using a stock & adjustable fuel press reg in series? Confusing results are now in...

[Wildsupra]

What you guys think will happen if i was to use a standard fuel pressure reg on my fuel rail then run the reutrn line to an adjustable one. Then the plan would be that it would always have stock fuel pressure at least, and then i could adjust the adjustable one higher to gain the higher pressure if needed.

Do you think running the second reg at a higher pressure would ultimately fuck up the first standard reg? or would the first one simply open at its set pressure say 40psi and then the 2nd one (connected in series between the 1st ones outlet and the fuel return line) raise the rail pressure to whatever i adjust it too?

I know it sounds really dodgy but if the 2nd one wont destroy the first one then really its a good safety to ensure i always have factory fuel pressure or higher.
And it also makes it a shitload easier to fit up now cos no where is open to buy the required fittings i need and probably wont be till the new year

Matty

[oldcorollas]

sure, but why would you want to?

if you are using stock injectors with higher pressure and an interceptor to tune it up high, then you may as well just run bigger injectors with an interceptor anyway..

think of rising rate regs as the ghey way to get more fuel






(and remember that your fuel pump volume decreases dramatically with higher pressures ... or don't, but take a video when the PVC catches fires )
anyway, both the fuel flow vs pressure of pumps and extra fuel from injectors with higher pressure is available on the net (as general idea and some specifics for supra pumps)

say you have 20psi boost. plus base 40psi. then you rising rate it to say 70 or 80psi...
are you going to buy a bosch high pressure pump to be able to get the fuel at such high pressure? i think not and if you did, then you wouldn't be using second ghey FPR anyway

[Wildsupra]

hahahha welcome oldcorollas.......
i explained in my first post why i want too. because no one is open to get the required fittings i need.
ohh and im not using an interceptor to tune it up.....so using bigger injectors will come down to fuel pressure only.
The fuel pump volume would only decrease if it was at its maximum limit already, which it wouldnt be anywhere near that......yet

so as per my question do you think the idea would work for the purpose intended? (which ultimatly is just to allow me to connect my new reg up today )

Matty

P.s. if the pvc melts or catches fire i'l be sure to post pics of its limitations

[oldcorollas]

hahahha welcome oldcorollas.......
i explained in my first post why i want too. because no one is open to get the required fittings i need.
ohh and im not using an interceptor to tune it up.....so using bigger injectors will come down to fuel pressure only.
The fuel pump volume would only decrease if it was at its maximum limit already, which it wouldnt be anywhere near that......yet

so as per my question do you think the idea would work for the purpose intended? (which ultimatly is just to allow me to connect my new reg up today )

Matty

P.s. if the pvc melts or catches fire i'l be sure to post pics of its limitations

well.. thats a shit reason to try to blow up yor engine.
bigger injectors down to pressure only? hmm.. and ho wmuch extra fuel do you want? 5%? 10%?

no, thats bullshit. if you don't understand how a fuel pump works, i suggest you find a graph of pressure vs flow.
actually, since i know you won't bother to look, here is one.
lets say you had a walbro 255L/hr one...
you run it at 13.5volts and you get 255L@ 40psi.
now put in 20psi boost with stock fuel reg, you only get 225L..
now add 20psi from rising rate reg... you only get 150L....
ie.. your limit of flow goes down with pressure..

ie, 80psi, you can inly run 6x 415cc injectors (at 100% duty) with NO RETURN TO TANK...

if you are not running a walbro or bosch (stock pump?) then your flow at pressure can be MUCH lower...
note the VR4 pump here with ZERO FLOW AT 75PSI



as per question, sure it will run.... but when you hit peak boost at high rpm.. just when you want the most fuel, your fuel pump capability will be going down fast, and when you least want it.. BANG

so.. be sure to up the pressure on the rising rate and take it for a full throttle spin to max revs to check it out


oh.. btw.. if the second reg is not rising rate (ie, more than 1:1 for boost).. it's not going to do shit....

