Well, after some conversations about where to place the sender for a fuel pressure gauge to get the most useful readout, I hope I got it right.

I was told that the AAM adaptor placement would only be useful for idle pressure since its not at the end of the rail. I attached the pic of that off their website for comparison.

I put my PTP adaptor at the end of the driver side fuel rail. That should be the place where the pressure drop is the most, correct? I attached a pic of my setup.

Is there really a difference between postions? Either way, this should tell me if a return fuel system is needed in the immediate future.


Oh ya, i am seeing mid 70 psi at idle after startup (cold motor, just wanted to make sure that the gauge worked). I'm running 650cc injectors and a walbro 255l. The yellow swirl jet orifice was drilled to .07" as well.

 

every single restriction in the path of flow will increase likeliness of a pressure drop. its all dependant on how much restriction there is and how much fuel your injectors are consuming. of course, pressure drop will always be the greatest in the system at the end of the system as there have been more restrictions in the path.

Since your fuel system is a non return with a static regulator it should always have the same fuel pressure throughout the entire system. if your car is idling at 70 psi, then the internal regulators restrictions are still too high. You will find that your pressure will be 70 at idle, then drop into spec as engine fuel consumption increases. It will spike back up again when you come back down to idle. Since your pressure is 70 at idle, you probably need to do the regulator modification, which involves drilling in it somewhere to some size - check the TN install, they have you do that - I have never had to mess with it.

When you are outside of your idle pressure spike, your pressure should always be the same. If you see it start to fall below spec at higher RPMs and full throttle then that means you are beyond the capacity of your fuel system.

So yes, if you see a drop, you need to do fuel system work. However, you dont have all the answers yet. By this point you usually just address it all at once rather than figure out precisely what is happening. The next question to ask is if the pressure drop is uniform or not. The only way to find that out would be to have a gauge BEFORE and AFTER the injectors. Then you will know if you are experience uneven fuel distribution to the injectors, which is a highly dangerous situation for your engine. If you see a uniform pressure drop before and after the rails, than only the supply to the rails themselves is what actually REQUIRES upgrading, this can mean larger feed lines to the rails and/or a larger pump.

Once that is done, since there is still a arguely small line feeding the drivers rail from back of the passenger rail, there is still a point where uneven pressure will be provoked. How far along that will happen, nobody knows, cause no one has really been checking.

in a nut-shell, what i am telling you is, if you dont see a pressure drop below spec EVER, then dont worry about it. If you see the pressure fall lower than spec under full throttle and high RPM, get a RFS ASAP.

 

the regulator mod as per Turbonetics install, would not be useful once/if I go with a RFS though? Correct? Or does that not even matter asyou can bump up or down the pressure with the regulator.

I guess I'll have a better idea about the #'s after a few days of driving.

** is "spec" around 50ish psi?

 

it wont matter what regulator mod you did if you go RFS cause you will toss out the regulator since its function is replaced by an external one. A return correction plug will go in its place.

 

so after a few street tune runs, I am seeing ~68-70 psi under load (need to video the gauge for better playback) and 74 psi at idle.

To get the A/F ratios that I need, I am seeing 100 duty cycle. Would a return fuel system make my injectors "bigger", IE would a RFS allow lower IDC while still keeping the fuel rate i need to get the proper A/F?

I thought that I read that people with a RFS can run smaller injectors and thats why most people go with the 600cc injectors to compensate for not having a RFS.

 

are you still using the vortech inline fuel pump and FMU?

 

no. tuner kit with walbro 255l and 600cc injectors.

 

its wierd that your fuel pressure is so high

 

Sorry to revive an old thread. But what is the definitive answer to this. Where should i tape the fuel line for my guage?

I'm currently NA w/ a 100 Nitrous Shot which is why I picked up the fuel pressure guage.

 

back of the driver side rail

 

Thanks mate

So just throw another Fuel tap on the drivers side rail?

 

Yup, just pick up an AAM or PTP fuel rail adaptor. Cheapest price I found - http://www.dynotunenitrous.com/store...?idproduct=245

 

Cool. Thanks guys. Already have one of the Dynotune ones for my wet shot. Will grab another.

 

i though you already had a RFS? My bad, i assumed because your sig says cjm stage 2.

 

He does now, but not when he made that post.

 

^^, ya my fuel pressure gauge really just confirmed what my 100% IDC's were telling me . But its nice to have now with the RFS.

but i do have the PTP fuel rail adaptor for sale (25$ shipped)now

 

So which Fuel adaptor is the best ? AAM is so expensive compared to DynoTune and they look identical, and there`s the PTP which one to get please ? and does both of them (AAM/PTP) fits both sides ? the Driver side and the Passenger side ?

Thanks in advance.

 

I went with the DynoTune one. I think it's just a re-branded AAM - it looks exactly the same. I think they can go on either side - but I put mine on the driver's side rail.

 

Thanks for conforming it, i asked the question because the OP said this:

"I was told that the AAM adaptor placement would only be useful for idle pressure since its not at the end of the rail."

so now DynoTune is the one to go with and i should put it on the driver side because it got the most pressure drop, Cool but what about the Port on the Adapter ? is it - AN as they say on the website or is it NPT ?

Thanks again

 

It's 1/8" NPT, or whatever a typical pressure sensor threading is (so don't quote me on the 1/8"). I just threaded my pressure sensor gauge right into it. It does come with some NPT to AN fittings though, if you want to go that route.

And yes - just install it on the end of the driver's side rail and you'll be fine.