which fuel pump 190lph or 255lph???

FoRCedInDuKsionGsT · 01-27-2005, 02:40 AM

Down below is a list of mods that i have so far, my next mod would be a fuel pump to support 16psi, but don't know whether to get a walboro 190LPH or a 255LPH... What is the stock fuel pump size? Would a 255 be over-kill w/ my mods? HELP!!!

imtheoneandonlyD · 01-27-2005, 03:36 AM

from what ive read if you planning bigger mods down the road you should just get the 255.

1stGenRocks · 01-27-2005, 07:47 AM

255 would be good for you. BUT if you get anything bigger then a 190 you should really have a new fuel pressure regulator since the stock one gets overrun causing too high of fuel pressures and maxing out the ecu's fuel trims which changes timing and makes tuning a pain.
i also didnt see any tuning/datalogging devices in your mods. you should probably get a pocketlogger/1G dsmlink or some type of tuning/logging stuff before you get into fuel mods.

FoRCedInDuKsionGsT · 01-27-2005, 12:34 PM

Thanks guys for your inputs...

guitarXgeek · 01-27-2005, 08:12 PM

How much airflow will a 16g make at 16 psi? A stock re-wired 2g fuel pump can handle 37 lbs/min worth of airflow at 15 psi (assuming base fuel pressure of 43.5 and a good batch of 93 octane) with an AFR of 10.2:1 (which is pretty damn rich)! Just some food for thought, you don't really need a new fuel pump yet, as long as you rewire your stocker

.

P.S. All of this information is being brought to you from Kevin Jewer's fuel pump flow chart! It's on his website at www.posracing.net under the tech pages. You need OpenOffice to view it, but a quick search on yahoo will show you the download (which is free). This chart is GREAT! I just wish I knew the actual formulas used so I can calculate for different boost pressures than what is listed.

97_3clipse · 01-27-2005, 09:16 PM

is the 255 overkill for the t25? dose it help that much? or is it just an investment for the future(EVO III)?

kjewer1 · 01-28-2005, 07:39 AM

Quote:

Originally Posted by guitarXgeek

How much airflow will a 16g make at 16 psi? A stock re-wired 2g fuel pump can handle 37 lbs/min worth of airflow at 15 psi (assuming base fuel pressure of 43.5 and a good batch of 93 octane) with an AFR of 10.2:1 (which is pretty damn rich)! Just some food for thought, you don't really need a new fuel pump yet, as long as you rewire your stocker

.

P.S. All of this information is being brought to you from Kevin Jewer's fuel pump flow chart! It's on his website at www.posracing.net under the tech pages. You need OpenOffice to view it, but a quick search on yahoo will show you the download (which is free). This chart is GREAT! I just wish I knew the actual formulas used so I can calculate for different boost pressures than what is listed.

Sweet! Glad people are using it. The formulas wont change if you change the boost pressure. You just need to know what the pump flows at that pressure. Unfortunately that data just doesnt exist, and its not linear so it can be hard to extrapolate it from the datapoints we do have. Use the pump flow numbers for the next highest boost point, since that will provide the safer result (pump flow goes down as pressure goes up), or make up a number in between. For example, some of the pumps only have data for 15 psi and 30 psi. If you wanted to do the math for 22 psi just take an average. But since the curve isnt linear, be sure to add a little fudge factor. You can also use the info on www.stealth316.com, you can see the curves. Hard to get an actual number, but you can easily guestimate between points based on the curve you see there.

The math is simple. Convert flow to gallons per hour (there is a program called "convert" that you can also download for free, its sick). Then you need to covert to a mass number, since AFR is a mass ratio. Water weighs 8.34 pounds per gallon. The weight of fuel is ezpressed as its specific gravity, or a percentage of the weight of water. Most pump gas fules are around .76, or 76% the weight of water (for race fuels you can get the exact SG of the fuel online. THe 117 octane sunoco race fuel I use is .724). Multiply gallons per hour by the resulting weight of the fuel to get pounds per hour. Diveide by 60 to get pounds per minute (What we measure airflow in). Multiply that by your target AFR. The result should be the maximum airflow per min that you can support at that flow rate, fuel SG, and AFR.

Hopefully I didnt miss a step in there, I just woke up ..

FoRCedInDuKsionGsT · 01-28-2005, 01:00 PM

you don't really need a new fuel pump yet, as long as you rewire your stocker.
--guitarXgeek

re:

How would i re-wire my fuel pump? Is there some kind of kit to get? When you say "RE-WIRE" does it mean bigger wires???

kjewer1 · 01-28-2005, 01:50 PM

Yes, run a larger wire (10 or 8 guage) from the battery to the pump, and use the stock wire as the trigger for a relay that switches the larger wire on and off. There is a set of instruction in the vfaqs.

JoeWagon · 01-28-2005, 02:31 PM

Quote:

Originally Posted by guitarXgeek

P.S. All of this information is being brought to you from Kevin Jewer's fuel pump flow chart! It's on his website at www.posracing.net under the tech pages. You need OpenOffice to view it, but a quick search on yahoo will show you the download (which is free). This chart is GREAT! I just wish I knew the actual formulas used so I can calculate for different boost pressures than what is listed.

I think Kevin covered this, but there are no forumlas for pump flow at a given boost pressure. I contacted all sorts of people to get some real numbers so I could finish my program to do what Kevin's spreadsheet does, but I haven't found someone with the data. The only problem is trying to figure out flow/boost of a given fuel pump. Like Kevin said, average 15 and 30 for 22psi OR look at the graph and estimate the flow for 22, both are going to be a bit inaccurate. I'd say good enough because there is always room for error from other things, maybe you have a boost leak and throw off the AFR. Anyway...

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