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LT1-LT4 Modifications
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Old 05-09-2012, 09:13 PM   #1
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Default How much hp can a walbro 255 support?

Okay guys i need this question answered from people who actually use them and
have maxed them out or come close. Every thread i read on this subject has such a large margin of horsepower differences.

It will be in a Naturally aspirated motor making 650hp AT THE CRANK.
Will a single walbro support this?
i have heard some people say 500 max and some say they have pushed them to 700 at the wheels.


Any input is greatly appreciated.
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Old 05-09-2012, 09:39 PM   #2
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With an investment like that I would NOT trust a single 255.
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Old 05-09-2012, 09:46 PM   #3
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it really depends on the operating pressure it is ran at.

Like all pumps they can pump more volume of liquid at lower pressures vs higher pressures.

really we would need to know more to even begin to estimate if a single 255 would support your HP/goal.

They do make larger pumps in the 325 area....
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Old 05-09-2012, 10:00 PM   #4
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I know they make bigger pumps then the walbro 255. I was looking into the aeromotive 340 but turns out it wont work/fit like a walbro does in a 4th gen Because of the wiring.

I am hopping to run the pressure between 43.5 and 50psi
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Old 05-09-2012, 10:02 PM   #5
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A twin 255 walbro is good for 1000hp so Id say 500 But as stated it really depends what pressure your set at Walbro has bigger pumps But a hotwire kit is a Must Do
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Old 05-09-2012, 10:08 PM   #6
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Google flow chart for a walbro 255 I cant recall specs for em
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Old 05-09-2012, 10:11 PM   #7
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500 only. But I would run twins
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Old 05-09-2012, 10:17 PM   #8
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Okay well how would you guys suggest i have the second walbro come on.

rpm switch?
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Old 05-10-2012, 07:43 AM   #9
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A friend of mine has a 408 LS1 making 500rwhp NA through a th400 and is running a single 255 with the upgraded wiring with no problems (racetronix). He has been running it for about 5 years now. I am in the process of finishing up my solid roller 383 LT1 build (prob 575 crank HP max when dialed in) and am going to use the same setup with 43.5 psi and 55lb injectors. I talked to Lonnie at Lonnie's performance about the dual pump setup and he talked me out of it as he stated the 255 pump with upgraded wiring would support ~650 NA hp and about 500 FI due to the inceased BSFC of an FI engine. BTW, the 340 is the same 255lph walbro pump but has a higher pressure efficiency range (nevermind...seen you were talking about the aeromotive). Lonnie also stated the fuel lines would need to replaced with bigger lines than factory when using the twin pump in order to get to the 1000hp support figure of the system. I assume to get the benefit of an Aeromotive 340lph pump you would also need to upgrade the 3/8" factory line.

If I was going to upgrade the enitire fuel system I would go with a Nasty performance setup as they are a drop in aftermarket fuel system for our cars with all the parts. I will most likely go with this setup in the future but seeing how my friend's car performed making more power than my setup will with a higher fuel pressure used I think I will be fine.
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Old 05-10-2012, 01:04 PM   #10
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i always thought they would be good for 600hp.....
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Old 05-10-2012, 11:31 PM   #11
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Well you never want to push them to max hp rating though.
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Old 05-11-2012, 12:12 AM   #12
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Dw301.

Fits in stock location. 40psi it will flow 320lph. Hotwired.
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Old 02-17-2013, 03:57 PM   #13
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Use the walbro 400 but you will need to upgrade the lines!
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Old 02-17-2013, 03:57 PM
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255, 255lph, 55lb, flowchart, horsepower, hp, injector, max, pump, push, rating, support, uch, walbro, welbro


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