s13 fpr = s14 fpr?

[Kreator]

Does anyone know if s13 fpr is the same exact thing as the s14 one? Just wondering, since i might replace my epoxy glued s14 one with the s13 fpr.... here's a pic (s14 on the left, s13 on the right):

http://www.wam.umd.edu/~iminin/images/pic1.JPG

PS: that little o-ring... has to be replaced right?

[drift freaq]

you can use it. The Tomei FPR fits S13 KA and SR,S14,S15, RB20,RB25,RB26,

[Kreator]

Is tomei adjustable?

Reason being, i know it fits in. I was more wondering if they both hold the same psi level.

[AceInHole]

AFAIK, both should be 3bar or 43.5psi

[d240t2]

I have compared the 2 before. They are completely interchangeable. The flange is slightly different, IIRC, in where the reg is in relation to the flange...but it all bolts up the same. In other words...the top of the reg on one is a little lower than the top of the other, when compared to the location of the bolt holes, but the flange is the same, the location of the inlet and outlet is the same in relation to the bolt holes, and they hold the same pressure level, 3 bar or 43.4psi (according to the FSM).

Dennis

[Kreator]

Thanx guys. I guess i'll try and make an afpr from my s14 fpr.... Could somebody answer my second question about the o-ring? should i buy a new one or the old one is fine?

[d240t2]

That's odd...just looked at the picture...my S13 reg doesn't have that long outlet with the bend. Is that a S13 SOHC KA reg? Or an SR reg?

The O-ring...you don't have to replace it, necessarily. If you can't get an O-ring that you are sure can withstand fuel and 3 bar of pressure, then just reuse that one. It'll probably be fine.

Dennis

[Kreator]

supposedly a kade fpr from the s13... :-/ who knows. Bought it from a guy on this msg board, (dave240sx?) but haven't seen him lately. so i have no clue... anyone with the fsm, whats the psi for the ka24e fpr? (just in case)

[Kreator]

hmmm gonna give myself a free bump instead of editing my last post :D

While on the topic. If i make an afpr, will i be able to run it with sr injectors by turning the pressure down? Like if i set it to 30.5psi (43.5*260/370) will it idle and run normally?

also, anyone got experience with sunpro gauges? i know they are crap, but all i need is for it to show me whether my afpr works or not. think it can do it? or should i cash out for autometer?

[AceInHole]

Originally posted by Kreator
hmmm gonna give myself a free bump instead of editing my last post :D

While on the topic. If i make an afpr, will i be able to run it with sr injectors by turning the pressure down? Like if i set it to 30.5psi (43.5*260/370) will it idle and run normally?

also, anyone got experience with sunpro gauges? i know they are crap, but all i need is for it to show me whether my afpr works or not. think it can do it? or should i cash out for autometer?

i'm guessing you'll be getting a mechanical gauge... it's sort of hard to screw something like that up, so i'm betting the Sunpro gauge will work fine (you can't mount it in the cabin anyways).

First thing: you can't just multiply by the percent difference, since pressure affects flow by a factor of a square root of the percent difference (I think.... it has a square root in it. I'm too lazy to look it up at the moment). So... the new flow rate would be calculated:

270 = 370 * sqrt(newrate/ 43.5)
(270/ 370)^2 * 43.5 = newrate
23.164psi = newrate
[stock injectors are 270cc]

As for the 30.5psi... the fuel pressure will drop to something like 16psi at idle, and I don't know for sure if that's too low for good atomization, but I'm betting it is (i.e. i think it won't work well.... if at all). I'd imagine that 23psi fuel pressure would work even less.... since at idle you'd be getting like 8.5psi.
Also, you wouldn't really be getting any more fuel than normal under full injector duty cycle, than you would with the 270's at stock fuel pressure.

[Kreator]

so is there any way to run 370cc with an afpr w/o doing any other mods? Just want to check that it will work before i take everything off the car for the turbo.

[d240t2]

(new flow/old flow)=(new pressure/old pressure)^.5

So...you need to know the new pressure...

[(new flow/old flow)*old pressure ^.5]^2 = new pressure

=[270/370*43.4^.5]^2 = 23.1psi. PJ got it right!

And absolute pressure in the rail doesn't matter...only differential pressure. At idle, you will pull ~8psi of vacuum, so pressure in the rail is only going to be ~15psi, but that doesn't matter since differential pressure between rail and manifold is still 23.1psi. Still...nobody knows how good the atomization will be at that low of a pressure.

What do you hope to gain by doing this? You basically will just have 270cc injectors in the end...you won't be able to put out more fuel on the top end!

And all the Nissan regs are the same fuel pressure...so you'll be fine. Most FI cars run off of that same fuel pressure...but some don't.

Dennis

[Kreator]

Originally posted by d240t2

What do you hope to gain by doing this? You basically will just have 270cc injectors in the end...you won't be able to put out more fuel on the top end!


Dennis

Nothing, absolutely nothing. I just want to be able to start the car and see if it idles normally so i can check that my diy fpr works. That's all i wanted. But actually, i think i'll just swap in the old 270ccs in check with that.

Thanx again guys.

Could someone explain what atomization is? Don't have the book near me at the moment (at work)

[AceInHole]

Originally posted by d240t2

=[270/370*43.4^.5]^2 = 23.1psi. PJ got it right!



heh... and if I had remembered the relative pressure I would've been 2 for 2..... :mad: