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-   -   I can see my FUEL PRESSURE!!! (https://www.miataturbo.net/diy-turbo-discussion-14/i-can-see-my-fuel-pressure-9645/)

samnavy 05-08-2007 04:41 PM

I can see my FUEL PRESSURE!!!
 
3 Attachment(s)
I've started a new thread to conclude this one about my 305's install:
https://www.miataturbo.net/forums/showthread.php?t=9555


Check out this pics, OH YEAH BABY!!!
I love my local hydraulic store. Those blokes are awesome. The guy set me up with this awesome little hose setup I'd never seen before. It's this super thin (think cocktail straw) nylon tube that you insert into little press fittings... one for the back of the gauge and one for the T-fitting on my feed line. You just push the tube into the connector, give a tug back out, and it seats in place. To get the tube out, you just push the connector together and the tube comes out. AWESOME! Dude said it would hold 250psi. I'm thinking about a permanent mount out there... just gotta deconflict from the wiper-arms.

So, results. Current setup, 305's, 10psi, Begi AFPR-set to minimum rise w/no restrictor.

2xONE WAY CHECK VALVES INSTALLED: With a dyno style pull from 2k rpm, showed a spike to 115psi around 4k rpm's, and a quick fall to about 100psi to redline. Running it through the gears and staying high in boost, fuel pressure stayed consistent at about 95-100psi.

1xONE WAY CHECK VALVE: Same spike to about 115-120psi, falling to about 105psi. Running through the gears showed same 100-105psi.

Conclusion, extra check valve gets about 5-10psi less pressure.
Based on that much fuel pressure, I'm going back to the 1.8's for NEDD... still gotta throw in that restrictor and see how much less pressure there is.

PS: LC1 is on the way!

Braineack 05-08-2007 04:54 PM

cool. i just used 4' of fuel hose, put the guage right under the driver wiper.

magnamx-5 05-08-2007 04:56 PM

your so silly sam.

MiataNuTca 05-08-2007 05:01 PM

Why don't you guys just buy a oil pressure guage with remote sender....I've been doing this for years to see my fuel pressure without sending fuel through my firewall. I bought a cheap Sunpro oil pressure guage with sender off fleabay for 30$. That way you can mount it right on your dash instead of the ghetto duct tape. Guage only reads up to 100psi, but I figure if I go above that, I'm being too dangerous anyway, since OEM HP fuel line is only rated at 100psi.

miatamania 05-08-2007 05:34 PM

I love it sam...duct tape ftw.

be careful about not leaving it on to long or it will be a PITA.

jayc72 05-08-2007 05:42 PM


Originally Posted by MiataNuTca (Post 110751)
Why don't you guys just buy a oil pressure guage with remote sender....I've been doing this for years to see my fuel pressure without sending fuel through my firewall. I bought a cheap Sunpro oil pressure guage with sender off fleabay for 30$. That way you can mount it right on your dash instead of the ghetto duct tape. Guage only reads up to 100psi, but I figure if I go above that, I'm being too dangerous anyway, since OEM HP fuel line is only rated at 100psi.

Ditto. I left the sender in place and removed the gauge after I switch to a non-AFPR based setup.

jayc72 05-08-2007 05:43 PM

After my experience with the BEGI AFPR and reading the difficulty everyone seems to have with getting enough control I'm thinking they aren't all they are cracked up to be.

jwarriner 05-08-2007 05:44 PM


Originally Posted by MiataNuTca (Post 110751)
Why don't you guys just buy a oil pressure guage with remote sender....I've been doing this for years to see my fuel pressure without sending fuel through my firewall. I bought a cheap Sunpro oil pressure guage with sender off fleabay for 30$. That way you can mount it right on your dash instead of the ghetto duct tape. Guage only reads up to 100psi, but I figure if I go above that, I'm being too dangerous anyway, since OEM HP fuel line is only rated at 100psi.

A mechanical gauge will be more accurate and you don't have to deal with delay from the sender.

There are isolators you can buy to put a mechanical pressure gauge in your car without running fuel through the firewall.

Braineack 05-08-2007 06:06 PM


Originally Posted by jayc72 (Post 110764)
After my experience with the BEGI AFPR and reading the difficulty everyone seems to have with getting enough control I'm thinking they aren't all they are cracked up to be.

I've had flawless control with them (2 that it). Use the restrictor provided, else you cannot see less than 90-100psi, the end.

with the restrictor in place, the diaphram does not get overloaded. you can adjust from 50-140psi with the tiniest of adjustmets from the needle valve.

