bhaas

Just got back from beating on the car some more. Fuel PSI went to **** under boost. 5 PSI boost and the FP was 3 psi. The turbos were making a loud whistle to. Never heard that before. There's no filters on them but I never heard it before today. Sure sounded cool and was quite loud. Any suggestions on what kind of regulator to get? I want one with a return on it and a port for boost and one for my FP gauge. Thanks.

Brad...

bhaas

Now that I think about it, this should be working. I took the line off the bonnet and blew through it. The pump isn't leaking air. The only thing I can think of is that the line going to the pump is too small. But there's not that much area to be filled with air inside the fuel pump. The fuel pressure should be rising. WTF???
I hate stupid problems like this. Especially if it's gonna cost another few hundred $$$'s to fix.

mefreema

Do you have a compressor and regulator? You could simulate boost to the fuel pump while its ideling and see how your fuel gauge reacts. Then you could see if it is working at all or play with different line sizes and see if you can get the 1:1 ratio your shootin for.

bhaas

Yup. I just did that. Fuel pressure rises no prob. So why isn't it rising while I'm under boost? So, if I can't get a rise in fuel pressure at my mech pump then I won't be able to get it to rise on a FPR. Hmmmmmm

Brad...

mefreema

Maybe your not getting a good reference signal from the bonnet. Maybe try a different spot like somewhere off the intake or somewhere closer to the turbo. Where is your boost gauge hooked up? It seems to be getting good boost signal, maybe you could reference from the same spot. Could you be emptying your fuel bowls and loosing pressure there? I know there is some formula to see if your pump will keep up with the HP your making. How much HP is your holley pump supposed to support?

bhaas

I'm getting my boost for the boost gauge from my manifold. I was thinking of hooking it up to that, but it will also see vacuum. Probably not good for the pump. I could use a checkball of some sort, so at boost it'll go to the pump. I have no idea how much HP my pump supports.

Brad...

mefreema

I dug up some old ATI procharger liture they sent me about carburated setup, it says:

To determine required fuel flow multiply total expected HP by .65 (brake specific fuel comsumption) this give you lbs/hr requirement. To convert to gallons per hour devide by 5.87. Another thing metioned : take idle pressure + boost pressure X 1.20 (20%) safty factor for total fuel pressure at max boost.

let say 5 psi idle +10 psi boost X 1.20 = 18psi at max boost could probably get away with 15psi

This is a Holley 12-327-11 Flows 110 GPH (free flow) 70 GPH @ 4.5psi

Lets say you will have 500hp at redline 6000.
500hp X .65 (BSFC) = 325 lbs/hr or devide by 5.87 for gallons per hour = 55.366.

From the attached chart (hopefully my post works) this particular pump would be good enough. As long and your getting 15psi at full boost. I know you mention you had a holley but I cant remember which model or how much HP your making. You may need to rework the #'s and find your pump's chart from the Holley site.

mefreema

Ya, try to reference it from a different spot with a check ball. Cant hurt to try.

F-BIRD'88

May have to hook up the boost reference line on a different spot
on the bonnet.

Airflow in the bonnet @ WOT may be rushing past the oriface in the bonnet causing a low(er) pressure signal at the boost reference line. (lower than boost pressure)

Try hooking it up to the full manifold vacuum port.
Do not operate at full throttle unless the fuel pressure is 3PSI or more above boost pressure.

F-BIRD'88

Extending the pickup tube into the air flow may give a better boost reference signal.
You may be getting boundary layer effect or venturi effect
at the pick up point causeing a lower pressure signal than
actual turbo boost pressure.

May have to hook a pressure guage in the reference line to be sure it matches boost pressure.

kevin v

don't try and split atoms here. get the biggest electric pump you can . you can't go to big. keep the boost reference port connected to the hat. it does not matter where or how far in the hat it's connected. when the hat sees boost the regulator will respond like it should.

bhaas

Hey Kevin, I don't think that's actually correct. If I'm not getting any reference where I have it now, how would I get reference to a FPR if I'm not getting it from where it's hooked up? I think moving it might be the solution. I'm gonna do that. I don't have a checkball so I'm just gonna hook it up to my manifold. I know I"m getting a boost reading there. Hope the vacuum doesn't hurt my pump. I'll keep you posted. I just hooked it up to the manifold. Taking a smoke break. It's 2:45 am so there shouldn't be too much traffic. Good Test and Tune time If this works then I drilled 2 holes in my very expensive and shiny bonnet for nothing. Doh!!!

