fuel pumps and injectors

[tylermartindc]

trying to decide on choosing new pump and injectors. my mods are in my profile for u to have a look. my question is, with the minimal mods i have, is getting a fuel pump such as walbro 255lph too much ? is it safe to run that considering what i have? and also how to choose injector size? im running around 12psi as of right now but the owner before me said it could run on 15psi. i dont see how it could have "safely" with stock pump and injectors.
any input is great.
thanks , tyler

 

[nightspeed87]

but still what will thischange if your running a n/t fuel pressure regulator on a 255, doesthat not change anythingas far as overrun? Im raising the boost a little, and have a hacked mass and knN filter, but It will still ran way too rich right?

 

[DSM90AWD]

but still what will thischange if your running a n/t fuel pressure regulator on a 255, doesthat not change anythingas far as overrun? Im raising the boost a little, and have a hacked mass and knN filter, but It will still ran way too rich right?

The NT FPR has a higher base setting than the turbo FPR but still has the same limitation of a small diameter internal return oriface.

The larger pumps are going to flow ALOT more fuel at the same Base FP so even if you're NT is set to limit base FP to 45psi, with a 255HP you will actually be seeing >45psi with no way to lower it. Pressure rise will also not be 1:1 under boost.

There is a point at which fuel consumption by the engine will equalize things as less fuel is being returned to the tank via the FPR, but all said, WAY easier to tune when you dont' have to worry about running uncontrollably rich at cruise, Idle and certain WOT points

 

[VelocitàPaola]

Pressure rise will also not be 1:1 under boost.

John, I don't know enough about 1G N/Ts, and I'm curious about this... will the 1G N/T FPR raise fuel pressure in response to boost at all? It doesn't seem as though it would, unless, like I said earlier, Mitsubishi used the same FPRs for both the N/T and turbo models.

 

[2gGSX]

A rewired Walbro 190 lph will be enough to support a bit over 40 lbs/min airflow with anything beyond about a 10.5:1 AFR on pump gas w/ specific gravity of .76. That being said, at least 95% of Evo III owners will never see the maximum airflow numbers the three fastest Evo III powered cars will (mid 40 lbs/min airflow). With that being said, for the vast majority who will stick with just the Evo III a rewired Walbro 190 will be enough.

I ran a rewired 190LPH walbro for years with a stock FPR and experienced no overrun (monitored via my TMO datalogger's LTFT values) and it supports ~420HP. So if you're sticking with the stock turbo for a while or even plan to run an EVOIII 16G this would be the pump I'd recommend without the need to spend an extra $200+ on an AFPR.

Also, raising fuel pressure should only be taken so far. Granted it will undoubtedly help stave off high IDCs, if you increase it too far and still use the car for daily driving you will eventually wash fuel past the rings and begin diluting oil. During off boost situations too much fuel pressure will cause the car to behave the same way as if it was experiencing FPR overrun. Remember that increasing base fuel pressure will only serve as a temporary solution to high IDCs or running out of injector, and thus will have its compromises and side-effects.

By all means though don't worry about raising your base fuel pressure moderately, but if you start bumping it by 10-15 psi you should reconsider. In the end, it may just be times to upgrade injectors!

 

[mobythevan]

As another reference point I got to drive a stock setup with a 255 fuel pump because the PO installed it, he also installed a fuel pressure gauge. The gauge did show that the pump was overrunning the stock FPR. However, I drove the car for 2 months before converting to a standalone ECU with no issues. It idled great, got 25mpg commuting to work, but still I wouldn't recommend using the stock FPR with the 255 pump.

 

[tylermartindc]

i have a question about fuel pressure gauges. why are they mounted under the hood? can you get one that you can have in the car?

 

[DSM90AWD]

i have a question about fuel pressure gauges. why are they mounted under the hood? can you get one that you can have in the car?

The ones most commenly used (and cheepest) are mechanical meaning the gauge directly measures fuel pressure. You should never mount this type of gauge remotely in the cockpit as if a failure occured (line/gauge fails) high pressure gasoline would douse you likely killing you in dramatic fashion

Same reason goes for mechnical oil/water pressure gauges.

Electric versions are available using remote sending units, but cost more. But if you are serious about these things, a good investment

 

[TSIMonsteR]

I'm kinda in the same boat. I will be upgrading to an Evo3 16g as well in the near future and I've been told to just go with the 255, yet I think i'd rather just get a 190 so I won't have to worry about an afpr. But after what DSM90AWD said, I'm leaning even more towards a 190. Just curious, what turbo do you plan on running and what injectors have you decided on? I'm also trying to decided on injectors myself as well.

