Hey guys,
I'm building my 00 motor with forged internals, and I'm considering what I need to upgrade with the fuel system. I have ID1050X injectors, DW200 pump, and that's about it. I'd be using a Pulsar PSR2860 turbo and I plan to use 93 octane and I plan to keep it the OEM returnless style. My goal is to get to 320whp to keep my stock drivetrain alive. This is a street car that does dozen autocross events and up to a couple track days a year, in case that matters.
I've read online that the stock fuel rail will be fine for my power goals, but I talked to Flyin Miata and their rep told me I might run into fuel starvation at high boost/high RPM as the stock fuel rail apparently can't flow enough Is this a real thing I need to worry about or will I be fine at my power goals?
Sidenote, I was also considering doing a return style conversion on my stock rail with some adapters as apparently my hot and lean restarts are a result of vapor lock from my engine bay heatsoaking but I'm also being told that's a tuning issue (I've messed with ASE a lot and I have to add a stupid amount to get close to stoich at hot restarts to the point where a cold start is really rich). Is this also something I really need to consider doing for my goals?

Let me know if you have any questions.

 

I don't imagine you're going to have any issues. I have a very similar setup running ~E65, ballpark 300-325 WHP. I don't have a fuel pressure sensor, so I can't say for sure, but I haven't encountered anything that makes me think the fuel system is inadequate at these levels. I did rewire the fuel pump to put it on it's own circuit.

Regarding ASE on hot restarts, I used to have to dump a ton of fuel in when I was on Speeduino to prevent the car from leaning out. I still increase ASE on the Link, but now I have Closed Loop Lambda (EGO/AFR Corrections) enabled at idle, so I think that masks a lot of it. Also, adding a flex fuel sensor gives fuel temp, so I assume the Link is doing something with that in the background to compensate as well.

 

I've seen people talk about rewiring the pump to be on its own circuit, does it have any benefits other than potentially saving your OEM pump relay?
Curious to know what your fuel system looks like, do you still use the stock BP4W rail and are returnless?
I have ASE on my BMM ECU, there is a delay on startup (like 30s), but even at the max ASE adder (20%) I'm still lean by about 15%. I am actually switching to a link g4x ECU, who tuned it for you?
It is a good point that you have a fuel temp value, I wonder if that helps at all since I think my main issue is from my fuel getting really hot at the rail.
Looking at your signature we're going to have very similar specs, I will also be using a PSR2860 I just ordered on my Kraken T25 manifold, same pump, but different rods and pistons.

 

FWIW, my hypothesis on the heat-soaked restarts that I see in my car is that it's a result of hot injectors having more resistance and thus larger dead time.

--Ian

 

Thats plausible, impedance will go up with temperature... anything you did to compensate for it?

 

I've never had hot start issues but I run a Hydra lol. I have 780s with an AEM pump, and radium fuel rail. I don't think the stock rail would be a restriction but I went with this rail when I built my motor so I have no way to say for sure.

I was able to make right over 400whp with no reg and the OEM returnless system. So with 1080s and your power goal you'll be totally fine.

 

I've logged enough fuel pressure drops on the dyno with turbo NBs to recommend just converting to a return style now. I know it's mainly because it's not boost referenced, but I hate having to upsize my injectors because of a less-than-ideal fuel setup.

Recently converted an NB to use Radium's hanger, fuel system, and rail. Using a single "hellcat" 525lph, -8 fuel line to rail, and return system, I've never logged such stable fuel pressure. That one's currently at 460hp on E85 with plans for 500. Hugely over kill, but if that's what you're after, It's a great option.

Even if you don't go the full Radium route, their rail gives you threaded ports for a pressure sensor, return port, etc. You can also take a look at all the pictures in their install instructions to see how they went about utilizing the factory feed line to a return line.

 

Heard, so if I just convert to return style, I should be good? I was planning to use an adapter to replace the damper on the rail, route it to a Turbosmart FPR I just bought off a guy here, and return to tank. Should I remove the stock regulator in the OEM hanger or leave it in? I'm unfamiliar with how stacking regulators affects things.

 

I like rising rate return style for reasons that should be obvious on higher power cars. You don't want the differential pressure to drop much and you want cooler fuel.

As mentioned, using the stock fuel relay to trigger a larger, dedicated relay and wiring, rather than the pump itself, is desirable.

Speaking of cooler fuel, please insulate the crap out of your exhaust where it passes beneath your fuel tank. I have heard my gasoline BOILING in my tank after shutting off the car ON THE STREET. Can you imagine what it was like on the track? Scary as **** when I heard it and figured out what I was hearing. Even stock exhaust at 100-whatever whp is shielded.

Hot restart was not a problem once I located my IAT sensor in front / beside the radiator and tuned it properly.

I also raised the idle, increased the alternator output, and added larger wires and grounds to the battery, main relay, alternator, and starter.

The DW200 should be plenty if receiving good power and ground once return and rising rate are implemented.

Insulate the exhaust from the transmission. Again, the factory does it at 100whp. You are pushing it to 3x the stock levels. 3x heat and 3x the load...

 

i believe there is already heat shielding under my tank, what do you suggest adding on to it? Thankfully I’ve never noticed my fuel boiling but idk what part of the country you live in.

my IAT is currently located just under my throttle body behind the rad, not sure if that’s going to be a feasible change for me since I can’t weld. I have IAT enrichment and my IATs at hot start look reasonable for a hot car sitting even with it running.

Interesting that you’re mentioning to insulate the exhaust from the trans. I do notice my tunnel getting warm after a while of driving.

what are your thoughts on my current fueling setup? Should I bother with converting to a return system?

 

If you convert to return style with a regulator in the bay for boost reference, you should remove the in-tank regulator.

 

100% yes. Heard lately about fuel pumps shorting in my local community. Even my previous NB.

 

Sorry, missed this reply. Maybe less relevant now, but yes, stock rail, regulator and returnless. That's been good to ~20 PSI on E65 so far (estimated 320-340 WHP).

Evap cannister deleted but I did add an evap solenoid back in due to issue with filling the fuel tank (also because the Link can control it properly and my old ECU couldn't). The main reason I rewired it was simply because it was recommended on here and I figured it would help stabilize power to the pump. Curly was one of the ones who recommended it IIRC and he's got way more experience with this stuff so I took his word for it. I tuned the Link myself.

 

Bit of a minor point compared to all of the other stuff but I went with a radium fuel rail just for the versatility. Allows for much more flexibility with how you route fuel lines, regulator, pressure gauge/sensor, etc. or for future options with different heads, intake manifold etc. It also looks pretty sweet and is relatively cheap compared to all the other stuff you're spending money on- plus now I know I never have to second guess if it's a restriction.

 

DW300 dead headed on the stock rail, OEM regulator removed and boost referenced regulator in the back, through ID1050's. Stock wiring will not support a DW300. Low 11' s with headroom on E85. Fuel starvation from extreme acceleration, gone after installing the long hydramat sock. Been running that way for years now. Not logging fuel pressure, but I could feel when there was an issue before.
The stock NB rail is not a restriction, maybe above 400WHP on E85, perhaps.