I am currently running 62 psi. Will it hurt SVO #24 injectors? Will it hurt the stock pump? Everytime I raise the FP, quarter mile times and trap speeds improve. Latest was a 13.9 @ 97MPH. (originally running a 14.4 @ 93 MPH with #22 injectors @ 50 psi). It seems like the engine wants more fuel. Thanks.

Joe

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1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

[This message has been edited by Joseph Andres (edited April 26, 2001).]

 

if you have a 355 with zz9, headers, and stall converter and you are only running a 13.9 @97 there is definitely something wrong with your car, your mph should be way higher even if you are spinning

 

You have been no help at all. We need advice not coments. If you think that something is wrong than why don't you say what it is?? In the meantime don't post anything here!

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1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

 

I've heard from multiple sources on the DIY_EFI Bulletin Board that "most" injectors can handle 100 psi.

Now that doesn't mean that the fuel pump can keep up the flow needed at that pressure. It also means that your system (fuel line, connections, flexible hoses) can take that pressure either.

As you increase pressure to an injector, the flow increase as the square root of the ratio of fuel pressure.

Uh????

New Flow = Old Flow * (New Pressure / Old Pressure) ^ 0.5


I HATE when people offer unconstructive criticism.


It really shows a lack of ability to use higher brain functions.

Hope this helps...

[This message has been edited by a73camaro (edited April 26, 2001).]

 

Thanks. I think I saw that equation in an old Car Craft article and it makes sense. Thanks for the help. So you know what I mean by some of these pointless posts. I'd like to keep things in a mature manner. Some people just don't know how to answer a question anymore.

Joe

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1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

[This message has been edited by Joseph Andres (edited April 26, 2001).]

 

I don't know about what pressure you can run those injectors at but I CAN tell you that running 63psi on a fuel pump, especially if it's stock, is going to burn up that fuel pump QUICK!!

 

What the hell was that for? You're going to get comments on here whether you like it or not. Beside, he just told you that something else is wrong if you're running that time w/ those mods. Just b/c someone doesn't know how to fix it doesn't mean that can't do you a favor by telling you that you have more power in your combo than maybe you thought you did. Chill out.

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87 IROC-Z, 5.7, auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, SLP .218/.224 .495/.502 cam, Comp 1.5 roller tip rockers, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax\Flowmaster catback. Coming Soon(?)- Fasttrack/Accell DFI

1989 Pontiac 20th Anniversary Turbo Trans Am - 161,000 miles, !cat, 9" K&N

 

Typical pressure for 24# injectors is 35-39 PSI. Lower pressure will not allow the proper spray pattern. Higher pressures cause the injectors to work harder to open and due to the pressure it forces the pintel to remain open longer before it can re-seet itself. The high presure normally will cause the engine to run rich at idle because the injectors cannot close fast enough to slow the flow of gas. The improved times are a result of the high pressure because of the gas flowby into the engine. You should be able to lower the pressure, then reprogram the chip accordingly . You may even see your times improve. However, at wide open throttle (WOT) the ECM ignors the O2 sensor.

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1972 Corvette LT1
Keith Black 9.7:1 Pistons
Comp Cams 480/480 lift @220 Duration
Original 4 Bolt Steel Crank
1.5 Roller Tip Rockers
336 Posi Rear Chunk
1991 Speed Density TPI setup
DUI Special order Tachdrive Distributor

 

Joeseph,
I think 72LT1VETTE the nail on the head and running 62psi will burn out your fuel pump real fast too like someone earilier said. But the last thing is are you running a custom chip?
There is a spot in progamming it to set the injector size and it has something to do with the pulse width of it too. Not to mention it also the ZZ9 cam needs some mods made to the VE tables and Spark Adv tables too in order to give you proper performance.
I know it doesn't give you an positive answer to your problem but if you don't have a custom chip that could be your problem but I would turn down the pressure to atleast 40 psi.
The last thing is I saw you were a member of JFA and was wondering if you are going to the meeting at the Mall on Saturday April 28? I plan on being there and we could talk there too.
Good Luck!

