Hello everyone, I am wanting to put a little more humph into my Bird and had a few questions to bounce off you. I want to use Edelbrock's matched cam and manifold setup. I truly enjoyed the Torker cam and manifold setup I had on my 81 Z28 and wanted to go with a similar setup on my 91 350 TBI Firebird TA Clone. Anybody have experience working with TBI units and how they faired mounted to a square bore manifold with the adapters available? My fuel pump is stock, will I be able to push enough fuel? Do I need to "chip" my ECM and if so suggestions? I do not require emissions were I live, I have shorty headers on it currently Dual exhaust, no smog equipment. I have a spacer under my TBI, I have it bored out as well along with an open air filter. She runs really well good on gas too. I know the Edelbrock performer setup would be fine but want the torker setup. I want to keep the TBI if I can. I have not worked enough with TBI units to know their limits and would really appreciate some insight.

Thanks
Scott

 

Have you ported the heads? From what I remember the stock swirlport ones tend not to flow well past like 4000. Even with work elsewhere. RobertFrank is the 305TBI Expert around these parts, so I'd inquire of him if you want good info.

 

Thanks for the info, yes the heads have been ported and polished nothing radical ofcourse. I will see if I can get in touch with RobertFrank much appreciated!

 

At the RPM range you will operate in the BEST manifold to use is a dual plane since it will give optimum performance from IDLE to 5500-6000 RPM

A single plane intake, like the Torquer, is not the best choice for a street car since it is made for 1500-7000+ RPM use.

Your engine, at best, makes peak HP at 5800 RPM.. a single plane is the wrong part to use because your PEAK HP occurs much lower and power falls off
from there... spinning the engine more yields no gain and hurt idle & low RPM throttle repsonce.


An excellent candidate for a street / strip engine is the Performer RPM Air Gap intake which is made for 4150 style carburetors.

IN THE LONG RUN THE STOCK 2 injector TBI WILL BE THE BOTTLE NECK to making any substantial power, past the OEM level.

250-300 HP at the most and that is with larger injectors... tuning, cam, etc.

 

Excellent info thank you, I have also been looking at aftermarket TBI units Holley seems to have a nice TBI setup, 502-9 any thoughts on this model? I have an Edelbrock performer TBI manifold I was thinking of putting on but as I mentioned I really enjoyed the torker setup but am wide open to suggestions I still want to get a decent cam for my bird, not the matching performer I want one with a little thump in the idle that would work with the performer manifold and some sort of TBI setup.

 

ALL BAD ADVICE!!!! The stock TBI unit is good to about 325 crank HP with tuning and fuel pressure. Above 325 HP the TB needs to be upgraded to 50 or 54MM and it needs bigger injectors. Dual small block TBIs run by an EBL with upgraded injector driver on an intake such as the air gap 2x4 intake would be capable of over 400 HP at stock fuel pressure, with stock injectors. With stock 350 injectors @ 18 psi that number would climb to 650 HP. TBI is not a limitation at all to making good power.

I tuned a 10 second 39 chevy that had a healthy AFR headed 406 with dual small block 350 TBI units on top of a tunnel ram! It would cruise around smoothly under 2,000 RPM in overdrive with the converter locked and would rap to 7,200 rpm in a heartbeat. It had a 4L60E with a 3,600 rpm Yank converter and 3.73 gears. The guy cruised it around with the a/c on. Went to the track where they asked him to turn the a/c off in the staging lanes and ran 10.20s @ 128 mph in the heat of summer. I built a custom injector driver circuit that took the 7427s injector output and amplified it for the 2 additional injectors. I removed the EGR, AIR, and CCP code from the 7427 and patched in my own controls for a PWM controlled cooling fan and pwm progressive nitrous control. He has yet to hook a bottle to the car.

Throw away your way of thinking with EFI.....TBI + Single plane will not lose ANY torque, only gain HP.

