I have seen this exact issue, manifested as fuel starve in a 140whp car with ~1gal in the tank. Added the extra piece of hose, ziptied it so that it aimed directly at the OEM fuel sock, and "found" another 3/4 of a gallon in the tank.

Ian, I vaguely remember mentioning this to you at least a year ago...

e: This is what I did in Acamas. Instead of trying to adapt, I just cut the flange off the return line, stuck a piece of hose on, and ziptied it down.

https://i.imgur.com/beXkbzHl.jpg?[/img[

$272 in new shocks would probably double the value of my truck :giggle:

Andrew, is that the fancy fuel submersion rated hose?

We had a conversation about it, but the takeaway I got from it was that the force the return flow was pushing fuel away from the pickup, rather than the return flow being aimed outside of the pickup bucket. After putting the video camera in through the fuel filler, the "pushing fuel away" theory didn't look likely, and since I didn't want to cut the pipe for regulatory reasons and I didn't have anything to bolt to it, I put it back in. The pickup hasn't come back out since then. :)

Now that I've got the bolt-on adapter, I just need a spare weekend when it's not 100+ degrees outside...

--Ian

this....1000x this

Great thread Ian. So full of win. I had a similar starvation in my fuel cell. Once I dumped the return into the catch can problems went away. Have you considered going to a 245 tire on a 10" wheel? Seems like you could really use it. Unless I missed it you're still running the rear muffler with the side entrance. That would be high on my list of things to do. Consider making a couple of different mufflers. One for Laguna and one for Sonoma/Thunderhill. No sense having that restriction (and weight) if you don't need it.

I measured the backpressure from the FM side-entry muffler and it's insignificant, so I'm not planning on touching the exhaust at this point. Currently the car is really quiet, it easily passes 90db days at Laguna. From a power standpoint, I need to take it back to the dyno and see if the Supertech valve springs had any effect, and then I've got a squaretop to try out.

Back when I was autocrossing the car regularly I thought seriously about 275s and 10s, but they weren't going to fit without cutting the fenders and I decided I wasn't willing to do that. I don't care for the bolt-on plastic/fiberglass fender look and I still drive it on the street I like it to be fairly low-key visually to avoid attracting attention. That's the same reason there's no aero or hood vents on it. I'm not sure if 245s would fit under the fenders or not, I don't think I know anyone locally who has a set I can borrow to test-fit.

--Ian

Your car sounds amazing on track.
All you hear is the turbo. Music to my ears

"Who has the NB that constantly makes the giant vacuum cleaner noise?"

Yes, that would be Ian. :giggle:

Albert has a single 245 on a 15x10 6UL.

Match making complete.

(*) Giant vacuum cleaner noise that is less than 90 db. :)

--Ian

I am surprised to hear that. The side entrance muffler looks to be a chambered muffler.
245 on a 10" wheel should be just a flat roll on a NB. Maybe slight pull. In your shoes I would do the same and avoid side flairs. Next time you're at Sears Point I can test fit a wheel for you.

It's a straight through muffler with a ~ 6 inch long chamber welded onto one end that the side entrance lets into. I was kind of surprised to find out how well it flows too, especially considering how quiet it is.

I might take you up on that. Dunno when I'll be going to Sears Point though -- haven't found any convenient events up there lately. I'll be at Laguna for the GGLC event in July, though.

--Ian

There's a drag race next week Ian ;)

Yes! Do this! I want to see Ian's car struggle for traction in the 1/4 :giggle:

Doesn't Andrew have a set of 10s with 245s on Acamas? Mabe you can sweet talk him into letting you fit one of his wheels? He said you can fit 10s with a roll. No pulling iirc.

Also in for Ian at Sanoma during 90* heat.

No you don't, because next week Wednesday my car will be at TC Design getting new seats in it. :)

The way the scheduling works out, to make it to Wednesday drags I'd basically need to take the whole day off, and I'm not that eager to blow up my 6-speed. :)

The 10s would fit, I'm less confident about 245s. What tires are available in 245, anyway? Isn't it just RS4 and RC-1? I'm not sure those are faster than 225 RRs. 245 Hoosiers would be, but I'm not buying purple crack just for track days.

--Ian

:cough: worth it :cough cough:

Cool. :)

http://www.codrus.com/miata/coolshirt/coolshirt1.jpg

--Ian

So I found some time this afternoon to take the fuel system apart again.

http://www.codrus.com/miata/fm2r/fuel-return1.jpg

Factory regulator flange adapter to AN. I had been originally planning on just shoving a hose over the AN fitting and pretending it was a barb, but it's really too big.

http://www.codrus.com/miata/fm2r/fuel-return2.jpg

So, here's an AN to hose barb fitting:

http://www.codrus.com/miata/fm2r/fuel-return3.jpg

Which fits this submersible fuel hose. It's 3/8", the biggest you can get. This is why I needed the hose barb, they don't make submersible hose that'll fit over a -6 AN fitting.

http://www.codrus.com/miata/fm2r/fuel-return4.jpg

All together. I decided to use some safety wire instead of a zip tie to hold it close to the sock, on the theory that stainless steel wire was less likely to get dissolved than random cheap zip ties. Yes, there were zip ties in there before (and still are), but they're the ones that came with the fuel pump, which suggests they're less likely to be a problem.

http://www.codrus.com/miata/fm2r/fuel-return5.jpg


And here's where it goes:

http://www.codrus.com/miata/fm2r/fuel-return6.jpg

The GGLC track day is in a week, we'll see if it fixes the starvation issue then.

--Ian

And a proper fuel line clamp as well. Anticipating a good report.