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89 IROC 350 Auto
Custom DUAL Exhaust
Edelbrock Performer 6085 Aluminum Heads
ZZ9 Cam
TPIS Level 5 Chip
14.01 @ 97.0mph with 2.77's gears and a bad ignition control module!
And Free mods.

 

Ski89Z28,
I am a member of JFA. I will be at the meet on Sat. but I can't make it to the Burlington meeting place because I will still be at work. I spoke with Tom and told him that we would meet later that day during the cruise at Tom's River. See ya there!

Joe



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1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

 

maybe your tranny is slipping? something big is up for you not to be doing better.

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-Tas
'89 Formula WS-6

305, TBI, auto, 14x3 chrome flat based open element with K&N, Milodon 160* thermo, functional Formula hood, cross-flow Flowmaster, '99z28 rear pipes and tips....

Soon to be installed:
Hooker 1-5/8" 50 state legal headers, Dynomax 3" I pipe (PN 44063 and 43248), Catco 3" cat, and injector spacer.

Super GRK_Taz World
F-Body Dual Exaust
EFI & Intake Options
AOL IM: superGRtaz

 

Under boost, my SVO injectors saw over 90 PSI, but it wasnt constant, only at WOT. They can handle a ton of abuse without locking up like the GM style injectors. It does sound like a tuning issue for you having to run 62 PSI of pressure all of the time..
I would get a scanner on there ASAP and see what it is doing.

 

Thanks, I know that it is not the trans because I installed a Level 10 PTS-3 under a year ago. It shifts very hard.

I do believe though that it is a tuning problem. I have had the hardest time trying to find a place that would get the best performance out of my PROM. I do run a custom chip from TPIS (level 4) but I think it is hurting me more than it is helping me. I know that because on the Dyno the car had more RWHP and RWTQ at WOT with the stock PROM in the computer. This shows that TPIS is off on the programming. I have recently sent the chip back out to TPIS for reprogramming for the #24 injectors. I also mentioned to them that the car performed worse after their chip was installed. Hopefully they worked on it a little more to get in detail with the programming. I included with the chip, the dyno runs and air/fuel print out results. When I get the chip back I hope that performance increases into the mid 13's and be at the 100 MPH mark. I know that I should purchase my own PROM burning tools, since that will be the best for me, but to tell you the truth I don't have the time to get into the programming, the learning of the language, and testing of the results because I am a full time college student and part time mechanic. Anyone have any ideas on how they can help me?

When I do get the chip back, and it shows no improvement in performance, TPIS said they would refund me the money for their PROM, which leaves me to the option of looking into other companies for PROM burning. I have heard that Ed Wright of Fast Chips is a good place to go to. Any suggestions?

Thanks,
Joe

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1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

 

Kevin G, were you the Kevin from thirdgen.org they spoke about in GMHTP magazine (might of been HPP) where you attempted to burn chips for the Magnum TPI but everytime you tried to burn a new prom the car got slower? They ended up being faster with the "off the shelf" chip?? Was that you?

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91 Formula 1LE 1 of 46
305 TPI 5speed
1LE/G92/WS6

Paxton SN92 supercharger(SN93 upgrade), Ford SVO 24#injectors, Crane AFPR,SLP airfoil, ported/polished plenum, March alt. pulley,Crane Gold 1.6rrs,MSD coil,MSD6AL (5200rpm limit),Holley 9mm wires,Ac delco R43ts plugs,custom chip,Bosch O2sensor,SLP 1 5/8" headers,SLP catback,shortened shifter,3:73s w/Auburn posi,170* t-stat,JET 195* fan switch, Macewen white face gauges, Autometer gauges, Zoom hi-performance clutch.

 

Ed Wright claims to be able to get the chip right the FIRST time 99% of the time and his company did win a chip burning award so he knows his sh*t!! He will also "fix" the chip, however, if it isn't right the first time!

 

Nope Formula, I guess it was a different Kevin.

