hes building it up for a stage 4 SVX here completly built engine that going for 800 horse, and the only reason hes not telling us is becasue he knows he would find SVXers constently trying to look at it and try to sleep in the car .

[Myetball]

I plugged some numbers into an online injector worksheet. Based on six injectors running max. 75% duty cycle, 0.60 brake specific fuel consumption, and 49psi in the rail. 720cc injectors would support up to about 550 crank hp. Assuming we're losing approximately 35% to the drivetrain that leaves 357 hp to the wheels.

Of course the numbers I used are generic but it sounds pretty close what I would expect. Then again, those are max figures. I wouldn't be surprised if the actual finished kit puts out over 400 crank hp.

[NikFu S.]

Crazy.

[longassname]

I installed the fuel rails with the 740cc injectors into our test vehicle thursday and did the preliminary tuning of the software to make it run. Yesterday and today I did the fine tuning and seem to have it down very nicely. Working backwards from the changes I made it appears the factory injectors are someting like 278cc's. Can't say exactly due to fuel pressure differences but they are definitely right around there somewhere. Factory idle was maintained without any problems.

Todays educational lecture:
The Nismo 740cc injectors are actually a little bit faster opening than the svx's factory injectors. Their flow rate is 2.65 times that of the factory injectors.These injectors are safely good for 550-600 hp depending on manifold pressure and assuming a bsfc of .6 and a duty of no more than 80%. The fuel pressure remains unaltered except that it will be increased by the same amount of boost. This is much better than running a higher fuel pressure for several reasons. First and most importantly we can accurately adjust fuel delivery with the ecu software. Second the fuel stream is more accurate so that a solid stream will hit the valve and be completely vaporized rather than creating a mist where more fuel is wasted. Third the fuel pump will last infinitely longer and be more dependable at typical oem pressures than at high pressure. These are the reasons oem's use the high 20's to mid 40's pressure range and they hold even truer for performance applications.

Summation of the fuel injector choice:
These fuel injectors will very accurately deliver fuel for stage III including at high rpms where the time available for fuel injection is short. They also have room to grow so once an engine is built to support higher levels of boost all that will be needed to have stage III put the power out is a smaller pulley.

[Matthewmongan]

what are you a mechanical engenier?

[SVXRide]

Michael,
Very nice! How does the A/F look at tip in (okay, an old "carb" question ) - let's say "off idle up to 2.5k rpms"
-Bill
p.s. how are you going to handle the "software" change to the stage 1 chip to provide the improved timing advance curve?