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2005 Pontiac GTO Intake Manifold and Throttle Body - Breathing Room

Fasterproms Extracts Hidden Power From An LS2 GTO With A Ported Stock Intake Manifold And Throttle Body, And A Custom Tune
September, 2009
By Kevin DiOssi
Photography by Kevin DiOssi
2005 Pontiac Gto Rear Left View
Proven Power of Tampa uses... 
   
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2005 Pontiac Gto Rear Left View
Proven Power of Tampa uses a 224xLC Dynojet, which features a load-control attachment to simulate road load. This allows the tuning to be more effective and precise for real-world driving conditions. All pulls are made in the 1:1 gear of the car. In this case, being an M6, Fourth gear is 1:1. If it was an A4, it would be Third gear. This is essentially the gear the car will be in when going through the traps in the quarter-mile.
2005 Pontiac Gto Computer
Jeremy makes adjustments to... 
   
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2005 Pontiac Gto Computer
Jeremy makes adjustments to the stock computer through HP Tuners software. Establishing a base tune is always a good idea because it can show you exactly where changes need to be made.
2005 Pontiac Gto Rear Left View
The result of mild tuning... 
   
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2005 Pontiac Gto Rear Left View
The result of mild tuning was an additional 8 rwhp and 8 lb-ft of torque. Jeremy says there is more to be found if he focuses on a full tune before the manifold swap. He reviewed the entire tune and made very mild fuel and timing changes, deleted torque management, adjusted the electric fans, and deleted the annoying skip-shift feature. When it was all said and done, we were in a pretty good ballpark.
2005 Pontiac Gto Engine Bay
Having done this "hundreds... 
   
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2005 Pontiac Gto Engine Bay
Having done this "hundreds of times," Jeremy brought all the tools necessary to swap out the manifold quickly. Since we've covered this process in other stories before, we don't detail it here again.
2005 Pontiac Gto Cylinder Heads
The majority of our time was... 
   
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2005 Pontiac Gto Cylinder Heads
The majority of our time was spent cleaning out the ports on the cylinder heads. Over 50,000 miles had their impact; the ports were black from combustion byproducts. Over time, it tends to build up and needs to be cleaned. Any oil consumed lowers octane rating and greatly increases the likeliness of spark knock. The less oil consumed, the better the overall octane rating, which in turn allows one to run a more aggressive tune.
2005 Pontiac Gto Engine Bay
Carburetor cleaner and a heavy... 
   
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2005 Pontiac Gto Engine Bay
Carburetor cleaner and a heavy towel were used to remove the buildup before installing the new parts.
2005 Pontiac Gto Throttle Body
The finish on the ported throttle... 
   
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2005 Pontiac Gto Throttle Body
The finish on the ported throttle body was impressive, with a consistent and smooth surface across the entire area.
2005 Pontiac Gto Throttle Body
The stock throttle body on... 
   
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2005 Pontiac Gto Throttle Body
The stock throttle body on the left has a large ridge around the bottom. This design is a means of torque-management and limits airflow up to about 50-percent throttle opening. "This is why it feels like the GTOs have poor throttle response," Jeremy says. "It's not the fly-by-wire system: It's actually the design of the throttle body." On the right, you can see it has been removed and the area smoothed. "There are many tables in the tune that limit overall throttle response and I made them much more aggressive. Together they make an outstanding difference in overall performance."Jeremy says that the average gain per port on the flow bench is over 10 cfm. "Most people look at the head flow but don't realize how much the intake limits the cfm one might see on the flow bench. Even a highly-ported heavily-modified FAST manifold will still bring down peak flow over 30 cfm on a head that flows over 300 cfm."
2005 Pontiac Gto Throttle Body
Here is a closer look at the... 
   
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2005 Pontiac Gto Throttle Body
Here is a closer look at the unfinished throttle body and its ridge as described above.
2005 Pontiac Gto Throttle Body
In addition to removing the... 
   
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2005 Pontiac Gto Throttle Body
In addition to removing the ridge, the throttle body is also port-matched to the ported intake, increasing overall flow. Most 90mm manifolds are brought out to about 93 mm to slightly increase plenum volume and allow more room for air.
2005 Pontiac Gto Open Intake
The intake entry needed some... 
   
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2005 Pontiac Gto Open Intake
The intake entry needed some work, as did the structural webbing inside. This is the stock intake.
2005 Pontiac Gto Open Intake
All opened up, you can fit... 
   
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2005 Pontiac Gto Open Intake
All opened up, you can fit a clenched fist inside. Jeremy wouldn't get into too much detail about what he does inside, but he says his goal is to reduce turbulence and increase interior plenum volume. He uses aggressive carbide bits and an array of cartridge sanding rolls to smooth the many surfaces and sharp angles.
2005 Pontiac Gto Runner
Here Jeremy demonstrates just... 
   
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2005 Pontiac Gto Runner
Here Jeremy demonstrates just how much material is safely removed from a runner. Notice the plastic is touching both sides of his thumb in the stock port.
2005 Pontiac Gto Runner
Check out the area around... 
   
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2005 Pontiac Gto Runner
Check out the area around his thumb in the ported runner. Fasterproms meticulously removed what is needed to increase power potential without degrading build quality or loosing velocity. What can't be seen in these photos is the amount of smoothing that was performed inside. "Since these are three-piece friction-welded manifolds, each one is different and none of them mate together perfectly,' Jeremy states. "We have gone inside and made sure that everything is smooth. There are certain parts to the manifold that we don't touch because of cost effectiveness. We only do what we can reach. In a FAST intake, we can take it apart and do the inside thoroughly. Because of this, we spend about three times more labor on a FAST than we do on an LS2.
2005 Pontiac Gto Engine Bay
Jeremy installed the new manifold... 
   
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2005 Pontiac Gto Engine Bay
Jeremy installed the new manifold and popped in the fuel rails.
2005 Pontiac Gto Enigne Bay
He plugged in the remaining... 
   
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2005 Pontiac Gto Enigne Bay
He plugged in the remaining components and tightened the fuel rail bolts.
2005 Pontiac Gto Front Left Side View
The Goat is back on the Dynojet... 
   
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2005 Pontiac Gto Front Left Side View
The Goat is back on the Dynojet to get the results. Instantly, the car shot up by over 15 hp at the rear wheels before tuning. The air/fuel ratio was mildly affected from the swap, so Jeremy took to the laptop to begin making adjustments. He says, "You have to see what the car likes because you never know what timing or fuel curve it wants until you try them."
2005 Pontiac Gto Dyno Graph Chart
With the final tune programmed... 
   
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2005 Pontiac Gto Dyno Graph Chart
With the final tune programmed in, the GTO was pushing 375.83 hp and 373.41 lb-ft of torque. That's a clean 29hp and 31-lb-ft torque gain from what we drove up with. Best of all, this modification is something Jeremy can knock out for you in about three hours using your cores as exchanges. Or you can ship them out to him and have them back in about two to five days. Also, the price is right and much cheaper than a new manifold. Now we're confident that we have more breathing room for our future plans.
FasterProms
19103 Sunlake Blvd.
Lutz
FL  33558
813/476-7364

www.fasterproms.net
Proven Power
www.provenpowertampa.com

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