Thread: Lame dyno results.

Originally Posted by 2003 SSEi

Agreed, The fact the 04+ is a returnless system does in fact give you less Injector headroom. I know many guys that have run out of injector on nearly stock setups

How so? also what is max PW in milliseconds?

Jeff

I'm not understanding what you're asking "how so" to.

I don't remember what my max pw's were on that car.

Sorry GTPower I quoted the wrong guy. I want to know why a returnless system would be inferior to a return style system. The question about pulse width is for anyone.

Jeff

A lot of platforms upgrade the Returnless to the return Style. Cobra, SRT-4's and Turbo Cobalts all do it just to name a few. they are able to run a boost Referenced FPR with a 1:1 Rising Rate (like the 3800 is in the return variant) All of the Returnless systems run a constant pressure with no compensation to boost Pressure.

the returnless systems was born from an emissions guy wanting less chance of fuel vapors entering the atmoshpere, (and manufacturing ease) so the intank fuel pressure regulators were born.
in a high hp scenario, return is the only option. controlling the pressure 8' away and not an easy way to control it via boost can lead to throttle in issuses. on some cars this can hide. just like an accelerator pump with a carb, you don't want pressure drop when you mash the throttle. this will happen with a returnless fuel set up. controlling pressure in the rails with a 1-1 pressure regulator can be easier to tune and more reliable.

I understand a lot of guys "upgrade" to return less style I think more for lack of understanding than anything else. The returnless style runs 10 PSI higher than max pressure on previous years. I used a rr regulator for years and understood the concept, but there is a way of compensating for boost and that is Pulse width. I understand the whole net verses gross pressure issue but unless you are outpacing your pump then would it not be able to handle it? I have run a fuel pressure gauge at the rail and have seen no fluctuation in fuel pressure even at full boost of 10 psi on a stock 05'. I just don't see changing unless there is an issue.

Jeff

I wouldn't expect to show any gain switching to a return style system, unless you're heavily modded.

I don't understand why you would show any gain at any power level. It seems to me that people just don't understand how to tune for a fixed fuel pressure. Everyone is so used to tuning with boost referenced systems, that no one learns it. Obviously if you are heavily modded and are out flowing the pump that would be an issue, but from what I can tell higher output pumps are available. Unless you are running in excess of 20psi on a supercharged car I don't see it as a problem. Or am I missing something?

Jeff

The biggest issue I see with a big pump and no return, is the extra heat generated. You could probably tune for it on these cars without switching to a standalone, but all that extra heat is bad for the pump.