C U IN REARVEIW

Im also going to a boost reference fuel regulator.....would the (boost referancing line) need to be before the meth?

schpenxel

Needs to be off the intake manifold, similar place to how the bypass valve, brake booster hose, etc. are connected

C U IN REARVEIW

I'm almost positive my tuner(brett bradberry) said I could put it in charge tube for quicker response in fuel pressure....(positive pressure vs. Vacuum)?

schpenxel

No, def don’t want it to be connected there. IMO anyways

C U IN REARVEIW

Isn't the rule of thumb +1 psi boost = -1 psi ffuel pressure?

schpenxel

Yes, but you want to be taking that reading for boost/vacuum at the same place as the injectors, so intake manifold basically

stevieturbo

No, fuel pressure should track manifold pressure so that a constant pressure delta is maintained across the injector at all times.

So +1psi boost = +1psi fuel pressure, and likewise with vac.

C U IN REARVEIW

So where should i be plumbing the line to then.....off brake booster like hobbs switch? I believe it may have been due to the fact my (in charge tube) fuel regulator is in the drivers rear wheel well...and vacuum pressure would be to delayed....?

stevieturbo

As everyone has said, it is normal to reference the FPR to the intake manifold.

If you make any changes, it will need tuned to suit.

C U IN REARVEIW

Urs this car has had alot of changes and will be tuning it as soon as im done....definitely a maiden voyage for me and im learning as i go. Thanks for your help.

schpenxel

Depends on what he meant. If he meant 1 psi of boost = effectively 1 psi less of fuel pressure on a stock setup, then that's right. I assumed that's what he meant.. but maybe I misunderstood

But obviously we're saying the same thing in a different way

stevieturbo

Yep, it sounded like he was asking or stating that fuel pressure should decrease with boost. It should not.

Even with a fixed rail pressure, whilst fuel pressure does not drop with boost, pressure delta across the injector does which will reduce ability to flow.

Not the end of the world for a low boost setup, but never a great scenario anyway.

C U IN REARVEIW

Lol...That's what I was trying say.....lol

C U IN REARVEIW

That's how it was explained to me....just couldn't relay it clearly I guess....

C U IN REARVEIW

Thanks for your help once again!

BLOWNBLUEZ06@RKT Performance

Correct. That is what I said. You can do it on either side of the throttle body. As long as the fuel tables are set accordingly, only boost referencing the regulator is fine. You don't need the help in the vacuum region, but you do need the help in the boosted region.

What I said is that without boost referencing, the delta or pressure differential across the injector diminishes 1lb for every 1lb boost applied. If you're making 20psi boost and you're set at 58psi without boost referencing, your resultant pressure across the injector is 38psi.

BLOWNBLUEZ06@RKT Performance

How come? If I set his tables up properly and fully tune the car, like I always do, it's not going to be an issue. Never has been in the past. It's a bit different thought process, I'll agree, but as long as it's set up right in the fuel tables, you get the same desired result.

Kingtal0n

Because 'charge tube' sounds like pre-throttle body tube, i.e. cold pipe, i.e. intake air tube leading to the engine.

There is no vacuum in this tube to drive the regulator into a vacuum reference

BLOWNBLUEZ06@RKT Performance

schpenxel

I stand corrected.. I've never done it that way (or heard of doing it that way honestly), but as long as the fuel injector data is setup accordingly I don't see any reason why it wouldn't work...