NB FPR into NA for 60psi
 

Not sure how many, if any have done this.. but it works. We were recently tuning an NA8 chassis with an NB1 motor/injectors on the stock fuel system for E85. Power goal was 140whp. We ended up running out of injector at just past 140whp. So we stuck an in tank NB FRP (60psi) onto the NB1 fuel rail for the return type NA8 fuel system and voila, 60psi. No reference port nipple so you might want to put a piece of cheesecloth or nylon over the diaphragm housing to keep grit out of the port hole. It works because the boss on the intake FPR is the same. Total Pnp. How cool is that?

We mounted the NB1 regulator on the forward boss where the damper usually goes. Lined up with the fuel hoses OK.

https://www.miataturbo.net/attachmen...1&d=1392693803

https://www.miataturbo.net/attachmen...1&d=1392693803

https://www.miataturbo.net/attachmen...1&d=1392693808

Pictures aren't showing up; is the problem me or you? Otherwise, nice to learn! What was the final #?

Pics work for me.

This is neat! I'll have to try it on my 1.6.

So with a turbo, there's no problem leaving it open to atmosphere with a tiny filter?

For turbo you really want manifold referenced. This is more of an N/A trick. Probably why I have never seen it mentioned. Most of the workaround type of fixes like this are discovered when trying to get turbos to stop blowing up I think.

its amazing...25 years later and we are still discovering little tricks to these cars.

I don't see why it wouldn't work for low to moderate boost.

Injectors work based on pressure differential. Typical NA FPR is rated for 43 psi at 0 vac + 1:1 rising rate with boost. Typical NB FPR is rated for 60 psi static.

Assume 10psi positive manifold pressure.

NA:
53 psi rail pressure (43 base + 10 boost reference rise)
less 10 psi manifold pressure
-----
43 psi differential pressure

NB:
60 psi rail pressure (static)
less 10 psi manifold pressure
------
50 psi differential pressure

Theoretical difference: NB regulator provides 7 psi additional differential pressure.

What does that mean for flow?
Adjusted flow rate = SQRT (50psi/43psi) x injector flow rate = 108%

So in theory, at 10 psi of boost, the static 60 psi NB regulator would would increase fuel flow through the injectors by an additional 8% as compared to a typical NA regulator.

For a n/a application, the theoretical increase in fuel flow at 0 vac is 18%.

Yah, some gain. Just not as much as an N/A setup. Can't beat the price. Most guys throw away the tanks. We have. New they're $120 or so. Tanks tend to get tossed out when tubs are scrapped. So yeah, now we'll salvage the regulators from any NB tubs we scrap.

I wonder if you could put this on a stock ecu 90-97 car and run E85?

That would be a bad idea. You'd be better off installing injectors with a flow rating 140% that of stock.

You'd be much better off with the addition a standalone EFI controller.

Problem is ideal lambda values for gasoline and E85 are different at lean cruise, light load and full load. You might back into something that sorta worked at full load but would be hella rich everywhere else. Like the guy that makes his living selling ECU's said, just get a programmable ECU.

No bias was intended in the previous post.

The stock ECU is expecting a rise in fuel pressure as load increases, and its fuel tables are set up accordingly. The combination of (1) super conservative (rich) power tuning and (2) fuel tables set up for low fuel pressure at idle and cruise would easily create conditions as described by Emilio...

IOW, bad idea. :)

So there is a hole already. Thread in and JB weld a barb and viola, 60psi base pressure regulator that is 1:1 referenced.

Might actually work.

I can't see the pics either.

I couldnt see the pics at work and figured it was just block at work. Now at home I cant see them either.

Pics no working? Most of you have probably noticed all the bugs in this site. Weird redirects, incorrect commands and dead links. No other VB ~3.8x site I'm on has them. If I use the image icon from the toolbar, nothing displays. So I have been manually entering every image this way for a year or two

[img]www.blahblahblah.com/carpronz.jpg[/img]

MT.nets server copies the file to it's own server and renames it as miataturbo.net/attachment that may or may not display.php?blah blah

That usually works. The image file I post are either on my server or inline from facebook. The links in the first post here display in chrome on my machine just fine. :dunno:

They're cached on your machine then and not available to either us or the MT net server. The little picture button has always worked for me.

Nope. Same webserver as my website so it's accessible 24/7, http, not https.

http://949racing.com/supermiata/NB_FPR.jpg
http://949racing.com/supermiata/B6_FPR_1.jpg
http://949racing.com/supermiata/NA8_FPR.jpg

That's what I manually add img tags to. mt.nets server caches and renames whether I like it or not. Might have something to do with being a site sponsor/advertiser. It's definitely a site glitch. I post inline images on forums all over the world, two of which cache and rename. The only site that has display issues is this one.

It's not complicated. Add img tags, done.

Ever had any troubles running E85 on the stock fuel system?

Not so far. We have a few NB's with hundreds of hours on the stock fuel system/E85. The NA's in our shop maybe 50hrs combined but so far no issues.

We always rotate fuel stock and try to burn off whats in the tank when we get to the next track event before refilling.