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Discussion Starter #1
I just went from a walbro 255 to a walbro 450 and noticed my afr's seem to be like a fuel point richer now across the board. Is this normal? I dont have a fuel pressure gauge so I dont know what the pressure is. Im still on the stock fpr.
 

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the artist formerly known as drexelstudent11
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You're outflowing the stock fpr; when a backpressure regulator like our fpr needs to flow more, it requires a larger pressure drop. The outlet pressure is already nothing because it's just dumping back to the tank, so the rail pressure necessarily builds up
 

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ej8
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Ok so can I just adjust the tune for now or do I need an aftermarket fpr?
Come on you should know this.
500cc injectors @ 42psi flow lets say 500cc
Now those same injectors @50psi will flow around 520cc
Hince the richness.

So you you need to either
Get a gauge to read the pressure and adjust the tune base on the new injector flow rate

Get a reg and gauge to bring the pressure back down.
 

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ej8
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Yes I understand that its running richer due to higher pressure. I can easily adjust the tune.

My concern is will it be ok to keep running the stock fpr? Will it be safe or can it fail due to higher pressure?
You can tune around it but without knowing some informationbyour be blind tuning.

How much richer are we talking about tho? Going from 14.7 to 13? Or 14.7 to 14.3?

And im not 100% sure on if it will mess up the stock reg or not.
I seen a few builds with 450 pumps but dont remeber of they used the stock reg or not.
 

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Discussion Starter #9
It went from idling around 14 to 13 and cruising is in the high 11's to 12's. Under boost is now in the 10's when before it was in the mid 11's. Im seeing my tuner tuesday, so Ill just get it tuned as is and we will see I guess.

I am also considering doing this The Old One - Energy Dynamics : Articles.

I would just get an aeromotive fpr, but it doesnt seem like there is any easy way to hook it up without changing lines and the fuel rail and what not.
 

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1992 Civic Si
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Get an FPR adapter for the stock rail, or just get an aftermarket fuel rail since they cost nothing for these cars. Then get an aftermarket regulator.

Also get a gauge for goodness' sake. I bet you're running like 55psi base pressure lol.

Aeromotives tend to leak vacuum/boost from their tops, by the way. Every single one I've tested to date.
 

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Discussion Starter #11
Get an FPR adapter for the stock rail, or just get an aftermarket fuel rail since they cost nothing for these cars. Then get an aftermarket regulator.

Also get a gauge for goodness' sake. I bet you're running like 55psi base pressure lol.

Aeromotives tend to leak vacuum/boost from their tops, by the way. Every single one I've tested to date.
I have a gauge but it leaks like crazy so I ordered a new one. The higher pressure might actually be beneficial, as I am hoping to hit 400whp.
 

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the artist formerly known as drexelstudent11
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It's going to be non-linear with the biggest change at idle. You can tune around it without issue
 

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You can tune around a lot of things wrong with a car. But when they're so easy and cheap to fix like they are on a Civic, is there really any excuse to?
 

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Two men shy of a group
99 civic sedan ex
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Get an FPR adapter for the stock rail, or just get an aftermarket fuel rail since they cost nothing for these cars. Then get an aftermarket regulator.

Also get a gauge for goodness' sake. I bet you're running like 55psi base pressure lol.

Aeromotives tend to leak vacuum/boost from their tops, by the way. Every single one I've tested to date.
Really? That's good to know, I planned on buying one eventually but probably wont. Which fpr do you recommend that works good? I know aem is garbage and I believe it was transzex who said a stock integra fpr would fix the fuel return issue
 

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Really most FPRs will work fine, even the Aeromotive ones. I just prefer my stuff to not leak. Radium makes an excellent FPR with interchangable tops available, sealed or adjustable. I've never used one but I'm itching to try one out. For a more traditional style regulator, Tomeis are great.
 

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Brokedick Millionaire
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trying to turn around a larger pump and a regulator that cannot bypass enough fuel makes the tuner HATE you.

Sure it can be done, close enough, but it will NEVER be right.

Get enough pump flow, get enough bypass, set pressure at 50 psi base, your tuner will thank you!
 

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Discussion Starter #18
trying to turn around a larger pump and a regulator that cannot bypass enough fuel makes the tuner HATE you.

Sure it can be done, close enough, but it will NEVER be right.

Get enough pump flow, get enough bypass, set pressure at 50 psi base, your tuner will thank you!
The problem is my tuning appointment is tuesday and it took a couple months to get that appointment. No time to wait for more parts. I emailed the tuner and asked his advice. Would you recommend doing this mod to the stock fpr? The Old One - Energy Dynamics : Articles
 

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Discussion Starter #19
I got some yellow ptfe tape and put my ebay pressure gauge back on. No leaking now and holy crap I had 80 psi at idle! I drilled a small hole in the regulator as said in that article. It brought the pressure down to 60 psi. I think ill just run like that. I know jvtec is running 60 base pressure on a 255.

 

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You just need a new stock fpr. I have never had such a huge problem with just a 255 in there. Your stock fpr should be able to hold a 255 without problems
 
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