[zildjian4life218]

Originally Posted by ap72

I you can jack your FP up to about 50-55 pounds then 24# injectors will just be enough for 400hp.

Yeah idk why I didn't think of that before. So really all I would need to get is the intake and I have a TPI wiring harness which I could wire up if I were to go MPFI. I like the simplicity and cheapness of the TBI setup but everyone knows you can't beat the benefits of the MPFI. http://www.summitracing.com/parts/WND-7542/

[E.Furgal]

the 454tbi is 2" throttle blades and 550 cfm
the small block is 1 11/16th and 500 cfm
the big block injectors flow 70 x2 is 140
8x24 is 192

one bottle neck coming right up. one must remember these tbi454 where peanut port headed engies with intake ports smaller than some small blocks..
good luck with your goal of 400hp.. hope you get there..
the data of parts being planned on being used , it don't look good..

your an fyi.. mr 72 in a thread on here "carb confused"

Im terribly conflicted... Carbs

post a 350 will need 750cfm..
now no matter what I think(650cfm) his post on that thread and him telling you you'll get to your goals with a 550cfm tbi.. well.
now if it was a 550 throttle body dry.. no fuel then maybe.. squeak by.. and thats a big if..
carry on..

[zildjian4life218]

Originally Posted by E.Furgal

the 454tbi is 2" throttle blades and 550 cfm
the small block is 1 11/16th and 500 cfm
the big block injectors flow 70 x2 is 140
8x24 is 192

one bottle neck coming right up. one must remember these tbi454 where peanut port headed engies with intake ports smaller than some small blocks..
good luck with your goal of 400hp.. hope you get there..
the data of parts being planned on being used , it don't look good..

your an fyi.. mr 72 in a thread on here "carb confused"

Im terribly conflicted... Carbs

post a 350 will need 750cfm..
now no matter what I think(650cfm) his post on that thread and him telling you you'll get to your goals with a 550cfm tbi.. well.
now if it was a 550 throttle body dry.. no fuel then maybe.. squeak by.. and thats a big if..
carry on..

The TBI injectors were rated at 80 or 85 and I can triple the fuel pressure going to them (Which equals more flow)..... I would think with your vast knowledge you would have understood that. As stated already by AP and myself by cranking up the fuel pressure on the LT1 injectors I can probably get by.... which Would only leave me with needing to buy an Aftermarket intake and doing all the extra wiring for the MFPI vs the TBI setup. Try This Out Click the witchhunter link.

[ap72]

Originally Posted by E.Furgal

post a 350 will need 750cfm..
now no matter what I think(650cfm) his post on that thread and him telling you you'll get to your goals with a 550cfm tbi.. well.
now if it was a 550 throttle body dry.. no fuel then maybe.. squeak by.. and thats a big if..
carry on..

Actaully, you're the one that brought up the 750, if it was a good quality carb I may have went a little bigger. The thing you don't seem to get is that there's a huge difference between buying a 750 over a 650 carb (both will run you over $300, and the difference in price can be negligible), or trying to spend a couple hours time smoothing out a throttle body to flow about 600-650cfm that you have a total of $15 in.

I know its easy to throw around $1,000+ when its someone else's money but I was offering a very sound and much cheaper alternative to zildjian, after all we're not all millionaires.

[E.Furgal]

Originally Posted by zildjian4life218

The TBI injectors were rated at 80 or 85 and I can triple the fuel pressure going to them (Which equals more flow)..... .

you can't up the fuel pressure that high.. the tbi regulator won't take it.. for one.
like a carb cfm there is a point that no matter how much psi you hit it with it doesn't flow more fuel through the injector ..
remember you have 2 injectors not 8.. getting 3% more flow out of an injector then times 8 makes a little differance... 3% more flow out of 2.. isn't gonna cut it..

buy the way the bbc injector rating of 80-85 is to high of a duty cycle.. for any long term use... drag car.. fine.. long hyway run.. you'ls let the smoke out of the injector drivers

[E.Furgal]

Originally Posted by ap72

Actaully, you're the one that brought up the 750, if it was a good quality carb I may have went a little bigger. The thing you don't seem to get is that there's a huge difference between buying a 750 over a 650 carb (both will run you over $300, and the difference in price can be negligible), or trying to spend a couple hours time smoothing out a throttle body to flow about 600-650cfm that you have a total of $15 in.

I know its easy to throw around $1,000+ when its someone else's money but I was offering a very sound and much cheaper alternative to zildjian, after all we're not all millionaires.

sorry you are not getting 50 to 100 cfm out of smoothing the tbi inlet the 2) 2" blades only allow so much air no matter what you do above it or below them..

no we are not all millionaires..
never enough money to do it right. but always enough to do it twice..
if he was going for a mild 300-330 hp.. I'd say sure go for it..

