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DIY Adjustable FPR

I could see rising rate fpr's being put down, but I don't get it with adjustable FPR's. Being able to increase fuel pressure no good, another means of adjustment where there is none previously? I don't know, didn't tune my car, but on LH 2.4 my mechanic got my now dead 740T running very well with the adjustable FPR. Yah, you might need to upgrade your fuel pumps, but I had the aftermarket fuel pump in it.

Of course if you have MS installed it would be superfluous, but seemed valuable tuning aid on LH 2.4.
 
aside from whats already been said, higher fuel pressure can also blow injectors open (not desireable), hold injectors open (also not desireable), and will really cause strange things to happen right around the max duty cycle the injector can run. with stock injectors on lh 2.4 if you think you're going to make any power at all you're going to be running the green tops way out.
 
Yah, I hear you on the injectors. Wouldn't say an AFPR is a way to turn up the power or anything, but good way to tweak LH 2.4 a bit. Actually changed the exhaust tone. Had bigger injectors ready, but you know there wasn't really any way to adjust LH 2.4 and tweaking the FPR a bit seemed to help get it running better.

Basically just a way to get some adjustability on LH 2.4. Not a replacement for fuel pump or injectors. Good supporting mod for upgraded pump and injectors imo.

Actually I got interested in AFPR after getting two sets of injectors, one big set, one huge set, and planning on being able to run E85. Throwing in larger injectors, nice to have that fuel pressure guage and AFPR to be able to adjust.

Not so much for stock injectors.
 
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Here is a pic of the Adjustable fpr that I made about 5 years ago...and it is still in operation today. All I did was move the port to the side of the body using brake line and apoxy. Then added spring and adjustment bolt. ( skipped some steps but it is the same theory, and you get the point)


DSC00268.jpg
 
this is why our society will ultimately fail. We've equated disagreeing with hate.


I don't hate, I educate ;-)

I do hate the idea of having something hokey like an AFPR on my car.. too many variables.. too much stuff to go wrong.

I did the math and if you raise a 31lb injector from 43psi to 50psi you're still stuck with only a 33lb injector..

Now that I've provided numbers, doesn't it just sound stupid?
 
doubling pressure (thats kinda impossible) only nets a 41% gain in flow (if the injectors can stay closed haha..). so for more fuel it is not very useful, just for minor tweaks.

the benefit could be the better atomization (if you use injectors that can take the higher pressure). with E85 that really helps.
 
Wait, one of your injectors went bad? One out of four? And you gonna crank the fuel pressure up on all four of them? Huh What?

Adjustable FPR is not gonna fix the broken injector.
 
damn dude... read... it was temporary because his dyno was scheduled soon and he couldnt get a new injector... oh and he also swapped all 4 to working smaller injectors... hooked on phonics works man..
 
you have used a bottle cap and jbweld on your pressure regulator...? that is worse than just putting vise grips on the return line to regulate it.

listen! we had a customer with a 1990 740 that came in for a fuel leak, the bolts holding the regulator to the rail were stripped, the tech recommended that the fuel rail be replaced or at least repaired, customer declined the repair and drove off with his dribbling fuel leak... two days later i am informed that smart fella kept on driving until the rail pressure popped the regulator out... that car just HAPPENED to be a regina car and the fuel sprayed right onto the coil and the car burst into flames.

NEVER compromise the integrity of a high pressure fuel system with half ass performance mods, you might be the one trapped in the car when it goes up in a fire.

i am dead serious here and just because it is on the vacuum side of things and it works, since you are the first to do it, you might also find out the hard way that isn't the way to do it.

adjustable FPR is $130 with adapter for volvo rail... why waste time?

/rant off
 
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Wait, wait, WAIT.....DCOEs.......now your talking my language.
Anyone got a source for a manifold?
(Maybe this hi-jack will save some of Matthew's ass from being chewed off, but I am interested in the carbs.)
 
damn dude... read... it was temporary because his dyno was scheduled soon and he couldnt get a new injector... oh and he also swapped all 4 to working smaller injectors... hooked on phonics works man..


Jeez man, it doesn't matter if the dyno day is tomorrow or in two weeks. If he runs it on the dyno like that and the injector completely fails, guess what....phonics won't help you there buddy.
 
Jeez man, it doesn't matter if the dyno day is tomorrow or in two weeks. If he runs it on the dyno like that and the injector completely fails, guess what....phonics won't help you there buddy.

You miss the part about swapping in different injectors?
 
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That is where I got the idea. It is much more elegant than may way, but the idea is still the same.




Or you can just BUY an accufab AFPR .... $120..... and have it installed in ~5 minutes? and not have a disaster waiting to happen under your hood...


Cross refrence part numbers from Buick Grandnational, or 80's Turbo dodge stuff.....
 
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