Some of you guys have mentioned an in line regulator. What brand/part number have you found that will work? Where did you get it and what did it cost.

The only external type that I have seen is intended for carburated motors and were only supposed to be used in systems up to 10 PSI.

What's up?

------------------
Black 1989 RS Convertible w/43,000 mi.
Excellent Condition
LO3 305 w/TBI
12 PSI Fuel Pressure
6* Timing Advance
Open Element 14x3 K&N
Hypertech Thermomaster
160 Degree Thermostat
Low Temp Fan Switch
Eddlebrock RPM Muffler
No Cat/No AIR Injection
B&M Stage 2 Shift Kit
17"x9" ATP 5 Spoke Alloys
P 245/45 Goodyear Eagle
HP Ultra Plus Tires
Lakewood Control Arms

Coming Soon:
3.73 Gears
Headmann Headers & Y Pipe
Lakewood Pan Hard Rod
MSD Wires and Coil

 

i used a NOS unit that my local speedshop just had collecting dust i dont know the part number but it came with two springs to make it a 0-15 psi regulator or a 15-50 psi regulator
there are more than a few externals that are like this i think mallory makes one

 

Hey Pablo, did you gut the internal regulator when you added your external? How'd you work that?

Steve

 

I was wondering that too.

Do you take out the diaphram inside the tbi injector pod when you put the external regulator in?

How much presure can you put thru the injectors before, whatever happens. Will the orings leak?? or something??

Also how much fuel can you run thru factory 305 heads. Meaning, With a 454 tbi, and stock heads, whats the largest injector that i could use with a hypertech stage 1, and still run correctly.

Lower pressure with bigger injectors or higher pressure with factory injectors??

Thanks..

------------------
ENGINE SPECS:
305 TBI,Open Element,K&N 14x3,Hypertech Stage I,160 Deg. Thermostat,454 GM TBI

STEREO SPECS:
JVC Kalmeleon kdlx3,Infinity Kappa 2way 6x9's,PPI 4x6 Coaxials,PPI PC2400 AMP @ 2ohm
DEI Studio 12" 4ohm DVC,Custom Box:Exactly 1 Cubic Foot

 

Higher pressure is generally better than bigger injecters. Hypertech chips are no more adaptable to modifications than stock chips. You cant look at fueling as a black and white issue, you might need a whole lot of fuel at W.O.T. but at idle your fueling is the same say for instance if you do some modifications like a cam etc. Bottom line, all the fuel in the world isnt going to do anything unless its introduced when it needs to be introduced, and not introduced when it doesnt need to be introduced which means custom tuning is in order.
To use an external regulator, simply plug the return on the tbi unit. Didnt touch the regulator in there at all, no need to.

this isnt the best way mainly because there is no bypass of fuel flow going through the tbi so whatever goes to the tbi gets force fed through the injectors and that includes whatever the fuel filter missed. Its no big deal to me though, its worked fine so far and if i was really **** i could put another inline filter between the regulator and tbi unit but its served me fine for a few thousand miles so far

[This message has been edited by Pablo (edited October 13, 2000).]

 

Now THAT is an accident waiting to happen!!!

The rubber diaphragm for the regulator that is sandwiched between the regulator body and the pod is only made to carry/handle bypass pressure and flow, or less than 2psi. (same can also ne said of that seperate little small gasket area, you know, for that longer single pod bolt) The regulaor body casting and the corresponding pod mating surfaces are not precision machined so BE CAREFUL! Over time, if you even get the smallest pinhole leak, there, Pablo, you will probably be in for an insurance consultation regarding the huge fireball that you used to call your car. ESPECIALLY with the 30-40psi that you are running. Ie LOTS of raw fuel on headers... and with two possible/probable places to leak, Just not smart.


I have already seen (even in my short TBI experience timeframe) a leaking TBI reg *** 'y...

 

could you maybe clarify the jargon of what you were explaining about the diaphram?
how much psi can the tbi hold before you start springing leaks. from either you gaskets or orings?
could you hypotheticlaly take it out if you were running an external regulator, and could you just put another regulator on the return line?

 

It's not jargon if you have takend one apart before. Too hard to explain without pictures but you cannot take it out. The way the fuel flows through the TBI's "internal" regulator, the fuel flows by the diaphragm (diaphragm/seat *** 'y is pushed upon by spring to create the regulator) and out the EXIT hole in the TBI pod casting. That rubber WILL deteriorate over time, as ALL rubber does, never mind that the rate is increased because it is in contact w/fuel. Also, the rubber MAY be able to burst like a balloon, I think (?) as the spring only pushes on the metal regulator seat/pivot assembly. Ie, PABLO's rubber diaphragm is probably blown-up like an over pressurized balloon inside his reg chamber. THIS rubber is not supposed to handle much/if any pressure!!! All that rubber was designed to do is make sure that the post regulator fuel flow does not leak out of the regulator *** 'y, which is attached by 4 flimsy bolts in a SOFT metal casting.

