Bigger injectors now what...

[ROLLingKING]

I'm not sure if I should be replacing the fuel pump in the tank with a higher flow unit or if its the unit above the fuel filter that I should mess with. I want to get a PNP mega squirt ASAP but want to get all my shit in order first. I only put 19lb injectors in from a m50 but I want to make sure I'm not maxing out the system I have at wot or whatever. Plus ill be boosted so something like a walbro 255 is what I'm looking for.

What I'm not looking for is to pay a whole lot more than I need to for name brand like "walbro" if there are competitors just as good out there.

This for example is an in tank universal pump marketed to perform just as we'll as the Waldron but quiter.

http://www.ebay.com/itm/82-91-BMW-E30-255LPH-FUEL-PUMP-316-318-320-323-325-M3-/320539086243?pt=Motors_Car_Truck_Parts_Accessories&hash=item4aa19e4da3&vxp=mtr

......versus this for $34 more bucks. Mind you, $34 here and there on a budget build means a temp sensor I need or wheel spacers. Every bit helps.

http://www.ebay.com/sch/i.html?_odkw=walbro+255+fuel+pump&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313&_nkw=walbro+255+fuel+pump+e30+BMW&_sacat=0#item4aa19e4da3

What would u upgrade? Internal or external. Name brand or no name

[vpilarrt]

Just so's you know - OEM M50 injectors are 17# at 3.5 bar pressure which equates to ~15.5# at the 3.0 bar the M20 runs at. Unless, of course, you've installed an AFPR. Also, don't you need like 25 or 30# for boosted engines? OEM pump will handle < 20# injectors no problem. Not really sure about higher rate injectors. Search in boosted build posts for other's experiences.

[sayed ali]

stock pump is fine up to ~300hp or a bit more ..

[AndrewBird]

FYI, bigger injectors and a high flow fuel pump do nothing for a stock engine. Unless you have a modified engine, it is all a waste of money.

[deutschman]

I think what he is trying to say is that he is planning on going with a turbo set up in the near future and that he wanting to know what kind of fuel system upgrades he should spend money on in preparation for his turbo build.
Yes putting larger injectors on a OEM engine with out any kind of aftermarket ECU will get you nothing. The stock FPR and ECU will just limit the amount of fuel the engine gets. Even if the FPR and ECU did not cut back the fuel, the engine would not be able to burn all the extra fuel and you would just run rich or flood the engine.
I recommend reading through the Forced Induction section of R3V to see what others have done/used.

http://www.r3vlimited.com/board/forumdisplay.php?f=134

Seams like some people have got 20psi out of their OEM pumps and others have had their pumps die at 10psi. I think if you bought a new OEM pump and some larger injectors you would be good for about 14psi with a aftermarket adjustable fuel regulator. You can get an affordable fuel regulator (FPR) at Ireland Engineering.

http://www.iemotorsport.com/bmw/E30-fuel-intake/e30adjreg.html

[ROLLingKING]

I think what he is trying to say is that he is planning on going with a turbo set up in the near future and that he wanting to know what kind of fuel system upgrades he should spend money on in preparation for his turbo build.
Yes putting larger injectors on a OEM engine with out any kind of aftermarket ECU will get you nothing. The stock FPR and ECU will just limit the amount of fuel the engine gets. Even if the FPR and ECU did not cut back the fuel, the engine would not be able to burn all the extra fuel and you would just run rich or flood the engine.
I recommend reading through the Forced Induction section of R3V to see what others have done/used.

http://www.r3vlimited.com/board/forumdisplay.php?f=134

Seams like some people have got 20psi out of their OEM pumps and others have had their pumps die at 10psi. I think if you bought a new OEM pump and some larger injectors you would be good for about 14psi with a aftermarket adjustable fuel regulator. You can get an affordable fuel regulator (FPR) at Ireland Engineering.
http://www.iemotorsport.com/bmw/E30-...e30adjreg.html

Woooow. Thanks everyone for talking to me like a dumbass.

I don't have a stock ecu. Otherwise why put in any injectors if the computer is telling them to do the same shit.

A lot of drift guys upgrade their fuel pumps when they get larger injectors and a mapped ecu for the injectors/whatever power bolt ons are there.

