TURBODUECE88

i have a T2 and just purchesed a full exhaust and an FCD. i have heard some people say they were hesitant to instal an FCD with the stock fuel pump. will doing this harm/ make the engine less stable or will it simply not allow for maximum hp gains and performance??

rick_tj

A fuel cut defenser tricks the ECU into thinking you're running less boost than the programmed fuel cut is. 5.5 lbs I believe. Don't be stupid with the go-pedal and you'll be okay.

Buy an aftermarket boost gauge too, and watch that thing! Using a FCD will throw off the stock boost guage, making an aftermarket one necessary.

NZConvertible

If you do nothing other than a full exhaust and a FCD, you will blow your engine because of the huge boost increase you will see. This is due to the S4's very small stock wastegate. The first thing you have to is remove the turbo and port the wastegate (search for the many threads on this).

And yes you should upgrade the fuel pump before installing the FCD. The FD pump is a good, mild upgrade.

TURBODUECE88

i know about the WG porting and all of that. but is it hazardous to run the FCD with the stock fuel pump? i know you said i should upgrade to the FD fuel pump but would it be okay to run it with the stock one for a while until i get some more money for the FD pump?

13b4me

FD pumps can be found for $30-50 all day in the FS sections of this forum...

rick_tj

with the full exhaust and FCD w/o ported wastegate, you're going to have boost creep issues.

TURBODUECE88

i know that and thats why im porting the wastegate... i wanted to know about the safety/reliablity of runnin it with a stock fuel pump

TURBODUECE88

bump

13b4me

Your question has already been answered... A higher volume fuel pump should be done at the same time as the exhaust, ported WG, and FCD... Personally I don't even recommend using an FCD at all, but hey it's not my car...

Turbonut

iTrader: (1)

I guess I'm from the old school. If a slightly larger pump (more volume) is installed, why would the engine receive more fuel? With the stock injectors and stock ecu, it will receive the same amount. Some will say that the larger pump will force more fuel through the injectors, and I don't buy that either. I have a GForce ecu with the FD pump, car runs and idles fine, and has passed NJ emission inspection the last 6 years, and no issues with rich conditions.

If you're spending money on the upgrade, just buy some 7-- secondary injectors and upgrade the pump along with the FCD (although I'd rather do some other electronic upgrade rather than the FCD).

13b4me

Exactly... The injectors won't recieve any more fuel, but the puny stock 180lph pump will max out before the 550cc injectors do... I agree though, and I believe the secondaries should be upgraded at the same time as the pump/wastegate/FCD/etc... Look into the Rtek v1.7 ECU as well, since it's about twice the cost of an FCD, but will eliminate the need for an FCD altogether...

TURBODUECE88

what is the max duty cycle of the 180lph fuel pump

13b4me

Check out the "mild to wild" section on www.fc3spro.com for more information on the modification "stages"...

The stock pump is really working hard @ 8-9psi I'll put it that way...

Brody8877

iTrader: (10)

i wouldnt put those stuff in until after u ported your wastegate, upgrade your fuel pump which is fairly easy, change the secondary injector to a larger size otherwise you could lean out and blow your engine. So yea. Also Fuel Management for the injectors.

NZConvertible

Because a bigger pump pushes harder. Pretty obvious really.

Totally wrong. The ECU cannot compensate for changes in fuel pressure from an upgraded pump except when in closed-loop (cruising). If the pump is pushing harder, the engine will receive more fuel, simple as that.

It most certainly will, there's no way around it. How can it not? If it didn't what would be the point of installing it? With a mild upgrade like the FD pump the difference at low flows is small enough to go unnoticed, but the FD pump is able to maintain the required pressure at higher flows than the FC pump can.

It sounds like your suggesting uncontrolled upgraded injectors is okay. That's just a good way to loose power and waste fuel.

NZConvertible

Injectors have a duty cycle measurement, not pumps. It's the percentage of time they're open per engine cycle.

Turbonut

iTrader: (1)

Just because a pump has a higher flow rate doesn't equate to more fuel being injected into the engine, unless a monster pump is installed which can overwhelm the fpr. The pressure regulator will control the flow, regardless of the pump capacity, so no reason a higher volume pump will increase injector flow without electronics upgrade. To put it simply, I'll assume it to be like an air compressor. If I
have the compressor to turn off at 150 psi, but the regulator/filter is set at 40 psi, I'm going to receive 40 lbs. If I turn the shutoff to 200 psi and leave the regulator at 40 psi, I'm still going to see 40 psi.
That's my stance.........Why install a pump if the injectors cannot take advantage either through larger injectors, or better electronics.
In your recap, your'e not even certain of the amount of fuel the larger pump would supply to the engine, so I consider this as uncontrolled...........Your term.

