GOY

Anyone use P/N 17113186 talked about here http://home.att.net/%7Enotdadsw41/tbi.htm

What were your opinions and how did things work out installation wise? I see a lot of info at https://www.thirdgen.org/techbb2/sho...ht=%2B17113186

... but can someone be very specific about what spring they used, where they got the vac specifically (what port did you go to? TB or at the manifold?) and and improvements in fuel economy?

Thanks,GOY

25THRSS

Dont use one. It's only a crutch for real tuning.

Fast355

iTrader: (2)

It can become necessary if you have to use an injector that is big like a 454 and higher fuel pressure (around 20 psi) to feed your engine. That gives you more control over the injector as you can dial in less duty cycle under high demands and more at idle. Basically it helps you lean out the idle on a car that needs a huge injector (cammed and head 383 for example)

25THRSS

So lower your pw at idle. IMO, they just make tuning harder.

Fast355

iTrader: (2)

Its actually increasing you PW at idle for more control of the injector and decreasing it under heavy loads to keep you from going static.

Basically look at it this way a TBI injector at a regular pressure is a garden hose. Turn the pressure up and it becomes a fire hose. With a fixed pressure regulator the fire hose is too much at idle and low loads, just as the garden hose is not enough under load and higher rpms.

TonyC

iTrader: (1)

I had this on my car for quite a while. I swapped from stock to LT1 Cam + Edelbrock Carb Intake + SLP 1 3/4 Headers + Cutout and the car drove around fine with just the Vacuum fuel pressure regulator and some more base timing. It was rich as hell at WOT but not anything scarily bad. I wanted to lean it out, but the screw on the regulator for some reason or another WOULD NOT adjust the fuel pressure at all. I ended up taking it out, and just using the stock one, except made it adjustable and haven't looked back since. I was using the TDS spring in it, but I really can't recommend the regulator. As intimidating as it sounds, there's really no replacement for doing your own comp. tuning, and for that, there's nothing easier than the prominator

25THRSS

It's not doing anything to the PW, it's simply allowing you to use different fuel pressure at different rpm and vaccum ranges. You are correct with your analogy, but as I said before it is simply a crutch for computer tuning, and when you finally decide to do the right thing and start burning chips, it only makes tuning that much more difficult. Get an adjustable non vaccum regulator, set the pressure to give you the max amount of fuel you need, and tune from there.

Fast355

iTrader: (2)

I think you are missing what I am trying to say. It is going to change PW in closed loop but I was talking about using it in conjunction with tuning. I was saying that it is a crutch but it can also be used with the proper prom tuning. 454 injectors are so large that it is difficult to control them at low idle speeds. When you are burning chips changing the pressure around will mean that you are using different pulsewidths to accomplish the same fueling. Tuning for a VAFPR isn't that hard because it is just part of the fueling. Dimented even added a table to reference its action by changing pulsewidth although that is not necessary.

I haven't had too much problems with the VAFPR on the engines I have been tuning. I have a 350 TBI setup with that regulator on a 307 olds that I am tweaking on (cheap engine to get my feet wet). I am now about to start working on the engine that just went into my van. 355 with a LT1 cam, Ported TBI heads, Edelbrock Intake, Ultimate TBI mods and a VAFPR.

Fast355

iTrader: (2)

I think you are missing what I am trying to say. It is going to change PW in closed loop but I was talking about using it in conjunction with tuning. I was saying that it is a crutch but it can also be used with the proper prom tuning. 454 injectors are so large that it is difficult to control them at low idle speeds. When you are burning chips changing the pressure around will mean that you are using different pulsewidths to accomplish the same fueling. Tuning for a VAFPR isn't that hard because it is just part of the fueling. Dimented even added a table to reference its action by changing pulsewidth although that is not necessary.

I haven't had too much problems with the VAFPR on the engines I have been tuning. I have a 350 TBI setup with that regulator on a 307 olds that I am tweaking on (cheap engine to get my feet wet). I am now about to start working on the engine that just went into my van. 355 with a LT1 cam, Ported TBI heads, Edelbrock Intake, Ultimate TBI mods, 90 lb/hr 454 injectors (going for 310 hp) and a VAFPR.

dimented24x7

iTrader: (2)

Sometimes a vac regulator is the only thing that will allow enough fuel at WOT while still allowing for reasonable PW's at idle. I even set my code up ahead of time with correction factors and adjsutable lag to allow for the use of a VacAFPR. I guess youd call it a crutch for only having two injectors.

What id like to see even more is a VAFPR that can do more then a 1:1 pressure decrease with rising vacuum.

ShiftyCapone

iTrader: (7)

Instalation of the VAFPR isn't to hard. I had to bend the line slightly to clear the air cleaner and I ran the vacuum line across the front of the TBI. It is not in the best spot at all but it is hard to twist and place the vaccum line where you need it to go. There should be some glances of it in stikcies above. It can be seen on some of those TBI shots.

Fast355

iTrader: (2)

My point exactly.

GOY

Any noticable increases in fuel economy?

Ronny

iTrader: (1)

i did not give it an honest chance. used it since i was getting inadequate fueling up on top with out chip burning knowledge. so i guessed on FP with shims. no WB. from what i heard it may give you too much fuel at top unless you run a second regulator to control(lessen) FP at WOT. also is a delay factor! in a 1/4 mile drag may be OK. but say autocross when you are on gas off gas on gas continuously what would the fueling look like? i am (was) struggling to get AE tuned without WB. now with it WB installed(10/2004) i have a chance to dial it in very nicely. i would expect a WB would be neccessary to tune in the vafpr along with multiple chips as well. i believe GM used for 454/502 application TBI. i bet they had fun tuning that. but they have resources we do not. vafpr= tuning nightmare unless you are tuning smart.