 

I would track down a set of 059 vortec 305 heads, use the Alex spring kit. Cut them for 1.94/1.60 valves. Angle mill them .020" and use them with a rubber embossed felpro 1094 shim style head gasket. Swap the factory camshaft out for something in the 210/220 @ .050 range. Then run them with an Edelbrock 2912 2bbl victor jr vortec and 454 TBI unit. Holley makes a nice water heated adapter to transition from their TBI unit to the 500cfm holley 2bbl pattern the 2912 uses. The heated adapter would help warm the intake and TBI unit on cold days, making a perfectly streetable setup that likes to turn to 6,000 rpm.

 

I agree with Fast355 to a point. That intake with the adapter will be VERY tall for a stock Firebird hood. Plus I think a 454 unit would be a touch too big for a 305. With proper tuning it SHOULD work but it would need supporting mods such as gears and a good stall to help with throttle feel and response. An Acdelco TPI pump with and adjustable regulator would be a step in the right direction as well.

 

 

Really do not feel that it would need a huge stall or more than 3.45 gears. Something along the lines of a S10 converter in the 700r4 with its low 1st gear would work very well with a 3.4x ratio. If it is a 7.5" rear, a posi 3.73 from a 2.8 S10 4x4 blazer would work well.

The intake would be tall, maybe too tall for stock hood. I have a super victor on the 305 in my 1980 Corvette and it fits under a 2" cowl hood with a drop base air cleaner. I had a 500 cfm edelbrock carb on it, but it was building vacuum above 5,000 rpm, so I swapped for a holley 680 vacuum secondary. A TBI unit is a bit shorter than a carb from flange to flange, leaving you room for the adapter. It ran low 13s and trapped 108-109 mph in the 1/4 with a stock stalled powerglide and 3.07s in it. With a TH-350 in it and a 2,800 stall, it will spin 265/50R15s all the way through first gear. Just a little .040" over 305 with flattops, a pair of 059 vortec 305 heads, ported and milled with 1.94/1.60 valves and an old school crane 272H10 cam with 1.6:1 full roller rockers.

Prior to the hooker super comp 1 3/4" primary long tubes and pypes 2.5" dual exhaust with magnaflow mufflers. Actually made decent power with the stock L82 manifolds and pipes exhaust/magnaflow mufflers.



I am considering swapping a 454 TBI on to this engine and swapping a 4L60E or T56 behind it.

 

Whats so funny???? Trying to rationalize the money you spent to go with a carb on an EFI vehicle to go backwards in driveability.

 

I wasn't saying a huge stall, the S10/Vette converter would be fine I agree. 3:42/3:73 would be a beneficial upgrade.

 

I really appreciate the feedback and suggestion, been working with carbs for ever trying to get myself up to speed with TBIs, Just to clarify I swapped out my 305 and am now running a fresh 350 with an auto behind it (for now) I have a T-5 I am going to swap in soon. The heads were ported but nothing radical, very mild cam and stock TBI intake at the moment. 9-1 comp, I did have my tbi opened up to 54mm with stock injectors and a spacer under it. I think at the moment I will stick with a single TBI unit. With that in mind would I get any benefit swapping it out for a big block TBI unit (454)? I have an Edelbrock Performer TBI manifold sitting on my shelf I thought about using but I do want a cam that will give me bit more of a thump at idle nothing crazy just a good healthy street cam. The torker to me was very streetable sounded awesome! I had the ac on running on my 81 Z28 4spd fairly good on gas for what it was and ran great with the matched torker manifold and a Holley Dbl pump on it. Anyways back to my setup, to get something similar on my 91 bird what would you suggest? My current modified TBI unit? 454 TBI? Performer TBI manifold? What cam with it to get the lope idle and power I want? Or go another route? Thanks!

Scott

 

I KNOW what I am talking about when it comes to TBIs. Mercruiser had a single TBI fed 502 big block that was over 400 HP, smooth idle, and would make 400 HP @ 4,600 rpm all day long. They had a wilder setup that used dual 2" TBI units and a supercharger on a 502!

 

Awesome! Looks great bet it runs as good as she looks too.

 

No benefit with a 454 TBI if yours was bored to 54mm or even 50mm.

Is your engine a roller cam block?