Have no idea what you're referring to as uncontrolled upgraded injectors.
I'm suggesting replacing the secondary injectors with 720's and keeping the original ecu. It will allow more fuel without a more expensive system, and he'll have the pump to maintain the fuel flow. People have done this for years, actually decades, since the TII was produced.
To each their own.

13b4me

If you install 720cc secondaries without any means of controlling the fuel delivery, then you're gonna have a very unreliable tune... That's why I suggested the Rtek v1.7... Even if you don't want an SAFC or other piggyback device, the Rtek will get you alot closer to a streetable tune by default with 720's...

vhold

Yeah I'll second that, the RTek is a great investment if you have 720 secondaries. Not too expensive, and if you're running bigger injectors, it's a great way to go - the anti-flood feature alone is worth the money IMHO. I am running an SAFC II also, but it's not really necessary if your mods are fairly mild.

HAILERS

******The pressure regulator will control the flow, regardless of the pump capacity, so no reason a higher volume *************

Tell you what. Go out to your car and get the engine fully hot. Now at idle look at your wideband and write the figure down. Now as the engine idles, go to the ECU and pull the wire 3D out of the plug. Pin 3D is the item that causes the pump/relay/resistor to change from approx 9vdc to full alternator/battery voltage i.e. from 9vdc to 14vdc.

The afr WILL go a touch richer when 3D is extracted having caused the pump to go from nine volts to alternator output voltage. And it'll STAY richer. NOT a full afr point like from 13.5 to 12.5 but something like from 13 to 12.8 afr.

I've been there and done that. I've also had this disagreement with the NZ before and the results show I LOST the argument. I told him the fpr would keep the pressure the same and the afr the same. Wrong.

This ancient thread, second page: https://www.rx7club.com/showthread.p...hlight=HAILERS

adrock3217

So..horrible..

Any fuel pump, over stock (FD, Walboro255, etc), WILL overpower the stock FPR. It WILL force more pressure through the fuel system, it is as simple as that.

And people who run bigger injectors, with a bigger pump, with no way to control fuel...are complete idiots. Simple as that! If the ECU thinks you are running 550cc injectors, and sees 4500rpm, it will compensate. Lets use 60% duty cycle as an example.

The ECU is having the injectors pump out fuel at 60% of their maximum. Now, you have put 720cc's into the secondaries...The ECU doesn't know that, and is STILL pumping out 60% duty cycle on the injectors. This is WAY too much fuel!! 60% on a 720cc injectors is a LOT more fuel then 60% on a 550cc injector.


I don't know how to make it simpler then that..but those are the facts.

TURBODUECE88

To make horsepower, your engine will consume a certain amount of fuel. That amount is referred to as the "Brake Specific Fuel Consumption", or BSFC. The BSFC is generally estimated to be between 0.45 and 0.50 for most naturally-aspirated (non-turbo/super-charged) engines, and between .55 and .60 for turbo/super-charged engines.

let's say that you have a naturally aspirated car that makes approximately 200 HP. Using the more conservative BSFC of 0.50, your engine requires approximately 100 pounds of fuel per hour. Now, fuel pumps are typically rated in flow of volume over time and not weight over time, and so we convert this to an international-standard of 63 liters per hour by dividing by 1.58. For a turbocharged engine that makes 300 HP, we use a BSFC of 0.60 to come up with 114 liters per hour.

even with a BSFC of .70 at 250hp(more than i will be making with my existing mods, and an extremely generious BSFC) the engine will only need 119lph to run safely. as i have been told the stock fuel pump on T2's is 180lph. even with age and ware( which a fuel pump with 85,000 miles on it will have little of) the stock fuel pump is more than sufficient to safely run light mods like an FCD exhaust ported WG and most importantly INTELLIGENT and NON JACKASS like driving

adrock3217

The problem with this equation is that the stock turbo pump cannot keep up with the pressure requirements.

This is the point of upgrading the fuel pump .....

speed_monkey

Wouldnt you have to take into consideration that it's a rotary and not a piston engine? They need more air per horsepower than a piston engine, so they would also need more fuel correct?

A FD fuel pump is cheap anyways.

Turbonut

iTrader: (1)

A FD pump will not overpower the FPR. Have been running one for 6 years.

DUH! That is exactly the point. Once you find the sec injector size that you need, it will cycle the same as the factory injector, but will provide more fuel to the engine. Simple as that. Isn't this what you need when you're running 10/12 lbs, and especially if using a fcd.

Better start doing some reseacrch, as your facts are not correct.