Ben 05-08-2007 06:10 PM


Originally Posted by jayc72 (Post 110764)
After my experience with the BEGI AFPR and reading the difficulty everyone seems to have with getting enough control I'm thinking they aren't all they are cracked up to be.

I disagree. I think it's a great solution for the price. I don't think my previous fuel tune was all that bad: entered boost at 12.0:1, slowly increased towards 12.5:1 about tq peak, then got richer to just richer than 11.0:1 after tq peak towards rev limit. The problem with "control" has more to do with the way the miata ecu ramps up injector duty cycle to over 90% after 6k rpm. Couple that with the fact that you keep seeing people use overly large injectors, and you're bound to be uber rich up top.

Braineack 05-08-2007 06:13 PM

yeah Ben nailed it. The ECU throws in a certain amount of fuel past 5.5K when WOT regards of any other conditions. If you are using larger injectors you will most certainly see 11:1 AFR after this point. But you can usually squeeze 10-12psi out of the FMU/Bipes/FP combo before it's too hard accurately control things....this is where MEGAsquirt comes into play.

Mach929 05-08-2007 07:36 PM

i recently put in my begi afpr works perfectly, i tuned to 80psi with my 305cc injectors. I think it's still rich on the top end

Mechazawa 05-08-2007 08:46 PM

Those are "instant fittings," the same type everyone uses for water injection.

A note, i have started to see some inexpensive electric fuel pressure gauges on the market, its tempting.

samnavy 05-09-2007 12:51 AM

4 Attachment(s)
OK, check out what I made! It took me about 3 hours and several different styles of mount. It clears the hood and wiper by about 1/2". It's at a perfect level for viewing in the cockpit. I'm very pleased with myself.

I threw the restrictor back in and went for a spirited drive... and I'VE GOT POWER! I don't know what happened the last time I had the restrictor in, but I cranked up the AFPR and got an initial 130psi spike.... WHOAH, dial it down. I've taken about 2 turns out of the needle and still need a little more. I've gone back to just one bleed valve until I can get WBo2. Bottom line, the Begi AFPR is VERY ACCURATELY ADJUSTABLE. 1 turn seems to be about 10psi. Based on the RC numbers, I'm aiming for 100psi to keep it safely rich, but not too rich.

I don't see why I can't get a great tune out of this car now. With the adjustments on the low end the O2clamp/AFPR offers at the onset of boost, and my ability to accurately control fuel pressure, both the rate of rise/PSI and the bleed up top, I should be good for Saturday. I'm changed my mind again and am gonna leave the 305's in.

jwarriner 05-09-2007 01:06 AM

My concern would be stupid ass kids fucking with it. What I've learned, by both being a kid, and being a victim of kids being asses, is that if you open yourself up to fucked with, it'll happen. Usually it's harmless, I found trash crammed into the fairings of my bike- but when they pull on your little black plastic tube they don't know it's gasoline and could start a fire later. Just my .02.

Braineack 05-09-2007 09:06 AM

nice install...id leave it untill you get things exactly where you want them, especially on the dyno...you'll want to make a note of what it's pegging at....then when you get the results from the run, you can easy take off the roller brake, get into boost and set it lower, then make another run and see how it reacts.

once everything is golden, id personally remove it.

MiataNuTca 05-09-2007 06:02 PM


Originally Posted by jwarriner (Post 110765)
A mechanical gauge will be more accurate and you don't have to deal with delay from the sender.

There are isolators you can buy to put a mechanical pressure gauge in your car without running fuel through the firewall.

Never had a problem with delay from the sender, but my gauge increments could be a tad smaller....goes in 15psi notches, but gives me a good idea of where I'm at.

speedf50 07-19-2007 05:17 PM


Originally Posted by Mach929 (Post 110822)
i recently put in my begi afpr works perfectly, i tuned to 80psi with my 305cc injectors. I think it's still rich on the top end

What fuel pump are you using?

Stripes 07-19-2007 05:51 PM

Nice fuel gauge install! I personally went the duct tape it to the window route when I was running my begi afpr.

You are going to get your car running perfect and then decide to install a standalone....happens to everyone;)

Pitlab77 07-21-2007 09:31 AM


Originally Posted by Braineack (Post 110745)
cool. i just used 4' of fuel hose, put the guage right under the driver wiper.

I used a liquid gauge from home depot when I made a setup :gay:


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