miataspeed1point6

iTrader: (1)

I want some opinons on my setup to see if some of my parts are worth installing. My goal is to run SAFELY at 8 psi, but if my system is capable of 10 I would spend a few more bucks to get it there.

What I have
Base Greddy kit
Emanage blue with olderguys Autotune (still trying to make it work)
Probe intercooler, has 1.75" inlets. Too small for 8-10psi? (will be front mount)
Vortec
1.8 injectors (need to be flow tested, not sure if I should go larger instead)

What I plan or might need
The fuel pump is stock, I read it can handle 8-10psi, but I'm skeptical.
I plan to add a duel feed rail
I'm searching for a new rear end, rx7 or torsen. Looking locally as I REFUSE to pay $400-700 for a diff.
The clutch will be upgraded later this year
I want a wideband, I will most likely settle for the dyno

What do you guys think? My guess is right now I'm safe for 6. I think with a fuel pump and a dyno tune I can do 8. Opinions please!

bripab007

I'm using a Probe GT/MX-6 GT intercooler at 8 PSI just fine. An intercooler would be rated in horsepower/airflow, not PSI...well, there would definitely be an upper limit for the intercooler rated in PSI, but that's probably ~50 PSI.

I think the stock Probe/MX-6 made like 145hp/180lb-ft, so that gives you an idea of what these intercoolers were designed for. Although, they weren't full on front-mounts, but mounted off to the side of the radiator inlet, so they should be more efficient sitting right in the air stream.

miataspeed1point6

iTrader: (1)

Yeah, I know all to well where they sit in the car. Spent a LONG time ripping it out. I was just worried the 1.75" inlets would hurt. But its good to hear from a third source it wont. Thanks.

boostinsteve

The stock pump is good up to 85psi, but it is like a 155lph. So, if you keep fuel pressure below 85psi, it is a great pump to get you up to like 300hp. Don't quote me on the hp level, but you get the idea. If you plan to run a lot of pressure, you need to upgrade to a high pressure pump.

Sactown_NA

1.75" inlets are fine.......plenty of people make good power with starion intercoolers and they are only 1.75" as well.

I wouldn't boost past 6 without a walbro 190hp though....the stock fuel pump is usually good to 85ish psi.......and the pressures required for 8+ psi with 1.8 injectors will be much higher.

$85 + a one hour install is worth it for the peace of mind

Arkmage

iTrader: (3)

I seem to recall telling you about a month ago that the 1.75" will be fine for your power goals... but I guess people here just don't listen.

miataspeed1point6

iTrader: (1)

No I listened! Note the "third source". I'm just one of those paranoid people. I want to make 100% sure I'm setting this up right because I can't afford to screw up. If you need proof look at my emanage thread, I'm driving olderguy nuts for sure.

As for the fuel pump, at this point which route should I go? The injectors I have now need to be cleaned and flow tested. Should I get the new 190hp or larger injectors? Cleaning the injectors is around $60, the new pump $90. No idea how much larger injectors would be?

miataspeed1point6

iTrader: (1)

I read through braineack's FAQ and came across the fuel injector part. I tried to do the math...I can't. I used the website to plug in my numbers, but I don't know the pump pressure. Then I read about people running the stock pump up to 250hp.

With the 1.8 injectors can I safely run 8-10 psi with the stock pump? Or should I upgrade my injectors or pump?

miataspeed1point6

iTrader: (1)

I spent some more time on the plug in page.
I plugged in

desired horsepower: 180
Number of injectors: 4
Brake specific fuel consum: .55
Max duty cycle: .70
Fuel system pressure: 90 ( I guessed the stock pump could do this, not sure)

I saw a few dyno sheets of members running this setup at this exact horsepower. I'm fairly confident the stock pump will work. Let me know please!

Ben

iTrader: (33)

I'd increase BSFC to .6
MDC to .8 (though I've seen up to .95 MDC from the oem ecu on my datalogs)
Max FP from stock pump, probably 65 psi with any reasonable amount of flow.

Your stock fuel pressure reg provides 48-50 psi max, so you'd need an afpr to increase pressure over 50.

With the 1.8 injectors, an afpr, and new fuel pump (walboro in tank or pierberg in line) you should be good for 220-240 whp.

miataspeed1point6

iTrader: (1)

Ok thanks. I wasn't sure about the stock fuel pump. 65 seems SO low, I thought for sure it would be higher. Looks like I need the 190HP and send out my 1.8 injectors to the cleaners.

As for the AFPR, I have 2. I have the JRSC one (the chrome one with the bolt on top) and the Vortec. Which one should I use? I think the vortec has a new disk (its blue/purple) from the PO of my kit. But some people have told me the JRSC one is crappy. Any ideas?

expensivehobby22

i bought a vortec recal kit with a bunch of discs that i never opened if you end up needing it. i got a begi that i'm going to install as soon as i get the car up again.

Ben

iTrader: (33)

I think the pump may be capable of 70-80 psi pressure without load. As pressure goes up, flow goes down, so there is a point where the pump can continue to make pressure, but it's not passing enough fuel.

VRTSid

I have a semi related question. Im running a stock pump and fpr, 330's and emanage, will I need to up my pressure? I've heard no but ...

miataspeed1point6

iTrader: (1)

Awsome on the calibration disks, I'm sure I'll need one. Thanks!

And from how I understand it, if you have large injectors you don't need as much pressure at the rail. But then again I'm just learning about engine computers and fuel pressure and what not.

And with my 265cc 1.8injectors and walbro fuel pump what calibration disk would I need to run?

akaryrye

iTrader: (5)

There is an aspect of pressure rising systems I had never thought about until now, but it makes sense. I can imagine a point at which the fuel does not flow more quickly with more pressure and I wonder if we are even getting close to that point.