Angel

Kinda made a few passes on the dyno today (03/22/03)...

We didn't have a laptop available for us today, but we were anxious to see what exactly was going on, so the car was put on the dyno. At idle, it is so lean it is scarey, and as soon as there is some throttle, it goes so rich it goes off the chart. So those items obviously need addressed during next dyno time with a laptop (hopefully tomorrow or beginning of the week).

While *rolling* onto the throttle (not WOT), we could take it up to about 4,000 - 4,500 RPMs before it would start detonating because of running too rich (we suspect). However, it does make full boost (15 psi right now) easily before 4,000 RPM. It spools VERY fast, and the whole car is very quiet, you can barely hear it running at idle and it stays very quiet during acceleration. The turbo spool is good stuff.

At about 4,000 RPM, it made 242 rwhp. I do not know the torque off the top of my head. We obviously didn't print the graphs because we couldn't complete a pass. When the tuning is totally done, I will be getting a copy of ALL of my graphs and posting them on my website.

At first I wasn't thrilled about the 242 rwhp, however, I took a bunch of things into consideration. This is 100% untuned ... and only 4k RPM. If we COULD run it to 7,000 RPM in the exact same state, and if the torque would stay the same to that point, we would yield approx. 420rwhp @ 15psi ... untuned ... so I am expecting to make my goal pretty easily .. .which initially was 450rwhp tuned on pump gas (15-17 psi).

Wish me luck....unfortunately, tomorrow we won't get to do much, if anything, because my mechanic is working on a friends car because he promised him ... but I do hope to have some real results soon.

5spdSC300

iTrader: (1)

last time i checked, running rich does not cause detonation so if your car is detonating, i high doubt it from running rich. someone please corret me if im wrong here.

~Kevin

Angel

There are lots of factors that can cause detonation, and running TOO rich is one of them. Regardless, we will get it worked out.

Angel

Another quick update - 03/27/03

Very MILDLY tuned ... this is what we have so far. The car made 312.56 rwhp @ 5,900 RPM @ 15psi. The A/F is 11:1 right now and there isn't a lot of timing in it. There is ZERO knock/detonation showing up, so we are going to start adding timing ... and continue with tuning We have come across a small/minor oil leak, so that is next on the agenda ... Still shooting for 450rwhp @ 15psi (at higher RPMs of course) ... Regardless, I will keep making my updates.

motorheaddown

Angel,

I'm installing my fuel system and recalled reading this from an earlier post on this thread:

"...The one feed line goes to the inlet of the FPR, the return line goes back to the tank, and the outlet goes to the rail. Reason being ... at least this is what we are figuring on... When there is low demand for fuel, the fuel going through the FPR will just recirculate back and the car will be basically just using the fuel from one pump. When the fuel pressure drops and there is higher demand for fuel, it will then use the 2nd pump (this is what we are hoping).

We have also considered T-ing the lines together and running them both directly to the FPR. We might be doing a little more research here to see what other people have done, however, I am satisfied with the current setup for now, unless anyone can give me a reason not to do it like that. I did see in a previous post that someone else used a setup that was identical, so that gave me some reassurance that it will work that way.
..."

It finally dawned on me that you're using the Aeromotive FPR for the return instead of building one into the fuel rail: http://www.turboforum.net/lexus/pict...3/image_2.html Hmm... sounds like a good idea for two reasons: 1) The "forward" end of the ge rail won't have space for a separate feed line, and 2) putting a center return could be a real PITA.

How is the fuel system performing so far? Also, any idea of any pressure variance across the rail on a per injector basis?

Where did you get the fitting that fits in the rail where the stock fpr goes?

Thanks,
-scott

motorheaddown

More questions...

For the Aeromotive FPR to work in this application, the line coming off the rail at the stock fpr location would have to support flow in *both* directions. At low demand, the extra fuel runs *from* the fuel rail (stock fpr hole) to the Aeromotive fpr. Under high demand (more than one pump can flow), fuel flows *from* the Aeromotive unit *to* the fuel rail. IS THIS POSSIBLE?

