jorj7

I had signed up for the Super Sport Division, 160 class with an unlimited Tech,
just like Cheryl and Tim, but I didn't achieve the same results. I had been
fighting fuel delivery issues all week, and had installed a new pump the weekend
before. So I was starting slowly and monitoring the gauges closely as the start
of the race. I got 27 miles into the 90 mile run and experienced a fuel pressure
drop. The AFR jumped to 16's and the temps started to climb quickly, so I
shut it down. I guess I'll have to wait another year for my run at 200...

My car on the Starting Grid:


The 160 Class:


My car off the road at the rest area at the end:


Here is a video from the run:

http://928.jorj7.com/mpeg/2009-Silver-State.wmv

I do want to thank John Speake for all his help with the Sharktuner and Tim
Murphy for his help with the new intake. Also a very big Thanks to Jim Morton,
Bill Ball and Dennis Kao for their help getting the car ready. They definitely went
way beyond reasonable bounds to get my car prepared for this event.

Thanks again guys.

Lizard928

George,

When I was looking at your fueling mods on Reutterwerk awhile back I noted that you needed to make some changes to prevent fuel starvation.
I am sorry to hear that you were unable to complete the event this year.

Best of luck for next year.

jorj7

Hi Colin,

The set up that I ran in the race had 1 pickup in the tank and 1 high volume/high pressure
fuel pump. Very simple and was different then the system I started with (as diagrammed on
RW). I still had problems running in a straight line with only 6-7 psi boost (9-10 psi at sealevel)
and 17 gallons left in the tank...

Lizard928

How big is your fuel cell?

Could I have you post some pics of your setup for me? I really would like to see it.

jorj7

Colin,

I've got a 22 gallon fuel cell. I don't have photos of the current set up as we finished it
at 12:30 AM on Saturday. I'm going to be do a few more modifications once I get time
to start working on the car again. I'll see if I can get some photos then.

Lizard928

Looking forward to seeing it George,

stuartph

Hi George

Can you tell us more about your new intake

Any close up pictures

AO

That's a bummer George. You'll get there one of these days. But it does show how difficult this stuff is.

dprantl

+1, that air filter assembly looks awesome!

Dan
'91 928GT S/C 475hp/460lb.ft

Bill Ball

It's not classic fuel starvation, at least not now. I.e., it's not just under high load. Otherwise he could have continued on at slower speeds. Once the fuel pressure drops starts, and it can happen under normal freeway driving, it continues even at lower load levels until the car gets a rest. My initial reaction was vapor lock or a variant on that in the pump, and there are a few reasons why George might have that now when others, like Tim and Cheryl, don't and he didn't before. He had classic fuel starvation before, that would appear even under a brief high load, such as a dyno run, then resolve immediately once the load decreased. George's efforts fixed that and even created richness at the top RPMs on the dyno, but introduced this new problem that did not appear until George drove to the race location. The lower atmospheric pressures at 5000-6000 feet made it worse than at home at sea level.

The very good news is that thanks to major effort and input by Jim Morton with help from Dennis Kao, George and myself, the motor itself is now very solid with no oil leaks and no oil consumption unlike before. Just have a few issues to resolve in the offseason.

Lizard928

Interesting information on that Bill.

I am curious then as to what your breather setup is like on the tank.

In order to get a vapour lock in the pump with the pump running the fuel needs to be extremely hot. Something that would take a great deal of time to happen.

What fuel pressure regulator is being used? and are you running any fuel dampers?

Bill Ball

When George told me that someone helping him check the fuel pickups inside the fuel cell said, "Gee, your fuel is hot!" a light went off in my head. High flow, with most of it being returned to the tank after heating up in the engine compartment, resistance from small gage (stock) fuel lines and elimination of an in-tank pump combined with the top mount pick-up hoses being sucked on by an external pump, all augmented by high altitude, created conditions we don't see much anymore. Yes, you are right - it takes a long drive for this to happen. But once the fuel gets hot enough, and this is naturally more likely as the fuel level falls, it continues until you add some (cold) fuel and/or take a long break. Simply backing off the throttle did not help. Pressure continued low even at idle.

Lizard928

Thanks for that Bill.

George I will shoot you off a PM as I have some ideas you might like.

jorj7

I sent Tim Murphy a drawing and ask if he could make me an new intake box.
He and Todd got together and made me one. I then found an air filter and
fabricated the shroud.

Here are a couple of photos:

Some components


Assembled and in place, along with the new C&R radiator:

jorj7

Colin,

Here is a photo of the top of the fuel cell. The black hose at the bottom of the
photo is the breather line. The smaller -6AN line is the return line and the
-8AN line on the right is the fuel pick up line. The other line currently capped.
I will be switching the return line to the unused -8AN line in the off season
and probably going to -10AN for the line from the pick up to the fuel pump.



The fuel pressure regulator is an Aeromotive 13105, which is suppose to be
good up to 1000 hp. I'll probably switch it out for the 13109, as I hear that's
more reliable and will make the plumbing a little cleaner.

I am running one fuel damper on the back of the fuel rail. The one on the
front has been removed.