t-von

iTrader: (8)

Sounds interesting and hopes this works for you. If it does I may be purchasing one myself. The only problem is, I've run out of aux outputs with my Haltech.

j9fd3s

iTrader: (3)

this is how the factory system works. it runs ~9v to to the pump until it sees 1psi of boost, and then it switches over to 12v. Mazda used a relay, and a resistor. with the FD when the relay is ON, the power goes through the resistor, and when it switches off its full whack, as they say.

Monsterbox

iTrader: (6)

1hr drive today in 90F weather. Street temp 110F.

Coolant temps reached 200F, settled around 200-205F in traffic with fans on medium switch.

Fuel pump running at 9v under 3,000RPM (switched it back over to RPM as I don't trust the speed of the map sensor response). Surprisingly, no noticeable decrease in AFR at low loads.

Car was a little difficult to restart at 200F, but if it cools down to around 190F it starts right up! I believe it may need less cranking fuel at higher temps.

No dancing fuel pressure, no cavitation sounds, and no drop in overall PSI at full speed! Pump is definitely quieter when I switch on the override. So I'd say running the pump at 9v helps keep fuel heat soak down tremendously! I'm going to see if I can get it down to 7-8v, as there's still plenty of fuel in the map, high 12's low 13's at idle-cruising right now.


Keep in mind, when I say 7-8v, the pump isn't actually operating at 7-8v, its operating off a PWM that can only be read as a voltage drop on a multimeter. I'm not sure how to explain the physics, but aeromotive explains that its not actually a voltage decrease to the pump as this would damage many 12v motors.

Vicoor

Wouldn't it be best to base fuel pump output on injector duty cycle?
After all, that's what determines fuel demand.

Monsterbox

iTrader: (6)

Yea that definitely makes the most sense. But its just pretty simple to program a 3k RPM switch-over and never think about it again, considering that there's no boost under 3K rpm anyhow, and majority of street driving is under 3k

t-von

iTrader: (8)

Your pretty rich under cruise. Under light loads/steady state cruising, you can run 14.7-15.50 range all day long and save some fuel. Remember all turbo rotarys are NA when not under boost. It wont harm the engine one bit. Your spark plugs will foul out less frequently also. My A/F is set at 15.40 on the highway for best economy. On the hot starting issue, do you notice a decrease in cranking energy compared to cold starts? I think I'm gonna try that diode tip from the your other thread because my cranking speed is just to weak during hot starts.

Monsterbox

iTrader: (6)

Yes, its certainly fat under cruise. Its even down in 10.5 in boost.

I don't mind so much, more 2 stroke oil in the motor I also have decel fuel cut off, so it continues to keep the motor lubricated on decel and deters tail gaters

But eventually, Ill go in and lean it out a little. I believe the gauge reads a little on the rich side, as the car doesn't want to drive much over 14.0 afr's


No, at hot start, cranking energy is just as strong. I see around 13.8-14v when the car has been cruising for a while. The diode trick might help, but do make sure you have large, at least 0 gauge wire to your starter from your battery!

kevinbtz

iTrader: (4)

Finally back with some results from the "pressurized 044" test. Both test done on the same day 98+ deg weather @ 26lbs of boost and 52 base fuel pressure on Shell 93. Before the installation of the 255 in the prepump location it would drop up to 30 psi between 7,000 and 8,000 rpm and had the noticeable loud cavitation sound at idle. After pressurizing the surge tank to 20psi (lowest it would go) the 044 lost the cavitation noise and was a good bit quieter over all, under boost the fuel pressure held rock solid all the way to red line. I am for sure keeping this set up.

t-von

iTrader: (8)

Wow thx for posting this info. Looks like I may be adding a regulator to my setup as well.

Edit: Hmm the more I think about this, the more I'm surprised it works. Keeping the surge tank at 20psi apparently isn't putting to much back pressure from the other fuel rail regulators return to the surgetank. Normally fuel from the fuel rail regulator will free flow into the surge tank. Now it's flowing back against 20psi pressure. I thought that back pressure from the primary rail might effect somethings. Guess not!

jetlude

iTrader: (9)

Interesting

WANKfactor

iTrader: (1)

^this is awesome. Hats off to yousir for making it happen. Did putting a pressure reg on the surgetank overflow cause need to readjust your main reg again?
Is it maintaining steady pressure? No gremlins at all?

Meanwhiles mines in for a tune and running out of fuel at lowly 10psi boost. Not sure if the pierburg "veyron" pump is the issue or not. Ill get the car back and do some tests.

Thinking to pressurise surge with a carter black to 044 again maybe.
Thinking to maybe run return line back to fuel tank? Thoughts?

kevinbtz

iTrader: (4)

Base pressure stayed exactly the same, I was ready to route the fuel rail return line straight to the tank but did not have to. Here are some screen shots of the before and after data logs of 3rd and 4th gear.