Indy GT
Yea, I got one...too
Myheritage, please allow me if you will to comment on some of your comments: (note I did not send you the PM)
“The comment above says that all you have to do is add a pulley and a tune and make 620 hp. Although that may be true, it is very expensive and very hard on your motor. Here’s why. First, you have to buy a new supercharger for $8-$10,000 and install it and tune it.”
From your response, I am not sure you fully understand the concept of “a pulley and a tune” (or the technical people who know this FGT engine and read these posts). To perform this upgrade you certainly do NOT have to “buy a new supercharger for $8-$10,000.” The PULLEY is the only thing you buy, and it does not cost $8K! The pulley is slightly smaller in diameter than the OEM pulley and thus runs the stock blower at slightly higher RPM, creating higher boost and thus more HP. Accompanying this upgrade is usually “a tune” in which the tuner can alter A/F ratio and spark advance to more effectively capitalize on the increased inlet pressure and the recognition of possibly using a higher octane fuel than Ford was required to certify the engine to.
“Second, you’ve over-boosted the motor.”
Unless you were one of the Roush engine design engineers on the engine team, how can you technically say that above 13-14 psi boost the engine is “over-boosted”? If you install a smaller pulley or a Whipple, it is certainly a fact that you are running the engine to a higher level of inlet pressurization than OE. Is this bad or limiting? It might be, or maybe not, I personally do not know the limits the engine can sustain and remain reliable….(nor do you I would guess).
As several of the technically savvy contributors have already stated, tubular headers on our engine do not produce the horsepower or torque gains most people like to immediately associate with these products. Why?
1. The stock high Silicon-Molybdenum manifold although unglamorous looking (but camouflaged under the radiation heat shield) incorporates a 2.75” outlet diameter flange to freely flow exhaust gasses from the cast individual runners. The designers did a pretty good job minimizing backpressure with these OE units thus adding tubular headers with the thought of increasing thruflow by lowering backpressure for increased performance is not (in my opinion) a cost effective performance enhancement. See SAE technical report 2004-01-1252 by Curt Hill, Glenn Miller and Bob Gardner on development of the FGT engine and powertrain. If looks are your thing, and you like looking at nice stainless steel tubular snakes- fine. Just don’t try to rationalize high dollar expenditure for great horsepower gains, as this tact will disappoint. In fact Sorush points out in post #1 his long tube Ford headers were “pretty disappointing” and made less power than the OE exhaust system.
2. Compound this with the fact that our engine is blown and again, tubular headers are not as important an exhaust scavenging tool than if the engine is normally aspirated. As previously noted, equal length tubular headers attempt to capitalize on the negative pressures of alternating firing cylinders to “scavenge” or reduce the exhaust port pressure of a cylinder whose exhaust valve is just opening. If the pressure is thus lowered more of the exhaust gasses can be extracted from the cylinder and a non-diluted (with exhaust) inlet charge can fill the cylinder for the next firing. With a blown engine with significantly higher (than atmospheric pressure) inlet pressure this reliance to cylinder scavenging is not necessary because the high pressure inlet charge just blows the old exhaust gasses out the exhaust port.
“JBA’s objective was to stay within the perimeters of the way Ford built the motor, i.e., 13-14 lbs of boost.”
Not sure of how you make a point that a header manufacturer’s “objective” is to stay within the “perimeters” of the engine design? As Bill correctly points out, headers can alter slightly the measured boost. If the OE exhaust system was restricted in general thruput then headers will make a larger reduction in measured boost due to the increased flow efficiency. If the OE system was good by design, very little change in measured boost will be seen.
“…but more importantly, with 19-21 lbs of boost the head gaskets, intake manifold gaskets, along with the rods, pistons and crank are not designed to take 19-21 lbs of boost.”
How do you possibly know this for a fact? As others have posted this 5.4L FGT engine (which by the way IS different in a number of ways from that offered in the Mustang) is very stout and has been modified in various forms (Whipple, twin-turbo configurations, etc) to reliably produce horsepower values significantly higher the OE 550/500 configuration. And it is certainly reasonable that the Ford/Roush engine design team did a significant amount of dyno development testing on our engine at much, much higher inlet boost pressures to determine where to comfortably set the OE boost pressure. If you have ever examined the internal parts of this engine, they are VERY carefully designed for strength and performance. Ask Jason Heffener who has studied these components.
“So, it IS the exhaust system and tune that truly makes reliable hp without the risk of doing damage to the motor.”
Sorry, I must disagree. For the reasons cited above, the headers will look good and if that is your goal, spend the money. If performance gains are desired, there are certainly more cost effective ways of increasing net power.
