# New fuel pressure regulator design: Opinions Please



## synapse (Jul 22, 2005)

This is not a commercial solicitation to sell product, just feedback on design.
It will bolt straight onto the rail on the return units, and we're also working on a returnless model as well. I'd appreciate some feedback. What I would really like to find out, is if the Nissan guys are interested in someone actually making a bolt-on fuel pressure regulator for the SR20, KA24, etc.

*Direct Bolt-On to the factory of aftermarket fuel rail with no additional fuel connections
*Piston-based actuator without a diaphragm to fail
*Will support over 1000+ HP
*Interchangeable bypass orifices to accomodate upgraded higher flow fuel pumps
*Adjustable static fuel pressure via a turn screw
*Chamber dedicated to 1:1 ratio
*Boost-only chamber for a total of 12:1 ratio
*Infinitely adjustable rising rate ratio from 1:1 to 12:1
*Retain fuel pressure in rail, so that you don't have to prime the fuel pump on the next startup










From an application perspective, here are some things you can do:

*Turbo/Supercharged, will raise the fuel pressure enough for up to 10 psi of boost
*Will allow you to trim back larger injectors and still add fuel as a ratio of boost
*NA- Can be used to accomodate a larger fuel pump or larger injectors
*NA- Can be used to simply fine tune the air/fuel ratio
*Nitrous- rigorous enough to sustain direct injection of Nitrous to richen mixtures under nitrous conditions
*Standalone Fuel Injection- Can be used a 1:1 ratio regulator to fine tune your EMS, or use some ratio (ie 2:1) to increase fuel atomization or extend the capability of your injector size.

Installation on an S2000 to show scale of size


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## wes (Apr 30, 2002)

Have you looked at most Nissan rails? I do not see an easy way to make an FPR of that size a bolt on affair with the stock rail as most of the popular Nissan motors have the fuel rail wedged in between the intake manifold and plenum...


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## synapse (Jul 22, 2005)

Wes, thanks for the insight. I believe on the SR20, th FPR sits on the end of the rail compared, say, to the Hondas. 

I really just want to find out if this is something that the Nissan guys are interested in versus having to run universal regulators. 

We're also working on a design that integrates an FPR in the fuel rail itself which may be the only way to go on the Nissans with the tight fittment issues.


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## wes (Apr 30, 2002)

synapse said:


> Wes, thanks for the insight. I believe on the SR20, th FPR sits on the end of the rail compared, say, to the Hondas.
> 
> I really just want to find out if this is something that the Nissan guys are interested in versus having to run universal regulators.
> 
> We're also working on a design that integrates an FPR in the fuel rail itself which may be the only way to go on the Nissans with the tight fittment issues.


IMHO I am skeptical of the market for this. With the Nismo AFPR (which is inexpensive and attaches to the factory rail) the market is pretty much covered. Even people who switch to a top feed fuel rail use the NISMO FPR, or if not they use an Aeromotive. For those applications you may have a bit of interest, but that is limited....


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## synapse (Jul 22, 2005)

So besides the SR20 swaps into 240's, is anyone playing with turbocharging on other Nissan models? Or is this unpopular in this space?




wes said:


> IMHO I am skeptical of the market for this. With the Nismo AFPR (which is inexpensive and attaches to the factory rail) the market is pretty much covered. Even people who switch to a top feed fuel rail use the NISMO FPR, or if not they use an Aeromotive. For those applications you may have a bit of interest, but that is limited....


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## NotAnotherHonda (Aug 7, 2003)

haha uhhh...go to sr20forum and see if anyone there has put a turbo on their sr20 haha. yea, i turboed my sr20 and 1.6, wes turboes his 1.6.....its the IN thing to do right now i suppose


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## dave_f (Dec 11, 2002)

what are you using for o-ring material? I would feel a little apprehensive about using o-ring seal in that application given the fact you are using fuel and a sliding conection. Dont get me wrong I love new and innovative designs, but saftey must be taken into account, esepcially considering you are dealing with gasoline in an engine compartment.
-dave


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## synapse (Jul 22, 2005)

Dave- Thanks for the insight. We're actually not using an o-ring per say for fuel sealing. We're using a u-cup type seal, yes the aerospace variety that runs about $15/ea in lots under ten. This type of seal is designed for working pressures in the 800-2000 psi range, depending on material. As pressure increases, the sealing increases as well. We've been working quite a while to derive the proper material specification and requisite durometer to withstand current gasoline and its composition of both ethanol and MTBE. The material spec is resilient to both. Manufacturing surface finishes really determine longevity of seals, and in well over 20,000 miles of road testing under boost and high engine temps, we still do not see any seal wear or fuel leakage.