I feel like stock pumps on larger injectors meant to run at 3.5bar, 3.5bar u said right, are running at full load just to keep up with the larger injector fuel needs. It may only be SLIGHTLY larger but it's not what the stock injectors were. Hence possibly making the pumps work harder... My coworker explained it to me in a more scientific way. But he was saying something like at idle the pumps at full volume trying to keep up with the tune. Idk

To me it seems like if your going beyond stock injectors it may be time for pumps that can flow better than stock also. Just kinda makes sense to me....idk

.....so which fuel pump is actually replaced when ppl put in a walbro 255 or something?? That's what I'm not sure of. All my buddies have 1 fuel pump. I don't like asking e30 ppl cause most ppl who haven't tinkered with what I'm asking about have a short useless answer.
I have a higher volume pump for the inside and outside of tank at this point. I'd sell one if I only need one. But why have two different flow rated pumps...the two pumps is throwing me off in general

[bmwguy325is]

Im guessing you have an early car?

[jlevie]

I don't have a stock ecu. Otherwise why put in any injectors if the computer is telling them to do the same shit.

A chip for larger injectors isn't really going to significantly increase flow through the injectors. It might bump the A/F ratio slightly, but the tune for the larger injectors is mostly to account for the higher flow rate of the injectors. Meaning that the DME doesn't have to "learn" a lower pulse width.

On a street car you don't want the AFR to go much below 13.5:1, if that low, to avoid carbon fouling the plugs and coking up the cylinders. And there is really not much gain to be had unless work has been done to the head to increase mass flow thorough the engine or FI is employed to increase mass flow.

A well built, fully stock engine & DME with a good exhaust, can make 160-165rwhp on a DynoJet. That might mean as much as 184-190hp at the crank. in my experience that is more than a chip and/or bigger injectors will produce. My guess is that a properly tuned MS on the same engine would yield a bit more.

[ROLLingKING]

A chip for larger injectors isn't really going to significantly increase flow through the injectors. It might bump the A/F ratio slightly, but the tune for the larger injectors is mostly to account for the higher flow rate of the injectors. Meaning that the DME doesn't have to "learn" a lower pulse width.

On a street car you don't want the AFR to go much below 13.5:1, if that low, to avoid carbon fouling the plugs and coking up the cylinders. And there is really not much gain to be had unless work has been done to the head to increase mass flow thorough the engine or FI is employed to increase mass flow.

A well built, fully stock engine & DME with a good exhaust, can make 160-165rwhp on a DynoJet. That might mean as much as 184-190hp at the crank. in my experience that is more than a chip and/or bigger injectors will produce. My guess is that a properly tuned MS on the same engine would yield a bit more.

Thanks man. I am in the works of getting a stripped head shipped to me so I can work on it in the house and increase that flow. I already have the high rev valve springs that vac sells and have my mind made up on their m20 performance valve kit. +1mm ftw!!

I have a 173 ecu here also but im still saving up for a pnp megasquirt to have put in. A buddy gave me his STI turbo after he went big turbo so I want to learn to tune a bit na and then I'll eventually be turbo.

I guess long story short, have people here had good results using the OEM fuel pumps all the way through a little head work, injectors, and turbo?

Please don't try and teach me how to build my car. This fuel pump specific. Thanks to those who have offered insight!

[ak-]

Nobody is trying to teach you how to build a car!
They all gave out legitimate answers. Regardless of your injector size, some pumps have failed at low psi and some at high.

Mine failed at aroind 8psi with 42#, kamotors is still going on oem 15psi+ with 42#'s.

[ROLLingKING]

Nobody is trying to teach you how to build a car!
They all gave out legitimate answers. Regardless of your injector size, some pumps have failed at low psi and some at high.

Mine failed at aroind 8psi with 42#, kamotors is still going on oem 15psi+ with 42#'s.

I was referring to the ppl trying to tell me how a stock ecu with bigger injectors is useless. Ppl nitpicking at my build style rather than answering my question.

In reality we all help each other get our builds done. That's why forums can sometimes be insightful.