 

I tuned one with MEFI Burn a while back....He had changed the pulley to go from 6 lbs boost to 10 lbs boost and we had to push the fuel pressure up to 40 psi, from 32 psi. Each TBI unit had a pair of high pressure 61# injectors, flowing ~ 94 lbs/hr each, they were over 100 lbs each @ 40 psi. He had fuel for ~700 hp and was using nearly all of it. The engine was in a 28' boat that had come with a MPFI 502 making 480 hp. With a prop change, the supercharged engine, the pulley change and tuning it would run over 80 mph! Across the water that is FAST!

 

Yes I see that, I am very excited with all this info you are willing to share! I am not concerned about a smooth idle in fact I wouldn't mind a little bump in it, am I thinking too old school with the bumpy idle?

 

Shouldn't go too bumpy with a TBI honestly, but I ran a Crane 272 H10 in a TBI 350 truck that had a nice sound and good strong midrange torque and decent HP.

 

Hydraulic cam still stock rockers, not wanting to go crazy just a solid street engine more so than it is now. It runs pretty good now, gets out of it's own way nicely. Just getting the itch for a bit more HP, I really want to stick with swapping the cam and manifold for now heads would set me back too much now. Kids and a wife Do I need to worry about the ecm at all or just add my cam and manifold and go?

 

That sounds like about what I am looking for. I want to do my car proud I want it to be a FIREBIRD not a chicken know what I mean?

 

I know what you mean....Any real changes mean you are going to be messing with the PROM chip and tuning the setup. Some cams are not even driveable on the stock chip, but tuned

 

What would I need to Tune/Work with my prom? Is there a reader or just swap out the prom?

 

https://www.thirdgen.org/forums/orga...best-pass.html

It starts, stops, and drives just fine.
all with a single 4 barrel at a fraction of the price and the time.

I hardly call that going backwards.


EFI been there, done that. OVER-RATED for my intended application.

IMHO people that talk about what they did to someone else's car, typically have no car of their own.

your turn to share with the group..

 

Fraction of the cost....PLEASE......EFI works so much better than a stone age carb.....I can tune and not even get my hands dirty. While you are buying a steady stream of jets, powervalves, pump cams, squirter jets, air bleeds, and gasket kits....I can adjust with a few key strokes and the turn of an adjustable fuel pressure regulator. To alter your distributor advance curve you are welding up and grinding advance plates, swapping springs, weights, and center pieces and then buying an adjustable vacuum advance to dial in part throttle timing. It always a compromise with a mechanical setup.

454 TBI unit with the 30 psi regulator on a carb to TBI adapter and manifold of your choice with an EBL......Less than $1k and it runs, drives great.

I don't really build cars, but I have had 3 different 5,000+ lbs bricks trap ~100 mph in the 1/4. A 383 TPI G20 Van, 2006 quad cab Hemi Ram, and a 2012 Titan crew cab.....ALL EFI and happy from sea level to 10,000+ feet from -10*F to 110*F. Twist the key and they ran and were instantly driveable.

The TBI 305 F-car I built went 11.83 in the 1/4.

 

If you are doing just one vehicle, I would recomeend upgrading to the Dynamic EFI EBL Flash.

 

I will explain this so even you can understand

A naturally aspirated engine needs 1/2lb of fuel per hp, per hour.

For example: A 700 HP engine needs 350 lbs of fuel per hr /.8 (injector duty cycle) = 438 lb/hr.

The Holley projection 4DI with the largest aftermarket TBI injectors are 85 # hr X 4 injectors = 340 #/hr which is insufficient to supply a 700 HP engine.

The coveted OEM 454 TBI injectors are only 90# Hr (if you do a dual setup).x 4 = 360 #/hr

Therefore the MOST power you could ever make with a 2 dual quad TBI or the 4DI system without exceeding injector duty cycle are:


Dual OEM 454 TBIs (Howell system) = 576 HP 288/.8 = 360 # hr
4Di = 544 HP 272 /.8 = 340 # hr

576 HP may have been enough to put that '39 hot rod you claimed to build into the low 10s...
but a 3rd gen is much heavier,That kind of power is good for mid-low 11s.

