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Discussion Starter #1
I have a Mustang GT engine. As you can see from my profile I have done many mods. My problem is that the power is not what I feel I should have. The last dyno I ran showed 265 HP. I used to get 29 MPG (Imperial gallons), now I get 19 MPG. The engine runs well, but I wonder why it's so hard on gas and so gutless. I would expect around 300 - 310 RWHP. Any suggestions would be appreciated.

:confused:
 

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Was that 29mpg after or before your tune and mods? Has your mpg dropped over time or all at once?

A few possible reasons for bad gas milage...very safe tune, your driving charecteristics, in need of tune up, slipping TC, vac leak, the list could go on.
 

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Discussion Starter #3
I already had the AED, removed FMU, 30#injectors, ,70MM T/B and 80MM MAF. I had 3.27 gears, stock exhaust (DynoMax CatBack). With this setup, averaged 29.2 MPG on an 1800 mile trip.

THen I swapped in a 2000 GT engine, installed headers, removed cats, true duals with x-pipe, 3.55 gears and GT T/C. Had the chip modified by He who shall not be named (Dennis). I expected noticeable gains in power, NOT!. I have new copper plugs, wires, K&N cone filter for the Mustang intake. I removed the stock T-bird box and used the filter housing from the Mustang. The MAF has been cleaned, and I replaced one Fuel Injector that was cracked. I have the LM-1 and the logs show average A/F is 14.6 with a low of 10.2 at 5600 RPM at full throttle.
 

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Bigbird,

What are your ACT's at WOT? What spark plugs are your running and what are they gapped at?

What pulley do you have on the blower? What length belt do you run? How much boost do you see at WOT? How much fuel pressure do you have at idle? At WOT?

How much spark timing do you have at WOT? What lb./min of airflow do you see at WOT?

Tell me all those answers and I'll tell you what's wrong with your car. To properly answer these questions, you'll need a FP gauge, a boost/vacuum gauge, and an Auto Tap or equivalent data logger.

A-Train
 

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Discussion Starter #5
Thanks A-Train, here's the scoop:

ACT = 135
Plugs = awsf-22c gapped at .040"
STock AED 6# pulley, stock pulleys on engine
Using the belt from the Rev 1 T-bird kit
Boost is 5# drops to about 3# at 5500 + rpm
F/P at idle = 32#, WOT 46# @ 5500+ RPM dropping to 42# @ shift to O/D
STopped in gear idle 590 RPM timing is 18.0
@ 45MPH 1500+ RPM timing is around 28.5 - 31.5
WOT @ 5775 RPM air flow is 36.6 timing is 12 deg
A/F is 14.6 at cruise with a low of 10.2 at 5600 RPM at full throttle
 

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10.2 at 5600, that is a little rich even on a safe tune.
That motor should be making power up past 6500, not that you should spin it that high, but if you do, and you are tuned that rich all around, then look out for black smoke. Most 10:1 motors I've seen under load look like deisels.

What is your Open Loop Throttle position set at?
If it is set to go open loop at a position that is too light, say 2 volts, then you are running wayy rich all the time except when you are light throttle cruise.
Also, if the TPS is goofy, it could be affecting it.

MAF would be a good place to check things too. If Xfer function is not right you will get rich results with open loop. Adaptive will keep it leaner in closed loop up to a limit.

good luck
rm
 

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Discussion Starter #7
Another quirk I noticed is: when I go WOT from about 50 MPH, the boost goes to about 6#, then droops a little to 5# till it hits about 5200 RPM at which time the gauge "twitches" to 3# until it shifts to 3rd at around 5800 RPM where it rises to 5 - 6#.
 

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Bigbird,

Well things make sense now.

The 135 degree F ACT's with 3-5 psi of boost is really high. I see 140-150 with 10 psi of boost on a 90 degree F. day. On a 30 degree F. day it goes no higher than 90 degrees F. at WOT. You may want to mix at least 80/20 distilled water to Dexcool antifreeze for your intercooler system and use a bottle of Redline Water Wetter in it. An auxilary heat exchanger would also help. If you have that mechanical AED water pump, ditch it and get a Bosch/FRPP electric water pump.