Thanks,
-scott

motorheaddown

FYI, I called Aeromotive tech support. Using the fpr as feed source is *not* recommended. However, the tech said it would probably work.

I was surprised to hear that they recommend dual pumps to a "Y" block with the fpr at the end of the rail.

-scott

motorheaddown

Ok... last post on this topic. I promise.

Angel,

I believe your logic is flawed here:
"...When there is low demand for fuel, the fuel going through the FPR will just recirculate back and the car will be basically just using the fuel from one pump. When the fuel pressure drops and there is higher demand for fuel, it will then use the 2nd pump (this is what we are hoping)."

Disclaimer: My logic below could be flawed, too.

The Aeromotive fpr has 2 inputs and 1 output. The two inputs are for dual rail return lines for use on V-8 engines. Consequently, the 2 inputs share a common chamber. Therefore, I believe the pumps will show approximately equal pressure at the fpr. I don't think you'll see one pump with no pressure flowing back to the tank when fuel demand is low. Both pumps should have fairly close pressure at their respective outputs.

While I think your logic is flawed, it probably is to your benefit. If the pumps share equal pressure, then you won't experience premature failure of one pump before the other.

Ok... I've beat this thing to death. Funny though, I'll probably run the same setup.

-scott

wmulli

OK, now *I'm* confused (not unusual for me ) If the FPR has two inputs, but only one output, how does it recirculate fuel back to the tank?!?!? What am I missing??

motorheaddown

Fuel *pressure* is actually caused by the restriction in the fpr due to the valve in the return line. As the fuel pressure varies as a function of injector pulse width, the fpr moves the valve restriction in the return line based on manifold pressure. Here's how (I think) Angel has it plumbed, and how it works:

One fuel pump feeds the the rail directly while the other pump feeds the *first* input to the fpr. The *second* input of the fpr is connected to the other end of the fuel rail. The return of the fpr goes to the tank. This setup would require that the fuel flows in either direction on the *second* input based on the fuel demand. Under low fuel demand, excess fuel (from the rail) flows from the rail to the fpr, Under high fuel demand (more than one pump can handle), fuel flows from the fpr to the fuel rail. In either case, all excess fuel not consumed by the engine goes back to the tank via the fpr return line.

Hope this helps.
-scott

Angel

Oh my .. that is a lot to read Just got home from work.

Well. I am not sure exactly how it is working, but I can tell ya that I was running way rich and we had to seriously lean out the fuel ... so regardless of how or if it works ... my main concern was taken care of and that was *enough fuel is being delivered*

Most people that I know actually use the "Y" and have everything go directly in like you were stating .. and this is how I suggested that we do it, but my mechanic didn't like that idea and wanted to be original. He was also not sure himself how functional it would be .. but ... so far so good.

We have other problems to worry about right now. He has been in Florida for over a week, so my car has been locked up and sitting on the dyno .. haven't had a chance to touch it .. but I have a really SMALL coolant leak and a significant oil leak (1.5 quarts lost in about 7 dyno pulls and a bit of idling and driving around the block) ...so those items need to be taken care of before anything else. The oil is leaking from the front of the motor, so we have to take the timing belt cover off first and go from there .. any suggestions on that would be great.

Let me know how your fuel setup turns out ... I am pleased with mine so far, as it seems rather easy to work with, and as I stated, it gets me PLENTY of fuel and lots of room to work with

motorheaddown

Angel,

Where/what fitting did you use in place of the stock fpr on the ge fuel rail? I'd like to get one.

Thanks,
-scott

Angel

Scott, sorry for the delay.

We used the factory FPR spot for the 2nd feed line. We just tapped it with a 1/4" MTP and then used a regular AN fitting for the fuel line. Is this the info you were looking for ?

wmulli

This was always my understanding. The idea is not to limit the pressure going TO the rail, rather use the FPR to "bleed off" excess pressure FROM the rail, usually from the center tap on the rail. While the tech is right, it will probably work in the manor you have it configured, I don't think it's optimum because of the change in fuel direction. I think this would lead to uneven pressure at best, or cavitation in the fuel line at worst.
This is probably for the rails that don't have a feed at each end, or a return in the center.