Bambam7

Just wondering what the specs are of the FD fuel pump compared to the TII pump and the walbro?
Is the pressure the same as the TII pump? How much more fuel does it flow compared to the TII pump and walbro?
My TII pump isn't enough.. and I'm upgrading....

Dumb question... will the FD flow more fuel with the same 4x550 injectors? (Same pressure...)
Thanks!

BTW- what is the weaker link in the stock system, the TII fuel pump or the 4x550cc injectors? What runs out of capacity first??? (I'm only just barely maxing out the stock system... I only need a little bit more. Injectors AND pump starts getting expensive.)

Scott 89t2

people claim the stock injectors max around 280hp and the pump around 250hp (flywheel)

at the same pressure. no matter how big the pump is you will get the same amount of fuel... the problem is when it gets maxed out. the pressure drops. so you need a pump that can give enough volume that won't max out and drop pressure.

however since the stock fuel pressure reg is small. putting a bigger pump in can raise the pressure a bit too which increases fuel. sorta the same idea as boost creep. the reg can't bypass enough fuel so the pressure goes up.

the FD pump isn't much bigger then stock. maybe good for around 300 I think. but it's cheap. bolts straight in. and won't give super rich idles like a walbro which will increase the pressure more.

Bambam7

NZconvertable stated in another post that in injectors or good for 300 hp. Seem's a little high to me.

My fuel system only conks out in 4rth gear, (and sometimes 3rd) when boost creep puts boost up to 13 or so psi, around 6K rpms. It catches back up at redline where boost drops to around 9psi.
Well, I'm bolting in an FD pump. Hopefully that'll bring things up a bit. Plus a rewire (havn't done that yet)
Man.. so that means that I'm seeing somewhere between 250-300 hp at the flywheel when the boost is up there. Well I beleive it, the car flies from 100km to 190km in a blink!
Can I also pinch the return fuel line a bit? (screw valve or anything similar) To bring pressure up, therefore forcing more out of the stock injectors?

White_FC

Injectors definatly good for about 200rwkw (aprox 300hp flywheel?).

RETed

The stock FD3S fuel pump is only good for about 15% more capacity over the stock FC3S turbo fuel pump.&nbsp The U.S. FSM on the FD3S do not explicitly state it's capacity, but they do for the FC3S turbo - weird.&nbsp I just found numbers on the Cosmo 20B fuel pump, which is "only" good for 185lph, but this is rated at 11VDC.&nbsp In comparison, the FC3S turbo fuel pump is rated at 198lph as an extreme high end spec.

Due to the small increase in fuel flow capacity, the stock FPR is able to regulate the FD3S fuel pump to basically the same fuel rail pressure levels versus the stock FC3S turbo fuel pump.



-Ted

adamlewis

So would the stock 550's and a Walbro be good for ~14 psi?

RETed

I guess you've never seen my replies before... *grin*
Yes, you should be okay.


-Ted

13bpower

What do you guys think of the N/A fuel system running boost?

For example, stock 4x460 injectors, TII or FD fuel pump, aftermarket fuel reguletor, and a S-AFC boosting at 8 psi on a TII turbo and aftermarket external wastegate.

From what I have read this would be fine. If I wanted to turn the boost up I would need bigger secondaries. Does that sound about right?

Bambam7

Umm... nope, don't like that at all.
For one thing, the S-AFC is a piggyback for the stock ECU, and no matter how rich you set it, you can never make the ECU push the injectors past its conservative max duty cycle, so it won't help one damn bit for enhancing max fuel capacity... it can just fine tune.

Not 100% here, but The aftermarker FPR should be able to increase the capacity of the stock 460cc's, but not sure by how much.
Why not just put 550's in the secondaries at least?? They are bone cheap, can find em anywhere.
External wastegate?????? If you are trying to cut costs by not upgarding the fuel system, where the hell are you going to geth the money for a custom manifold and external wastegate??? You would need it too, there is now way unless you stick tennis ball in the exhaust that you are going to keep boost down to 8 psi with the higher comp engine. I see 13 psi in mine with a ported wategate and a stock downpipe.
The last thing. If you are planning on running this on a higher compression N/A motor, you are going to need even more fuel (run it richer) than a regular TII motor, to prevent detonation.
So I'd say no, but maybe others have a different opinion.

