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Discussion Starter #1
Hey guys, I have a chance to get some 39 pound injectors and 90mm maf calibrated for 39's from a friend for my 4.6 cougar. My question is would it be worth my while? How much gains should I expect?

Here's my mod list:

3.73 gears
t-45 swap
Full exhaust
bullitt intake
twin 50mm tb
75 wet shot of nitrous
chip from DD

Any help would be greatly appreciated! Thanks,
Ben
 

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WOT Junkie and avid corn burner
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The MAF is never tuned for a certain set of injectors by itself. It's all in what is in the program in the computer. If those mods are what you currently have, then you'll gain maybe 5-10 hp, mostly due to the larger and more precise MAF. Having the bigger injectors is nice, especially when running N2O or also using E85. Now if you tune it for E85 and use it, you can run with more ignition timing. I put a 90mm MAF and 39 lb injectors in mine too, to be used for E85.

From a heads up comparison to what you have now, it won't seem like much, but it'll give you some room for improvements later on. I also suggest upgrading your fuel pump if you haven't already.
 

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Discussion Starter #3
The MAF is never tuned for a certain set of injectors by itself. It's all in what is in the program in the computer. If those mods are what you currently have, then you'll gain maybe 5-10 hp, mostly due to the larger and more precise MAF. Having the bigger injectors is nice, especially when running N2O or also using E85. Now if you tune it for E85 and use it, you can run with more ignition timing. I put a 90mm MAF and 39 lb injectors in mine too, to be used for E85.

From a heads up comparison to what you have now, it won't seem like much, but it'll give you some room for improvements later on. I also suggest upgrading your fuel pump if you haven't already.
Thanks for that info! If that's the case, I'll just get some underdrive pulleys for now, I figured I would gain a little more hp than that, but that's why I asked! Lol. So wait, mafs for 4.5's don't have sample tubes that are calibrated for injector sizes like my supercoupe? I thought they did
 

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Your stock heads and cams are the restriction. The intake will get you 10 HP or thereabouts, but where that intake really shines is in the 6000+ RPM range - the power curve with stock heads will flatline by 5000 (check out my dyno charts of the two combos I've tested in the dyno sheets sticky).

The combo of the exhaust, chip (assuming a good 93 tune), manual trans and intake will get you maybe 40 HP at the wheels compared to stock, but in the lower RPM range you'll lose a little because of the intake. With a manual trans this will be amplified because of the loss of torque multiplication through a torque converter.

A "calibrated" set of a MAF and injectors will trick the PCM into delivering the right amount of fuel. However the PCM uses MAF sensor data to calculate the load on the engine, which it uses to determine the proper spark delivery. If the MAF sensor isn't representative of the actual airflow data (in your case it would read MUCH lower than the actual airflow/load) you'll be giving either too much or too little spark (in your case you'd be giving much too much spark)... and bad things can happen. Since you're getting a chip (why not just get a flash tuner, much easier to work with and more tuners support them) you can have the program written to accommodate the injectors and MAF so the PCM is getting accurate airflow data.

Since you're swapping in a manual you'll be able to rev about 1000 RPM higher than before and thus take better advantage of the intake.... but this would be more amplified with good heads and cams to mate it to. The stock internals can handle about 6300-6500 RPM safely, but as I said the heads and cams will severely restrict the airflow at anything > 5000 RPM and you'll see virtually no more power past that point.

My advice... if you're serious about this thing, save your money for a set of worked heads (PI or nPI) and cams, then you'll really be able to take advantage of that combo's potential. Also be aware that bigger cams generally need good exhaust scavenging to maximize their potential (read, mid-length or longtube headers).

And lastly, IMHO, skip the nitrous, especially with a stock fuel pump.
 