All this being said I defer to my original comment,
because if a dual OEM 454 TBI kit is only good for 360 # hr
A single one is capable of only 180 # hr... OR supplying fuel for just 288 HP.

A new 5th gen with direct injection V6 makes more power than this.

I was actually generous when I said 250-300, you should have bit your lip.

AUTOMOTIVE MATH... give it a try sometime. TBI is not for everyone, been there ran my low 12s... moved on.

still if want to play with dual TBIs and that power level is fine for you.

http://howellefi.com/tbi-kit-twin-tb...ig-blocks.html


When you are done spending 1900$ for that kit get back to me on the performance edge
you have over a 750$ race carb.

the new FAST EFI is much more capable because it has 8 injectors... but it cost almost 3 grand
to yield the same peak power as a carb.


Suddenly everyone with a laptop is a tuner, yet you don't even understand fuel supply.

 

Save the math for someone who needs it!

I was making 450 crankshaft HP out of a single 454 TBI unit with Brazilian injectors....125 lb/hr each.

The 454 injectors are 90# @ 12 psi, now bump the pressure to 20 psi and you are much more capable.....Marine high pressure 61# injectors with the 30 psi regulator flow more than 100 lbs/hr each. The supercharged engine I worked with had 40 psi of fuel pressure and ran an observed BSFC around .45. The 61# injectors flow 112 lb/hr each at 40 psi......448 lb/hr......Roughly enough for 850 hp

I made an 11.83 pass on street tires in a F-car with an engine that only made 425 flywheel HP.

With EFI and good heads, decent cam, decent quench you run roughly .45 BSFC not .5.... 0.5 is a number for a fuel pig of a carb.

The marine TBI units flow 660 cfm dry @ 1.5 in/hg pressure drop with the IAC valve closed. Fully open the IAC flows about 40 cfm. 700cfm x 2 = 1400 cfm subtract about 6% for fuel and you get 1340 cfm.....Plenty of flow for just about any streetable application.

FWIW a big block 90# injector @ 20 psi is good for ~458 hp.

 

sure you did.

61 # hr injectors flow just that.... 61 lb per hour... you cannot defy the laws of
physics, mechanics or fluid dynamics.

A perfect example it your clear misconception about fuel pressure .

Increasing fuel pressure does not increase fuel volume.

Fuel pressure is simply the force at which the fuel is delivered, it has nothing to do with volume.

Diesel engines have several hundred pounds of fuel pressure and there is a reason for that.

Modern gasoline EFI operate on higher pressure for the simple reason that it atomizes the air with the fuel better.. Diesel engineers have known this for a century !


The only way to increase the volume to the engine is to increase the size of the injectors, the fuel pump, and the fuel lines..

.5 BSFC is a general rule of thumb for a NA engine
.6 for supercharged
and has nothing to do with the induction system (carb or EFI the same rules apply)

Tell me, what size pump and lines were you running on your mythical creation with Brazilian injectors... this ought to be good

IF TBI is so great why did each and every OEM ditch them for MPFI ?


By comparison my CARB setup operates at just 7 PSI... but flows enough fuel to supply over 1000 HP...

 

Someone needs to go back to physics class and learn a very simple relation ship between velocity, pressure, and flow!!! Higher pressure = greater velocity = high flow!! PERIOD! Raising pressure is not a linear relationship, but easily calculated. SQRT(New pressure/Old Pressure) x Flow Rate......Injectors are rated at a specific flow at a specific pressure. If you raise the working pressure, your flow increases, lower the pressure it decreases. Why do you think the port fuel injected cars had a vacuum reference fuel pressure regulator......To lower the pressure at idle when the delta pressure difference across the injector increased flow due to vacuum on the injector tip. (New returnless systems do this with PWM control of the fuel pump)

Brazilian injectors were being fed with a 3/8" single fuel line and a 1/4" return...I was running the GM Delco EP381 (same pump as the Ramjet 502).....PLENTY for a 450 HP fuel injected engine.

