If you ever plan on really taking the EVO III to it's limits and adding cams, I would strongly recommend the 255. If you want to run lower boost, then a 190 would be OK. Keep in mind though that as you increase airflow, you increase fuel demand and thereby commensurately increase fuel volume requirements.

I'd keep what you have and enjoy the additional tuning that the AFPR offers, but it's not my money. If you do keep it, you'll have a more than adequate fuel system to support a larger turbo and room for future growth.

Hope that helps,

Andy

I say stick with the 255+fpr+install kit. The evo 16 is good for 400 with all supported mods and the 255 is ideal for it or any other turbo. Correct me if I am wrong but the 190 fuel pump would only supply enough fuel up to 300hp or so. Its also better to go big either way because you can adjust for the recommended fuel but you would not be able to add with a 190 if needed.

You should really first look into your budget and the hp goals you are trying to achieve and work from there. If your not planning on alot of boost and HP now or later down the road 190 should be fine.

Once you start modding the car you will than see that it was a great idea going with the 250 FP. I suggest rewiring either fuel pump you chioce to go with for a consistant fuel flow.

If you never plan on going larger then the evoIII and money is really tight then you can run the 190 pump, they are good for 400 or just slightly under whp. It is nice to have the fpr, just for the adjustability & making it easier to tune properly. Plus if you ever do descide to max out the evoIII or step up to a larger turbo you'll already be set.

The formula for sizing the fuel system is based on target HP. Brake Specific Fuel Consumption for a turbo engine ranges from .60 to .68. Maximum Injector Duty Cycle should be between 80% to 85%. 10.5 is the coversion from lbs of fuel per hour to cc per min.

Starting with injector sizing:

((HP * BSFC)/(#injectors * MaxDutyCycle)) * 10.50 = size (cc)

(325 * .65 / 4 * .85) * 10.5 = (211.25/3.4) * 10.5 = 62.13 * 10.5 = 652 cc (at base pressure)

From a given set of injectors:

(((size (cc) / 10.50) * MaxDutyCycle) / BSFC) * #injectors = HP

(((650 / 10.5) * 0.85) / 0.65) * 4 = 324HP

Fuel Pump Sizing:

Your fuel pump should be able to 20% to 30% more fuel that needed at max HP.

FP (lph) = (size * #injectors * MaxDutyCycle * 60) / 1000 = (650 * 3.4 * 60) / 1000 = 132.6 lph (at max boost + base pressure) or 159 lph with a 20% safety margin.

It would like like a 190 lph pump is all that you need.

The injector flow rate doesn't change as boost or vacuum changed the fuel pressure but the fuel pump must flow the required fuel at your max fuel pressure to make the HP.

Steve
(hopefully I did all the math right)

BAH! Math. Here's some math for ya :

190 pump $85

255 pump $99
AFPR and "install kit" $150 (search, there are 100 threads where to go, what to get and how to do it)

That's $164 more, not $300. Better safe than sorry I'd say. Room to grow. Unless you are pinching pennies...then again there's always the "you should have an AFPR with a 190 pump too" discussion as well.

That's my 36 cents.

edit: for reference:
http://dsmtuners.com/forums/showthread.php?t=233858
http://dsmtuners.com/forums/showthread.php?t=232322

i was in the same boat as you a couple of months ago in decieding a upgrade pump..
I ended up just getting a 190lph from lightningmotorsports, and they claim that they carry high power 190s.... Therefore that is what I bought, and I installed it in my car last weekend but didnt get to wire it yet because I dont fully understand the instructions from vfraq on wiring some ima talk to more ppl about it soon, which im not in a rush to wire it anyways.... I wanted to get the 255 but didnt have extra money to get the afpr needed to run it right, so one day ill just upgrade to like a supra 260 with a afpr; also because I hear the 260s are quieter, I dont really care too much for a loud pump and my 190 is so quiet that i wouldnt hear it unless I put my head under the car to the actual pump...
( by the way are Walbro 190lphs suppose to be that quiet, and whats up with the highpowered 190lph I got since some ppl say no ones ever heard of a 190lph hp )

A 190 pump will take anything a Evo 3 could throw at it, but since you already have the FPR stick with what you have.

stevie, thanks for the formulas.

weith: dont add up numbers from random places. I wrote i already bought the fpr+install kit+gauge. so whatever you're quoting there isn't the one i got.

