engine help

bigsexxy422 · Dec 7, 2009

hey guys, i am swapping out the old tired 5.0 out of my 89 gt for a freshly built one. when i had the new one build it was also ported, polished, bored .30 over, and a new cam put in. it also has new valve spring, valves, and roller rockers (1.6 to 1). the commpression should be around 10.5 to 1. also some long tube headers, a cromoly steel flywheel (lightend) and a 6 puck clutch kit. I was already sweapping the intake from the stock one to the one in the ford exploder, and was also thinking of getting a 70mm throttel body and MAF sensor. is there anything else i should think about getting? any help would be great.

bgoins · Dec 7, 2009

underdrive pulleys. might want to consider upgrading ur injectors to 24lb and MAF to match.

stykthyn · Dec 7, 2009

before anyone can offer advice we need to know what cam is in it. by ported an polished I am assuming you meant ported and polished heads? are they ported stock heads? or did you mean that the block was bored over? we need more info.

if you have stock heads and a stockish bottom end then there is no way you are going to need 24lb injectors. the stockers will handle just fine.

bigsexxy422 · Dec 7, 2009

the heads are ported, and yes the block is whats bored out. the bottom end is almost all stock except for the pistons. they are speed pro forged pistons. as for the cam i dont have my card in front of me. but i will update asap. when i had the engine built i had a edelbrock torquer 2 manifold put on it, and was told with the right carb the engine should put out close to 400hp. but as i have been doing research, i think i wanna go fuel injected. what size are the stock fuel injectors, and can i still get the 24lb fuel injectors so i have room to grow?

skunk21 · Dec 7, 2009

bigsexxy422 said:
the heads are ported, and yes the block is whats bored out. the bottom end is almost all stock except for the pistons. they are speed pro forged pistons. as for the cam i dont have my card in front of me. but i will update asap. when i had the engine built i had a edelbrock torquer 2 manifold put on it, and was told with the right carb the engine should put out close to 400hp. but as i have been doing research, i think i wanna go fuel injected. what size are the stock fuel injectors, and can i still get the 24lb fuel injectors so i have room to grow?

If that engine has the potential to pump out 400hp with a carb stay carbed, if you go EFI don't put an explorer intake on it get something better and you need bigger than a 24lb injector, you probally looking at #42 if you want room to grow. what kind of heads you got on this motor anyway..I don't think they are stock.

bigsexxy422 · Dec 7, 2009

i am not shure what number heads thay are. but as far as i know they are just stock heads with bigger valves, a port and polish job, roller rockers, dual springs, new valve guids, and new spring retainers, and keepers. i would love to get a new intake for it, like a bbk or a trick flow, but they are alot of money, and i wanna get this thing going. anybody selling one? cheap

2000xp8 · Dec 7, 2009

Use 19lb injectors, you would need alot of cubic inches and some serious port work to need more than them.

bgoins · Dec 7, 2009

here's a nice quick summary on the proper fuel injector sizes. i attached a link to the whole article which is really good.

"(number of injectors x injector size) / BSFC = Max safe hp
BSFC (Brake Specific Fuel Consumption) varies with application.
Normally aspirated cars use between .45 and .55,
Supercharged cars use between .55 and .65

As an example, a supercharged car with 24 lb. injectors can safely make 349 hp while a normally aspirated car with the same injector can safely make 426 hp. "

MotorSports Digest

skunk21 · Dec 8, 2009

2000xp8 said:
Use 19lb injectors, you would need alot of cubic inches and some serious port work to need more than them.

incorrect. A 300hp motor will run a 19lb injector @ 100% duty cycle no good.

Formula: HP X BSFC=lb/hr, LB/HR divided by 8 inj. = lb/hr per cylinder, LB/HR per cylinder divided by 90% duty cycle = total LB/HR requirement.

Example: 300hp x 0.50bsfc = 150 lb/hr, 150lb/hr divided by 8 injectors= 18.75lb/hr, 18.75 divided by 0.90= 20.83lb/hr or 21....this means a 19lb injectors is too small the next size up from 21 is a 24lb injector.

His motor is a rated @400 hp doing the formula he needs atleast a 30lb inj or a 39 if he wants room to grow.

2000xp8 · Dec 8, 2009

greensvt21 said:
incorrect. A 300hp motor will run a 19lb injector @ 100% duty cycle no good.

Formula: HP X BSFC=lb/hr, LB/HR divided by 8 inj. = lb/hr per cylinder, LB/HR per cylinder divided by 90% duty cycle = total LB/HR requirement.

Example: 300hp x 0.50bsfc = 150 lb/hr, 150lb/hr divided by 8 injectors= 18.75lb/hr, 18.75 divided by 0.90= 20.83lb/hr or 21....this means a 19lb injectors is too small the next size up from 21 is a 24lb injector.

His motor is a rated @400 hp doing the formula he needs atleast a 30lb inj or a 39 if he wants room to grow.

This is the real world, you can do all the math you want based on charts and calculations, but when implemented onto a real car, you do not need 24lb injectors on a car that makes 255rwhp. People stretch them to 300rwhp, now that's pushing it, but 255, i don't think so.

