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Do upgraded heads require a tune?

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Old Mar 9, 2009 | 06:12 AM
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From: New Smyrna Beach, FL
Car: 1988 GTA
Engine: 305
Transmission: 5 Speed
Do upgraded heads require a tune?

I am going from stock heads to a set of trick flows. I am curious if this will REQUIRE a tune or if I can still run the car hard without one. Also will it affect drivability. My logic says that the air flow is metered by the mass air flow meter so it shouldn't make that big of a difference.
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Old Mar 9, 2009 | 07:08 AM
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From: Chasing Electrons
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Re: Do upgraded heads require a tune?

Spark advance requirements will change. You'll be able to drive the car with what is in there now. But best results will be from you re-tuning it.

RBob.
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Old Mar 9, 2009 | 07:42 AM
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From: New Smyrna Beach, FL
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Transmission: 5 Speed
Re: Do upgraded heads require a tune?

If you were to guess, what would you say the power gains from swapping heads is? 75hp?
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Old Mar 9, 2009 | 11:54 AM
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Re: Do upgraded heads require a tune?

35 to 40hp if tuned right!
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Old Mar 9, 2009 | 01:16 PM
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Re: Do upgraded heads require a tune?

I read once that MAF is limited in the amount of air flow it can monitor. Once you see increased airflow/horsepower the MAF may have to go. Search.
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Old Mar 11, 2009 | 05:59 PM
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From: West Central Ohio
Car: 86 vette
Engine: 383
Transmission: 700R4
Axle/Gears: 3.07
Re: Do upgraded heads require a tune?

With 19# injectors, it is unlikely to max the Maf. You would need to be bigger than 24# to even get close.
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Old Mar 11, 2009 | 06:43 PM
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From: New Smyrna Beach, FL
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Engine: 305
Transmission: 5 Speed
Re: Do upgraded heads require a tune?

What does injector size have to do with how much air maf can meter?
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Old Mar 11, 2009 | 07:01 PM
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Re: Do upgraded heads require a tune?

Interestingly enough, with a 13:1 AFR, 19 lb injectors and the MAF will max almost simultaneously.
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Old Mar 12, 2009 | 10:49 AM
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From: Chasing Electrons
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Re: Do upgraded heads require a tune?

Once the MAF reading is max'd fuel can continue to be added via the PE tables. This is a common method. Note that the injectors still need to be properly sized. As I am not saying that this will continue to add fuel once the injector DC is at or above 100%.

RBob.
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Old Mar 12, 2009 | 06:05 PM
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From: New Smyrna Beach, FL
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Transmission: 5 Speed
Re: Do upgraded heads require a tune?

How much power can you make with 19lb injectors?
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Old Mar 12, 2009 | 06:45 PM
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From: West Central Ohio
Car: 86 vette
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Re: Do upgraded heads require a tune?

A data log will tell you alot about where you are on air flow and injector flow.

As to max HP with 19# injectors 300 FWHP by calculation @ 43.5 psi fp 100% duty cycle .5bsfc.

Maybe someone with a similar setup could give a dyno rating.
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Old Mar 12, 2009 | 07:17 PM
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From: New Smyrna Beach, FL
Car: 1988 GTA
Engine: 305
Transmission: 5 Speed
Re: Do upgraded heads require a tune?

Right now I use tunerpro RT for tuning and datalogging. What would you recommend for tuning? What would you recommend for datalogging?
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Old Mar 13, 2009 | 08:03 AM
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From: West Central Ohio
Car: 86 vette
Engine: 383
Transmission: 700R4
Axle/Gears: 3.07
Re: Do upgraded heads require a tune?

Those are fine for tuning and data logging, they are what I use.

What is your max Maf grams/sec and your max injector ms and at what rpm do they happen? They should repeat as you go up the gears.
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Old Mar 13, 2009 | 09:15 AM
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Re: Do upgraded heads require a tune?

This is what I found for you. Save to your favorites.

http://www.users.bigpond.net.au/ben_...ctorsizing.xls
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Old Mar 13, 2009 | 12:14 PM
  #15  
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From: New Smyrna Beach, FL
Car: 1988 GTA
Engine: 305
Transmission: 5 Speed
Re: Do upgraded heads require a tune?

thanks for that calculator. I will definitely be using that!
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Old Mar 13, 2009 | 02:17 PM
  #16  
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From: West Central Ohio
Car: 86 vette
Engine: 383
Transmission: 700R4
Axle/Gears: 3.07
Re: Do upgraded heads require a tune?

Try this, it has been added to and "a work in progress", just remove the".txt".
Attached Files
File Type: txt
6E Mod 09 0204.xdf.txt (164.2 KB, 50 views)
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Old Mar 13, 2009 | 03:13 PM
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From: New Smyrna Beach, FL
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Engine: 305
Transmission: 5 Speed
Re: Do upgraded heads require a tune?

Thanks big time!
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