I didn't mean to sound ignorant about what is being played with these days, but I'm really here to learn about what engine packages you are playing with and how to determine if we should even develop that application. If there is no interest in this arena we simply won't develop the application.




dave_f said:


> what are you using for o-ring material? I would feel a little apprehensive about using o-ring seal in that application given the fact you are using fuel and a sliding conection. Dont get me wrong I love new and innovative designs, but saftey must be taken into account, esepcially considering you are dealing with gasoline in an engine compartment.
> -dave


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## dave_f (Dec 11, 2002)

I wasnt concerned so much about the pressure, but the effect of fuel swell and heat on a sliding seal. It sounds like you are taking it into consideration. It was just the first thing I though about when I looked at the design. Working in the automotive fuel sytem bussiness has trained that reaction into me.
-dave





synapse said:


> Dave- Thanks for the insight. We're actually not using an o-ring per say for fuel sealing. We're using a u-cup type seal, yes the aerospace variety that runs about $15/ea in lots under ten. This type of seal is designed for working pressures in the 800-2000 psi range, depending on material. As pressure increases, the sealing increases as well. We've been working quite a while to derive the proper material specification and requisite durometer to withstand current gasoline and its composition of both ethanol and MTBE. The material spec is resilient to both. Manufacturing surface finishes really determine longevity of seals, and in well over 20,000 miles of road testing under boost and high engine temps, we still do not see any seal wear or fuel leakage.
> 
> I didn't mean to sound ignorant about what is being played with these days, but I'm really here to learn about what engine packages you are playing with and how to determine if we should even develop that application. If there is no interest in this arena we simply won't develop the application.


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## synapse (Jul 22, 2005)

I learned about swell the hard way myself, but that's R&D, it has been resolved and calculated for. Since you're in the fuel system industry, please check out this chart and let me know what you think. Pink is the Synchronic technology, Blue is a standard diaphragm fuel pressure regulator with the industry standard spring backed metal to metal bypass surface. This was sampled at 1000/sec, or 1 ms. So would you conclude the same as me that the Synchronic produces less noise in the fuel rail than current technology, and has lower standard deviation for fuel pressure?













dave_f said:


> I wasnt concerned so much about the pressure, but the effect of fuel swell and heat on a sliding seal. It sounds like you are taking it into consideration. It was just the first thing I though about when I looked at the design. Working in the automotive fuel sytem bussiness has trained that reaction into me.
> -dave


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## dave_f (Dec 11, 2002)

interesting chart.... 
was the data taken on the vehicle at idle with a vaccum reference? 
what kind of engine was used 4 cylinder? did it have an aftermarket pump?
-dave


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## synapse (Jul 22, 2005)

Dave- All variables equal on the same engine, 1 mu at idle with vacuum reference, data was normalized to have accurate comparison against time and RPM. Data was logged from a 4 cyl. The only thing changed was the regulators, air temp was the same, as well as system voltage. It is an aftermarket pump, Walbro 255. 

What can you infer from these results?

-Peter



dave_f said:


> interesting chart....
> was the data taken on the vehicle at idle with a vaccum reference?
> what kind of engine was used 4 cylinder? did it have an aftermarket pump?
> -dave


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## dave_f (Dec 11, 2002)

your regulator seems to be more stable at idle than the diaphragm style. I'm surprised you have so much fluctiation just at idle. What size injectors are you running? Have you looked at the flow vs pressure of the valve? That will tell you the most about the regulators ability to maintain set pressure at all flows. 
-dave


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## synapse (Jul 22, 2005)

Dave- The Injectors are the OEM Honda S2000 F20C injectors. Remember, that this data was collected with all variables equal, the only thing varied was the regulator. The Synchronic regulator is designed to have interchangeable fuel bypass orifices (in a manner that doesn't infringe on Adam Echo Mary's patent claims). Our implementation has orifices in increments of .5 mm. I've tried 2.0, 2.5, and 3.0 mm bypass diameters to fine tune flow and indicated pressures do not change, but what does change slightly is Air/Fuel Ratio, about .2 a/f to the leaner as you go bigger in bypass diameter.

From a design discussion perspective, ultimately, I believe that what differentiates my regulator design, is the fact that it actually seals with the valve with each actuation event. Which we haven't even discussed. Whereas the OEM and aftermarket designs, all use metal to metal which doesn't necessarily seal with each actuation, but through surface finish control, is able to squeeze fuel off the valve in order to maintain pressure when the engine is shut off, but I hypothesize, that this does not happen with each unique actuation/valving event. 

There are some other exciting effects that I can't quite discuss yet that positively impact idle quality and speed, for which I still have to collect and analyze data.


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## synapse (Jul 22, 2005)

For those of you concerned with size and the Synchronic regulator looking big, here's a comparo with the regulator that Comptech (same as BEGI, Vortech, Paxton, ETC.)uses on their kits.


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## wes (Apr 30, 2002)

It appears to be a very nice design, although the mechanics of it are above my head! It also appears to be decently sized. I think you could do well to offer one in a kit that eliminates the factory FPR in some way, as I do not think it will fit in the stock rail given the tight confines between the head and plenum. 

I love seeing advanced stuff like this!


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## synapse (Jul 22, 2005)

I really need to take a closer look at the confines of the SR20, the flanges fit right on the end of the rail, but like you mentioned, room is of concern. I may just design a fuel rail with an integrated regulator for this one.




wes said:


> It appears to be a very nice design, although the mechanics of it are above my head! It also appears to be decently sized. I think you could do well to offer one in a kit that eliminates the factory FPR in some way, as I do not think it will fit in the stock rail given the tight confines between the head and plenum.
> 
> I love seeing advanced stuff like this!


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