 

Joseph,
I can't make it to Toms River but I can make it to the Mall so I'll catch you the next time, maybe May 4th ?
As for the chip I heard GOOD things about Ed Wright chips but kinda expensive, $350. But Make sure you kept copies of the dyno runs to send to him if not happy with TPIS.
I think the dyno sheets will help give a better idea to TPIS for programming the chip.

Good Luck!
SeeYa on the Flip/Flop!

 

Thanks so much fellas. Will do!

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1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

 

Can someone explain why running more pressure on the injectors, will cause the fuel pump to fail quicker?

The way I see it, the fuel pump is pushing 60-70 psi, what's not used is bypassed to the tank, turning up the regulator shouldn't cause any ill effects on the pump.

Or am I missing something?

 

I dont know about stock pumps and higher pressures, but I have a NOS (Bosch) in line pump that was made specifically for higher pressures.
I wouldnt think 60 psi on a stock pump would hurt anything though.

 

I don't know what psi the stock intank pump is rated at! I was kinda just going by an Accel EFI INLINE pump that I saw that is only good up to 45 psi! There are some good inline pumps out there that will handle up to 90 psi but again, I don't know about the stock intank pump! Might call GM or a parts store to see if they know!

 

The Accel pump you mentioned is also a Bosch made pump that can easily handle higher pressures than 45 psi. It has a flow rating that is advertised @45 psi, but it can handle much more than that no problems. It is very similiar to the NOS pump I use made by Bosch.

Some in tank pumps like the Walbro 255lph will not support 85+ PSI ratings, from my personal experience using them.

Most people wont ever need a pump to run high pressures, unless you run smaller injectors on boost or N20 like I did.

I also used a Kenney Belle Boost-A-Pump on a stock in tank with no problems hitting 60+ PSI .

[This message has been edited by Kevin G (edited May 01, 2001).]

 

So I'll be ok with the stock pump for a while? I don't plan to set FP past 62 psi.

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1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

 

It takes more power for the pump to make higher pressure. This causes the pump to heat up. The hotter it get while running, the shorter the life the pump will have.

 

Won't the fuel in the tank keep the pump cool?

------------------
1988 GTA 5.7L TPI Auto
355 ci. block,TPIS ZZ-9 Camshaft, SLP Headers, Borla Cat Back, B&M Holeshot 2400 Stall Converter, 3.73 Richmond Gears

"Why ride a stang when birds can fly?"

http://www.geocities.com/thegta

 

Please explain.

As I mentioned before the way I see it the pump is outputting 60-70 psi, what is not regulated and used through the fuel injectors, is bypassed back to the tank.

How does turning up the AFPR increase the workload on the pump? Whether the regulator is set to 30psi or 50 psi, the pump is still putting out at it's rated capacity, isn't it?

 

Sorry for the lateness, I've just got back from Hawaii.

Basicly a pump adds a constant amount of energy to the fluid it is pumping.

The three forms of energy are

Pressure - psi
Flow - lb/hr
Head - How tall a column of fuild can the pump push.

A simple form of the Bernoullie equation is

(k1 * Pressure) + (k2 * Flow) + (k3 * Head) = Constant energy

So if pressure is increased, flow has to decrease.

As for gas recirculating and cooling the pump, Joseph is right, an in-tank pump is cooled by the fluid, allowing it to be driven harder and not affect its life.

 

What is wrong with this post? Why is the guy being flamed, because he spoke the truth?
Joseph, take it any way you want, but you should really look into your car deeply, because it aint running right by a long shot (unless you live at really high altitudes) and I honestly don't think it's a fuel thing unless you have a clogged line or something of that matter. Take a look at your plugs; they will tell you what's going on with the engine. If they are in the range of brown to powdery black, then it isn't a fuel problem.
Don't get so pissed off man
Rick

 

All the fuel pumped from the tank that re-enters the tank (by being bypassed at the pressure regulator) is higher than the datum line. Thats the head part. Energy is expended at that point that could otherwise be used for flow or pressure, so its possible to increase the pressure and not lose flow to some extent, a point of which I dont feel like crunching numbers to figure out.