GT40P HEAD SWAP HELP PLEASE

9

90stangLX302

New Member

Dec 2, 2003

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Good ol' Bellaire Ohio

Mar 3, 2004

#1

• Mar 3, 2004

• #1

WHAT DO YOUDO WITH THE THERMACTOR WHEN SWAPING THE HEADS. it is the pump that pumps fresh air inot the rear of the head in the exhaust port.

 

Michael Yount

Mustang Master

Apr 10, 2002

9,039

6

79

Charlotte, NC

Mar 3, 2004

#2

• Mar 3, 2004

• #2

The P's don't have the openings for that air injection unless they've been drilled, I believe. If you don't have emissions issues, take the pump and plumbing off. The P's will also deprive your intake manifold of exhaust for the egr.

 

9

90stangLX302

New Member

Dec 2, 2003

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Good ol' Bellaire Ohio

Mar 3, 2004

#3

• Mar 3, 2004

• #3

the prt about depriving. is that good or bad for performance?

 

Michael Yount

Mustang Master

Apr 10, 2002

9,039

6

79

Charlotte, NC

Mar 3, 2004

#4

• Mar 3, 2004

• #4

Properly functioning egr won't hurt your w.o.t. performance - the computer closes the egr when it senses w.o.t. However, not having it may impact part throttle drivability and fuel mileage. The egr system injects a bit of exhaust into the intake during part throttle conditions to cool the combustion chamber. This reduces NOx emissions and allows the computer to add more timing resulting in better mileage. When the computer tries to add timing, but no exhaust is present to cool the chamber, some people experience a bit of pinging or detonation requiring them to pull their timing back a bit - which does impact performance. There's no way to tell what's gonna happen with an individual car until you try it.

 

9

90stangLX302

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Dec 2, 2003

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Good ol' Bellaire Ohio

Mar 3, 2004

#5

• Mar 3, 2004

• #5

Will taking off the thermactor affect the O2 sensors since there will be no fresh air pumped in by the pump into the exhaust

 

9

90stangLX302

New Member

Dec 2, 2003

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Good ol' Bellaire Ohio

Mar 3, 2004

#6

• Mar 3, 2004

• #6

I checked the head out and tey have the port for the EGR, so i dont have to worry about that one
Still lost on the air pump and thermactor

 

Michael Yount

Mustang Master

Apr 10, 2002

9,039

6

79

Charlotte, NC

Mar 3, 2004

#7

• Mar 3, 2004

• #7

Great question 90Stang - I don't know the answer.

 

9

90stangLX302

New Member

Dec 2, 2003

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Good ol' Bellaire Ohio

Mar 3, 2004

#8

• Mar 3, 2004

• #8

Poll: Did anyone that took off the air pump (a.k.a. smog pump) notice any changes in performance, drivability, gas mileage, etc. please respond if anyone has the answer,...thanks

 

I

Idwitheld-1`

New Member

Nov 30, 2003

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Portland Oregon

Mar 3, 2004

#9

• Mar 3, 2004

• #9

The egr exhaust gasses are now replaced with standard atmospheric gasses. I did notice an increase in pinging. This was tuned out (quenched) with an AFPR. Bit faster...not seat of the pants...but noticeable. I also ran a short belt...so it's hard to tell which variable had the greatest signifficance. But they are accumulative.

 

S

schiccc

New Member

Feb 1, 2004

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Mar 3, 2004

#10

• Mar 3, 2004

• #10

90stangLX302 said:

Poll: Did anyone that took off the air pump (a.k.a. smog pump) notice any changes in performance, drivability, gas mileage, etc. please respond if anyone has the answer,...thanks

Click to expand...

i also have p heads which are not drilled for smog and i pulled off the smog pump and pluming, i really did not notice a diffrence. i bought my car with the heads already on it. do you know the cc on combustion chamber. i am trying to figure out if there are two diffrent sizes

 

9

90stangLX302

New Member

Dec 2, 2003

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Good ol' Bellaire Ohio

Mar 3, 2004

#11

• Mar 3, 2004

• #11

I dont the cc's for sure, i think they are 59, from what i have read. But everywhere say's the GT40P's are smaller than stock E7's and i thought E7's were 58cc. Correct me if i am wrong

 

9

90stangLX302

New Member

Dec 2, 2003

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Good ol' Bellaire Ohio

Mar 4, 2004

#12

• Mar 4, 2004

• #12

I was talking to a Ford mechanic, and he said that removing the thermactor may affect the O2 sensor readings because it is depriving them of the carbon dioxide. It works by injecting fresh air into the exhaust ports, when it is mixed with hot exhaust gases, oxidation is increased reducing the concentration ofhyrodcarbons and carbon monoxide converting them into hramless carbondioxide and water vapor

 

Michael Yount

Mustang Master

Apr 10, 2002

9,039

6

79

Charlotte, NC

Mar 4, 2004

#13

• Mar 4, 2004

• #13

As mentioned before, the egr valve is closed at w.o.t. - so there's no performance benefit to removing it or having it be non-functional; however, if you have to retard timing to stop the pinging, that can hurt performance. So, there may be a benefit to having the egr hooked up unless you turn off the egr function in the computer with a chip.

The air injection works as your mechanic friend described - excess oxygen is required for additional oxidation to occur after combustion has occurred in the chamber. The chemical reactions that the cats speed up need excess oxygen to occur. The O2 sensors will still, however, read the exhaust stream, and when you're in closed loop, they'll help the computer adjust the amount of fuel injected. At w.o.t., the engine goes back into open loop, and it ignores the O2 sensor readings anyway - the so the lack of excess air being injected is a non-issue performance-wise. One of the most common 'mods' out there is either removing or bypassing the air pump - and folks hardly ever report any drivability or check engine light issues. The computer will throw a diagnostic code into memory related to the malfunctioning components - thermactors - but it doesn't seem to harm anything. Unless, of course, you have an emissions test to pass.

 

stanglx

Founding Member

Aug 8, 2001

86

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0

Mass.

Mar 4, 2004

#14

• Mar 4, 2004

• #14

I have P heads with the smog pump removed. I have no pinging/detonation problems at all and this is with 17 degrees of timming (after it was tuned of course). I am usually between 42-45psi with my fuel pressure depending on conditions. If I remember correctly I usually get about 16 miles to the gallon and that would be a mix of highway and city driving.

Good luck with your combo!
Ken

 

9

90stangLX302

New Member

Dec 2, 2003

76

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Good ol' Bellaire Ohio

Mar 4, 2004

#15

• Mar 4, 2004

• #15

Another question i have is,...will the stock pushrods work with the gt40p's?

 

9

90stangLX302

New Member

Dec 2, 2003

76

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Good ol' Bellaire Ohio

Mar 4, 2004

#16

• Mar 4, 2004

• #16

I searched all around when i live and i couldn't find a place that has a lifter bleeder to check the clearance,... i was wondering if there are any other ways to check the pushrod clearances