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A "calibrated" set of a MAF and injectors will trick the PCM into delivering the right amount of fuel. However the PCM uses MAF sensor data to calculate the load on the engine, which it uses to determine the proper spark delivery. If the MAF sensor isn't representative of the actual airflow data (in your case it would read MUCH lower than the actual airflow/load) you'll be giving either too much or too little spark (in your case you'd be giving much too much spark)... and bad things can happen.
Not only this, the greater the difference in the flow rate of the new injectors compared to what is programmed in the PCM, the greater the difference in calculated load. In the case of 39lb/hr injectors your calculated load will be off by a factor of ~2. The calculated load will be only 1/2 of the actual REAL load by necessity, in order to keep the fueling somewhat proper, leading to the PCM looking up spark values in the tables much greater than they should be. So instead of the pcm delivering, say, 20° of spark advance, it looks up the lower load values (because it has now been tricked by the sampling tube) and could be delivering, say, 40° of spark advance when the combustion event can only tolerate 20°. Detonation. There go your ring lands.

In the end, no maf can be truly calibrated for any injector, even the "SC" mafs. This is because the load, and thus ALL the spark delivery will be off. Sure the air:fuel ratio can be set adequately, but proper fueling is only part of the equation--a true pcm calibration has to take everything into account.
 

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Discussion Starter #6
Your stock heads and cams are the restriction. The intake will get you 10 HP or thereabouts, but where that intake really shines is in the 6000+ RPM range - the power curve with stock heads will flatline by 5000 (check out my dyno charts of the two combos I've tested in the dyno sheets sticky).

The combo of the exhaust, chip (assuming a good 93 tune), manual trans and intake will get you maybe 40 HP at the wheels compared to stock, but in the lower RPM range you'll lose a little because of the intake. With a manual trans this will be amplified because of the loss of torque multiplication through a torque converter.

A "calibrated" set of a MAF and injectors will trick the PCM into delivering the right amount of fuel. However the PCM uses MAF sensor data to calculate the load on the engine, which it uses to determine the proper spark delivery. If the MAF sensor isn't representative of the actual airflow data (in your case it would read MUCH lower than the actual airflow/load) you'll be giving either too much or too little spark (in your case you'd be giving much too much spark)... and bad things can happen. Since you're getting a chip (why not just get a flash tuner, much easier to work with and more tuners support them) you can have the program written to accommodate the injectors and MAF so the PCM is getting accurate airflow data.

Since you're swapping in a manual you'll be able to take better advantage of the intake.... with good heads and cams to mate it to. The stock internals can handle about 6300-6500 RPM safely, but as I said the heads and cams will severely restrict the airflow at anything > 5000 RPM and you'll see virtually no more power past that point.

My advice... if you're serious about this thing, save your money for a set of worked heads (PI or nPI) and cams, then you'll really be able to take advantage of that combo's potential. Also be aware that bigger cams generally need good exhaust scavenging to maximize their potential (read, mid-length or longtube headers).

And lastly, IMHO, skip the nitrous, especially with a stock fuel pump.
Oh the car is together already and runs great, I'm pretty happy with it, it has a 190lph walbro, so no worries about that. The same guy that has the maf and injectors has a set of stage 2 cams with springs for $400. I'm seriously thinking about getting those, but do they require notching the pistons? I have a set of PI heads already laying in the shop that I got for free :cool:
 

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Discussion Starter #7
Not only this, the greater the difference in the flow rate of the new injectors compared to what is programmed in the PCM, the greater the difference in calculated load. In the case of 39lb/hr injectors your calculated load will be off by a factor of ~2. The calculated load will be only 1/2 of the actual REAL load by necessity, in order to keep the fueling somewhat proper, leading to the PCM looking up spark values in the tables much greater than they should be. So instead of the pcm delivering, say, 20° of spark advance, it looks up the lower load values (because it has now been tricked by the sampling tube) and could be delivering, say, 40° of spark advance when the combustion event can only tolerate 20°. Detonation. There go your ring lands.

