here is a short crappy video of my saab turbo'd 04 cav. i have the stock fuel pressure regulator and i know some people have had questions about it being boost referenced.... it IS boost referenced 1:1.... my boost guage is at the top and fuel pressure is the bottom guage. and yes i know my oil pressure guage is not working... this video was shot on 5 psi... you can see the boost guage going up and the fuel pressure guage goes up at the exact same rate.... enjoy... watch ths in full screen to really see the fuel pressure guage.... sorry for the quality..... and yes this is open downpipe LOL....
Edited 3 time(s). Last edited Tuesday, February 21, 2012 12:13 PM
Wouldn't the correct temr for it be vaccum referenced, since the car does not see boost stock????
It's both... Everyone wondered if it was boost referenced as well... And the answer is yes....
I've posted very detailed information about this subject several times in the past. On a stock pump it will reference boost 1:1 all the way to deadhead in most cases.
ASE Master Certified Automotive Technician
i was actually looking for the post. I know you documented it in one of my threads. but yeah CaliforniaDomestics tested this with i think the stock one, but for sure with the Aeromotive AFPR on my car.
Yeah I just felt like showing proof as well. John higgins I believe it was wanted me to make the video when I mentioned it but I couldnt find the post.
Sometimes on this site proof has to be in a form that people can see. not just someone saying something.
I will be honest the video I could not tell much, other than the fuel pressure was going up, but to what psi does it go to?
FU Tuning
I saw this and thought to myself... duh...
Why would it NOT be 1:1? A FPR in stock setup references one bar of pressure... that is one atmosphere or 14.7psiA... so if it is designed to be linear from 0psiA to 14.7psiA it HAS to be linear from 14.7psiA and beyond unless its got multiple springs etc... which ours would have no reason for given its only used below 14.7psiA.
I wonder about some people...
Buildin' n' Boostin for 08' - Alex Richards
The fuel pressure got to about 58-59 the center of the guage is 50. Mine idles at 40-41 psi with the 550cc injectors
Edited 1 time(s). Last edited Wednesday, February 22, 2012 10:38 AM
God can't you freaking people read.... There was a post that I cannot find. John higgins said the stock fpr is 1:1 and someone questioned everyone's explanation so I told him I'd make a video to show it and he said I'd be a good idea... So I did....
Sorry... us "freaking people" help people like you. A LOT.
We read just fine... otherwise we wouldn't have been able to answer your HUNDREDS of questions regarding that car you bought turbo'd off another member - right?
That video doesn't show much, and your explanation shows that the fuel pressure is going up 1:1 with boost - which ANY STOCK FUEL PRESSURE REGULATOR ON THE PLANET WILL DO. It has been discussed ad nauseum since 2002. 5 psi of boost will add 5 psi to the fuel pressure above the FPR's set rate at vacuum. This isn't brand new information.
So as I said - what has been questioned in the first place?
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Comeon man lol jk... No I did not buy this car boosted I did all the work and tuning (which needs a ton of work lol)
Sorry, was a cranky moment for me - I apologize.
Your stock FPR will raise equally with boost since it's 1:1... all FPR's will do this unless they are a rising rate FPR specifically to rise at a different rate when they see positive pressure.
This is why generally at very low PSI applications some people feel that their fuel needs are "covered" since the fuel pressure is coming up a bit with boost but in most cases it's nowhere near enough fuel at peak, but definitely a good little offset at part-throttle boost.
Naturally Aspirated the fuel pressure at full vac usually jumps about 10 psi from the static fuel pressure at idle on J-bodies, it seems. After that it will rise relative to your boost pressure.
That's something to always take into account when sizing your injectors.
-Chris-
-Sweetness-
-Turbocharged-
Slowly but surely may some day win this race...
Nah man your fine... I just wanted to show proof like like John said..
SLO CAV (autocrossing dude) wrote:The fuel pressure got to about 58-59 the center of the guage is 50. Mine idles at 40-41 psi with the 550cc injectors
ok sorry to say this, but I feel I must.
I always thought on a N/A Eco the max fuel pressure was 62psi? Does anyone know for sure?
If it is 62psi, then his readings in boost would not mean the FPR is a 1:1 in boost. It should have been roughly 66psi of fuel pressure with 5psi of boost. Am I wrong?
FU Tuning
You are wrong, you cannot think just because the boost rises 1psi that equals 1psi increase in FP. it just means the FP does not increase exponentially after atmo.
Buildin' n' Boostin for 08' - Alex Richards
And on top of that I'm on 550cc injectors too so you'll have a pressure loss due to them. And I found a crack in the rubber piece that connects my vac lines to the intake manifold. I'm fixing that this weekend and ill do another vid.
SLO CAV (autocrossing dude) wrote:And on top of that I'm on 550cc injectors too so you'll have a pressure loss due to them. And I found a crack in the rubber piece that connects my vac lines to the intake manifold. I'm fixing that this weekend and ill do another vid.
The Fuel Pressure regulator will compensate for injectors...
Buildin' n' Boostin for 08' - Alex Richards
SLO CAV: can you tell me what your fuel pressure is at idle with vacuum line connected, and then with vac line off?
FU Tuning
Sure thing I will tomorrow I have to.work tonight..