“The comment above says that all you have to do is add a pulley and a tune and make 620 hp. Although that may be true, it is very expensive and very hard on your motor. Here’s why. First, you have to buy a new supercharger for $8-$10,000 and install it and tune it.”
From your response, I am not sure you fully understand the concept of “a pulley and a tune” (or the technical people who know this FGT engine and read these posts). To perform this upgrade you certainly do NOT have to “buy a new supercharger for $8-$10,000.” The PULLEY is the only thing you buy, and it does not cost $8K! The pulley is slightly smaller in diameter than the OEM pulley and thus runs the stock blower at slightly higher RPM, creating higher boost and thus more HP. Accompanying this upgrade is usually “a tune” in which the tuner can alter A/F ratio and spark advance to more effectively capitalize on the increased inlet pressure and the recognition of possibly using a higher octane fuel than Ford was required to certify the engine to.
“Second, you’ve over-boosted the motor.”
Unless you were one of the Roush engine design engineers on the engine team, how can you technically say that above 13-14 psi boost the engine is “over-boosted”? If you install a smaller pulley or a Whipple, it is certainly a fact that you are running the engine to a higher level of inlet pressurization than OE. Is this bad or limiting? It might be, or maybe not, I personally do not know the limits the engine can sustain and remain reliable….(nor do you I would guess).
As several of the technically savvy contributors have already stated, tubular headers on our engine do not produce the horsepower or torque gains most people like to immediately associate with these products. Why?
1. The stock high Silicon-Molybdenum manifold although unglamorous looking (but camouflaged under the radiation heat shield) incorporates a 2.75” outlet diameter flange to freely flow exhaust gasses from the cast individual runners. The designers did a pretty good job minimizing backpressure with these OE units thus adding tubular headers with the thought of increasing thruflow by lowering backpressure for increased performance is not (in my opinion) a cost effective performance enhancement. See SAE technical report 2004-01-1252 by Curt Hill, Glenn Miller and Bob Gardner on development of the FGT engine and powertrain. If looks are your thing, and you like looking at nice stainless steel tubular snakes- fine. Just don’t try to rationalize high dollar expenditure for great horsepower gains, as this tact will disappoint. In fact Sorush points out in post #1 his long tube Ford headers were “pretty disappointing” and made less power than the OE exhaust system.
2. Compound this with the fact that our engine is blown and again, tubular headers are not as important an exhaust scavenging tool than if the engine is normally aspirated. As previously noted, equal length tubular headers attempt to capitalize on the negative pressures of alternating firing cylinders to “scavenge” or reduce the exhaust port pressure of a cylinder whose exhaust valve is just opening. If the pressure is thus lowered more of the exhaust gasses can be extracted from the cylinder and a non-diluted (with exhaust) inlet charge can fill the cylinder for the next firing. With a blown engine with significantly higher (than atmospheric pressure) inlet pressure this reliance to cylinder scavenging is not necessary because the high pressure inlet charge just blows the old exhaust gasses out the exhaust port.
“JBA’s objective was to stay within the perimeters of the way Ford built the motor, i.e., 13-14 lbs of boost.”
Not sure of how you make a point that a header manufacturer’s “objective” is to stay within the “perimeters” of the engine design? As Bill correctly points out, headers can alter slightly the measured boost. If the OE exhaust system was restricted in general thruput then headers will make a larger reduction in measured boost due to the increased flow efficiency. If the OE system was good by design, very little change in measured boost will be seen.
“…but more importantly, with 19-21 lbs of boost the head gaskets, intake manifold gaskets, along with the rods, pistons and crank are not designed to take 19-21 lbs of boost.”
How do you possibly know this for a fact? As others have posted this 5.4L FGT engine (which by the way IS different in a number of ways from that offered in the Mustang) is very stout and has been modified in various forms (Whipple, twin-turbo configurations, etc) to reliably produce horsepower values significantly higher the OE 550/500 configuration. And it is certainly reasonable that the Ford/Roush engine design team did a significant amount of dyno development testing on our engine at much, much higher inlet boost pressures to determine where to comfortably set the OE boost pressure. If you have ever examined the internal parts of this engine, they are VERY carefully designed for strength and performance. Ask Jason Heffener who has studied these components.
“So, it IS the exhaust system and tune that truly makes reliable hp without the risk of doing damage to the motor.”
Sorry, I must disagree. For the reasons cited above, the headers will look good and if that is your goal, spend the money. If performance gains are desired, there are certainly more cost effective ways of increasing net power.