[ap72]

Originally Posted by E.Furgal

you can't up the fuel pressure that high.. the tbi regulator won't take it.. for one.
like a carb cfm there is a point that no matter how much psi you hit it with it doesn't flow more fuel through the injector ..
remember you have 2 injectors not 8.. getting 3% more flow out of an injector then times 8 makes a little differance... 3% more flow out of 2.. isn't gonna cut it..

buy the way the bbc injector rating of 80-85 is to high of a duty cycle.. for any long term use... drag car.. fine.. long hyway run.. you'ls let the smoke out of the injector drivers

um I hate to be the one to teach you math, but a 3% net increase is a 3% net increase- no matter what. you can slap 2, 8, or 493 in front of it the 3% net increase remains the same.

Secondl its super easy to modify a TBI regulator- probably the easiest factory regulator to modify actually, and yes it can handle the pressure.

Lastly, your injector flow rate is ALWAYS measured at 100% duty cycle. And unless you're cruising on the highway at peak power (maybe in a cop chase?) you won't be even close when cruising.

Oh, and the 2" blades are NOT the restriction on a TBI unit the stock 50mm blades can flow more than enough for 500hp- the restriction is the injectors and all the irregularities ahead of the throttle plates that disrupts airflow.


Its pretty obvious that you have NFC when it comes to fuel injection.

[zildjian4life218]

What do you think of this Aeromotive 340 Stealth Electric Fuel Pumps 11140 - SummitRacing.com Under Aeromotives website it says that its compatible with Chevrolet cars and trucks from 85-92. That will more than support my fuel system whether I go EFI or not... Maybe just a 255lph?

[E.Furgal]

Originally Posted by ap72

um I hate to be the one to teach you math, but a 3% net increase is a 3% net increase- no matter what. you can slap 2, 8, or 493 in front of it the 3% net increase remains the same.

Secondl its super easy to modify a TBI regulator- probably the easiest factory regulator to modify actually, and yes it can handle the pressure.

Lastly, your injector flow rate is ALWAYS measured at 100% duty cycle. And unless you're cruising on the highway at peak power (maybe in a cop chase?) you won't be even close when cruising.

Oh, and the 2" blades are NOT the restriction on a TBI unit the stock 50mm blades can flow more than enough for 500hp- the restriction is the injectors and all the irregularities ahead of the throttle plates that disrupts airflow.


Its pretty obvious that you have NFC when it comes to fuel injection.

hat to teach YOU math. but 3% increase of 8#24 injectors isn't the same as 3% increase of 2) 80..
no matter how you cut it.. you get 3% more flow PER injector..
****PER INJECTOR***** is 8 more than or less than 2..

if you where going to run synquental.. you'd have a point.. but with batch.. not so much

[ap72]

Originally Posted by E.Furgal

hat to teach YOU math. but 3% increase of 8#24 injectors isn't the same as 3% increase of 2) 80..
no matter how you cut it.. you get 3% more flow PER injector..
****PER INJECTOR***** is 8 more than or less than 2..

if you where going to run synquental.. you'd have a point.. but with batch.. not so much

3% net increase is 3% net increase, the number of injectors is entirely irrelevant.

BTW, we're talking about TBI vs MPFI, not sequential vs batch.

[E.Furgal]

Originally Posted by ap72

3% net increase is 3% net increase, the number of injectors is entirely irrelevant.

BTW, we're talking about TBI vs MPFI, not sequential vs batch.

if you turn up the fuel pressue.. you get more flow.. out every injector..
if it's 3% more fuel out 2 it's what out of 8 I'll make it easy.. it's 12% more fuel

[ap72]

Originally Posted by E.Furgal

if you turn up the fuel pressue.. you get more flow.. out every injector..
if it's 3% more fuel out 2 it's what out of 8 I'll make it easy.. it's 12% more fuel

LMAO.

um... no... Its still 3%.

You may want to delete that post as it is basically 3rd grade math (its called the associative property of multiplication and division).

[vinniekq2]

E? if you put 8 quarters in the bank and you get 3% interest and you put a 2 dollar bill in a different account making 3% interest,which account will make you more money?

[zildjian4life218]

Lets ASSUME for our example here we have a TBI setup with 2 80lb/hr injectors and a MPFI setup with 8 20lb/hr injectors (This will make numbers easy )

Okay so again ASSUMING we give both systems the same net increase in pressure we can easily find out the extra flow.

(Since percentages are out of a 100 it is import to divide our figure of 3% by 100 to obtain .03)

20lb/hr*.03 = .6 <-- This means that we will gain .6 lb/hr per injector
20.6*8 = 164.8 lb/hr

80lb/hr *.03 = 2.4 <-- This mean that we will gain 2.4 lb/hr per injector
82.4*2 = 164.8 lb/hr

WOAH!!! this is of course assuming we give each setup the same increase in fuel pressure from factory which we can give the TBI system a larger increase since it was setup to run from 15-18psi.

[zildjian4life218]

so..... to get back on track. What do you guys think of either an aeromotive or walbro 255 lph universal intank pump along with the aeromotive regulator I posted earlier? Assuming I will run a carb for now and upgrade down the road to an efi setup either TBI or MPFI that will both need around 45psi and need it to support at least a 400hp engine. I will modify the current pickup to accept the 3/8" feed and return. Will a 255 lph handle this?