Maybe the Adjustable Fuel Pressure Reglator area in Tech on this site has pictures. I think it does. You'll be able to see what I am referring to. Go to HOME page and then tech section and look for article in there.

[This message has been edited by FastBroker (edited October 14, 2000).]

 

Dude you are so off base its not even funny
first of all, the rubber diaphragm ALWAYS SEES THE PRESSURE OF THE PRESSURE SIDE
How do you think it regulates the pressure? Dont come back with "oh you need to take it apart and see how it works" because ive taken it apart numerous times and i see exactly how it works, its a rubber pad with a small circular metal peice with a pintle on the other side the circular metal peice is supported by a spring that is tensioned by a screw supporting the base that rides on said screw. As excess fuel needs to be returned to the tank, pressure builds up on the pressure side, and causes the rubber diaphragm to yield downwards, and the aforementioned pintle lets fuel go by out the exit which goes to the return line
SO THE RUBBER DIAPHRAGMN ALWAYS SEES THE SAME PRESSURE AS THE SYSTEM Its what maintains the pressure!
Now that that is established, lets talk about how much this diapragm can take pressure wise. Late model TBI trucks ran the same tbi system at 28 to 32 psi from the factory ( i should know, i have a fuel pump from one and its max rated pressure is 36-38 psi)
the diaphragmn didnt change, only the regulator cover assembly and spring. Besides, the diapraghm can only move so much before bottoming out in the cup especially if you have raised the platform as high as it will go (as i have done). But dont take my word for it ask the 454 SS guys out there running twin tbis on roots blowers pushing 70 psi through their stock tbi units, or how about the paxton rep shane buss spoke to that had his fmu set on his 1500 truck so that max pressure was 90 psi! Ive personally run 50 psi on mine with no problems whatsoever and am currently running about 20 psi
as for the return where the long screw goes, you are silly to think that it wouldnt hold pressure seeing as how the injector pod top is sealed in the same fashion, by a gasket!

And believe me, if there was a firehazard on my car id be the first one to fix the problem.. i only have basic coverage, fire = me on foot.

[This message has been edited by Pablo (edited October 14, 2000).]

 

I am sorry, Pablo, but YOU are the wrong one. As soon as the fuel gets by the metal-to-metal pressure seat and enters the rubber diaphragm area, the pressure is instantly dropped to the return line presure (as you pretty much stated), or maybe a LITTLE more little more until the fuel fully gets out of the restriction of the pod exit.

If you were right, there would be regulated presure in the return line all the way to the gas tank, and you know that is not the case.

Sorry, buddy. Ask around because I know you don't believe me. It's basic physics. the spring is pressing on the pivoting seat and MAKING the regulated pressure. Once the fuel gets by there, pressure all gone, ideallly.

I believe the the people you mentioned created bypass systems, but I am not sure, because the OEM reg cannot flow enough fuel for their huge hp big-blocks... I thought I saw external regs on those vehicles???

Either way you are wrong.

[This message has been edited by FastBroker (edited October 14, 2000).]

 

btw you could put another regulator on the return line

BUT YOUD STILL SUFFER THE SAME GRAVE FATE according to fast broker.. since the stock regulator will always go into bypass

which of course doesnt mean squat because thats what the regulator does on your car now at idle

 

Pablo is right, I accidentally ran 95 PSI on my 79 when it had TBI, NO leaks, NO damage. hehe, and I even had about 25 hose clamps on RUBBER lines then too

The effect is simple, if you plug the return on the TBI, it has no choice but to run the PSI you are feeding it. The diaphragm is pretty damn strong, and so is the cup holding it in.

------------------
Shane McConnell
macgyver@nethirdgen.org [*]Owner of a 1991 Camaro RS, 305 5-speed.[*]Owner of a 1979 Camaro Z28, 350/350.[*]Webmaster of www.NEThirdgen.org

 

You are making absolutely no sense whatsoever
the reason the return line doesnt have pressure is because there is no regulator on it and the amount of fuel bypassed by the stock regulator isnt enough to pressurize the return line!
you are thinking the mechanism to cover the hole is in the path of fuel when its not! the diapraghm is on the PRESSURE SIDE and the whole freakin thing moves Downward exposing the hole to the return!
you are just out of it man

 

Pablo,

rgulated EFI systems are ALWAYS in a state of bypass. That is, there is ALWAYS fuel going out the return port. If not, there would be starvation.

