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Limit of factory L28ET fuel pump?????


jgkurz

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Hi all, I recently upgraded to larger injectors, but am still running the factory turbo fuel pump. When the "Z car" fund is full again I'll probably buy a Bosch or MSD pump. In the mean time I'd would like opinions on the limitations of the factory pump.

 

Has anyone found the magic boost pressure where the pump couldn't keep up the flow?

 

Thoughts?

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As I recall, the turbo pump still has an internal pressure relief, which limits the ouput pressure to 65psi (90% sure on this value).

 

So, this will put a very real limit on the boost that you can run (regardless of flow), depending on your base fuel pressure, and whether you are using a rising rate FPR or not.

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You may want to upgrade in the near future. In my 3.1, anything over 10 lbs of boost and the fuel pressure dropped through the floor. I went w/ the Walbro GSL-392 inline pump and no pressure drop, even up to 20 Lbs of boost (43psi baseline). I purchased it through Alamo Motorsports. I think it was ~ $150.

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Great info...Thanks. Using 90 liters/hr I converted that to 1500CC/min then divided by 6 for the cylinders. This equals 250cc/min for each injector. Assuming 250cc/min per injector flow ability, the safe flywheel HP would be roughly 239. This is according to my Electromotive Tec3 software. At 13psi I'm pretty sure my engine will make more than 239HP. Looks like it's time to start pinching pennies for a new fuel pump. frown.gif

 

Best Regards,

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Originally posted by SleeperZ:

Just for your info, I ran a high 13 on the stock pump and injectors before I swapped it out. I don't know how lean I was getting, but it seemed ok. That is about 210-220 to the wheels I think.

I ran a 13.7 and 105.36MPH on the stock pump and injectors. Strangley it rev'd slower above 5500RPM. I think I know why now... bonk.gif
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I still have a new stock fuel pump in my 76z and it's fine.I am gonna get a bigger one this year but i ran 18 psi on the stock fuel pump and 370cc injectors.I had no probs with running lean and i actually ran rich smile.gif I plan to get a tec 3 or somethinglike that how much did you pay for yours?

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The Tec3 can be had for well under 3K depending on the parts you already have and the work you want to do yourself. Sias Tuning and Top End seemed to have the best prices when I was shopping. I decided to buy from a shop near my house for the local support.

 

Thanks for the info

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