19# injectors, Stock MAF, How much HP HP can they support

daves302gt · Nov 18, 2005

Ohhh, wow. So what causes the headgaskets to go? Well, naturally it's either extra heat or extra pressure. So is it the regular pressure from making HP or extra high pressure from detonation? Cuz we already discussed the timing retard thing. And pressure from HP would be the same tuned or not. Heat I could see being held down by richening the mixture with a tune, but that also costs you ponies, no? Would the same thing happen on a 400 bhp NA 302 with stock headgaskets and the Inj/MAF combo? Can I use a Adj FPR to boost the Fuel pressure to richen it up at WOT? I'm guessing a A/F ratio meter could help identify problems if there were some, right?
oh, and i don't know that my cam is any more extreme than a stocker with 1.7 arms, and the GT-40s aren't anywhere near an alum head either.

CManT1914 · Nov 18, 2005

The blowing head gaskets are more common on boosted applications I think because of the pressure created by the blower. Think about it, on an N/A app., the engine will only suck in as much air as it needs. On a blown app., the blower FORCES air in. Also, running lean is a dangerous problem on boosted apps., as most have the tendency to do before a tune. That's really what causes blown HG's.

daves302gt · Nov 18, 2005

I'm not trying to be a jerk, I'm just trying to learn what the big fuss is about if it goes counter to theory!!! I really do appreciate all the help and thoughts presented! Thanks for the help from before AND in the future!

CManT1914 · Nov 18, 2005

No problem Dave! Nobody here thinks you're trying to be a jerk (it must just come natural to you, , j/k!) Most of the guys on here would rather be safe than sorry. That's why we always advise to get a tune before you go romping on a boosted car. Without a custom tune, it's like having sex with a hooker.... lol.

daves302gt · Nov 18, 2005

But, with that said, the blower forces air in and every cubic inch of it is accounted for by going past the MAF. if it doesn't go in the MAF, it doesn't get in the engine... blown or not. 1 'standard' cubic foot past the MAF goes thru the blower and comes out a .55 cubic foot at 6.5 psi, but it's still a standard cubic foot worth of oxygen and nitrogen. so the air in is seen by the computer and it's associated fuel curve is looked up, and the proper duty cycle is selected for the injectors. Seems good to me, but some slop in the MAF tricking process could account for the leaning out. I still think this could be fixed with the A/F monitor and adj press reg. Still just a theory tho.

daves302gt · Nov 18, 2005

mmmm..... sex.... anywho hookers are dangerous, aren't they! People won't wear other peoples underwear, but they will F with 'ladies of the night'. weird.
I understand the fear, but i would like to hedge my bets without the tune if i can, and design a system to work right regardless. I'm still currently thinking about the 30 lbs injectors with the 30 lb cal'd MAF 9and the adj FPR. Injectors should be good for 480 bhp. I'll be happy with ONLY 400, really! then leave it at that.

daves302gt · Nov 18, 2005

my bad, that goes in 1 CF at ambient and comes out .69 cf at 6.5 psi.

final5-0 · Nov 18, 2005

daves302gt said:
Right, i understand the trickery involved, but I'm usually a little skeptical of the actual need for a tune for SAFETY on a mild setup. I understand the tune can give more power, but the companies who make the re-cal'd MAFs have to err on the rich side, otherwise EVERYBODY who bought one would be burning up pistons from going lean! How many guys have you (ya'll?) heard of burning pistons from a mild s/c setup and a recal'd MAF injector combo? (thats a real question, not a jab)

Might wanna talk to Keven about what happends to a blown combo that pegs a maf with too small a cal.

He's got some pistons I bet he would sell ya real cheap!

Grady

CManT1914 · Nov 18, 2005

daves302gt said:
Seems good to me, but some slop in the MAF tricking process could account for the leaning out.

BINGO!! Without the computer knowing exactly what kind of maf transfer it's reading from, and injector sizes, the added fuel isn't gonna match 100%. Also, the computer's adaptive learning strategy can only do so much.

I didn't understand all that cubic feet stuff, but I'll take your word for it.

final5-0 · Nov 18, 2005

daves302gt said:
I understand the fear, but i would like to hedge my bets without the tune if i can, and design a system to work right regardless. I'm still currently thinking about the 30 lbs injectors with the 30 lb cal'd MAF 9and the adj FPR. Injectors should be good for 480 bhp. I'll be happy with ONLY 400, really! then leave it at that.

Hi Dave

Saw your low post count so welcome to our site :SNSign:

The bulk of stuff you see on the net is all about the Fox Stang.

Some of the stuff you talked about above applies to the Fox Stang as well.

Our Stangs have a pcm that is based on Load where the pcm in the Fox is based on rpm.

Now I am the one who is saying to you that ... I'm not trying to be a jerk ... but lots of info about what Load is to our Stangs has been posted on this site if you wanna do the research.

but ......

In a nutshell ... the pcm uses the data from the maf to determine Load.