I am not saying you cannot attain high pressures, guys, I am just saying it is a recipe for disaster as the rubber is only loaded from one side... IN OEM situation, pretty much ambient pressure on both sides of the rubber but in pablo's sitution, abient press n one side and his fuel pressure on the other.

 

lemme try explaining it like this


you think the pintle is covering a hole that hole is what leads to the pressure side
as the pressure builds it forces the pintle open and lets fuel past

its the other way around
the pintle is on the pressure side of the fuel sitting on a spring loaded platform, as that platform senses too much pressure it has to yield downward thus making the pintle move out of the way of the hole and letting fuel out of the system

 

you are taking things i say out of context to misrepresent what i am saying as if it were an extreme like saying that fi systems arent always in bypass somehow trying to correct me and put yourself on an upper level of knowledge. The point i was making by that statement is that there is much less bypassed at wot than at idle
lets focus on the issue here

the diaphragm is on the pressure side always , and will always see the pressure of the system, there is no diaphragm on the return side of the system the return side of the system is just a hole at the top of the injector pod where by fuel escapes to the return line
the hole is blocked by a little pintle that is sitting on a platform suspended by a spring that is in the DIRECT PATH OF FUEL
as the pressure in that "Chamber" increases such that the PAD (diaphragm) yields downward and the hole for fuel to escape is exposed because the pintle is attached to this pad
its really quite simple here dude you just have no clue what you are talking about

 

http://www.nethirdgen.org/mac/tbiexploded2.jpg

take a look here for yourselves everyone

that hump on the top of the injector pod is the return passage
as you can see the diaphragm presses up against this hump because there is a small hole there
its not on the return side
its on the pressure side, and as such, always sees the pressure of the system

 

Pablo/all, I apalogize.

I just wend outside with my trust Maglite and tok off my aircleaner. by looking at the casting, it seems that you are correct! It IS a backflow reg, not a positive flow reg, like I thought. I only took it apart once to put gasket set on it and in passive glancing I thought it was pos flow. I was looking at it wrong for sure. I apalogize again. I pulled an Ed.

On the converse, I am gonna go buuy external reg and 0 psi ressure gage tomorrow and be like PABLO!!!

[This message has been edited by FastBroker (edited October 14, 2000).]

 

Hey, while I got you here, wouldn't it make sense (to improve flow) to replace the diaphragm/spring assembly and just put a steel plate and rubber gasket in the place of that big regulator housing??? then, use the existing RETURN line (now to be pressurized) as the input line to the external reg??? Then you will get flow through the TBI at all times???

Oh, how much can those little plastic "O"'s as seals take (where the lines attach the TBI)

[This message has been edited by FastBroker (edited October 14, 2000).]

 

How would that improve flow?

the only negative to not running fuel through the injector pod is that crap can accumulate there but as i stated before i havent had a problem
if you want to put it on the return line, by all means, do so, but it doesnt really make a differance what you do with the stock regulator

 

btw since the plastic 0s on the pressure side are the same as those on the return side and the fittings are the same, im gonna go out on a limb and guess they can take the same pressure

 

Yeah, I guess it wouldn't improve flow by much but:

Make a cleaner insatall

Eliminate stagnant fuel/particles (like you said)

Improve inertial flow to pod (in your setup, entire body of ful has to "speed up" to get into pod whereas my way fuel would be constantly flowing through pod/injector area...)


c'mon, man. I admitted I was wrong, can't you admit it sounds like a good idea? That reg *** 'y gone would be cool. I'm gonna be the first guy on my block with it gone. Gonna to it tomorrow. DOUGH. What pressure you running at? 40?

Oh, my return line fitting is a little smaller (seal, too) and what is max pressure? Probably higher than we will run, eh?

[This message has been edited by FastBroker (edited October 14, 2000).]

 

If removing the stock regulator from the pod makes you rest easier then go for it

i disagree with your inertial flow to pod hypothesis because my regulator setup is the same as if it were coming out of the return side being that the injectors only care that fuel is being fed to them and not where it exits. The only point that may be raised using your analysis is the distance of the regulator from the injectors (the closer it is the more responsive), which can be a problem whereever you put the regulator, on the pressure side of the tbi or the return

[This message has been edited by Pablo (edited October 14, 2000).]

 

and im running 20 psi

 

I guess, but in my scenario, flow will always be "towards" the injectors and not stagnant... No biggie but it may be when I approach 400hp.

