Mazdaspeed Forums - Why Different Designs In Pumps?

to the pump stuff - all names aside, Autotech APR mrlilguy or CP-E, lets talk about the designs.

The APR design: a thicker piston from top to bottom, which allows for more volume of fuel to enter the pressure chamber of the pump per stroke. What you get is higher pressures throughout and more volume pressurized. Their new internals are pictured here:

http://www.mrlilguycdfps.com/random/aprinternals.jpg

As you can see, the APR internal upgrade utilizes new seals, a drilled retainer nut, a new piston, a stiffer spring, and new bore, all while maintaining the same factory Hitachi retainer.

I have no pumps with me right now, so I cannot work out the math, but will do so once I return to Dallas. That way you guys can understand the new volume displacement by the upgraded pumps, which will also show that the upgrade kit that I utilize outflows the APR design, which is used by CP-E.

Moving onwards...

The other guys, Autotech, have a different design, noted as 'plunger style'. This allows for the stock retainer to be used, as well as the stock seals. When APR decided to go with a complete thicker diameter piston, they HAD to drill the retainer nut to allow the new piston to fit through, which also requires the use of new seals. Both designs are acceptable - both do the job, both seal the compression/pressurization chamber from the head of the motor (where possible fuel/oil dilution could occur). The plunger style, once again, allows for the stock seals and retainer to be used. Also, the stock spring is used. Although many have presented controversy about this, the mass difference in the Autotech design, is minimal, further proven in this post.

Here is a picture of the plunger design, as well as the new retainer.

http://www.mrlilguyCDFPs.com/random/autotechpump.jpg

Looking closely, you can see that the bottom end of the pistons diameter is larger than the top end - which defines 'plunger style'.

Look again, here, at my amateur photography and out of focus pictures:

http://www.mrlilguyCDFPs.com/random/autotechpumpME.jpg

Clearly, the larger end of the piston is shown. This, just like APR's design with a larger diameter full length piston, has a larger diameter part of the piston where it matters, just longer than the stroke of the actual piston as the tri-lobe of the intake camshaft forces the piston in and out out the pump, to create pressure.

As stated, I'll work the exact math for you guys to prove the new volume displacement and flow percentages, between APR and Autotech designs. Also, dada stated earlier in this thread that the Autotech designs were never tested. They were before production began on a diesel pump tester up the road, which proves the mathematic equations to be true, just like Physics. You do the math and figure out your solution, or you can do the mechanical experimentation and lab work to further take note of data, to get your answer. Autotech opted not to purchase and build an $80,000 test rig, and use one up the road from their facility in Aliso Veijo, CA.

As to the debate with the increased mass of the new piston (in either design) as well as the spring force, I will quote myself from another thread, in which I also added more details for futher clarification:

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Quote:

Originally Posted by ptperformance (Post 1884)

It looks like the spring for the pump upgrades may be bouncing off the lobes under very high RPM. The additional weight of the bigger piston may be over working the stock spring, looks like a better spring may be needed as well.

The mass difference between my piston and the stock piston is about a gram, if not less. I don't have a scale next to me at the moment, but I'll be sure to measure and take some picssssss. Also, the car's RPM isn't really increasing. Redline is still near 7k rpms. My buddy JC has a monster of a 2.0t GTi and drives it up to 8k, using this pump, and no side effects have presented themselves :D

Quote:

Originally Posted by Direct from Brian@Autotech (AutotechRD)

Brett[@APR], you keep bringing up the fact that we didn't use a special return spring to match our pump. With an already marginal contact wear situation, a stronger spring would, in my opinion, create the an increased chance of abnormal wear on the fuel pump lobes of the camshaft. Keep in mind that the piston in our pump didn't increase in weight as much as yours, either.

Thanks for looking out though!

Quote:

Originally Posted by dadasracecar (Post 1894)

Interesting. My cp-e pump came with a bigger spring presumably for reasons you've articulated. I'll see if I can dig up a side by side comparison pic.

Yes indeed it did, for the whole piston in the APR pumps is larger diameter and larger mass, from beginning to the end. Therefore, APR found it necessary (and I agree) to include a new, stiffer spring for the increase movement in mass. After weighing in, the new retainer and piston assembly weighs approx. a whopping 1.25g heavier.

