tecart

so you know guys, i ran the 928 gts pump for 3 years with no leaking or problems, it bolted straight on, i did it myself in 1/2 hour from start to end in my driveway, the stock rubber cover of the stock pump will not fit on the 928 gts pump due to it being too big (i cant remember if it was due to being too long or too wide but it was too big to reuse the rubber cover) so i wrapped it up in thick foam carpet insulation, then wrapped it in duct tape about 4 times. I thought it would be louder or id hear a humm from the pump from the lack of rubber insulation but it was not noticeable to me

NZ951

That sounds shoddy! Does the cover have to go back on?

Under Pressure Performance

In case anyone is interested, we have this 928 GTS pump available. It was a recent take off from a project we have in the shop. It is off a running car and has extremely little use. The current engine project requires more fuel, so we no longer need this pump.

$100.00 plus shipping.

Thanks in advance!

Sam Lin

Scott, I'd like it.

Sam

Duke

I'd like it as well!

Under Pressure Performance

Well, seems as though the fair thing to do is offer it to Sam first as he was the first to respond.

Sam, look for my PM.

Thanks!

Under Pressure Performance

Sam, I guess you are not set up for private messages? If that is the case, please feel free to PayPal $110.00 to: speedfreak@area951.com - Please be sure to include your shipping address.

Thanks in advance

Sam Lin

My PMs are indeed shut off, I much prefer e-mail. I have paid you via Paypal, thanks!

Sam

Under Pressure Performance

Thank you.

Laust Pedersen

Danno was kind enough to give me this reference to Walbro pumps: http://www.autoperformanceengineerin.../ext_pump.html and I just ordered the GSL392 unit. My horses are thirsty.

Laust

Danno

Just for comparisons sake, that pump that Laust got is good for 254 L/hr @3-bar or 223 L/hr @4.5-bar, which would be the actual pressure used on his car at 2.5-bar on the stock FPR +30psi boost on top of it. While researching fuel-pumps, I came up with a fuel-pump Flow-rate comparison chart to compare various fuel-pump options. You may notice that flow-rates vary continuously with pressure, where increasing pressure resulting in lower volumes of flow. Anyone have these types of flow-charts for the Bosch pumps we've been discussing?

Interesting tidbit is that the voltage supplied to the pump changes its flow as well. That's something to consider since a fuel-pump upgrade can end up drawing twice the current through the stock wiring. If there's some resistance that drops the voltage, your new high-volume fuel-pump may not actually be delivering its maximum flow. The SupraTT Denso pump is interesting in that the car uses a dual-voltage control circuit that uses either 9v or 13v. At low-RPM/low-boost/low-flow conditions, it uses 9v to keep pump noise down and to extend its life. Then at high-RPM/high-boost, it switches over to a higher voltage to get more fuel-delivery.

We suspected that Laust may be running out of fuel with 72# injectors. Another way to select fuel-pump sizing is to add up your injector flow-rates at 100% duty-cycle. So four 72# injectors is 4x72= 288 lb/hr = 48 gal/hr = 181 L/hr @ 65psi minimum needed from the fuel-pump.

Duke

But that's only to be on the safe side to max out the injectors before the pump?
I'm going to run 72# but only put down below 350 rwhp so I assume the stock pump should be fine for that.
I mean, shouldn't be harder for the pump than using 55# for the same rwhp?

J Chen

Duke, do you think it's wise
to safe on a USD 180 fuel
pump. Have you considered
the performance of an aging
fuel pump ?
Going to 72lbs injectors means
you're going for big hp gains.
Is it worth it to stay with an
old pump & assume that it's
performing like new ?

Duke

Fundamentally you are right, but somewhere one has to stop. 55# would be enough for me at the moment, but I like to be prepared for the future.
The pump will be upgraded at some point, but it will be easy to find out when it's time since I'm going to install a wb02 at the same time.
When the top end gets lean no matter how I adjust fuel, I know it's time

Danno

"I'm going to run 72# but only put down below 350 rwhp so I assume the stock pump should be fine for that. I mean, shouldn't be harder for the pump than using 55# for the same rwhp?"

Yup, that's OK if you're using the same power-rating. The injectors will just operate at a lower duty-cycle and the pump won't notice a difference. The injectors are easy because I can just hook up a duty-cycle gauge and see that they're hitting 100%. Just that it's harder to diagnose a failing pump or one that's delivering insufficient volume. I would also recommend upgrading the fuel-lines when you're doing the pump as well.