I've done a few 700-850+ rwhp cars with the regulator in the rear. Haven't broke one yet, and I'm not afraid to drive them hard. I had one that broke after I sold it, but that wasn't due to a rear regulator; that was nosing it over with an EFI tank that wasn't baffled well enough to work at 1/2 tank or lower with the acceleration of that particular car. Those were boost referenced though, so you'll be happy about that. :thumbsup:

My Cobra was n/a and had a front regulator, but still no reference line. Ran fantastic. All of these cars had O2 bungs on both sides and the sides were always within a couple tenths in A/F; nowhere near a full point difference. That was with comparing the computers wideband to the in-dash wideband gauge, to the handheld Innovate.

As far as fuel taking the path of least resistance, it seems like you'd see the pressure issues on a gauge. I have the gauge on the rail, and on the regulator, and I am not seeing any movement, fluctuation, or dropping pressure on mine.Seems like the regulator is working fine if the pressure is dead steady, a/f basically match side to side, and the car runs great. I do not doubt what you've seen, just that I do check and don't see it on mine. A/F differences from side to side can be due to heads, intakes, etc. as you know. Interesting that you've seen a difference with just moving a regulator. I've just been doing it a different way and my stuff runs good and doesn't blow up. And I never do a mild engine................ :lol:

Again, it's just the "must" wording that I cannot agree on.

Ok, if you still don't get it then lets look at the straw example.

This is the whole key... think of it as a straw that you blow through.. if you blow normal with no pressure or vac then you blow x amount of air. (WOT sea level 0 vac and 0 pressure)

If you have a suction on the other side and blow the same pressure then you actually get more air through the straw. (engine vac)

If there is someone blowing on the other side of the straw then you need to blow more pressure than they do to get the same amount of air out the other side. (boost)

So the way you are tuning is... there is actually more differential pressure at idle and cruise (more fuel flow)... then you lower the PW more than you should have to since the line is disconnected.... then you chase the fuel injector fuel flow change AND the VE air flow through the table while you are tuning.

This will get you in big trouble when you have say a 4.6 mod engine with 160# injectors that makes decient engine vac at part throttle. You can't lower the PW enough to make up for the extra flow the injectors are flowing....

It is a must and the correct way to do it PERIOD... if you say it isn't then you are just passing bad.. efi info around yet again.

It is the exact same reason you boost reference the regulator... and everyone does that.

Appreciating the dialog gentlemen, and learning a lot. Keep it up! :thumbsup:

Put 8 O2 sensors in the headers then tell me how constant they are, especially on a bank to bank EFI system. Moving the regulator from one at the end of the one rail to a setup with a y feed in and out made a huge difference. Two collectors are just an average of 4 cylinders each. You can have two really lean and two really rich and wouldn't even see it.

If you really think you will see pressure drop on a gage you are kidding yourself.. you lose fuel flow long before it actually hits the gage. By the time the gage actually moves you are OUT of fuel.

Brian --

I'm calling Brizio to have him hook up a vac line to the pressure regulator.... Well -- maybe not -- this is something I'd rather do myself. When the car was built - the line was run - just not used - so is a simple deal now. SMART HUH?!

Just 'cause the next time I see you (SEMA) I can say I did it right.... ">)


It all makes "sense" --- but on a little crate motor... I'm doubting it changes much... but then again -- I'm TOTALLY ready, willing, and able, to learn. You'll never hear me say that I know it all.

First off, your example of a 4.6 Ford with 160# injectors is not something that's seen every day. :lol: Yeah, with that large of an injector idle issues are a concern.

I have not had a single idle issue yet doing it my way. I've never had the pulsewidth go "too low" at idle and cause issues. I've never "chased" the tuning because of this.

You seem to take it personally that I have made it work well in a way different than you think it should be. You've given good advice, I see the purpose of referencing the regulator. But with a rear mounted regulator it's just one more line to run, plus I'm not sure there may not be an issue with the length of the line. Couldn't see an issue with the forced induction builds and the line length, but never tried on N/A.

I don't try to hand out bad info, I simply try to help with things that work for me. I have no problem with your view and would recommend people follow your advice, you're the pro. What I don't agree with is you keep saying that the reference line must be used. That's where you lose credibility. It's obvious that it isn't required or none of my cars or any of the other examples in this thread would run. I mean, they wouldn't even start up according to the "must" claim. That's my point.

I understand all that, was simply asking a question. You may not mean to but you come across as talking down to people if they question you, and for someone who instructs that's not good. Just some feedback, take it as you wish.

I'll stick with Jody's tuning. I know his works well.

Same here, I've seen numerous bad-as-sed cars come from Jody's hand. Plus, he's a righteously nice dude to boot. His cred here is well established.

Since this is clearly Brians meat an potatoes, I'm sure he knows what he's talking about. With that said, there is perfection and damn close. Engines don't require perfection to run well or cars likely wouldn't exist. I'm pretty certain my 850 holley isn't perfect. :D