[brett_celicacoupe]

i explained in my first post why i want too. because no one is open to get the required fittings i need.

gut the oem reg, easy fixed.

[thechuckster]

this suggests that you're trying to 'tune' by increasing fuel rail pressure - go for it if yu think it's worth it, but i think the consensus in the earlier thread about it was that this would be a pointless and difficult thing to do.

just stick with the stock FPR and get an interceptor ECU - they'll be about 2 times the price of a new fuel pump or regulator and you'll get 18936% more tuning capability than that got by tweaking fuel rail pressure.

[Wildsupra]

ok i'l explain a little further my intentions....
firstly i agree with what all of you have said bout upping pressure being risky and not the best way to approach the situation.
Here's my situation, i was running a 20 year old pump on my 1jz, making around 330hp on 15psi, afr's were around the 13.5 mark (yep too lean i know)
i installed a walbro pump and monitored the afr's once again (i have a wideband O2 sensor with digital gauge and data logger on my laptop) the afr's are still at 13.5 with new pump. SO pump must be in good order now either way.
What i want to do is simply up the fuel pressure ever so slightly just to drop the afr's back into the 12's to make it a touch safer.
Im not looking to run much if any more boost over the 15psi im already running (depending what my afr;s read a few psi higher) Once i get the reg installed i will then use other methods (prolly nos) & maybe extra injectors on a standalone ecu (maybe megasquirt) to supply fuel above the 15 or so psi of boost.
Sure a microtech or other ecu will do all this for me, but then im at the hands of dyno tuners to get it all sorted, i love doing this shit myself, and im loving the results i've had to date.
Sure i may push it too far and it may blow up or woteva but i'd rather blow it myself than have a dyno operator "tune" it and then it blow. I realise alot of people will not agree with my methods but hey its my car and i believe im fairly competant with wot im doing. Hell i even have a piece of paper that says im a qualified mechanical engineer......

Matty

p.s. how would i gut a sealed fuel pressure reg? screwdrivers and acid or something?

[brett_celicacoupe]

p.s. how would i gut a sealed fuel pressure reg? screwdrivers and acid or something?

drill?

....

[The Real Roadrunner]

ive put regs inline b4.

s14s are most common as its a 45min adventure to pull the rail or 5 mins to mount the reg and cut the return line.

just add in about 5psi above std base pressure and make sure it doesnt go above 70psi or some injectors refuse to open (aswell as the pump not pushing bugger all fuel at that point)

cheers
linden

[Wildsupra]

ive put regs inline b4.

s14s are most common as its a 45min adventure to pull the rail or 5 mins to mount the reg and cut the return line.

just add in about 5psi above std base pressure and make sure it doesnt go above 70psi or some injectors refuse to open (aswell as the pump not pushing bugger all fuel at that point)

cheers
linden

cheers mate thats the info i was after
I wont be exceeding 70psi that for sure.

Cheers
Matty

[thechuckster]

ah... this is safety management not tuning - sorry for my post sounding a little harsh then.

fwiw: once you go the megasquirt route - you've got total control over your AFRs and no tuning shop will lock you out of your ecu - and with a wideband you can do a fair amount of seat-of-pants tuning before requiring a dyno shop. There'a slreayd a few guys running MSextra code on 1JZ and 2JZ and some of htem would be quite willing to share maps.

btw: where are you measuring the AFRs at? collector after the turbos or at the tailpipe?

