Increase Fuel Pump Capacity 50% for Free.

Okay, this article doesn't apply to everyone, but we all love risky, warranty voiding modifications to squeeze unintended performance out of a product. Don't worry, this doesn't involve fancy five axis CNC port work...while this modification can be performed by anybody with a drill and hammer, we suggest you leave this modification to an expert.

As of this writing, the TI Automotive F90000267 is the standard fuel pump to run on high boost street/strip cars running ethanol blended fuel. While this is currently one of the highest performing electric pumps available, the safety relief valve is a weakness that needs to be considered if you're pushing your fuel pressure past 80 psi.

TI Automotive publishes the following performance curve for a new F90000267. Detailed performance data between 80-90 psi is not provided, but the change in the slope of the performance graph indicates the relief valve may actuate anywhere in between 80-90 psi and still be in specification.

Broken-in pumps perform better than new pumps; however, repeated actuation of the relief valve causes degradation in the relief spring. In order to find out "which one" wins, we took a used pump (that had spent some time at high pressures) and tested before / after the modification. As you can see, performance before relief valve actuation is better than the new pump, but performance after the relief valve could be unsafe for some cars...especially if the valve is allowed to degrade under repeated actuation after the initial tune.

APPLICATION

Thanks to Tony and his crew at T1 Race Development for pushing us to get more out of these pumps and proving out the effectiveness of these changes. He was gracious enough to provide the following screen before/after captures from a couple R35s at his shop:

HOW TO MODIFY

First off, you have to completely remove the fuel pump from the hanger/module. If you are using one of our cartridge based modules, it is best to plan ahead an purchase an o-ring kit for reassembly...the o-rings will likely tear when you take everything apart.

Drill a 4.5mm hole as shown...(but try to do a better job of getting the hole on center...CNC is our thing...not necessarily hand tools):

Use a M4 screw to find the depth of the spring seat, then adjust the jam nuts so you can press the spring seat down another 1.5mm.  (FYI, two turns on a M4 screw = 1.4mm)  Done.

Here's what you did.  There is a spring behind the ball...you simply pressed down the spring so that the ball doesn't spring open at 80-90 psi.

WILL THIS BENEFIT YOUR APPLICATION?

This won't help everybody...this is only valid if you're pushing the pumps beyond 80 psi. Remember, in a boost referenced application, the fuel pump operates at base pressure + boost pressure + system losses.  (do you monitor the loss across your fuel filter...like this?)

DOES THIS PUT THE PUMPS AT RISK?

Absolutely forget a pump warranty...but you're probably used to hearing that if you're using 80 psi of fuel pressure. By the way, TI Automotive is planning a future revision in the F90000267 to increase the blowoff pressure to 110 psi. Until then, this is the best way to accommodate high base+boost cars.

405 vs 465 LPH Pumps...The Real Comparison

Since TI Automotive (owner of Walbro) released the fabulous 405 lph DCSS fuel pump last year, many of us have long awaited the "465 lph" version.  The DCSS465 promised higher performance, complete E85 compatibility, same dimensions as the 405, and slightly higher pricing...it sounded almost too good to be true.  See for yourself:


E85 COMPATIBILITY
The 405 can expect a 15% shorter life expectancy in E85 compared to the 465.  Considering the 465 has an average life expectancy of 10,000 hours in E85, we can expect the 405 to live 8,500 hours in the "corn."  If you drive your car an average of 45mph, that is still 382,500 miles.  Let's face it, the 405 is absolutely fine in E85.


PERFORMANCE ADVANTAGE
The 465 barely outperforms the 405...to be accurate, the margin is only 5%.  Why you ask?  The 405's published performance is 405 lph in E85.  The 465's rating of 465 lph is rated for gasoline.  This is NOT a fair comparison.  Let's even the playing field:

In gasoline at 40psi and 13.5 volts:
"405" flows 440 lph
"465" flows 465 lph

In E85 at 40psi and 13.5 volts:
"405" flows 405 lph
"465" flows 430 lph

In the practical sense, the 465 outperforms the 405 by only 5% under most conditions.

FORM FACTOR:

The upper and lower diameters are the same at 39mm and 50mm, respectively.  The 465 comes with a worthless Delphi connector that you're going to snip off (leaving you with wire ends to splice) whereas the 405 comes with more convenient male quick disconnect terminals.  Both have a outlet barb for 3/8" hose.  The biggest difference between the two pumps is the inlet to outlet length.  The 465 is nearly 1/2 inch longer...not good in the tight confines of a fuel tank.

COST:

DCSS405:  $160

DCSS465:  $220

The 465 costs 37.5% more than the 405.  No need to say more.

BOTTOM LINE:

We pay almost 40% more for the 465 that gives us 5% more performance with no tangible pump life benefit.  It doesn't sound very promising...unless you really care about that 5% performance increase.  Considering our fuel hats with dual 405s match or outperform nearly every available electric external pump, then we can't see the benefit of offering this pump to our customers.

If you must, we do have both the 405 and 465 in stock:
DCSS465
DCSS405