Get off your high horse! If you can do it with a carb, I can do it with EFI better, EVEN TBI! Using your analogy, CARBS DIED BEFORE TBI!!! EVERY OEM DITCHED CARB AND HAD TBI at some point. Chrysler, GM, and Ford all had TBI as did a plethora of imports.

 

The 423 HP .040" over 305 was in a 2,900 lbs race weight RS Camaro, with a 2,800 stalled 4L60E and 3.23 gears with bridgestone pontenza street tires on it, hence the slow 60' time.

--RT = .380s
0060'= 1.95s
0330'= 5.11s @ 71.7 mph
0660'= 7.65s @ 96.2 mph
1000'= 9.94s @ 104.3 mph
1320'= 11.83 @ 119.1 mph

MPH alone that car had a mid/low 11 in it....Only 423 HP at the flywheel on an engine dyno. 4L60E was programmed to lock the converter at WOT at 60 mph, and shifted 2-3 and 3-4 with a locked converter, adding ~15 rwhp. 1-2, 2-3, 3-4 shift points were all 6,400 rpm on a 6,800 rpm rev-limit.

Edit....Found the dyno numbers from the 312 too, BSFC was an observed .43 at peak HP, 13.4:1 afr.

RPM------HP----TQ
2,400----147----323
2,600----166----336
2,800----185----347
3,000----207----362
3,200----223----365
3,400----238----368
3,600----263----384
3,800----281----388
4,000----301----395
4,200----322----403
4,400----347----414
4,600----363----414
4,800----378----413
5,000----382----401
5,200----393----397
5,400----401----390
5,600----410----385
5,800----417----378
6,000----421----369
6,200----422----357
6,400----423----347
6,600----419----333

I was only using 68# cop car injectors @ 32 psi in a 7.0L 427 truck TBI. SQRT (32/11) * 68 = 115.98 lb/hr x 2 =231.96 / .43 =539 x .8 =431 hp.......I know my math as far as TBI and injectors and fuel pressure are concerned! The 427 truck TBI unit was by design....Used some custom code in the 7427, to use the governor assembly as a throttle stop off the line, only used 50% throttle under 40 mph.

 

with just a primitive carb...

let me know when you arrive at the finish line so I can reheat my coffee..
LOL

 

421 cid will do that for you. I know of several 454s that make 700 hp @ 6,000 rpm.....speed costs money, how fast do you want to go?

 

http://aeromotiveinc.com/power-planner/

take your pick... Carb or EFI system design.


http://www.magnafuel.com/support/index.htm

How much fuel flow is enough?
The correct volume of fuel is that which is required to support the amount of horsepower that the engine can produce. Most engines that are using gasoline burn approximately .5 pounds per horsepower-hour. This is sometimes called BSFC (Brake Specific Fuel Consumption). What this means is that for each horsepower produced, it takes ½ pound of fuel. This is a general statement and sometimes engines can be a little more efficient than .5lb/hp-hr., but it is a good practice to plan and measure fuel system operation using this number. Carburetors must have a stable supply of fuel in order to maintain the correct liquid fuel height. This is most difficult with drag racing vehicles that sometimes have forward acceleration and wheel stand at the same time. Each time that a nitrous system is engaged, additional fuel supply demands must be met or melted parts may result from "system lean-out." The fuel required is in excess of the .5 lb/hp-hr. for normally aspirated conditions. The additional fuel requirements for nitrous system planning is about .7 lb/hp-hr.


I will adhere to the fuel system experts advise.

 

Thanks for proving my point....With an EFI system AN-06 ~3/8" and is good to 700 HP according to the EFI planner. The carb system needs AN-08 for roughly the same HP (750). Same size pipe with less fuel pressure would be less flow!

 

someone needs to go back to basic plan reading

On the 500 HP EFI sytem:

The main fuel line from the tank, to the pump,and to the fuel filter is -8 AN. it then necks down to -6 AN to feed the fuel rails.. the return line is -6 AN.

I guess you see only what you want to see... which proves my point.

Only a fool would plumb the entire 500 + HP fuel system with -6 AN when the diagrams say otherewise.

so at this juncture I bid you farewell.