I got aeromotive from import evolution, and their install kit.
install kit runs for like $190, and fpr for like $140, and guage for $20. And that makes it $350

and ya, heres reference:
http://www.importevolution.com/default.php?cPath=24

I have decided to order the 190, because it surpasses all the requirments I need, plus i save that 350 dollars, plus the headache some dsm thing going wrong. i dont know why something always goes wrong during installation. a messed up bolt, dropping a injector spacer and losing it. etc

thank you guys for the help

Damn Steve! That's a lot of math...useful math though. I might just have to subscribe to this for future reference. Although I'm more of a "plan for the future" kind of guy and opted for the 255/AFPR route. I already know that eventually I'm going to want more than the 190 will dish out.

I would have said if you already found the money to buy the setup in the first place, just keep it.

my $0.02.

steve said:

Fuel Pump Sizing:

FP (lph) = (size * #injectors * MaxDutyCycle * 60) / 1000 = (650 * 3.4 * 60) / 1000 = 132.6 lph (at max boost + base pressure) or 159 lph with a 20% safety margin.

It would like like a 190 lph pump is all that you need.

The injector flow rate doesn't change as boost or vacuum changed the fuel pressure but the fuel pump must flow the required fuel at your max fuel pressure to make the HP.

Click to expand...

I forgot to check the data on the flow rates for the walbro 190 lph pump at the expected pressure (43.5 + 25 psi). Figuring in some loss in tthe lines and filter the pump would see close to 73 psi exit pressure.

http://www.roadraceengineering.com/fuelpumpflowrates.htm

Based on this the GSS-250 isn't able to keep up the needed flow rate at 73 psi.
The regular 255 (GSS-317) might but you loose some margin at 12.5v.
The HP version wouldn't have any problem keeping up.

Steve

1998gstspyder said:

weith: dont add up numbers from random places. I wrote i already bought the fpr+install kit+gauge. so whatever you're quoting there isn't the one i got.

I got aeromotive from import evolution, and their install kit.
install kit runs for like $190, and fpr for like $140, and guage for $20. And that makes it $350

Click to expand...

You could always return and buy from somewhere that isn't overcharging you...but yeah, sorry, missed the "already bought" part. I'd still put the gauge in, that way if you are having fuel related problems, you can see if your pressure is too high/low/etc to rule that out. You are changing a part and assuming it will be functioning properly, with no way of monitoring its performance.

1998gstspyder said:

I have decided to order the 190, because it surpasses all the requirments I need, plus i save that 350 dollars, plus the headache some dsm thing going wrong.

Click to expand...

Good luck!

1998gstspyder said:

stevie, thanks for the formulas.

weith: dont add up numbers from random places. I wrote i already bought the fpr+install kit+gauge. so whatever you're quoting there isn't the one i got.

I got aeromotive from import evolution, and their install kit.
install kit runs for like $190, and fpr for like $140, and guage for $20. And that makes it $350

and ya, heres reference:
http://www.importevolution.com/default.php?cPath=24

I have decided to order the 190, because it surpasses all the requirments I need, plus i save that 350 dollars, plus the headache some dsm thing going wrong. i dont know why something always goes wrong during installation. a messed up bolt, dropping a injector spacer and losing it. etc

thank you guys for the help

Click to expand...

Are you sure you got your numbers correct? The install kit for $190 INCLUDES THE FPR, it should be $190 plus ~$20 for a gauge. If you just buy the -6AN reg that most run (can't remember the part #) it is ~$135 and you can pick up the install kit anywhere for under $100 or less if you piece your own together, plus whatever for the gauge. Not 190+140+20. So depending on what fpr & hose style it should be $210-255 with a gauge, not $350.

See here, fpr included in the $190

http://www.importevolution.com/product_info.php?cPath=24_45&products_id=1620

wow you're absolutely correct, but too late anyway. thanks for all the helpful posts.

I think you'll regret your decision eventually. Specially if you run into FPR overun with the 190. It does happen