13bpower

So a S-AFC can't increase duty cycle? I was not aware of that. I thought that was the point of it. What exactly does it adjust in the fuel system then?

Bambam7

Interrupts and modifies the signal from the AFM to fool the ecu into thinking more or less air is going into the engine, therefore modifying the fuel curve.
You can tune it for more or less fuel at any point in the rpm range to tune for the most power.
It's also good for when you put in bigger injectors. The ECU is still going to think that the car has stock injectors, and is going to pulse them accordingly. Leaning out with the S-AFC in the part-throttle curve compensates for running too rich.

Kahren

iTrader: (13)

my friend just dynoed his t2 at 220 whp with stock injectors and 255 walboro bump (rewired) he is leaning out to 13.2 AFR at 10 psi of boost at around 5k rpm. thats where his max boost is. this is with a lot of ice on the intercooler, the intercooler was very cold.

so u decide

oh by the way here is a plot of his AFR

i tuned it with the afc and can NOT get it lower then 13.2 at that rpm which means his injectors are MAXed

RETed

Wow, I guess he must always drive around with ice on his IC then.


-Ted

Kahren

iTrader: (13)

ted if u tune with the coldest possible then he can only run richer making his car safer, so on the street he actaulyl wont see that same 13.2 afr....

what i was trying to say is his ic was actually warmer before he even got on the dyno then after we did a few runs with that ice.

the ic was still very cold with the ice on there

on the third run u coudl see the afr were gettign richer eventhough no changes weere being made which tell su the car is pushign hotter air and thus in more danger of detonating from the intake temps....

NZConvertible

I really have my doubts about the supposed "maximum" duty cycle of the stock ECU. I've never heard of any other cars' ECUs doing this, but I have heard many stories of other cars starting to lean out because the injectors have reached 100% duty cycle.
Mid-range DMM's can measure duty cycle, so this could easily be answered. I'd be really interested to see this proven either way.

Also, regarding fuel pumps, if you have a fuel pressure gauge (or temporarily fit on, say for a dyno run) you can easily check the performance of the pump. Fuel pressure should rise linearly with manifold pressure. If it levels out while boost is still increasing, or even worse starts to drop, then the fuel pump needs to be upgraded.

White_FC

good call NZConvertible
I can't see mazda wasting money on relativly large injectors and only let the ECU run them upto this supposed ~63% of thier max. duty cycle.
Doesn't make much sense to me..
If my DMM could read duty cycle (time for a new DMM.. ) I would've allready checked this out with my ECU..

RETed

I doubt any "mid-range DMM" can measure duty cycle, unless I'm looking at the wrong equipment!&nbsp "Duty cycle" is a reference of pulsewidth (in absolute time) versus RPM reference.&nbsp I have never come across a DMM that can do that - does yours have an RPM reference input or something?

As a side note, my G-Force reprogrammed ECU did hit 95% as displayed on an A'PEXi Super AVC-R (Gen I).


-Ted

NZConvertible

I'm looking at an electronics catalogue, and the cheapest DMM that can measure duty cycle only costs NZ$89.95 (~US$50).

Kahren

iTrader: (13)

what is this dmm i would love to see injector duty cycle on my car

Bambam7

I can't remeber who, but there is a maker of a combination A/F gauge and duty cycle graph! It's a LED scale, pretty cool, but it was kindof ugly. Wish I could remember who made it... it's on a web page.
I'd love to see that.
Man.. Now I'm worried that my FD pump won't be enough!!!!!

Kahren

iTrader: (13)

u really need to know how much MORE pressure the pump is adding if u didnt touch the FPR to have not to worry about it.... i cant belive so many peopel stick mods in their cars and then wonder they blow...because no one EVER bothers to go to teh dyno and see the AFRs!!!!

NZConvertible

Digital Multimeter. Cheap ones measure voltage, resistance and current; more expensive ones add things like capacitance, temperature, continuity, duty cycle and more.