Brad...

bhaas

Well, I now have a boost referenced fuel pump. But my FP is like at 0 at cruise, but under boost it goes up, but I'm still leaning out real bad. Jets too small? I got .119's in the secondaries. Do I need bigger or is my carb just too big for this? It's an Edelbrock 800 1412 carb. I'm thinking a checkball is definately in order here. Thanks.

Brad...

B4Ctom1

0 psi at cruse? what is it under full boost? alot of people have EFI style pumps on their cars. If you are trying to run a carburated style fuel pump on this boosted application then this could be a problem. the EFI pumps mostly have a 255 LPH rating at around 40-45 psi. at lower pressures these pumps can deliver even more volume. consider a nice in line EFI pump hooked up at your lower PSI through a return style boost refferenced regulator (as we talked about before) the 1:1 refference will help you overcome the problem of boost pushing the fuel back to the pump through the needle and seat by raising fuel pressure above that of the boost. if you run 6 to 7 psi at no boost then you will need that same amount of pressure above the level of boost to compensate for the opposing forces (6 psi fuel pressure at no boost, 16 psi of fuel at 10# boost)

bhaas

Yup. I understand all that. My problem was not getting the extra PSI to the fuel pump. Where I had it connected to the bonnet wasn't working. Works great off the manifold except the vacuum while just driving around gives me 0 psi so I'm gonna go get a checkball/valve right now so it won't see vacuum, only boost. Then I should have the PSI I need for the pump. And if I have the right amount of fuel pressure and I"m still leaning out then it has to be carb issues.

Brad...

mefreema

The zero psi is because the higher vaccum at cruise lowering fuel pressure just as boost raises it. Just put the check valve in the reference line and all should be cool.

bhaas

Yup. I just got back with it. Installed. It's pouring down and rain as usual around here so now I have to wait before I can drive it.

ATOMonkey

If you're leaning out, and can't run any fuel pressure then you don't have enough flow. If the jets were too small you should still be able to make pressure. Time for a bigger badder pump.

BOTLFED

Sounds like you've got it all figured out man, let us know what happens...

Cheers!

F-BIRD'88

Ok if your fuel pressure raises properly while under boost
3#'s+ psi over and above boost pressure Then your
pump is keeping up.

The pump shpould be enough for 500/550 hp
as long as it can maintain enough fuel pressure too.
At WOT.

You can try upping the sec jetting and upping the primary jetting.
You want to increase the fuel flow at WOT only so a bigger jet
combined with a rod with a lean cruise step and a rich (thin)
power step will provide this.

Again as long as fuel pressure is maintained at 3+psi above boost pressure, you have enough flow.

You may want to consider using your intank fuel pump and
line for an auxillary fuel system.
Its a simple curcuit where the pump is plumbed to a
restriction and a hobs switch and then to a EFI fuel injector.
The hobs switch turns on the pump and opens the injector
when the boost pressure hits say 3 to 4 psi. The injector is
mounted on the air inlet to the bonnet.
The injector (when it is on) runs at 100% duty cycle so no
computer control is nessessary. Calibration is by varying the size of the inline restriction and pump voltage.( pressure)
This extra fuel makes up for the increased density provided by the turbo. Because the turbo reaches full boost relitively quickly
the amount of extra fuel needed is constant ( almost).
This extra fueler has been used on a simular twin turbo setup as yours. It works well.

This allows you to keep near stock carb jetting for nice clean cruiseing and light acceleration while provideing all the extra
fuel nessessary while under boost.

It is explained better here.
http://www.toohighpsi.com/BudgetTT/tthowto.htm

You already have the in tank high pressure pump.
Once the extra fuel cuircuit is set up and calibrated, the only time it should need adjustment is if you change the maximum boost (wastegate setting) . Increased boost will need a corresponding increase of extra fuel. ( bigger restriction.)
and/or higher pump voltage.

F-BIRD'88

...

F-BIRD'88

wiring

bhaas

If I can, I'd rather not have to add any injectors. But it would be cool looking with an injector or 2 sticking out of my bonnet. I don't have enough room to put one in the front of the bonnet anyway. But if that's what I have to do, then so be it. Doesn't look like I'll be making it to the track this Sunday. Maybe in a few weeks. Nice drawings. I like those. But you forgot a turbo on the first pic. What did you do them with?