 

360-400FWHP is not too complicated with TBI https://www.thirdgen.org/forums/tbi/...imple-fun.html

 

The only -8 is the suction side of the pump.....my pump is submerged in fuel. -6an is plenty for the setup.

 

How does fuel pressure affect pump delivery? You can bet that as system pressure goes up the pump’ volume will go down.

To illustrate this, take one of the most popular and efficient EFI pumps on the market, Aeromotive’ A-1000 part #11101. Lets examine various pressures to demonstrate the effect this has on flow volume:

· Carbureted, Nat Aspirated, 9psi and 13.5v, volume 791lbs/hr. 1,582 HP @ .5 BSFC.
· EFI, Nat. Aspirated 43.5psi and 13.5v, volume 614lbs/hr. 1,228 HP @ .5 BSFC.
· 20psi boost/1:1 Regulator, intercooler, 60psi and 13.5v, volume 529lbs/hr. 881 HP @ .6 BSFC
· 10psi boost/4:1 FMU, intercooler, 80psi and 13.5v, volume 426lbs/hr. 710 HP @ .6 BSFC
· 6psi boost/8:1 FMU, intercooler, 91psi and 13.5v, volume 370lbs/hr. 616 HP @ .6 BSFC

Measuring a high efficiency Aeromotive pump such as the A-1000, from 9psi to over 90psi, flow volume is reduced a total of 53%. Comparing volume at 60psi for a high boost kit with correct injectors to 90psi for a low boost application, with small injectors and an FMU, volume is reduced by 28%. Clearly the effect of rising fuel pressure has significant impact on flow volume. What is not shown (and rarely published) is the devastating impact this has on less efficient, traditional pumping mechanisms used by much of the competition.


http://aeromotiveinc.com/2010/01/fue...omment-page-1/


Like I said... Fuel volume and fuel pressure is not the same.

if you increase pressure you still need a big enough pump (and fuel lines) to supply the correct volume of fuel.

Simply cranking up the fuel pressure on a "stock" TBI system will not do anything to increase the volume of fuel..

LOL . Perhaps you can take up your argument with Aeromotive..

 

I see why EFI DOES NOT WORK WITH YOU....YOU ARE CLUELESS!!!! Fuel pump capacity via pressure vs flow has nothing to do with the flow rate of injectors and fuel lines, which increase in flow as pressure rises. Guys are safely making over 500 HP with the stock fuel pump and stock 5/16" fuel lines on the newer Dodge Rams.

 

If you are running a TPI pump in the tank, IT ABSOLUTELY WILL INCREASE FUEL VOLUME by increasing pressure.

 

In line pump or in tank pump makes no difference.

The OEM uses in tank pumps to control sound and increase the service life of the pump. However in-line pump that has the correct volume of fuel supply should not have over-heating issues The fuel flowing thru it is enough to keep it cool.

I do find it funny that when someone presents written documentation (facts) from experts in the field your first instinct is to reply with an insult.

Yet you provide no facts of your own to back up anything which you are claiming.

My suggestion is you should drop the insulting attitude and quit giving out "advise" which is purely biased and based on fiction, not facts.

Perhaps you should "READ MORE" & INSULT LESS.

I am thru with this topic, good luck to you.

 

I see the issue, you are fixated on the injectors themselves.

Yes raising "injector pressure" = more fuel out the injector..

HOWEVER, the rest of the system must be able to supply the correct volume of fuel to the injectors which is why I always consider the pump and lines first and foremost.

"This brings us to our third fuel pump performance factor; voltage supply as measured at the fuel pump terminals. Voltage to an electric motor is like fuel pressure to an injector, more pressure in equals more volume out. Higher voltage at the pump terminals increases motor torque, resulting in more rpm and an increased flow volume for a given pressure. To illustrate this, the A-1000 Aeromotive fuel pump at 80psi will see a 40% increase in volume when voltage is increased from 12v to 13.5v. This factor is often overlooked and can make or brake pump performance, especially at high pressures. The key here is to figure flow at voltage if an alternator is used or not. Often deleted on drag cars, the presence or lack of a correctly sized and properly functioning alternator is vital to consider when choosing a fuel pump".