In the end, no maf can be truly calibrated for any injector, even the "SC" mafs. This is because the load, and thus ALL the spark delivery will be off. Sure the air:fuel ratio can be set adequately, but proper fueling is only part of the equation--a true pcm calibration has to take everything into account.
I don't want you guys to think that I was wanting to do the maf and injectors without a tune, whatever I do to it,it WILL have a proper tune to accommodate for everything. Very interesting though considering a lot of people put injectors and a "calibrated" maf on their cars without a tune, thinking everything is peachy :)
 

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I'd suggest going to a 255 lph or better fuel pump.
 

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I don't want you guys to think that I was wanting to do the maf and injectors without a tune, whatever I do to it,it WILL have a proper tune to accommodate for everything. Very interesting though considering a lot of people put injectors and a "calibrated" maf on their cars without a tune, thinking everything is peachy :)
that's good. You can now relinquish the thought that mafs are calibrated to a specific injector size just because they came together on a certain car. :)
 

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I'd suggest going to a 255 lph or better fuel pump.
I'm gonna go with a 255 if I get these cams for sure

that's good. You can now relinquish the thought that mafs are calibrated to a specific injector size just because they came together on a certain car. :)
You have taught me a lot on these forums...lol
 

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You should look into running E85 sometime if you can get it. It's just a station and a tune away!
 

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Discussion Starter #12
You should look into running E85 sometime if you can get it. It's just a station and a tune away!
What exactly is e85? Just a mixture of race fuel and gas? I don't think there's any stations around here, but I could check and try and find one if it's worth it. How much horsepower can I expect? I know I can 110, but its to darn expensive!
 

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E85 is a blend of gasoline and Ethanol. 85% Ethanol, 15% gasoline. Where Premium sells for $3.80 per gallon here, I get E85 for $3.23 per gallon. It has an octane rating equivalent to 110-113. You could see a gain of roughly 11%, so I have been told. I can personally tell you that it dropped around 3 tenths of a second off of my quarter mile time and gained me 2 mph at the traps. I'm just N/A on a pretty much stock motor.
 

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Discussion Starter #14
E85 is a blend of gasoline and Ethanol. 85% Ethanol, 15% gasoline. Where Premium sells for $3.80 per gallon here, I get E85 for $3.23 per gallon. It has an octane rating equivalent to 110-113. You could see a gain of roughly 11%, so I have been told. I can personally tell you that it dropped around 3 tenths of a second off of my quarter mile time and gained me 2 mph at the traps. I'm just N/A on a pretty much stock motor.
Premium is $3.90 here, so if i could find e85 that would be awesome! Faster car and cheaper fuel :D
But what about mpg?
 

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Yeah, that's the only drawback. You'll burn about 20-30% more fuel, but you can't have everything. It's still a hell of a lot cheaper than race gas though, despite having less fuel mileage. Think of it as one grade above premium and priced accordingly.
 

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Discussion Starter #16
Yeah, that's the only drawback. You'll burn about 20-30% more fuel, but you can't have everything. It's still a hell of a lot cheaper than race gas though, despite having less fuel mileage. Think of it as one grade above premium and priced accordingly.
Yea, this is my daily driver, so that won't work...lol, I'd definitely be interested in running that in my supercoupe though
 

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You don't have to run it 24/7. I have tunes for both fuels. My T-bird is my daily too. When I want to switch over to E85, I run my tank about 2-3 gallons away from dry, then fill up. When I want to switch back, same procedure. Just got to switch the tunes with my handheld tuner.
 

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All I did to mine was install 39 lb injectors, 90mm Lightning MAF, 255 lph fuel pump, and have RobertP tune it.

The LMAF isn't required, but I figured why not.
 

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E85 is a blend of gasoline and Ethanol. 85% Ethanol, 15% gasoline. Where Premium sells for $3.80 per gallon here, I get E85 for $3.23 per gallon. It has an octane rating equivalent to 110-113. You could see a gain of roughly 11%, so I have been told. I can personally tell you that it dropped around 3 tenths of a second off of my quarter mile time and gained me 2 mph at the traps. I'm just N/A on a pretty much stock motor.
Why do all that when you can run low 14's High 13's on a basically stock NA set up without going to all that trouble, and on premium pump gas. And you still have the mileage.
 
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