Still gonna try a 2" TBI w/Victor Manifold (can't use my Strip Dom w/Vortecs, bummer) and XE268 COmp Cam w/vortec heads... Kinda like that CHP crate motor quest engine... What'day think about that? 400 hp from TBI in daily driveable doable??? Maybe I should go with an RPM manifold, like CHP did... and maybe XE 262 (not 268) like Comp Cams suggested...

Can you find a 2" for me? I STILL can't find one, man.

How much HP do you think you have?

[This message has been edited by FastBroker (edited October 14, 2000).]

[This message has been edited by FastBroker (edited October 14, 2000).]

 

actually thats a good point i see what you are saying now, and you are right there will always be flow to the injectors but i think the difference we are talking about is pretty minute especially with a high output pump. Definately a consideration on an extreme application though


as for that setup, sounds killer, and i think it can be done. But some things i have been tinkering with have led me to start thinking that maybe two barrel tbi isnt the best setup in terms of fuel distribution, and if you really wanna go for the jugular, id suggest going with a four barrel tbi

ill explain what i mean if yo uwant in another thread

 

Nah, I'm with ya, though. You probably know that I am not too fond of Holley stuff.

How about that 2" TBI OEM for me? Any ideas/leads I can call?

My other thoughts are just keeping my existing heads (or use the RPM's I still have) and use an Edelbrock 350o ProFlo intake/TB/injector/reg setup and kep the TBI ECU. Hmmmm. I bet it'd be ok? I used the 3500 a lot as you know and it was ok. few quirks but I bet that system would be ok w/1227747...

[This message has been edited by FastBroker (edited October 14, 2000).]

 

if im not mistaken, edelbrock makes a retrofit kit for trucks like that but you need a special injector driver board (that edelbrock includes in their kit) to handle the different power requirements of hte different injectors. Im no expert on that, if that were the route i was gonna go id just use a 730 ecm just to have it be plug and play

 

hey sorry i caused a big arguement between you too. i thought my eyes were going blury when i saw that somebody had told pablo he was wrong about a tbi question. he he.

FASTBROKER, i forgot, did go to my local u pull it and a few salvage shops, and called my dealers. nothing, nothing, and 450$ wholesale cost on the 454 rochester. 630 retail. we just bought a gm dealership last week so ill get a price on cost here soon for you.

I think your best bet would be to redesign the top plate of the injector pod in CAD, it could be machined for about 200 bucks and youde have a custom, tbi with one high flow fuel line without a return line at all, and mount your regulator wherer youre coil is now.

BY THE WAY, sorry if i sounded like an idiot, but i have taken that thing apart quite a few times, and i know what it looks like, but i could never figure out how the flows went, or more so what you were trying to say about 2psi etc..

Now that i think about it.
Orings in ac systems hold 200+ psi. i think ours in the fuel system are mounted actually more securely so they should hold as much as you put at them.

Pablo you are running a truck tbi fuel pump?
install modifications? which truck maybe a p/n.

Anyway, i think i understand the tbi a little more, and thats what this place is all about right.

Discussion really got heated there for a minute.

You too kiss and make up ok?

------------------
ENGINE SPECS:
305 TBI,Open Element,K&N 14x3,Hypertech Stage I,160 Deg. Thermostat,454 GM TBI

STEREO SPECS:
JVC Kalmeleon kdlx3,Infinity Kappa 2way 6x9's,PPI 4x6 Coaxials,PPI PC2400 AMP @ 2ohm
DEI Studio 12" 4ohm DVC,Custom Box:Exactly 1 Cubic Foot

 

Snuffy,

Thanks for checking on the 2" TBI's for me. I anxiously await your post on the at-cost price from the dealership you bought. I cannot find any 2" still, either. TONS of the 1-5/8" versions, though.

Thanks again.

 

whats a good price for one anyway, i know i got mine a little over a year ago along with a turbo city afpr, matched 68 lb/h injectors , turbo city wiring conversions, and a tbi spacer for 200 bucks, i know thats a steal. What are you looking to spend anyway?

 

I don't want to spend more than $150 but I don't need all the stuff you got for $200, either. I just want:

TBI body (used is ok, too)
IAC (that works)
80lb OEM Big Block injectors (or 90lb OEM's)
TPS

And that's all I need. I have been quoted $100-125 for one and I am on waiting lists at 5 garages, the places who gave me the quotes. They just DON'T have any and they are not coming in... Don't see many big blocks in boneyards, I guess...

I guess I don't even know if you can get me that price even at your cost... Would you rather call me to discuss this privately?

[This message has been edited by FastBroker (edited October 18, 2000).]

[This message has been edited by FastBroker (edited October 18, 2000).]