Well, right now I have a small 16g, and I'll probably keep it for a long time. I eventually want to upgrade to a dbb 50-60trim style turbo. As far as injectors, just what ever I can get a good deal on... I'll be running DSMLink, so if 880's are the same price as 660s.... guess which I'll pick. I'm leaning towards the 190 for now since the resale on them is pretty high. $95 sounds much better the $280 (IE Kit) .. and I think the 190 will suffice for my goals anyway

 

[oldman]

Well, right now I have a small 16g, and I'll probably keep it for a long time. I eventually want to upgrade to a dbb 50-60trim style turbo. As far as injectors, just what ever I can get a good deal on... I'll be running DSMLink, so if 880's are the same price as 660s.... guess which I'll pick. I'm leaning towards the 190 for now since the resale on them is pretty high. $95 sounds much better the $280 (IE Kit) .. and I think the 190 will suffice for my goals anyway

Just so you're aware that although rare, I have helped out 4 members (yes I've been counting) so far in two years with 190 overrun issues. I suspect there are more due to the fact that most of 190 users doesn't have a gauge, at least install a filter mounted gauge so you can keep an eye on it.

 

[TSIMonsteR]

Thats very interesting to take into consideration.

Just for kicks, what are all of the pros to having an AFPR such as the aeromotive unit?

-More precise control of fuel pressure
-The ability to change fuel pressure
-Your able to squeeze more out if you injectors

what else?

 

[DSM90AWD]

what else?

extra bling factor could put you over the top with the ladies

 

[TSIMonsteR]

haha.... I already got some spinners on the way. They are the ones that show messages and pictures!!! I got a really good deal on them, they were only a grand each when combod with the lambo door kit

 

[TSIMonsteR]

just kidding by the way

 

[2gGSX]

Just so you're aware that although rare, I have helped out 4 members (yes I've been counting) so far in two years with 190 overrun issues. I suspect there are more due to the fact that most of 190 users doesn't have a gauge, at least install a filter mounted gauge so you can keep an eye on it.

I considered the same thing that most 190 users don't talk about about FPR overrun because they don't expect to and don't have a gauge that tells them otherwise. Would monitoring fuel trims be enough to give an idea of the presence of FPR overrun/the degree of overrun?

The ones most commenly used (and cheepest) are mechanical meaning the gauge directly measures fuel pressure. You should never mount this type of gauge remotely in the cockpit as if a failure occured (line/gauge fails) high pressure gasoline would douse you likely killing you in dramatic fashion

Same reason goes for mechnical oil/water pressure gauges.

Electric versions are available using remote sending units, but cost more. But if you are serious about these things, a good investment

Just to make sure, but for something like fuel pressure where a change does not cause an immediately devastating problem the electrical would be acceptable, but for something like oil pressure would the delay caused by the electrical gauge be enough reason to use a mechanical gauge (in your opinion)?

 

[oldman]

I considered the same thing that most 190 users don't talk about about FPR overrun because they don't expect to and don't have a gauge that tells them otherwise. Would monitoring fuel trims be enough to give an idea of the presence of FPR overrun/the degree of overrun?

Not reliable enough because fpr overrun is only one of many factors that can change your fuel trim, a fuel pressure gauge that costs less than $30 is the only way in my opinion. With that said, due to the none linear (inconsistent) characteristics of an overrun (load based), incosistent trim readings would be a better indication than just rich readings alone.

 

[nightspeed87]

A rewired Walbro 190 lph will be enough to support a bit over 40 lbs/min airflow with anything beyond about a 10.5:1 AFR on pump gas w/ specific gravity of .76. That being said, at least 95% of Evo III owners will never see the maximum airflow numbers the three fastest Evo III powered cars will (mid 40 lbs/min airflow). With that being said, for the vast majority who will stick with just the Evo III a rewired Walbro 190 will be enough.
Also, raising fuel pressure should only be taken so far. Granted it will undoubtedly help stave off high IDCs, if you increase it too far and still use the car for daily driving you will eventually wash fuel past the rings and begin diluting oil. During off boost situations too much fuel pressure will cause the car to behave the same way as if it was experiencing FPR overrun. Remember that increasing base fuel pressure will only serve as a temporary solution to high IDCs or running out of injector, and thus will have its compromises and side-effects.

By all means though don't worry about raising your base fuel pressure moderately, but if you start bumping it by 10-15 psi you should reconsider. In the end, it may just be times to upgrade injectors!

well its because im doing a swap from a n/t and all i have is the n/t fpr. I dont have the stock gst fpr so i was just going to use that. But your saying dont use it because it will flush too much fuel through the motor especially when not under boost? correct?Since it pushes 10 psi more. And i never understood the over run thing, will this n/t fpr with more fuel pressure increase fpr overrun, make it worse or better? Answer in the form i asked because i wont understand all the scientifical answers. ok thanks.

