Injector sizing ????????

RYC CUKR

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May 19, 2002

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Mar 3, 2007

#1

• Mar 3, 2007

• #1

I have a spare engine and the one in my 88 is starting to get a little old so before it completely croaks I am planning on building a 331 NA motor with a set of ported twisted wedge heads, custom cam and moving the intake mods from 93 over to my 88. My question is what size injectors will I need to run cause I don't think that the stock 19s are gonna cut it anymore?

I want to get all of my parts in advance so I can just swap it all out and get it back on the road when the time comes.

 

C

canesstangnitro

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Aug 27, 2006

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Metairie, LA

Mar 3, 2007

#2

• Mar 3, 2007

• #2

I would use the 30 # injectors with the setup you have. I like to always build my setup to use 42 # injectors because you get a lot more flow with those. I am a ford parts guy so I would get the ford racing 30 # injectors

 

3

304billet

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Sep 16, 2005

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Mar 5, 2007

#3

• Mar 5, 2007

• #3

30's

 

Mustang5L5

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Feb 18, 2001

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#4

• Mar 5, 2007

• #4

If leaving N/A....30's

 

Grn92LX

Fidanza Man!

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Mar 5, 2007

#5

• Mar 5, 2007

• #5

36's at least. I have 30's and they're near maxed out up top on my n/a TW headed 347. I'd step it up on the manifold too. TFS R, holley or a victor efi.

 

jrichker

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Mar 5, 2007

#6

• Mar 5, 2007

• #6

Injector HP ratings: divide flow rating by.5 and multiply the result by the number of injectors. This uses a 100% duty cycle. These ratings are for naturally aspirated engines.

Example:
19/.5 = 38, 38 x 8 = 304 HP
24/.5 = 48, 48 x 8 = 384 HP
30/.5 = 60, 60 x 8 = 480 HP

The preferred duty cycle is about 85% maximum, so for a safety factor multiply the final figure times .85.

304 HP x .85 = 258 HP
385 HP x .85 = 326 HP
480 HP x .85 = 408 HP

Remember that the above ratings are at 39 PSI. Increasing the pressure will effectively increase the flow rating. Example: a 19 lb injector will flow 24 lbs at 63 PSI, and a 24 lb injector will flow 30 lbs at 63 PSI.

See http://users.erols.com/srweiss/ to get the calculators used in these examples.

 

5spd GT

"the 5.0 owns all"

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Aug 7, 2002

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Mar 5, 2007

#7

• Mar 5, 2007

• #7

30's no doubt!

If you want more injector, you would like a tune. Fortunately for you, you won't need any more...good luck! Nice combo!

 

Grn92LX

Fidanza Man!

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#8

• Mar 5, 2007

• #8

Just try and listen to those with experience with similar stuff. My 30's are near maxed out and you have better flowing heads. 36's are the ticket.

If you need more help/personal experience, PM me.