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And how much power are you making? List your combo please.
 

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I was making 371 rwhp with a 190 intank solely and ended up blowing a head gasket from it running lean. I swapped to Dart Sr heads from the E7 factory ones and was thinking about just putting a 255 intank in there but now pondering if I should get a inline to work with my 190 or a inline with the 255.
 

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I made 455.5 rwhp with a 255lph on my 99 Cobra. I'm now making 400rwhp on my 95 with just a 255lph
 

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A Walbro 255lph GSS340 hi-volume intank pump with a good power source will support 80lbs of fuel pressure and about 550rwhp-575rwhp.

Troy
 

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snipe656 said:
I was making 371 rwhp with a 190 intank solely and ended up blowing a head gasket from it running lean. I swapped to Dart Sr heads from the E7 factory ones and was thinking about just putting a 255 intank in there but now pondering if I should get a inline to work with my 190 or a inline with the 255.
You should've been able to make around 425 RWHP with a 190lph pump. I don't think the pump was the reason for the blown head gasket.
 

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That assumes the 190 is working perfectly, a 190 is not even "technically" enough for a car with stock rails and 42lb injectors in a boosted environment according to places like Pro-M(if they are even right, they say a 205 is needed)
 

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Troy,

How much HP will the GSS307 (standard 255lph) pump be good for and at what fuel pressure? I'm not running a FMU and using FMS 42# injectors.
 

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A Walbro 255lph GSS340 hi-volume intank pump with a good power source will support 80lbs of fuel pressure and about 550rwhp-575rwhp.
If this is the case then why are so many people out there/here running @ least 190 or 255lph inline pumps with 190 or 255lph intank pumps. Not trying to start something, just looking for a legit answer.
 

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I ran a GSS307 w/30's + 6:1 FMU for a few months before I went to the 331, it was maintaining pressure easily upto 65-70psi. I think I was around 370-75rwhp. Just make sure you get a solid line of power to the pump from my experience--I run underdrive pulleys, & it appears to effect the performance of the pump.

Now running a GSS340/42's no FMU. Since my last set of upgrades and no big change in tune, I get some detonation >5200 rpms, so last weekend I installed a 255 inline. An overkill? Probably....
 

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snipe656 said:
That assumes the 190 is working perfectly, a 190 is not even "technically" enough for a car with stock rails and 42lb injectors in a boosted environment according to places like Pro-M(if they are even right, they say a 205 is needed)
That may be true, if you maxxed out the 42's - which can make more than 500 RWHP even on a blown motor - you would need something like a 205 lph minimum, however, at 377 RWHP, you are not even close to maxxing out those injectors - see what I mean?
 

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Redsnk95 said:
A Walbro 255lph GSS340 hi-volume intank pump with a good power source will support 80lbs of fuel pressure and about 550rwhp-575rwhp.

Troy
Redsnk95,
What qualifies as a good power source?

Thanks,
Matt
 

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Cougar5.O said:
That may be true, if you maxxed out the 42's - which can make more than 500 RWHP even on a blown motor - you would need something like a 205 lph minimum, however, at 377 RWHP, you are not even close to maxxing out those injectors - see what I mean?
But you still have the injector in a rail that was designed for no more than a 24lb injector. A 42 maxed or not, will still spray out a bit more every time it opens than a 19 or 24. Which will in turn drain the rails quicker so the pump needs to force flow into the rails and if you do not have a strong enough pump, you could feasibly end up running lean even at a hp rating much under your max hp abilities of the injectors. If that were to happen then the first place it would expose itself is on the drivers back side, which is 7 and 8.

This all of course assumes Pro-M's "theory" is correct, it might be a bunch of bs in hopes of selling something. I certainly am not going to say just because they printed something then it must be right.

Regardless,I lost a headgasket between 7-8 from a insufficient fuel system. Never even had signs of detonation, actually lost the thing driving like Ms Daisy. So would be stupid for someone in my shoes to not upgrade the pump after upgrading the heads during the head gasket "repair". The only thing I debate is just adding a inline for added "safety" and piece of mind.
 

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MCLFLN said:
Redsnk95,
What qualifies as a good power source?

Thanks,
Matt
Run a constant from the battery using a relay that is triggered from the factory pump signal. This is how I did my twin bosch pumps on my LX, it was easy to do since I already had a fuse block in the hatch for the stereo.
 

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Redsnk95 said:
A Walbro 255lph GSS340 hi-volume intank pump with a good power source will support 80lbs of fuel pressure and about 550rwhp-575rwhp.

Troy
:joy:

I only have the 255 gss340 intank pump and my fuel pressure's fine
 

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If the fuel pressure don't drop while at max boost/max power, I don't see how the rails could be running dry or inducing a lean out condition.
 

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it isn't a pressure thing it is a volume thing. you can maintain the pressure but lose volume and starve the injectors. I belive I have read that #8 is the first one to go lean.
 

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FWIW I took a stock in-tank pump with a t-rex to 468rwhp :) and intank was a 88lph :)
 

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2stangs69-91 said:
it isn't a pressure thing it is a volume thing. you can maintain the pressure but lose volume and starve the injectors.
I don't see the reasoning behind that. How can the pressure stay constant, yet there isn't flow?:confused:

Flow rate is proportional to pressure applied, reduce pressure means less flow and vice versa.

I think the saying you're referring to might mean where the fp guage is attached is not what the injectors are seeing, especially the #7 or #8.

Isn't most HG issues happening at the #3 cyl though? Did for me.
 
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