 

[2gGSX]

Your engine should be ok with the stock turbo FPR even if it does push 10 psi more. I was saying that you would push fuel past the rings with a large increase in base fuel pressure. Thus at the stock turbo fuel pressure (even though it is 10 psi more than the N/T) you will be fine.

 

[nightspeed87]

Your engine should be ok with the stock turbo FPR even if it does push 10 psi more. I was saying that you would push fuel past the rings with a large increase in base fuel pressure. Thus at the stock turbo fuel pressure (even though it is 10 psi more than the N/T) you will be fine.

no no you got my question wrong. I needto change my profile where it says n/t with turbo, put it this way i have a gst i dida gst motor swap... Now im using the n/t fuel pressure regulator... This means it has about 10 fuel psi "more" then the gst stock regulator..... And im putting a 255 pump in... Now answer the question with that in mind.

 

[nightspeed87]

you had it backwards then n/t regulator ( for whatever reason) actually has 10 more psi then the turbos models fpr )

 

[DSM90AWD]

Just to make sure, but for something like fuel pressure where a change does not cause an immediately devastating problem the electrical would be acceptable, but for something like oil pressure would the delay caused by the electrical gauge be enough reason to use a mechanical gauge (in your opinion)?

Actually if your fuel pressure dropped during a WOT run you'd immediately run super-lean and likely blow a HG, burn valves or hole a piston. If oil pressure dropped, you'd have more of a grace period to escaping serious damage (talking seconds here).

In my opinion, most gauges are worthless unless there is some external indicator (buzzer/flashing idiot light/Engine Cutoff) to tell you something is amiss. In a race situation how are you going pay attention to the Tach, Fuel Pressure, Oil Pressure, EGT..etc and the road ahead?

I dont' know of any mechanical gauges that have this feature, but most electronic versions do

 

[2gGSX]

Actually if your fuel pressure dropped during a WOT run you'd immediately run super-lean and likely blow a HG, burn valves or hole a piston. If oil pressure dropped, you'd have more of a grace period to escaping serious damage (talking seconds here).

In my opinion, most gauges are worthless unless there is some external indicator (buzzer/flashing idiot light/Engine Cutoff) to tell you something is amiss. In a race situation how are you going pay attention to the Tach, Fuel Pressure, Oil Pressure, EGT..etc and the road ahead?

I dont' know of any mechanical gauges that have this feature, but most electronic versions do

With these issues brought up (fuel pressure dropping, oil pressure dropping), would you say the benefits of the warning from an electronic gauge warrant the extra lag associated with these types of gauges? I'm inclined to say you will say yes but I wanted to make sure I wasn't putting words into your mouth (fingers?)

 

[DSM90AWD]

Really electronic is the only way to go with these (slight delay or not) if you want them in the cockpit. Many of the old-school V8s had their gauges mounted on their cowl so would be both safe from a "failure" and within line of sight in case of an emergency.

My personal opinion, get the electronic oil pressure gauge and get the mechanical fuel gauge and mount in the engine compartment. Only time I ever look at my fuel gauge is to set base pressure and can't do that from inside the car

 

[packinkimber45]

a lot of members are saying that me running my walbro 255 w/o bigger injectors, and aftermarket fpr will overrun my stock fpr... I do not doubt this, since it is coming from experienced individuals. I did not mention that I have an safc in the car. does this change my situation, a buddy of mine told me that since I have an safc that overruning the fpr will not be an issue since the safc can control the injector duty cycle. can anyone confirm on this?

 

[zippyshoe]

a lot of members are saying that me running my walbro 255 w/o bigger injectors, and aftermarket fpr will overrun my stock fpr... I do not doubt this, since it is coming from experienced individuals. I did not mention that I have an safc in the car. does this change my situation, a buddy of mine told me that since I have an safc that overruning the fpr will not be an issue since the safc can control the injector duty cycle. can anyone confirm on this?

This is incorrect. Having an SAFC will not help you in preventing FPR overrun - the only solutions are to either re-install your stock fuel pump or purchase an adjustable FPR and adjust it for proper base fuel pressure. Also note that FPR overrun has nothing to do with your fuel injectors - it is due to an upgraded fuel pump.

 

[nightspeed87]

With larger injectors and all what is the biggest amount of boost you can run on a 190lph?
Like anyone with experience of the 190s? There isnt a pump in the middle between the 190s and 255s huh? Because 255 is seeming a little too big for what im going for right now, also because i have no afpr or tuning devices. But i didnt want to drop in a 190 and later down the line have to step up to the 255