Regulators, Fuel Plumbing, and Forced Induction - Jody?

[rwhite692]

In my car I have a 434 SBC / twin turbo setup and am mapping out my fuel plumbing. I want to locate the bypass regulator back at the tank, to avoid circulating and heating of fuel by sending (most of) it up to the hot engine compartment / fuel rails and then returning it back to the tank (as has been discussed here extensively, in the past).

My question is, should I run a second regulator (see attached) after the fuel rails (which would be a boost referenced regulator) and then return any fuel bypassed from that second regulator, to the tank, also? The amount of fuel returned from the engine bay in this scenario would be relatively small.

OR, should I just simply bypass back at the tank, and "deadhead" the rails, with NO return to tank from the engine bay at all, and forget about using a boost-referenced regulator after the rails?

[GregWeld]

Why wouldn't you just boost reference the one regulator? There shouldn't be a need to return fuel other than from the first regulator… because all else is going to be rail pressure which is what you're after..

But I've never done a twin turbo motor - so hopeful someone that has steps in.

[GregWeld]

Rob ---


Here's Aeromotive power planner for EFI - Forced induction with various HP levels



http://aeromotiveinc.com/wp-content/...werPlanner.pdf

[rwhite692]

Originally Posted by GregWeld

Why wouldn't you just boost reference the one regulator? There shouldn't be a need to return fuel other than from the first regulator… because all else is going to be rail pressure which is what you're after..

But I've never done a twin turbo motor - so hopeful someone that has steps in.

I was thinking that it would not be possible / practical to accurately boost reference the regulator back by the tank?

[rwhite692]

Thanks GW the Aeromotive guides are sending all the fuel up to the rails....no bypass back at the tank....

[GregWeld]

Originally Posted by rwhite692

I was thinking that it would not be possible / practical to accurately boost reference the regulator back by the tank?

It's a closed loop system so I don't know why that would make a difference -- vacuum is vacuum as long as you don't have leaks -- and then a drop in that vacuum is a drop… so I don't see any issue with the small distance.

A guy could run a SS hard line back to the regulator if he wanted to and then just use a short piece of tube between it and the "source" or a piece of -3 SS braided for the flex section.

[GregWeld]

Originally Posted by rwhite692

Thanks GW the Aeromotive guides are sending all the fuel up to the rails....no bypass back at the tank....

The regulator doesn't care about anything except that the "excess" goes somewhere…. and it doesn't care about anything except that it's "set" to allow "X" pressure on the pressure side…anything in excess of that goes out the bypass side (back to the tank)... It's a dumb piece of equipment. LOL


You can make that a long trip or you can keep it short and sweet. Most prefer to keep it short and sweet - and as you've pointed out - keep the fuel away from the heat source.


Personally -- I see more mistakes on the tank plumbing than anything else - with guys returning the fuel and aerating the tank --- or not having a sump for the pick up point. Or running too small supply side plumbing.

[GregWeld]

Originally Posted by rwhite692

Thanks GW the Aeromotive guides are sending all the fuel up to the rails....no bypass back at the tank....

Sorry -- just went back to the page with the link -- and for the life of me - all I want to do is come down there and

Go back and look at the system --- they're just showing you parts -- and there is a return to the tank from the regulator in every section.

Have you been checked for cataracts?

[rwhite692]

GW, I know how regulators work - this ain't my first rodeo...my point was, that in every example case that they show, Aeromotive is not bypassing and returning back by the tank - They are doing so w/the regulator located after the fuel rails, up in the engine compartment, which would be returning (heated) fuel back to the tank which we know can cause problems etc.

My main question is really if I can avoid having to run any return, after the rails (ie, just regulate/bypass and return back by the tank, and "deadhead" the rails) and just forego the idea of boost-referencing the regulated fuel pressure. It would certainly simplify things. (diagram below)

I have not been able to get a clear idea on whether or not boost referencing would actually matter, in my case. My max boost will be 12PSI with 96lb/hr injectors. It seems that boost referencing matters more on engines running tons of boost, but, this is only anecdotal observation, on my part.

The fuel pump I have is one of the new Holley (two bosch-type pumps in one case) and the plan is to have the BS3 ECM turn on the second pump based on RPM. The primary pump will have the Aeromotive PWM speed controller on it so that it is not running at max output when I'm just cruising around, etc.

Cataracts? no, but I am basically blind in one eye, so, there ya go

[BBPanel]

I inquired w/Aeromotive Tech Support re the same issue w/A1000 (although I'm not running boost) and I was told that their documentation says it needs to be at the fuel rail but at the tank will work as well, they just don't advertise that fact. They also said in my case I did not need to connect the vac reference. In my mind, if there was some specific/ironclad reason not to return at the tank it would be stated in bold red letters. Not sure if that helps - I will be bypassing at the tank and I'm sure if its a problem it will manifest itself relatively quickly. -Bob