Spark plugs...you need at least TWO heat ranges colder than stock to keep the engine less knock constrained. With your boost levels, it's not that important, but when you up the boost you'll need the colder plugs. I suggest AGSF-12 FM1 plugs gapped at 0.038".

Get a 2.5" blower pulley to feed the PI heads. Drop down to a JK6-110.6 belt or something in the 110.5" range. The stock belt is JK6-1118 (111.8") That will raise the boost to a respectable level. I know I've said that boost is bad and you don't want boost since it adds heat, however in order to keep the cfm flowing you're going to need to spin the blower slightly faster. The fact that you have 36.6 lb/min of airflow at WOT means you're down on power. You need to be around 45 lb./min to reach 300-320 RWHP on your set-up.

Fuel pressure should be 1 psi for each psi of boost you have at WOT. So if you say 3 psi of boost at 5,500 rpm you should see 43 psi of fuel pressure. Your spark advance is low, you should be around 18-19 degrees at WOT. Especaially with the ACT protecting you.

That's what EECDOC and I have seen with our set-ups. Your A/F ratio is also very rich (as Richard stated) which doesn't need to be. You'll find max power around 11.7:1 to 12.0:1 at WOT for most AED applications.

Then you need to look at your inlet tube. If you are using the AED stock plastic tube that connects the throttle body to the inlet tube, ditch it. I found 40 RWHP was being tied up with my set-up. I went from 287 RWHP (STD) to 320 RWHP (SAE) by using a less restrictive tube there.

I hope this helps,

A-Train
 

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Bigbird,

"Twitches" well that sounds like belt slippage to me. Boost drops off at WOT then comes back...hmmm. I though 3-psi was rather low. Is the belt leaving black powder all over the front cover and rubbing on the idler bracket?

A-Train
 

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So if your ACTs are around 170 at 6-7psi whats wrong? I was hitting that this past summer at WOT when we hooked my car to an Auto Tap. I thought it was high......and Im running more cooling medium than the stock AED kit comes with.

Suggestions?

(Not trying to Hijack your post either Bigbird, just curious)
 

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Discussion Starter #11 (Edited)
Again, thanks for the input. The belt was replaced last October and no, it doesn't appear to be leaving any black powder. I tried some belt dressing to see if it would improve things but it did not, still might be the belt though.

I ditched the mechanical pump and replaced it with the better version of the Centri-puppy as came with the AED except with better (Mechanical?) seal.

I still have the plastic adapter from AED so I will try to get something made to replace it. I have the SCT Tuner so I will get someone ??? to create a new file for me with the info that I have so far and try to get better performance. Who is good right now? I know my usual guy is "persona non grata" right now.

I guess the too rich condition is contributing to the poor gas mileage. Right now I am paying 84.9 cents per liter, ouch!!
 

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Discussion Starter #12
AEDM8 said:
So if your ACTs are around 170 at 6-7psi whats wrong? I was hitting that this past summer at WOT when we hooked my car to an Auto Tap. I thought it was high......and Im running more cooling medium than the stock AED kit comes with.

Suggestions?

(Not trying to Hijack your post either Bigbird, just curious)
I see 150+ when the weather gets hot. I've tried adding a second cooler (B&M tranny cooler) but it doesn't help much.
 

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Discussion Starter #13 (Edited)
I made a replacement for the plastic adapter that AED supplies for the T/B to intake tube. Here's a few pics.







Now the boost stays at just over 5#, even @ 5800 RPM.

It does look like the belt may be rubbing on the timing cover, near the idler pulley just above the power steering pump.
Any one else ever see this?
 

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Bigbird,

Yes, that tube is restrictive as it has to clear the fuel rail. With the PI heads, you may have been down as much as 40 RWHP due to the stock tube.