[Wildsupra]

ah... this is safety management not tuning - sorry for my post sounding a little harsh then.

fwiw: once you go the megasquirt route - you've got total control over your AFRs and no tuning shop will lock you out of your ecu - and with a wideband you can do a fair amount of seat-of-pants tuning before requiring a dyno shop. There'a slreayd a few guys running MSextra code on 1JZ and 2JZ and some of htem would be quite willing to share maps.

btw: where are you measuring the AFRs at? collector after the turbos or at the tailpipe?

yeah no worries buddy, thats why i clarified hehe
im measuring my afr's at the collector from the twin dump pipes, welded in a new bung so its pretty much permanant.
Yeah the wideband setup was purely so i dont have to go back and forth to a dyno and let other people "play" with my car. Its not like im miles out with any of my boost/afr's so its purely a fine tuning tool at this stage.
I want to bust up the fuel pressure just a touch to bring the afr's back into the low 12's then i'l up the boost a tiny bit at a time until i reach the high 12 afr's and leave it there. Basically i wanna find the limits of the mines ecu im using.
After that as i said earlier i'l look at the megasquirt or maybe nos, either way they will be using their own additional fuel system to prevent affecting the current setup.

Cheers
Matty

[brett_celicacoupe]

depending where you want to drop the afr's, you could always intercept the map signal.

this wotn help you once your FCD has clamped the circuit though

[Wildsupra]

Ok here's an update.
Ive installed the adjustable reg in series after the factory pressure reg.
Unscrewed adj reg out so it wasnt restricting any flow and the fuel ratios are around 9.5 at idle and around 13.5 giving it a boot at 15psi.

So then i adjust the press reg to base rate of 40psi at idle, afr's are much the same all round (i assume this is approximately stock pressure anyway's)

Then i tried raising base pressure to 45psi and the afrs at full boost crept up to around 13.8 at 15psi.

Then i tried raising the base pressure considerably to 50psi to see what would happen and the afr's got even worse cracking a massive 14.3 at 15psi.

So after that i decided to lower the adj reg back to 0 to cancel any difference from stock and now its seems to be running afr's around 12.9 at 15psi.

Any one got any ideas wot the hell is going on? Almost seems the results are backwards.......

Please only constructive opinions/info.....

Im wondering if maybe after screwing the adj reg to a base rate of 50 psi and giving it a belt maybe i cleaned out some shit in the injectors or something which is why back at stock pressure she is now a tiny bit better on the ratio's.

Matty

[oldcorollas]

Ok here's an update.
Ive installed the adjustable reg in series after the factory pressure reg.
Unscrewed adj reg out so it wasnt restricting any flow and the fuel ratios are around 9.5 at idle and around 13.5 giving it a boot at 15psi.

So then i adjust the press reg to base rate of 40psi at idle, afr's are much the same all round (i assume this is approximately stock pressure anyway's)

Then i tried raising base pressure to 45psi and the afrs at full boost crept up to around 13.8 at 15psi.

Then i tried raising the base pressure considerably to 50psi to see what would happen and the afr's got even worse cracking a massive 14.3 at 15psi.

So after that i decided to lower the adj reg back to 0 to cancel any difference from stock and now its seems to be running afr's around 12.9 at 15psi.

Any one got any ideas wot the hell is going on? Almost seems the results are backwards.......

Please only constructive opinions/info.....

Im wondering if maybe after screwing the adj reg to a base rate of 50 psi and giving it a belt maybe i cleaned out some shit in the injectors or something which is why back at stock pressure she is now a tiny bit better on the ratio's.

Matty

hahahha

ok.. idle is 40psi - manifold pressure = less than 40... for a start.
say you have 50kpa manifold pressure at idle.. thats about 7psi-ish.. so stock pressure is what? 33psi? 50psi is 17 up on that.. so at 15psi, you are running 40+15+17... = 72.. = danger territory for fuel pump duh...
you could adjust it up say.. 5psi at a time.. and see if you get a peak (trough) in the AFR's.. if you do, then you are killing the pump.

maybe you are adjusting it backwards?

what size are your injectors? how many of them? what is duty cycle at full noise.
which fuel pump? 315 or 341?

oh.. what fuel pressure reg is it? malpassi? is it rising rate? or 1:1?
gto any misfiring or poor combustion to affect the AFR's?

more info needed


ps, if it is a Malpassi, you have got the best results you can hope for