Big picture rather than sweating the details.

I am thru with this topic, good luck to you.

 

I think you are missing the point 3/8" line at 60 psi can drown a 600 HP engine with more flow than it could possibly use.

You responded with NOTHING to prove you point other than the flow characteristics of a FUEL PUMP...NOT A FUEL LINE.

I am DONE with you on this subject as well.

1.) Fuel injectors DO INCREASE IN FLOW as pressure rises
2.) As pressure rises, flow through the same diameter hole or line increases
3.) In tank pump makes a difference because it is submerged in fuel rather than having to fight the restriction of an inlet line or G-force.
4.) Your comment on charging system is a moot point in an EFI application as an EFI system needs proper voltage to work correctly anyway.

 

EFI only needs 12 V to function properly... however the pump mentioned has the voltage raised from 12V to 13.5V to increase the volume to compensate for the higher pressure...

Some race cars operate on 16V system for this very reason..

Moving on

http://www.holley.com/data/TechServi...ech%20Info.pdf

As you see in another article: pressure and volume are "inversely proportional".


When sizing a fuel system according to Holley:

5/16 lines should be avoided for hi-performance use.
The stock line on a 3rd gen is 5/16 with a 1/4" return line.

3/8 (-6AN) is minimum for a "Street/Strip combo" making less than 550HP.

1/2 ( -8AN) is a better option and not much more money to plumb.

Ensure the fuel is supplied through lines that are of the correct size for the application

 

some more facts:

http://www.stangtv.com/tech-stories/...ht-components/

Lines

The best fuel pump, filters and regulator are of little use if the method for their delivery is inadequate. Fuel lines must be matched to the size of the pump outlet, as well as to the flow and pressure requirements of the fuel system. Inside diameter, and length of the line both have an impact on how well the fuel pump can deliver fuel.

OEM lines were only intended to support OEM power levels. As such, tasking those lines with supplying fuel to an engine that now makes 50% or more power than it did from the factory is like asking the fire department to put out a 4-alarm fire with your garden hose.

These guidelines are a good starting point for selecting fuel lines:
•-6 AN up to 550 hp
•-8 AN over 550 hp
•-10 AN 1000+ hp

 

Anyone that tells you otherwise is simply giving bad advise which is not based on facts.

That being said if OP wants a mildly upgraded stock TBI system there are some
obstacles to overcome.

Without knowing OP's performance goals it is hard to determine an answer other that what I said in
my original post that the stock 2 injector TBI system is the bottleneck to a major performance increase

add to this The stock fuel line, pump are also going to be too small and will limit HP potential.

Hopefully the links, factual information, and personal experience with a race car I built and drive, will help OP thru this process..

Please excuse the bickering, but some people just don't know when to stop or admit when they are wrong.

Best of luck OP !

 

Somehow this does not sound right, are the numbers you posted RWHP ?

I'm just wondering, because I build this mild 360 ci TBI engine, fueled with 2 #80 injectors @ only 20psi fuel pressure, using a stock TPI fuel pump https://www.thirdgen.org/forums/tbi/...imple-fun.html

 

Just ignore his ignorance of things EFI and let him stick to something he knows best, CARBS.

I guess he does not realize I had a single 454 TBI with 61 lb/hr injectors feeding a 370 RWHP 350. I was also spraying this engine with a 150 HP shot of nitrous on a stock replacement TPI fuel pump and using stock GM 5/16" TBI G-van fuel lines.....I had an autometer fuel pressure sensor in the regulator, monitored by the EBL, and maintained 32 psi even with the N20 flowing. Only casualty was the 700r4. Same pump with TPI held 50 psi of fuel pressure as I put down 380 RWHP. Also sprayed it with 100 HP a few times, blew another 700r4 to pieces, but never had even a hint of fuel supply issue.

 

I do not understand why he put all that effort into talking down TBI, probably he just had a bad day.

Thanks Fast355 for sharing all your experience, sure makes a big difference to have someone on these boards sharing real world knowledge.