I made 287 RWHP (STD) and 375 RWTQ (STD) in NY (Dec) with Jerry. The car was identical to the Feb pulls in VA, except I made a custom intake tube to replace the plastic AED tube. The car then made 320 RWHP/380 RWTQ (SAE). That's 40 RWHP no matter how you look at it. Also my boost went from 8 psi to 10 psi, so I knew that it worked correctly.

The belt rubbing is nothing new. It happens on most AED cars. You may want to check the idler bracket to make sure it isn't sticking out and into the belt. Grinding some of the bracket down on a belt sander wouldn't hurt. Repaint it and off you go. I recommend you replace the belt as well.

A-Train

 

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Discussion Starter #15
A-Train,

Do you still recommend the 2.5" pulley? Seeing as I still only have 5# boost it might get the numbers back up without hurting the motor.
 

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Bigbird,

1 psi of boost is enough to crack a ring land on the 4.6L engine. The 2000 4.6L engine actually has a weaker ring land set-up when compared to the older 4.6L pistons. The ring land package was moved up a tad higher on the PI engines.

A few naturally aspirated 4.6L engines have lost ring lands when knock was present. It doesn't take much. Others have run for years with knock and a lean A/F ratio without any piston problems. How lucky do you feel?

Changing to the 2.5" pulley will raise the boost and also raise the ACT's. It will also drop your longevity with the stock internals. Since boost is nothing more than back pressure, you may or may not make more power. It depends on the tune.

If your ACT's could jump from 150 to 175 F at WOT, at which point, you'll be more knock constrained. So timing may have to be backed out slightly and fuel may need to be added to help cool down the combustion chambers. So you may not gain as much as you want or think you should have gained.

You'll need a 110.5" belt (JK6-1106) with the 2.5" pulley and if you have 30 lb./hr. injectors, you may want to upgrade to 36's. 30's will be at a high duty cycle with your PI heads and the smaller pulley.

A-Train
 

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Got a question....if you make your heads flow more does that mean you will lower your ACTs in the process? Compressed air is hot air so less compression would equal less heat.....unless Im way off on my thinking. If so please enlighten me.

I wonder if I was losing power last year....I never upgraded my belt when I downsized my pulley. Sounds like a necessity with the 2.52 pulley. I could see where the belt was bouncing/moving across my front cover when I pulled it off this winter. I had alot of rubber pieces as well......

Anyone have a PN for the gatorback belt in that size by chance. Makes it easier on the idiots I have behind the counter....:rolleyes:
 

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Discussion Starter #18 (Edited)
AEDM8, from A-train's post:

Get a 2.5" blower pulley to feed the PI heads. Drop down to a JK6-110.6 belt or something in the 110.5" range. The stock belt is JK6-1118 (111.8")
 

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Discussion Starter #19
I ran a compression test today. The engine was warm, but nowhere near normal operating temps. The compression 190 - 200 on all cylinders. Seems a little high. The plugs looked a little sooty with some rust coloring, but not rusty, if you know what I mean.
 

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Discussion Starter #20
A-Train said:
Bigbird,

1 psi of boost is enough to crack a ring land on the 4.6L engine. The 2000 4.6L engine actually has a weaker ring land set-up when compared to the older 4.6L pistons. The ring land package was moved up a tad higher on the PI engines.

A few naturally aspirated 4.6L engines have lost ring lands when knock was present. It doesn't take much. Others have run for years with knock and a lean A/F ratio without any piston problems. How lucky do you feel?

Changing to the 2.5" pulley will raise the boost and also raise the ACT's. It will also drop your longevity with the stock internals. Since boost is nothing more than back pressure, you may or may not make more power. It depends on the tune.

If your ACT's could jump from 150 to 175 F at WOT, at which point, you'll be more knock constrained. So timing may have to be backed out slightly and fuel may need to be added to help cool down the combustion chambers. So you may not gain as much as you want or think you should have gained.

You'll need a 110.5" belt (JK6-1106) with the 2.5" pulley and if you have 30 lb./hr. injectors, you may want to upgrade to 36's. 30's will be at a high duty cycle with your PI heads and the smaller pulley.

A-Train
You have the same engine as I do, what is your setup like, injector size etc. ??
 
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