I've been doing this a long time, and i prefer real world experience to a bunch of crap people come up with, with a pen, paper and calculator.
If we go by your math, pretty much anything other than a bone stock engine requires 24lb injectors.

The link bgoins posted above is much closer to being realistic than the numbers you have come up with.

BTW, you don't size injectors "with room to grow", you size them for what you are doing now. Makes the car easier to tune and gives better driveability.

liljoe07 · Dec 8, 2009

Posted via Mobile Device

Every injector chart I've seen is based on Flywheel HP, not rear wheel.

2000xp8 · Dec 8, 2009

liljoe07 said:
Posted via Mobile Device

Every injector chart I've seen is based on Flywheel HP, not rear wheel.

That's why i took his numbers and shaved them down by 15%.

liljoe07 · Dec 8, 2009

I know guys in the high 80% duty cycle on 30lb with 306's N/A. I personally rather use an injector that uses a lower duty cycle than one that closer to 85%. Im my experience, an injector thats around 55-60% is easier to tune. It just controls the fuel better. Thats why I use 24's on almost anything mild. Im sure it just varies on how effecient the engine is, and thats where the calculators get lost at.

Shving 15% off of 400= 340 rwhp. Now if he has 400hp, who knows.

skunk21 · Dec 9, 2009

It isn't my math it is based off of charts and that came from tuners in the real world. The numbers are facts not made up so you can do what you will but the fact is a 300 flywheel hp is maxing out a 19lb inj. even using this basic chart which shaves of some of what I used and gives a 80% duty cycle he still comes in over 30lbs at 400 flywheel hp.

Fuel Injector Calculator from WitchHunter Performance

bigsexxy422 · Dec 9, 2009

so are you guys saying that for a 400 flywheel ph engine i should just get 24 injectors and run the fuel pressure a little high, or just get the 30s and try and tune it with them?

from what i have herd the 24s sound like what i need, but you guys are the experts, not me,

skunk21 · Dec 9, 2009

bigsexxy422 said:
so are you guys saying that for a 400 flywheel ph engine i should just get 24 injectors and run the fuel pressure a little high, or just get the 30s and try and tune it with them?

from what i have herd the 24s sound like what i need, but you guys are the experts, not me,

If you are going to choke your motor down some meaning not run it at the full potential then yeah maybe like 2000xp8 stated 24's would be fine but pushing more pressure behing an injector that isn't up to task will most likely push it over 100% ds. If going by 2000xp8s statement that 300rwhp will push a 24lb injector over the edge and figuring static loss your motor has the potential to push a 24 w/o much effort if your motor builder is correct but with an EFI and tgood tune it may have more or less . The 30lb injector I think is the right size and a tuner can adjust it, that way if you do throw on a better intake, larger maf etc you will be right there. again IMHO save getting beheaded

bigsexxy422 · Dec 9, 2009

ok so i will be good with 30 lb injecters, like a 70 mm maf sensor, and a 70 mm throttel body. and a good intake. make a good combo? and how much fuel pressure should i run

skunk21 · Dec 9, 2009

bigsexxy422 said:
ok so i will be good with 30 lb injecters, like a 70 mm maf sensor, and a 70 mm throttel body. and a good intake. make a good combo? and how much fuel pressure should i run

run stock fuel pressure with a stock non adjustable regulator. tuning with FP is not really the way to go, use stock fuel pressure and do any tuning that's intended to result in mixture changes with the maf or the ecu -- via chip.
stock fuel efi fuel pressure should be 38-39 psig measured with a motor @ operating temp at idle with the vacuum line to the regulator temporarily disconnected and plugged. Hook the line back up, and with a stock set up it should drop into the 32-33 psig range. A tuner will set up your a/f, etc .

2000xp8 · Dec 9, 2009

2000xp8 said:
This is the real world, you can do all the math you want based on charts and calculations, but when implemented onto a real car, you do not need 24lb injectors on a car that makes 255rwhp. People stretch them to 300rwhp, now that's pushing it, but 255, i don't think so.

Let me edit this statement.
What i meant was that people stretch 19's to 300rwhp.
Not the 24's, 24's easily handle 300rwhp.

24's are good to about 350rwhp
30's, are good to above 400rwhp when NA.

Another reason calculations do no good is that a supercharged engine requires much more injector than a NA.

As far as tuning, there is no chip needed if your car is set up properly, a $750 dyno tune with a chip will only lighten your pocket.
A proper setup on the stock computer is just as good and sometimes better than someones custom chip.
I've seen it tested first hand.

Big sexy, if you use 30lb injectors with an e7 setup, you are going to be wayyyyyy over injectored. At most use 24's, even though i still bet it will run fine with 19's, i don't think people realize that even the best ported E7 isn't that good.

bigsexxy422 · Dec 9, 2009

ok cool i will run 24lb injectors, and a e7 setup. i guess that e7 stand for 70 mm maf sensor, and throttel body. thanks guys you have been alot of help,
i will be shure to post pictures as it comes together.

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