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Twin 340lph on E85 questions

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Old Aug 17, 2020 | 11:37 AM
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Default Twin 340lph on E85 questions

Running twin intake 340lph with dual -6 out of the tank into a Y then -8 all the way to the rails with -6 return.
I’m running a 6l with 20lbs of boost and E85, and my pressure has been dropping off at top end. I can get about 65 psi and then it drops hard. I had upgraded the pumps from 255’s thinking it would be enough but it looks like I may be wrong.

is anyone else running a similar setup that is taking these pumps to 800whp on E85?
Only reason I didn’t go with larger pumps was I’m limited on space. The larger frames won’t fit in my 96 impala tank.
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Old Aug 17, 2020 | 10:18 PM
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Originally Posted by nvmy2000ss
Running twin intake 340lph with dual -6 out of the tank into a Y then -8 all the way to the rails with -6 return.
I’m running a 6l with 20lbs of boost and E85, and my pressure has been dropping off at top end. I can get about 65 psi and then it drops hard. I had upgraded the pumps from 255’s thinking it would be enough but it looks like I may be wrong.

is anyone else running a similar setup that is taking these pumps to 800whp on E85?
Only reason I didn’t go with larger pumps was I’m limited on space. The larger frames won’t fit in my 96 impala tank.
What's your base pressure set at?? Going really high pressure your gonna run into that problem. With a boost referenced regulator it's usually 1:1 so if you start at 65 psi and add your 20 psi boost pressure your 85 psi now and most pumps don't keep high flow getting way up there
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Old Sep 1, 2020 | 12:25 AM
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Originally Posted by nvmy2000ss
Running twin intake 340lph with dual -6 out of the tank into a Y then -8 all the way to the rails with -6 return.
I’m running a 6l with 20lbs of boost and E85, and my pressure has been dropping off at top end. I can get about 65 psi and then it drops hard. I had upgraded the pumps from 255’s thinking it would be enough but it looks like I may be wrong.

is anyone else running a similar setup that is taking these pumps to 800whp on E85?
Only reason I didn’t go with larger pumps was I’m limited on space. The larger frames won’t fit in my 96 impala tank.
One thing you need to take into consideration is the size of your injectors. The smaller your injectors, the more fuel pressure you will need in order to make the injectors flow enough fuel. However, the more fuel pressure you add the less fuel your pumps can typically flow.
The advertised flow of a fuel pump is usually at a specified psi. Usually around 40ish psi in my experience. Go over that and fuel flow will drop.
I have a stock 6L ls2 running 10 pounds on e85. I have 2 400lph pumps with 1000cc injectors making between 560-600rwhp. Originally I calculated that I would need about 450lph for that amount of power, so I got a second pump just in case. Overkill for sure.
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