Originally Posted by BLKMGK

Sadly no. What pressure would you choose? Pressure varies based on manifold pressure. If you simply chose base pressure it wouldn't come on until too late under hard boost. If you chose peak boost pressure plus base then it would be on all the time during cruise. You must take both desired base and manifold pressure into consideration...

Originally Posted by AMS

Aha, not that simple... how can I put this, you can't just simply add a fuel pump in-line to the system. We spent a few days testing different configurations to see what worked and what didn't. As a warning, don't just add an inline fuel pump to stock fuel system, it can possibly cause severe fuel starvation!

To answer your question though, the rail pressure would change with the boost you're running. With a stock 3.8 FPR and 25psi of boost for example, you should be at 80psi of fuel pressure if the pump is sufficient. A Bosch 044 is capable of flowing around 280-290 liters per hour at 80psi of pressure which should be able to support around 700whp on a 996tt engine. So if you're under that level you'll maintain fuel pressure, if you're making more, then rail pressure with start dropping.

-Martin

Originally Posted by Boost Logic

It is on my master TO DO list... but I need a donor car to get it all going...

Originally Posted by Chris Green@USP

I am so glad you said this, 2 years ago I tried everything for fueling and doing a inline was almost worse then just running the stock pump alone.

Its funny that some companies are still selling inline 044 kits for p-cars.

Martin do you plan on using stock lines in your kit?

Originally Posted by Hogapalooza

Thanks! Just another example of how everything I know and or have done to a car/truck that doesn't apply to these cars. I sure am glad for this place and some of the people here willing to share what they know.

Originally Posted by MARKSKI@911tuning

I respectfully disagree that running a second fuel pump the way we do on stock pressure can be devastating. Protomotive has probably done a few hundred of these over the last 6 years or so and it works very well. We put down 750 rwhp on our basic second pump in series. Many members here have this set up. I have never heard anyone here have catastrophic engine failure do to a a poorly designed 2nd pump approach. I'm not saying it's the best nor the only way but it works very well on our set ups.

I have a dual parallel set up on my car as a few other 1000 rwhp cars do here on 6speed.
Not discrediting any new finding at all but just stating known facts.
Mark

Originally Posted by BLKMGK

The thing to recognize is that an 044 pump will flow that sucking gas on it's own. However if it's FED gas it should flow more. Companies, like Markski, sell this because in their experience it has worked. It might not still be enough for say an E85 car but it should still up flow. It won't double it for sure but it should up the volume and under high pressure volume should remain higher than just a single pump on it's own. IMO it's not optimal but it's being done, it's working for many, and when you consider the science projects some guys have under the bonnet up front it's cleaner and cheaper. It's just not going to make 1K at the wheels....

Originally Posted by Chris Green@USP

I am so glad you said this, 2 years ago I tried everything for fueling and doing a inline was almost worse then just running the stock pump alone.

Its funny that some companies are still selling inline 044 kits for p-cars.

Martin do you plan on using stock lines in your kit?

Originally Posted by BLKMGK

Sadly no. What pressure would you choose? Pressure varies based on manifold pressure. If you simply chose base pressure it wouldn't come on until too late under hard boost. If you chose peak boost pressure plus base then it would be on all the time during cruise. You must take both desired base and manifold pressure into consideration...

Originally Posted by BLKMGK

It also works opposite under vac in the intake. What's desired is a constant level volume of fuel - at least on a return system. When the intake is in vac the engine is trying to suck fuel out like a thirsty baby on a teet. Under boost it's trying to blow the fuel back up the line. So, vac means lower pressure, boost means higher pressure - all to counter what the engine is doing. Hope that makes sense. Only the newest EFI cars, so far as I know, don't do this - they run returnless systems and the fuel pump is ramped up and down as fuel is needed. Much harder to modify I think but the fuel not going round and round means less heat in the gas tank and less vapor emissions.

Hope that helps and clears things up, fire me a PM if that still sounds nutz

Originally Posted by ttboost

This is the kind of stuff that gets done in the Supra world, at least MY Supra world. Paralleled 2 pumps and welded -6 & -8 fitting onto the pump assembly, maintaining all the factory plugs. I did keep the fuel pump control in the AEM standalone. Can this be done or is this what you guys are doing?

Originally Posted by BLKMGK

So you're advocating understanding how our cars work and closer monitoring? Excellent! I think the picture above of corrosion on a fuel pump lead is an example of NOT watching over things carefully and using CRAP connectors. There are some good ones out there that I think would've held up better.....

Originally Posted by Chris Green@USP

That can be done but since the top plate on the porsche is plastic you would make one in metal. 2 044's will not fit into the stock porsche pump basket thats the next problem.

but I know 4 walbro's will fit