Do I need a MAF and injectors?

Tripoli

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Mar 30, 2005

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Dallas, TX

Mar 8, 2008

#1

• Mar 8, 2008

• #1

My setup by the end of the week will be as follows:

Fox Lake stage 2 heads
VT Stage 2 N/A cams
Mac Cold Air
Stock mass air
Accufab 75mm throttle body and upper intake plenum
stock lower intake manifold
Stock injectors
Hooker LT headers with 1 5/8" primaries
Off-road exhaust

I'm going to be revving the motor to at least 6500 RMP, maybe a bit higher.

Do I need, or will I benefit from, upgrading my MAF and my injectors? If so, why?

 

S

spederman

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Apr 13, 2005

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Mar 8, 2008

#2

• Mar 8, 2008

• #2

Which shop are you taking it for a tune in DFW? I'm sure once they throw it on the dyno, they will be able to tell asap if your maxing out your injectors/MAF and need larger. IMHO i think you'll need bigger injectors.

 

Tripoli

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Mar 30, 2005

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Dallas, TX

Mar 8, 2008

#3

• Mar 8, 2008

• #3

Archie at Lone Star Performance will be doing the tune. I just talked to him and he said he'd determine if they are needed or not when he's turning it. He suspects I will need to upgrade to 24- or 30-lb. injectors along with an SCT MAF. That's $600-700 I wasn't wanting to spend yet.

 

CobraRed_96_GT

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May 20, 2006

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UCSD/La Jolla

Mar 8, 2008

#4

• Mar 8, 2008

• #4

usually i'd say no, but it's quite possible

 

jstreet0204

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Jun 26, 2003

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Winston Salem, NC

Mar 8, 2008

#5

• Mar 8, 2008

• #5

If he is telling you you need a new MAF with those mods he is lying to you. Stock injectors will be usable, but MAY be toward the top end of their duty cycle.

 

DBMSTNG

I fantasize about it being BIG!

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Mar 8, 2008

#6

• Mar 8, 2008

• #6

i agree with jstreet0204. the stock maf is good for over 300rwhp, i'd go to 24lb injectors max. your 21lb should suffice however.

 

Tripoli

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Mar 30, 2005

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Dallas, TX

Mar 8, 2008

#7

• Mar 8, 2008

• #7

DBMSTNG said:

i agree with jstreet0204. the stock maf is good for over 300rwhp, i'd go to 24lb injectors max. your 21lb should suffice however.

Click to expand...

"good for over 300rwhp"

Well, I'm at 290 RWHP before putting the heads on. I'm shooting for 325, and within a year or two I'm planning on getting a supercharger.

 

DBMSTNG

I fantasize about it being BIG!

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#8

• Mar 8, 2008

• #8

Tripoli said:

"good for over 300rwhp"

Well, I'm at 290 RWHP before putting the heads on. I'm shooting for 325, and within a year or two I'm planning on getting a supercharger.

Click to expand...

well if you are getting a supercharger, you'll need atleast 42lb injectors and the maf. that changes everything. but why put in N/A cams tho if you are getting a supercharger?

 

S

SilverBullet00

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Mar 8, 2008

#9

• Mar 8, 2008

• #9

Your maf is going to be sufficient. if not get a lightning MAF for $100 on ebay. Your stock injectors will more than likely be fine.

Let us know about dyno numbers... 325 might be a little high from what I have seen in the past.. maybe around 310-315..

 

Tripoli

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Mar 30, 2005

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Dallas, TX

Mar 8, 2008

#10

• Mar 8, 2008

• #10

DBMSTNG said:

well if you are getting a supercharger, you'll need atleast 42lb injectors and the maf. that changes everything. but why put in N/A cams tho if you are getting a supercharger?

Click to expand...

Because I got the cams a year ago, and will be getting the supercharger a year or two from now. Just doing this little by little.

 

jstreet0204

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Winston Salem, NC

Mar 8, 2008

#11

• Mar 8, 2008

• #11

The stock MAF is good to around 350 or so. The old KB 1.6l kits used the stock MAF with no problem, but keep in mind that you can stretch fuel compontents further on a N/A application because the BSFC is much lower than on a forced induction set up. If you are upgrading to a supercharger don't buy 24lb injectors they'd be waste IMO. If you know you are going to get a supercharger go ahead with at least 42lbs. They will just run in the low range of their duty cycle. But should not cause a problem and will keep you from buying two sets of injectors.

 

Tripoli

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Dallas, TX

Mar 8, 2008

#12

• Mar 8, 2008

• #12

How much power would those 42 lb. injectors be good for?

 

jstreet0204

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Mar 8, 2008

#13

• Mar 8, 2008

• #13

Tripoli said:

How much power would those 42 lb. injectors be good for?

Click to expand...

Each car is a little different, and it depends on how high you are willing to push them in the duty cycle, but you should be able to get up over 450.
You can use a calculator to get an idea. BFSC for a forced induction car is usually around .6

http://www.witchhunter.com/injectorcalc1.php4

 

Tripoli

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Mar 30, 2005

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Dallas, TX

Mar 8, 2008

#14

• Mar 8, 2008

• #14

jstreet0204 said:

Each car is a little different, and it depends on how high you are willing to push them in the duty cycle, but you should be able to get up over 450.
You can use a calculator to get an idea. BFSC for a forced induction car is usually around .6

http://www.witchhunter.com/injectorcalc1.php4

Click to expand...

My end-goal is 600-650 RWHP on pump gas with the blower and a built shortblock. Sounds like if I need injectors now, I should stick with something appropriately sized for the time being because I'm going to need something much bigger when the time comes.

 

Tripoli

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Mar 30, 2005

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Dallas, TX

Mar 23, 2008

#15

• Mar 23, 2008

• #15

After we got it on the dyno, Archie decided it did not need a new MAF or injectors. There was no fuel pressure spike which would indicate the injectors weren't keeping up. The car pulled 308 RWHP and 323 ft/lbs torque.