Quote:

Originally Posted by palerider (Post 1903)

What the hell is this big spring all about? Do I have one? I did Ants spring mod.... does that count?John? John?....lol

A stiffer spring is suggested for a significant increase in mass.

edit: Pics found.

http://is.rely.net/2-4481-32346-l-xJ...fmRaYgxSPQ.jpg

^^^^that is the stocker and the retainer^^^^^^^

http://is.rely.net/2-4481-32345-l-tj...c4RI5um5mw.jpg

that is the piston we use, without the retainer. the retainer weighed in near 4.25grams (no scale is perfect). btw - the cloth weighs 7g

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As shown, the increased mass for the plunger style, is almost negligible (1.25grams), where as the APR design - larger diameter piston has increased mass from top to bottom - has an increased mass throughout, resulting in probably 4 or 5grams heavier. This, although doesn't sound like a lot of weight, is moving at 3strokes per revolution of the intake cam, which is a lot of mass to be thrown around at such high speeds.

Also, a new design has surfaced from VF-Engineering. They make good stuff, but have rough customer service as I used to directly deal with them.

Here's a picture:

http://www.mrlilguyCDFPs.com/random/VFpump.jpg

Notice that even though half of the piston is the increased diameter, they still retain the stock spring, and use an aftermarket retainer.

There is another company that is in the production phase of their kit. They have a pump from me, and perhaps they'll show something new and impressive. Honestly, I have no concern in switching manufacturers for any reason. All of the pumps designs have been proven to work.

Another point of comparison is here:

The contact point on the cam follower unit, with the new pump upgrade. APR decided to use the factory Hitachi pump retainer unit, great idea, thats nice.

The contact area with the Autotech upgrades to the cam follower unit is the same, as shown in the picture. Notice that the very center circle of the retainer which is pictured 'closer' to you, is the only point of contact on the cam follower unit:

http://www.mrlilguyCDFPs.com/random/contactarea.jpg

I hope this all makes some sense and shows you that both pump upgrades will do the job, and both are extremely effective solutions. The only difference which can actually be proven to create a different end result, is the larger diameter of the piston, which Autotech surpasses APR, but only by the smallest margin. Both companies did their homework on the design, and both companies have hundreds upgrades performing flawlessly for over hundreds of thousands of miles.

So, in conclusion to all of this explaining - Thumbs up to both designs. CP-E's pump will get the job done, and so will mrlilguy's. Both are taking orders and both are shipping soon. Last week CP-E said 2 weeks, I would think that would mean next Monday. mrlilguyCDFP's will go out this week.

Furthermore, if there is any questions or concerns, let me know through PM's.

Also, PTP has been developing their own upgrades and this is the information I've got from his forum, as well as clarifications on differences:

Quote:

Originally Posted by ptperformance (Post 35161)

The stock parts are coated with a "secret sause" coating. We have no idea what it is but... we will be ti-nitride coating ours (this is what they coat dril bits with). The "others" no coatings at all that I have seen.

my fuel pumps go through a thorough hardening process and are ridiculously polished and heat-treated to provide very extremely frictionless characteristics.

CP-E's fuel pumps have a 'DLC' coating which stands for 'diamond-like coating'. I don't like the acronym, but the parts are definitely coated and look almost like black chrome.

Quote:

Originally Posted by ptperformance (Post 35161)

The weight of the retaining hardware from the "others" is 3 to 8 grams more then the stock assembly (some come with a new spring others do not). Ours will be using titanium retainer and moly locks that come back 2 to 4 grams ligher then the stocker. This will give less load on the spring to keep it from bouncing off the cam lobe at high RPM's.

The complete piston/bore/retainer assembly on the upgraded parts which I provide vs. stock is about 4 grams heavier, for the COMPLETE ASSEMBLY. The stock retainer vs. the titanium retainer and locks I use is actually less in weight, just like what youre going to offer.

As far as the CP-E pumps go, I don't know the right specs but I do know that they use the stock retainer, but the piston is 'significantly' heavier than stock, so there is a stiffer spring supplied with their kits.

Quote:

Originally Posted by ptperformance (Post 35161)

Price... now this is all over the place with the others, anywhere from $800 to $349. We have targeted our pump to be priced at $299 and so far it looks good to hit that target mark (waiting on the ti-nitride process quote).

Current Price breakdown:

mrlilguyCDFP: $549 for the mail in upgrade or core exchange/$899 for a brand new fuel pump with upgraded parts.

CP-E: $622 (via StreetUnit) for the mail in upgrade or core exchange/$997 for a brand new fuel pump with upgraded parts.

PTP parts (from what has been said): $299 for a do it yourself kit.