I am sick of mis-information, here is the truth of Speed Density cars!
Thread Starter
5th Gear Member
Joined: Jan 2006
Posts: 2,645
From: So-Cal
I am sick of mis-information, here is the truth of Speed Density cars!
OK, people on here do not seem to have a clue about speed density. Speed density is a form of controling the air/fuel mixture by pre-set codes in the computer. YOU CAN MANIPULATE THEM WITHOUT A CHIP!
Speed density was the first form of air management for the multiport EFI Mustangs. It was used into the 90's in trucks and non-H.O. 5.0's, such as Lincolns and T-Birds. For the Mustang, it was used in all 5.0's in 1986, 1987 and all 88's except for the ones sold in California.
All and all, you can do anything that you want to do to a speed density car except for a large cam. Speed density requires vacuum, at least 19 inch pounds. Stock 5.0L HO cam's advertised specs are 266°/266° duration, 0.444"/0.444" lift, Iskidarian makes a cam that works well that is 252°/257° duration and .465"/.480" lift. The reason why the cam works well is that the lobe center is 112°, good for vacuum.
I am currently running a speed density 1986 5.0 with a 65mm Accufab throttle body, a REAL Ford Cobra intake, GT40 Y heads, the cam listed above, equal length headers, a custom X-Pipe and Dynomax Ultra Flow mufflers. My fuel system is a Walboro 155 lph pump, an Accufab adjustible fuel preasure regulator and FRPP 24 pound injectors.
The trick to running speed density is to have a cam the produces enough vacuum, and to adjust the fuel and air flow correctly. As you increase the air, you will have to increase the fuel in equal ratios to stay within the factory programming. Some will tell you that this is not possible, but it is. The best thing to do is to work with a shop that has a dyno and can read air/fuel exhaust ratios. I daily drove my 86 with this combo for over 50,000 miles without issue.
Speed density was the first form of air management for the multiport EFI Mustangs. It was used into the 90's in trucks and non-H.O. 5.0's, such as Lincolns and T-Birds. For the Mustang, it was used in all 5.0's in 1986, 1987 and all 88's except for the ones sold in California.
All and all, you can do anything that you want to do to a speed density car except for a large cam. Speed density requires vacuum, at least 19 inch pounds. Stock 5.0L HO cam's advertised specs are 266°/266° duration, 0.444"/0.444" lift, Iskidarian makes a cam that works well that is 252°/257° duration and .465"/.480" lift. The reason why the cam works well is that the lobe center is 112°, good for vacuum.
I am currently running a speed density 1986 5.0 with a 65mm Accufab throttle body, a REAL Ford Cobra intake, GT40 Y heads, the cam listed above, equal length headers, a custom X-Pipe and Dynomax Ultra Flow mufflers. My fuel system is a Walboro 155 lph pump, an Accufab adjustible fuel preasure regulator and FRPP 24 pound injectors.
The trick to running speed density is to have a cam the produces enough vacuum, and to adjust the fuel and air flow correctly. As you increase the air, you will have to increase the fuel in equal ratios to stay within the factory programming. Some will tell you that this is not possible, but it is. The best thing to do is to work with a shop that has a dyno and can read air/fuel exhaust ratios. I daily drove my 86 with this combo for over 50,000 miles without issue.
3rd Gear Member
Joined: Apr 2006
Posts: 551
From:
RE: I am sick of mis-information, here is the truth of Speed Density cars!
ORIGINAL: Twister
OK, people on here do not seem to have a clue about speed density. Speed density is a form of controling the air/fuel mixture by pre-set codes in the computer. YOU CAN MANIPULATE THEM WITHOUT A CHIP!
Speed density was the first form of air management for the multiport EFI Mustangs. It was used into the 90's in trucks and non-H.O. 5.0's, such as Lincolns and T-Birds. For the Mustang, it was used in all 5.0's in 1986, 1987 and all 89's except for the ones sold in California.
All and all, you can do anything that you want to do to a speed density car except for a large cam. Speed density requires vacuum, at least 19 inch pounds. Stock 5.0L HO cam's advertised specs are 266°/266° duration, 0.444"/0.444" lift, Iskidarian makes a cam that works well that is 252°/257° duration and .465"/.480" lift. The reason why the cam works well is that the lobe center is 112°, good for vacuum.
I am currently running a speed density 1986 5.0 with a 65mm Accufab throttle body, a REAL Ford Cobra intake, GT40 Y heads, the cam listed above, equal length headers, a custom X-Pipe and Dynomax Ultra Flow mufflers. My fuel system is a Walboro 155 lph pump, an Accufab adjustible fuel preasure regulator and FRPP 24 pound injectors.
The trick to running speed density is to have a cam the produces enough vacuum, and to adjust the fuel and air flow correctly. As you increase the air, you will have to increase the fuel in equal ratios to stay within the factory programming. Some will tell you that this is not possible, but it is. The best thing to do is to work with a shop that has a dyno and can read air/fuel exhaust ratios. I daily drove my 86 with this combo for over 50,000 miles without issue.
OK, people on here do not seem to have a clue about speed density. Speed density is a form of controling the air/fuel mixture by pre-set codes in the computer. YOU CAN MANIPULATE THEM WITHOUT A CHIP!
Speed density was the first form of air management for the multiport EFI Mustangs. It was used into the 90's in trucks and non-H.O. 5.0's, such as Lincolns and T-Birds. For the Mustang, it was used in all 5.0's in 1986, 1987 and all 89's except for the ones sold in California.
All and all, you can do anything that you want to do to a speed density car except for a large cam. Speed density requires vacuum, at least 19 inch pounds. Stock 5.0L HO cam's advertised specs are 266°/266° duration, 0.444"/0.444" lift, Iskidarian makes a cam that works well that is 252°/257° duration and .465"/.480" lift. The reason why the cam works well is that the lobe center is 112°, good for vacuum.
I am currently running a speed density 1986 5.0 with a 65mm Accufab throttle body, a REAL Ford Cobra intake, GT40 Y heads, the cam listed above, equal length headers, a custom X-Pipe and Dynomax Ultra Flow mufflers. My fuel system is a Walboro 155 lph pump, an Accufab adjustible fuel preasure regulator and FRPP 24 pound injectors.
The trick to running speed density is to have a cam the produces enough vacuum, and to adjust the fuel and air flow correctly. As you increase the air, you will have to increase the fuel in equal ratios to stay within the factory programming. Some will tell you that this is not possible, but it is. The best thing to do is to work with a shop that has a dyno and can read air/fuel exhaust ratios. I daily drove my 86 with this combo for over 50,000 miles without issue.
5th Gear Member
Joined: Jan 2006
Posts: 3,926
From: Puerto Rico
RE: I am sick of mis-information, here is the truth of Speed Density cars!
FYI....you may also want to check other cam alternatives you'll find at http://www.50tech.com/viewtopic.php?p=51824#51824 , for SD Mustangs...
1st Gear Member
Joined: May 2006
Posts: 60
From:
RE: I am sick of mis-information, here is the truth of Speed Density cars!
So what is really going on with my 88GT ? My air delivery consists of a K&N cone on the pipe that is it, all hardware was removed by previous owner. Is this a bad thing?
