Originally Posted by JasonC SBB
(Post 1382868)
Hang on that's not right.
10 ft of 8 gauge is 6 milliohms. The 20A fuel pump will cause 0.12 V of drop. Not worth worrying about. Wire it to the battery using 14 gauge. Be sure to fuse it with a 30A fuse, sitting near the battery. |
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I am using one-way distance, so the round trip is 16ft.
http://www.calculator.net/voltage-drop-calculator.html |
Originally Posted by Savington
(Post 1383288)
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[QUOTE=Savington;1383288]I am using one-way distance, so the round trip is 16ft.
Just ground it to the nearest chassis point. It's silly to ground it back to the battery. |
Originally Posted by JasonC SBB
(Post 1383298)
Just ground it to the nearest chassis point. It's silly to ground it back to the battery.
More to the point, knowing the voltage drop from alternator to battery is only half what we had originally assumed does make me feel better about running the FP power from the battery. |
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How much do you charge for that? My 01's headlights are beginning to look crappy...
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^ this
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X3
I might have a friend or two interested. |
Originally Posted by Chilicharger665
(Post 1383839)
How much do you charge for that? My 01's headlights are beginning to look crappy...
Hoping to have it back up and running next week. Just a few details to finish up and then it's back on the road. |
^not that great. Light output is very splotchy because of the inferior lens, and bulb placement, but bright in some ok spots. I have a 50W system in my stock headlights, measured over 5000 lumens in the hotspots, but the light is all over the place (2001 miata projector)
Still way better visibility than stock. |
Originally Posted by thumpetto007
(Post 1384106)
^not that great. Light output is very splotchy because of the inferior lens, and bulb placement, but bright in some ok spots. I have a 50W system in my stock headlights, measured over 5000 lumens in the hotspots, but the light is all over the place (2001 miata projector)
Still way better visibility than stock. |
anyone that needs this done and is serious not just a tire kicker just pm me, plz don't clutter up Sav's thread.
Originally Posted by thumpetto007
(Post 1384106)
^not that great. Light output is very splotchy because of the inferior lens, and bulb placement, but bright in some ok spots. I have a 50W system in my stock headlights, measured over 5000 lumens in the hotspots, but the light is all over the place (2001 miata projector)
Still way better visibility than stock. for most people, the regular 01+ lights work just fine with HID
Originally Posted by ridethecliche
(Post 1384143)
But you're also comparing this to the lights you're selling for over 2 grand so....
Originally Posted by Savington
(Post 1384095)
Not enough. Can't wait to see how they look with the 4500k HIDs.
Hoping to have it back up and running next week. Just a few details to finish up and then it's back on the road. |
I completed my Fuel Pump re-wire project today, so I figured I would post the results to finish out my contribution to the discussion.
1991 Chassis, DW200 in-tank fuel pump. Battery Voltage 12.4VDC Meter: Fluke 179 My approach was to retain the stock relay location, source power from the AIR BAG battery fuse located in the relay & main fuse block. The air bag fuse is changed from the 10A to a 20A. This is possible because, well ... no airbag. A 40A relay is used (MEISHUO MAH-112-C-3) in place of the stock DENSO. I don't know if the DENSO has the current carry capacity, but the contact and coil share a common internal connection, so it is impossible to de-couple the coil source from the contact source. The air bag backup battery harness is located really close to the '91 fuel pump relay so this is convenient. The coil for the new relay is driven using the RED-WHT wire that was used to drive the original fuel pump relay. I did this, because after reviewing the wiring diagrams, the only reason I can see for Mazda to have wired it this way in the first place was that there were safety concerns relating to the fuel pump having power when the main relay either failed open or the engine fuse blows. With the RED-WHT driving the new relay coil, this relay will open under either of these conditions. A double fault failure (the new relay, and a failure in the main relay circuit) is an unmitigated risk. There are two additional reasons I decided to go this route: - the previously discussed voltage drop to the battery, which measurements show could be a very real concern - Sourcing the current directly from the battery will increase the current through the 80A MAIN fuse in the relay and main fuse block. I do not know how much margin Mazda put into the fusing current there, but I would be surprised if they incorporated THAT much margin. Don't know ... I took measurements of the voltage drop from the stock relay location to the pump with both the stock wiring, and the new 10AWG stranded pure copper primary I used. They are presented here: Stock wiring: 0.482V 10AWG: 0.198V DW's posted specs are at 13.5V for this pump. They claim 9.2A current draw for 40PSIG. This current will obviously increase at lower voltages. My meter has a 10A measurement limit, and I didn't feel like blowing the internal fuse. Anyway, hope this helps |
2 Attachment(s)
Final FPR/filter config. Filter is a Fuelab 818 with 6ppm fiberglass element (E98/Methanol safe). That feeds into the left side of the Fuelab 535. Return to the tank comes out the bottom, feed to the fuel rail comes out the right and jumps into the OEM line. Not a published use of the 535 but approved by Fuelab nonetheless. Pressure sensor feeds into the MS3 on an analog input. My MS3 didn't have a 5vref on the DB37, so I asked Dimitris to add one - turns out he was one step ahead of me and all current units include it. :party:
Attachment 233254 Published data on my transducer: 0.5v = 0psia 4.5v = 100psia Convert to gauge pressure and 0-5v gives you this: 0v = -27.2psig 5v = 97.8psig Attachment 233255 Working on IC pipe production samples next, but there won't be many pics of those. :) |
The fixed 0v and 5v really piss me off, cause seems like all the sensors I use are .5 or 4.5 like yours.
Also, I just used Dimitris' wiring instructions to add whatever I want on the DB37. So far 5v ref and tach out. Gotta ditch the little plastic grommet in the DB37 case pretty quickly. |
It's because the ADC reads 0 at 0v and 1024 (maybe? Not sure how many bits it is) at 5v. So you are calibrating any 0-5v input. Not just sensors.
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That would be my guess... dynamic vref designs are not particularly efficient when resolution is so cheap these days (assuming proper anti-alias filtering and adequate sample rate). Dynamic control on the low side requires a second ADC or differential front end. At 10 bits, even with the 20% loss in valid codes, you still get resolution that typically exceeds the filtration/sample rate limitations or sensor capabilities.
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furthermore, with the custom channel feature you can simply bypass the voltage conversion all together and go straight from the adc code to output value. This eliminates some floating point math, which is a good thing.
Edit: even if the use fixed point (unlikely) you teduce clock cycles |
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