Brad...

F-BIRD'88

Windows Paintbrush. Just an idea of a way to get the fuel enrichment ya need using the pump(s) ya have already.

bhaas

I've been to Mikes site many times. Didn't he eventually take off that injector and still have it work? But if I can't get it to work I'll go the injector route. Now that I think about it I could put the injector on to of the bonnet inlet. Is that what you meant, or in the front pointing into the bonnet. I was also thinking of putting one in the side of the bonnet pointing towards the carb.

Brad...

F-BIRD'88

Yes I would install the injector(s) so they fire towards the carb.

How about a injector(s) from the junk yard?

F-BIRD'88

Yes, According to the tt capri site he did try it with the carb richened up and the injector disabled. But he said he wanted to go back to the injector because it allowed him to use leaner jetting (closer to stock) which allowed much cleaner (leaner) cruiseing and mileage.

ATOMonkey

If you use JY injectors, try and grab one from a Ford turbocoupe. Those injectors are low impedance so they run longer at 100% duty cycle than the normal high impedance injectors. The last thing you'd want is for an injector to burn up at 10 psi and 5500 RPM. The other thing that could work would be to use a resistor at the power input so the injector wasn't at 100%. Just some of my thoughts.

mefreema

I hear about people that use cold start injectors off of sabbs I think.

bhaas

After thinking about it. Putting an injector on this would be kinda cool. I'm liking the idea more and more.

Brad...

83 Crossfire TA

iTrader: (2)

A high impedance injector is less likely to have problems running static since it will draw less current and the coil doesn’t get as hot in it.

I don’t know if you found a check valve, but depending on where you’re looking 2 good sources are 80’s and earlier fords (they used tons of them in their emissions crap) and you can also buy them cheap from a fish/aquarium store.

Instead of moving the fitting around why not just put a T in the line to the pump and connect your boost gauge there temporarily to make sure that the fuel pump is seeing boost pressure (then you don’t have to worry about any airflow problems not giving you a proper boost reference if you can confirm boost pressure getting to the FP).

If you confirm that and you’re still not getting a stable pressure rise with boost even with a good boost reference then I’d guess that your pump is not big enough to keep up with your fuel use.

Didn’t we have this discussion before you started and I said something like it could be made to work but you’ll end up going through a royal hassle tuning and getting everything to work together on the carb setup? (sorry)

bhaas

[q]Didn’t we have this discussion before you started and I said something like it could be made to work but you’ll end up going through a royal hassle tuning and getting everything to work together on the carb setup? (sorry)
[/q]

Yes you did. I did get some of those check valves off some old Fords. I thought I had a pile of them laying around here but I guess I threw them all away. In another post I have a pic of them.
https://www.thirdgen.org/techbb2/sho...hreadid=157872
I had to use 2. With just one, the pump had no ventilation so I had to T in another one so it could breathe. So, now under boost the breather one closes and the pump sees the boost and it works great. Might get to the track tomorrow. Looks like I'll have to drive it up there. Went out and bought a trailer. Won't get to pick it up till Monday. Went halves on it. Wanted to use it tomorrow but that's not gonna happen. I also drilled out my secondary jets to .146. Not going lean anymore. I think I might be good to go. We'll see.

Brad...

F-BIRD'88

In another post you mention that you are getting detonation whiile under boost. I would hold off going to the track till ya get that sorted out.

Turbo detonation is not like the knock ya get on an old car going up ahill. It will destroy your motor in seconds.

This is where the ignition retard, water injection and extra fueler come in.
Unfortunatly your compression ratio is a bit too high for a turbo motor ( on street gas).

You can 1.Limit the boost.
2. retard the total timing
3 inject water/alcohol at high pressure into the carb bonnet
4. Add a extra fueler ( injector)
5. switch to high octane racing gas.
actually a combination of these will be nessessary.

There is a limit to the amount of fuel that will flow through the secondary jet down well so installing a .146" sec jet may not richen it up as much as you think.
I would richen up the primary jetting too and drain the tank and get some 110/114 octane racing gas until you can rig up a water injection system.
I know you're ancious to get to the track to get some passes but
unless ya get the fuel /timing sorted out to eliminate detonation
the motor will self destruct.
When you set the timing at 6 deg initial what is it at full advance
@ high rpm? without vacuum advance/

What jetting do you have in the carb now?
primary?// rod? secondary?