85vettelovin

I'm just about finished with all the parts for the 383 i'm having built. What size fuel injectors should I be looking at. The engine should make in the 450 hp range. Anyone have a chart as to what fuel injectors support what horse power? any direction would be helpful!

vvv90

You'll need a chip burn no matter what, so if you're in the 30-36# FMS range, you should be fine.

call someone at http://www.tpis.com and they'll set you straight.

:cheers:

braddammit

As I understand it the Ford SVO #30's would probably be OK. Also get an adjustable fuel pressure regulator - and I would definitely recommend the Holley. Whatever you do DON'T get the BBK!!!!

My $0.02

CORKVETTE1

do your self a favor use 24lb svos :cheers: use more and you will be sorry

vader86

Somewhere around 30 or just shy of that.

SPEED750

:iagree: Most people go way to big and can't figure out why the car runs like crap.I've gotten this advice from Lingenfelter and Doug Rippie.There is an old saying " lean is mean :steering:

CORKVETTE1

yes vader he is wants to be at 450 hp that would put him about 70-90 hp less than me and jesses car had with a injector that is 25% larger sounds like alot of black smoke to me :cheers:

85vet

Definately go with 24# Ford injectors. I am in the same process as you and I have seen how efficient they are in the 406 motors of Corkvette1 & Ski_dwn_it's.

:cheers:

MrSpeedyBob

I've got a physics book here that lists the density of dry air at 0 degrees C and 1 atmosphere of pressure to be 1.29284 g/L = 0.0807232 lb/cf
14.7 parts air to 1 part fuel means 0.00549137 lb fuel/cf air.

a 383 turning 6000 rpm at 100% VE is consuming 665 cfm = about 39900 cf/hr

39900*0.00549137 = 219 lb/hr of fuel devided by 8 injectors = 27.375 lb/hr

at 85% VE 24 lb/hr is just barely sufficient.

I'd go with 30 so you'll have some room for accel enrichment.

ZD1

24 SVO's are like 28 Accel/gm due to difference base pressure flow rates...So 30 SVO'x would be really big.

CORKVETTE1

so what does yor book say for a 406 at 6300 rpm running rich with a 24lb injector that are what we are doing with our cars
dont be a book worm and you can run fast too
you just have to want to learn from expierience not books the text will come back and bite you on your azz everytime :D :cheers:

CORKVETTE1

i remember a book also said it was impossible for a car to accerate past 200 mph in the qtr mile hmmm
what is the record now 330+ mph hmmmmm :cheers:

85vettelovin

Why are the ford injectors so much better? From what I see they are alot cheaper too. I'll go with the 24lb svo injectors and see how it goes from there. the mechanic recomended 30-36lb injectors??? thanks guys

vvv90

Not better just cheaper than chevy injectors......of course, anything is better than accels ;)

SPEED750

The ford injectors are Bosch.Most products made by Bosch are the best you can buy.They engineer the heck out of their products. :chevy

CORKVETTE1

:iagree: yes the svo are bosch units the best you can buy and cheap also :cheers:

0ski_dwn_it

Corky and a few of the others really are right. As Corky mentioned we can our 406 below 39psi and were still at times rich, even in 300' DAs.

Rkessel, the calculator I have says a 406CI motor at 100% efficiency at 6500RPM, with 12.5 A/F ratio, and 70*F air, only consumes ~656CFM of air.

We know that our motors are not 100% efficient, so not that much air is coming in, probably more along 90% or ~590CFM. Also I made at the rear wheels almost as much as he wants to at the crank with 24# injectors. So I would say that 24# injectors SVOs rated at 39psi, which consequently will be almost 27#ers with a little more than the stock GM 43psi rating.

The thing people fail to see when using too large of injectors is the fact when you trim them back as he will find he will need to do with fuel pressure, is you loose atomization with every pound of pressure you drop back. Ultimately what they do to get them to work properly is reduce the efficiency of their engines to match the wrongly selected injectors.

There is nothing at all wrong with raising the pressure a little should one find that his injectors in an application are a little small to gain more room. In fact you will have more control and better atomization, as I explained before doing that.

Both Corky and I are building 434CI motors and had the individual that bought my intake and heads not wanted my 24# injectors, I would have most likely ran them at about 55psi to make well over 600chp. At 55psi the injectors would be about 28-29# injectors. I am still debating whether 30#ers will be too much and more of a hassle than they are worth.

If I would have listened to the calculators on my motor it said I needed 42# injectors for the previous 406 setup :eek: Text books are great, but just as all my pofessors said in engineering, use a reality check after getting an answer. I find that real world sucess speaks volumes when it comes to performance while textbooks are well, as good as the writer of the book.

PS: I have a buddy mark errick in chattanooga, TN. Know him? :cheers: :cool:


[Modified by ski_dwn_it, 8:07 PM 12/7/2003]

J Z06

Not to hi-jack the original post topic author...but Jesse, I couldn't help but notice you said you we're building a 434. My best friend has a Lingenfelter 18* head 434 and it uses 36 pound injectors with a bosch in tank fuel pump going through some pretty big braided lines to the rails(I posted a photo of the intake compared to Jeb's single plane unit) I forget what the pressure is, but it isn't too much more than what my 383 has(48 with the hose off).

I can't get a straight answer, but my injectors are supposed to be 26#s. Their part number on my build sheet is 223. One or two people that know injectors said those we're only 22 pound inj. :crazy: Ya got me!! I am not arguing with a 120.2 mph trap speed in my daily driver :D

CORKVETTE1

jay even if they are 22s you still have more than you need i think me and ski could still use the 22s with the 406s and we are traping 125 mph :cheers:

MrSpeedyBob

[QUOTE]Rkessel, the calculator I have says a 406CI motor at 100% efficiency at 6500RPM, with 12.5 A/F ratio, and 70*F air, only consumes ~656CFM of air.

...

PS: I have a buddy mark errick in chattanooga, TN. Know him? :cheers: :cool:

QUOTE]

What's you calculator taking into account that I'm not? 406 CI at 100% VE consumes 406 cubic inches every 2 revolution. At 6500 rpm that's 764 cfm. Is the other 108 cfm fuel vapor? I thought fuel during intake was still atomized liquid but maybe I'm wrong. Or maybe your number is getting adjusted to cfm at a specific temp and pressure. Is that a specialized engine calculator?

Also, when you read an injector rating at, say, 24 lb/hr what are the standardized conditions that rating is made at. Pressure obviously makes a huge difference but temperature is also going to affect the density and viscosity of the fuel and thereby change the actual flow rate.

Don't know a Mark Errick but then I'm too buisy / poor to go racing much. Maybe once I finish college and get a real job I can start to play. :)