6 hours ago, Mike said:

I've been using the Holley Premium Red Electric fuel pump.  It's a great pump, but, a bit too loud for my taste. 

I want something a little less noisy.  I'm running triple Mikuni's, so I'll need something compatible.  Not sure if this one will be any less noisy but I'm strongly considering the Nissan Nismo pump (if I can even find one).  Zcardepot.com has them listed, but, out of stock.

The K&N from MSA you listed above looks interesting..  Airtex is also a possibility...  I do like the simple design of the Airtex.  It doesn't stand out as aftermarket.

Do you have a part number? We could do some looking for availability

5 minutes ago, Patcon said:

Do you have a part number? We could do some looking for availability

I believe it's the Nismo 17010-A7601.  Not sure if 1.3L/min @ 29kPa/4.2psi is enough for the Mikunis though.  Not sure what they require, but I am liking the Airtex more and more due to its simplicity.

Edit:  Nevermind, the part number above appears to be for the HIGH flow version.  Still looking for the low flow version for carbs..

m

4 minutes ago, Mike said:

I believe it's the Nismo 17010-A7601.  Not sure if 1.3L/min @ 29kPa/4.2psi is enough for the Mikunis though.  Not sure what they require, but I am liking the Airtex more and more due to its simplicity.

Edit:  Nevermind, the part number above appears to be for the HIGH flow version.  Still looking for the low flow version for carbs..

m

I measured the fuel pressure of the airtex 8012 and the psi was 3.2 

7 minutes ago, jalexquijano said:

I measured the fuel pressure of the airtex 8012 and the psi was 3.2 

Thanks!  I wonder what the Mikuni's require..  (russells around trying to find the Mikuni manual)

Aha!  Found it...  Now I just need to convert it to PSI... 

oh wait!!    2.84 lb/in² - 4.98 lb/in²    *IS*   2.84 - 4.98psi       

Now searching for something to reference the volume requirements...

 

My mechanic says that although PSI is important to maintain the proper fuel system pressure/response, the FlowRate is the key parameter in filling the bowls.  30gph is the flow rate rate for both the Airtex 8016S (2.5-4.5psi) and Airtex 8012S (5-9psi) pumps which works nicely for SU's and Weber DGVs .  Airtexs are very quite based on feedback here and external reviews. 

For your triple Mikuni's .. try to find out what FlowRate is needed and use a lower psi pump that fulfills that. 

From above... the Nismo 17010-A7601 puts out 1.3L/min ==> 0.3434gal/min or 20.6gph.  This seems way to low of a flowrate.... you need at least 30gph or higher...

The Airtex 8012 will be better, but not sure it satisfies the triple Mikuni's needs..  

Edited May 23, 20195 yr by moritz55

5 minutes ago, moritz55 said:

My mechanic says that although PSI is important to maintain the proper fuel system pressure/response, the FlowRate is the key parameter in filling the bowls.  30gph is the flow rate rate for both the Airtex 8016S (2.5-4.5psi) and Airtex 8012S (5-9psi) pumps which works nicely for SU's and Weber DGVs .  Airtexs are very quite based on feedback here and external reviews. 

For your triple Mikuni's .. try to find out what FlowRate is needed and use a lower psi pump that fulfills that. 

From above... the Nismo 17010-A7601 puts out 1.3L/min ==> 0.3434gal/min or 20.6gph.  This seems way to low of a flowrate.... you need at least 30gph or higher...

The Airtex 8012 will be better, but not sure it satisfies the triple Mikuni's needs..  

However, you will never burn a full tank of fuel in an hour and the car doesn't hold 20 gallons full IIRC

True...... ????????? .... but I would hope the higher flowrate keeps the fuel bowls in short bursts full when accelerating.

Possibly, but there is a diminishing returns thing. Where the higher flow above a certain point just adds back pressure, which creates noise. @ 20 MPG @ 60 MPH there is roughly 6 hours of fuel in the tank. So 20 GPH is 6 times over sized for what the car would need at a steady state. Now admittedly getting on it pretty good would burn fuel at a much faster rate but I suspect even getting on it good you never get into the 3 MPG range. There are other issues too. Is the rated flow with 0 head pressure? Because the system will have some head pressure to overcome pumping the fuel from the tank and up to the fuel rail and that will reduced the actual flow numbers.

Zed, where is the factory flow test procedure. We could back calculate the designed pump flow rate for SU's as a baseline

Patcon... here's what I found in the 1971 240z FSM .....

Static pressure tested at Carburetor Input running engine at various speed :  3.4psi - 4.3psi

Capacity Test at 1000rpm :  1600cc/min ==>  0.423gal/min ==> 25.4gal/hr   .. or 3.71pts/min ==> 0.464gal/min ==> 27.8gal/hr ...

I guess .... 30gph is sufficient for our SU's.... based on the FSM.  

1971 FSM 240z Fuel Pump Test.pdf

14 minutes ago, moritz55 said:

Patcon... here's what I found in the 1971 240z FSM .....

Static pressure tested at Carburetor Input running engine at various speed :  3.4psi - 4.3psi

Capacity Test at 1000rpm :  1600cc/min ==>  0.423gal/min ==> 25.4gal/hr   .. or 3.71pts/min ==> 0.464gal/min ==> 27.8gal/hr ...

I guess .... 30gph is sufficient for our SU's.... based on the FSM.  

1971 FSM 240z Fuel Pump Test.pdf 316.35 kB · 2 downloads

Excellent! A little surprised it's that high

I contacted Steve Epperly today (ztherapy) about switching out my fuel pump.  He said Mikuni’s should have the capability to take higher compression pumps. According to him, a pump designed for a fuel injected system should also work.

He did say the Holley I’m currently using is loud. He uses the Holley pump on his race cars all the time. But they just make a lot of noise. He didn’t have a specific alternative for me, but was extremely helpful in understanding my options.

For the SU guys - He also mentioned the SU’s absolutely need a low pressure pump.  You can’t give them too much pressure (definitely should not use pumps designed for fuel injection)  

FWIW

Mike

3 hours ago, moritz55 said:

My mechanic says that although PSI is important to maintain the proper fuel system pressure/response, the FlowRate is the key parameter in filling the bowls.  30gph is the flow rate rate for both the Airtex 8016S (2.5-4.5psi) and Airtex 8012S (5-9psi) pumps which works nicely for SU's and Weber DGVs .  Airtexs are very quite based on feedback here and external reviews. 

For your triple Mikuni's .. try to find out what FlowRate is needed and use a lower psi pump that fulfills that. 

From above... the Nismo 17010-A7601 puts out 1.3L/min ==> 0.3434gal/min or 20.6gph.  This seems way to low of a flowrate.... you need at least 30gph or higher...

Unfortunately I cannot seem to locate the flow-rate requirement in the Mikuni manual.  I'll do some more searching on the web. 

Some of the sites that carry the Nismo pump are saying it works with Weber carbs.  Not sure if that carb setup has the same requirement or not.