The methods used by the after market maf companies that allow one to use their product without using a tune can cause the load factors get all hosed up.

The Fuel and Spark tables in the pcm also use Load which is now hosed up due to the inaccuracy of the after market maf.

Final deal here is ... this stuff hurts us more that the Fox boys!

Grady

94-302-vert · Nov 18, 2005

Grady, So can we do the larger injectors and jsut get a tune with the stock MAF?

Dave, Glad to see you are here man... Welcome Buddy!

Chris, Sex with hookers.. not always as safe as you would like now is it...

CManT1914 · Nov 18, 2005

94-302-vert said:
Grady, So can we do the larger injectors and jsut get a tune with the stock MAF?

Dave, Glad to see you are here man... Welcome Buddy!

Chris, Sex with hookers.. not always as safe as you would like now is it...

Well, you can get a tune to compensate for the larger injectors however.........

.........the stock maf can only read so much incoming air flow, around 925 kg/hr. I dare say most h/c/i combos suck in a lot more air than that. My 80mm Pro-M is calibrated to read more than 1500 kg/hr of airflow, so it is much better suited for a bigger breathing engine. A stock maf on a h/c/i combo is gonna get pegged and hold you back on top end. Look at Grady's sig, he made 293rwhp with the stock maf, throttle body and catback, which is great! But since he upgraded those components, I'm sure he is over 300 now.

And I wouldn't ever mess with hookers, it's like playing russian roulette with your junk!

final5-0 · Nov 19, 2005

94-302-vert said:
Grady, So can we do the larger injectors and jsut get a tune with the stock MAF?

For me, a short answer is not the norm, lol.

But for this one it is ......YES!

however

IMHO, if one looks at the bigger picture or long term game plan for his Stang, a good bit of money is gonna be spent if the objective is 300 or better rwhp.

If one is gonna self tune, you would have that option open to you and pretty much any other as far as tuning is concerned. This means you can tune to what ever condition your combo is ... at any given time ... and the cost of changing that tune is not a factor.

You do have the investment of tuning equipment which needs to be considered for sure.

but

If you are gonna have a Pro do the tuning, that method would cost you at least two Pro tunes cause, as Chris said, you will run outta steam with the little stock maf as you approach the 300rwhp mark.

As a matter of fact ... now that I think about it

If you can't get access to the pcm, you will peg the stock maf at maybe (ballpark value here) 275 to 280rwhp cause Ford puts a cap on the voltage the maf can send to the pcm at around (IIRC) 4.7 volts

The max the maf can send is 5.0 volts.

If you got access to the pcm, you can give yourself a bit of breathing room by bumping that value up to 4.998 volts.

I only say this cause ... peeps talk about me using the stock maf and almost making it to the 300 mark. That was due to me puting the fudge factor in place ... so that fact is a bit misleading ... if you see what I'm trying to point out here.

Grady

daves302gt · Nov 21, 2005

Ok, i gotcha...
SO lets assume from now on I'm getting a matched MAF/ Injector combo (I'm NOT going to keep the stocker) lets say a 36# combo, and to keep the injector flow the same at pressure, boost the Fuel pressure 6.5 lbs.
Now, as far as options go:
1. I can get a tweecer and a laptop etc and do it myself for how much (not including pain and suffering)
OR
2. I take it to somebody (Who in new england area is good? check that, who is IN new england? I'm in Southwest CT)

So with the new maf, injectors, FPR and tune, i should be at around 300 rwhp, no? I'm thinking around 850 bucks more, then i can leave the engine alone.

final5-0 · Nov 21, 2005

daves302gt said:
Ok, i gotcha...
SO lets assume from now on I'm getting a matched MAF/ Injector combo (I'm NOT going to keep the stocker) lets say a 36# combo,

I'm with you here.

and to keep the injector flow the same at pressure, boost the Fuel pressure 6.5 lbs.

I'm not with you here.

Now, as far as options go:
1. I can get a tweecer and a laptop etc and do it myself for how much (not including pain and suffering)
OR
2. I take it to somebody (Who in new england area is good? check that, who is IN new england? I'm in Southwest CT)

So with the new maf, injectors, FPR and tune, i should be at around 300 rwhp, no? I'm thinking around 850 bucks more, then i can leave the engine alone.

1) Tweecer 550 Laptop 50 to 200 WB 200 to 400 EA Program 50
you can get started with out WB & EA
2) A chip will do the trick and you won't have to learn stuff

I have a lot of basic info that answers Q's just like these on my site that may help you as well.

Grady

daves302gt · Nov 21, 2005

Grady,
I'll check that site out a little more in depth. thanks a ton. my head gaskets and butt-dyno will thank you too... but not my rear tires. :-D

plus, 94-302-vert will be sooooo jealous!

94-302-vert · Nov 27, 2005

Dave, Which way we going... We going to do the Tweecer?

19# injectors, Stock MAF, How much HP HP can they support

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