I'm going to search other builds, but NO ONE has explained the 2 fuel pump system or anything. Which pump would a higher flow walbro 255 go??

I have a pump going (warm starts just crank and crank sometimes unless I gas it) and would rather not buy a oem pump and a higher flow rated down the road when I turbo in a few months.


Where would the high flow pump go?
In the tank? Outside of the tank above filter? Or both. At this point I might just fuck with both of me.

[ROLLingKING]

A chip for larger injectors isn't really going to significantly increase flow through the injectors. It might bump the A/F ratio slightly, but the tune for the larger injectors is mostly to account for the higher flow rate of the injectors.

To me it seems like if the flow rate is increased but not the flow through the injectors, then the flow through them should be upped. A FPR would help but I still think that would then be putting the stock lower flow rated pump through more stress.

Idk a lot of Nissan, ae86 drifters, and my buddy with nitrous in his Lexus all suggested now that I've started f'ing with injectors and a chip I should up the pump before I mega squirt and boost. Especially since they've heard my car not want to start when it's time to leave a meet. (fuel pump issue)


Which fuel pump?! Does one do most of the pumping and then the other just does what?
Can anyone explain the 2 pumps instead of trying to talk me out of doing my own experimenting. If I can understand the system more I'd understand why upgrading would be a waste more than u just trying to tell me ppl have had stock shit last up to whatever. Sometimes upgrading the part is cheaper than stock....and may yield more enjoyable benifits

[BergerNJ]

so....the first pump just pulls the fuel from the tank, its a low pressure pump....The second pump, the out of tank pump, is high pressure, and pressurizes the system. If memory serves correct.....

Also, I think I read a long time ago, from quick browsing, that some guys eliminate the 2 pump system when they upgrade.....not for nothing but a simple search would yield results...

Jlevie posted a quick and simple response, but just from memory alone I can tell you he has written some very in depth fuel related posts......so go search for it brotha

[dnguyen1963]

To me it seems like if the flow rate is increased but not the flow through the injectors, then the flow through them should be upped. A FPR would help but I still think that would then be putting the stock lower flow rated pump through more stress.

Idk a lot of Nissan, ae86 drifters, and my buddy with nitrous in his Lexus all suggested now that I've started f'ing with injectors and a chip I should up the pump before I mega squirt and boost. Especially since they've heard my car not want to start when it's time to leave a meet. (fuel pump issue)


Which fuel pump?! Does one do most of the pumping and then the other just does what?
Can anyone explain the 2 pumps instead of trying to talk me out of doing my own experimenting. If I can understand the system more I'd understand why upgrading would be a waste more than u just trying to tell me ppl have had stock shit last up to whatever. Sometimes upgrading the part is cheaper than stock....and may yield more enjoyable benifits

In tank is the low pressure pump. Its main purpose to to feed the high pressure (outside) pump. You can call Tre Performance and ask for their recommendation as to which pump you should use. As with any pump, there will be good and bad reviews. Personally, Tre pump has been reliable for me and it is way cheaper than stock.

[jlevie]

As stated above, cars with the 55L tank have a low pressure high volume pump in the tank to supply fuel to the external high pressure pump. Cars with the 63L tank have a single in-tank high pressure pump. If the pump(s) are in good operating condition (not 20'ish years old and worn) you probably won't have flow problems below about 14psi of boost.

One thing to consider. While you could install a higher capacity pump in anticipation of FI in the future, until then too large of pump could overwhelm the FPR as the car sits now.

To me it seems like if the flow rate is increased but not the flow through the injectors, then the flow through them should be upped. A FPR would help but I still think that would then be putting the stock lower flow rated pump through more stress.

I'm not exactly sure what you mean there. The flow into the engine is determined by the rail pressure, injector flow rate, and injector firing pulse width. As long as none of those dependancies get too far off the DME will make larger injectors look like the stock injectors with respect to the fuel delivered to the engine and the resultant AFR.

The other thing to keep in mind is that the high pressure pump is always working at full capacity with excess fuel being returned to the tank via the FPR. So the stress on the pump doesn't materially change with a change in flow rate of the injectors. You only need a higher capacity pump if flow into the engine gets high enough that the pump can no longer maintain proper rail pressure.