CIS Fuel Pump Options for more fuel!

[911st]

One of the ways we get more fuel is to bump the System Pressure at the Fuel Distribuitor. However, it might be the pumps can not keep up under higher duty and become the limiting factor.

I believe Therrey found that replacing the front pump with a higher spec 044 he could get more fuel up top out of his stock 91 Turbo FD.

Note that the 413 seems to be the granddaddy of them all.

Found the following info hidden in another N/A post and thought it might be valuable on our quest to get more HP out of CIS and easyer to find with a tittle that might help others find it latter.

Originally Posted by WERK-I

I was able to find a Bosch Fuel Pump Spec Sheet, if anyone is interested.

Originally Posted by WERK-I

Thought I would add yet another chart for cross reference.

This chart shows the Bosch Part Numbers for Fuel Pumps.

Good work Dave!

[JFairman]

Good post and interesting stuff..

I googled the 413 pump and from what I read, the 044 and 413 pumps are the same pump.
The Bosch flow rates are conservative.
Bosch tests some 044 pumps and the ones that flow the higher rating are renamed 413 and given a higher price.

Link to Bosch PDF on the 044 and 413 pumps: http://www.bosch-motorsport.de/pdf/components/fuel_pumps/FP-200.pdf

Here's a copy of someones post on a corvette forum almost 5 years ago...

" Bosch Fuel Pump Information for High HP Applications"

--------------------------------------------------------------------------------
"I did a little research on the Bosch pumps that are being used and this is what I found out from Bosch Motorsports and one of their US distributors.

Let me first preface this by saying that pumps flow different amounts under different conditions. Typically less voltage to the pump, higher pressure, and higher temperature means less flow out of the pump. The flow numbers and max HP approximations I am reporting are the numbers Bosch supplied for the various models and I do not have information for other pressures or voltages yet. The distributor did say that the flow and HP numbers are a little conservative.

Pump #1: Bosch 0 580 254 979

This is the pump I hear referred to as the 310 LPH pump frequently.

Bosch Rating: 165 LPH at 72.5 PSI and 13.5 V

Bosch Rating: 230 LPH at 43.5 PSI and 13.5 V

Bosch Approximate Crank HP rating at 72.5 PSI and 13.5 V: 600 HP

Best Price I Found: $219.00


Pump #2: Bosch 0 580 254 044

This is the pump I hear referred to as the 420 LPH pump frequently.

Bosch Rating: 200 LPH at 72.5 PSI and 13.5 V

Bosch Approximate Crank HP rating at 72.5 PSI and 13.5 V: 750 HP

Best Price I Found: $220.00


Pump #3: Bosch B 261 205 413

This pump is the same pump as pump #2, but this pump is flow tested and rated at 116 PSI instead of 72.5 PSI. What Bosch does is flow some of the pumps and sort them out. This pump they will guarantee to flow its rated capacity at 116 PSI instead of 72.5 PSI. Since lower peressure generally means more flow, all else equal, I think this pump will outflow pump #2 at typical working rail pressures (60 - 80 PSI) or at least maintain a high flow rate if rail pressures above 72.5 PSI are required in high boost / high HP applications.

Bosch Rating: 200 LPH at 116 PSI and 13.5 V

Bosch Approximate Crank HP rating at 116 PSI and 13.5 V: 750 HP

Best Price I Found: $382.78

A side note on pump #3 is that it is only available from a Bosch Motorsports dealer, which is different than a regular shop that sells Bosch products.

Obviously at lower pressures the pumps will flow more volume. Also, with the addition of a voltage booster, the pumps will flow more volume. Therefore, it is apparant that the pumps can support more power than the Bosch Motorsports representative indicated given more favorable conditions (less pressure and more voltage)."

[Dr J]

With this part done, do different FD's have different flows or is the basic restriction the injectors?

[911st]

Injectors have been an open question for some time so that seems to be an open question.

The 930's seem to be the largest of the 930 injectors but there is a credible report that the 3.6 injectors offer less restriction and thus increase flow.

If you think of the injectors like a nozzle on a hose, a larger less restrictive opening should flow more. At some point you may lose your atomization.

[David]

With CIS, wouldn't increasing the fuel pressure lean it out?

I'm running stock pumps and fuel lines and have no trouble with AFR's at max power.

[911st]

No.

No matter what the fuel pump is able to deliver the reg built into the head maintains the same System Pressure in the head.

If one's fuel pump is not performing well the car can run lean.

One can jack up the System Pressure at the FD built in reg and get more fuel.

You might be thinking of Control Pressure. If you did increase that it would lean the motor.

[David]

D'oh! I guess I never looked very close at the Bosch drawings

For some reason I was thinking the control pressure went to the injectors. I see now that the fuel pressure bypasses to the injectors and the control pressure just opens the piston to meter flow.

[911st]

Control pressure pushes on the top of the meterin pin which fights against the air flow entering against the metering plate.

Control pressure when higher pushes harder and the plate and pin do not advance as much.

[911st]

Again, excellent info I am stealing from another post because it it just to neat.

Originally Posted by WinRice

Not necessarily, you may be hitting the flow limits of your pump.

Look at the charts below, I couldn't find a chart for your 053, but the 979 is close:






Once you hit around 5.5 bar the flow rate drops drastically, and the current demand goes way up, indicating the pump is maxed out in efficiency.

Now lets look at the 044



You should be able to run that pump at 6 - 6.5 bar fine, giving a flow rate around 3.3 L/min (1650cc / 30 sec), which is close to the 1500cc / 30 sec given by the factory 930 system.

Also notice the big flow rate drop after 7.5 bar, if you need more than 7.5 bar with a good flow rate, a series pump system like the 930 is the way to go.

More pump info:

Bosch and Lucas Fuel pumps