stevieturbo

Correct can mean different things to different people. I'd agree that a boost referenced system is correct and the typical way to do it.

However, times change, technology changes and ideas of how things should be done change.

A local guy who does R&D for OEM companies built his own pump controller. Operating via monitoring fuel pressure and pump current draw along with some engine parameters he developed a controller that runs closed loop, it's dead end with no regulator at all. So no flow is wasted going out the return, which leaves all the pump capacity to make power. It's also neater. And can run up to 3 pumps as required.
Which sounds superb....I just cant convince him to make a simple version !

Lonnies Performance

iTrader: (16)

A few things to think about.

1. Flowing through the regulator as illustrated can offer a flow restriction. I have personally witnessed a pressure control problem as the regulator restricted the flow to the rails. If you look into a regulator, you will see there is not a straight shot to the other side.

2. As posted here, the best way to mount a regulator is at the rail. This provides the fastest response to engine fuel pressure & line restriction is not an issue. If you choose to do otherwise, your decision... It works fine in lower HP applications, but you are only saving a few feet of return line & a set of rails in the grand scheme of things. If you need this level of fueling, you already have tens of thousands in your build... saving $2-300 is questionable if it compromises performance or reliability.

3. The 5# drop is not unheard of front to rear at the 1000hp range... even much more with a stock line. Been there, measured it & learned from it.

4. My recommendation is do not compromise on the fuel system. Your engine will thank you. It is unfortunate, but about 10% of my customers call for a fuel system after they hurt their engine or have problems with their cheap, inadequate systems that they tried to build cheaply. Doing it twice is rarely economical.

qqwqeqwrqwqtq

Stevieturbo- Vaporworx makes a controller system like you describe. I consider that correct as well and considered using it in my Cadillac but decided on a mechanical regulator for simplicity.

Lonnie- I agree on all points.

To the OP, if necessary you can regulate it at the rails by feeding the regulator via the test port. This would avoid flowing through the regulator on the feed side for reasons Lonnie mentioned.

stevieturbo

Just tee the regulator like I described, then you are not flowing through it prior to supplying the engine.

In some ways it is actually better. As you are no longer circulating fuel into the hot rails to get heated and then back to the tank. So the fuel system will run cooler by installing the reg prior to the rails and running the rails as a dead end.

qqwqeqwrqwqtq

I see your point about heating the fuel, I just prefer to have it after the rails as you then have no worries about internal pressure drop on rail crossover.

stevieturbo

Although I would also be inclined to split the supply and run 2 dead end rails, as opposed to flow through and a single dead end.

Probably makes little difference in reality though.

I run my primary injectors as a dead end, although the secondarys receive fuel flow all the time.

skinnies

iTrader: (33)

Proven to work fine at 850 rwhp on E85 for many street miles. Regulator as far from rails as hidden in fender in my ltd.

killernoodle

If it works just fine for him, how is it not the correct way? That's like saying boosting a non-built, junkyard engine isn't the correct way of boosting an engine. May not be "correct" to you, but if it works, then how is it not "correct" for them?

I'm just stating the fact that lots of people run setups like this all the time and encounter no problems what so ever.

qqwqeqwrqwqtq

It's not correct because working around a drop in fuel pressure is not correct. If the regulator is at the back of the car and boost referenced instead of up at the rails where it should be you will be dealing with some type of pressure loss across the feed line, be it minor or severe.

Now you tune the car by adding a bunch of fuel up top to compensate for a pressure drop and any small loss in pump output is going to send you dead lean because the pressure drop across the line will amplify any problem. How repeatable is this? Also the problem gets worse at higher boost levels/fuel flow rates so maybe at base boost it drops a couple of pounds and at high boost it drops 5-10 or more pounds. Trying to dial in the tune on something when the fuel pressure is not consistent is not correct.

Regulated up front this would be much less sensitive to a decrease in pump output. Maybe you're on a pass and you lose the alternator, now this pressure drop you tuned around becomes very severe and you lose an engine.

Doing things like this with the fuel system is setting yourself up for failure. If by design you will have a drop in fuel pressure or if it will not sustain one to one ratio then I consider it incorrect. If you disagree I am fine with that, feel free to mount the regulator on a trailer behind the car but I am trying to give people good advice on how to do things properly and in this case doing so costs you almost no more money or time.

skinnies

iTrader: (33)

Buying rails and running the regulator after them is what is needed for higher hp setups and is the "correct" way to do this, I've always agreed with this.

That being said, we have ran before the rails on several setups(few should be well over 900rwhp) without any issues, thats with 90 plus lbs of fuel pressure in boost too. For sub 900rwhp on e85(I'd say well over 1000rwhp on race gas) this setup works great and is cheap.