I just sold my 89 LX and was looking at another LX but this one is a 1986 car with speed density. How does this system work? what are the pros and cons compared to a carb setup and/or MAF? I like everything about this car. It is in perfect shape inside and out, but this speed density crap is got me thinking. Thanks for the help!
Well speed density measures incoming air by using the vacuum pressure. The one thing with speed density is if you are planning on a large cam upgrade then it will no longer work because a larger cam will lower the vacuum pressure. So if you are not planning on changing the cam then there is nothing at all wrong with sd. But if you really like the car and do plan on a cam then you can always convert the car to MAF pretty easily. I am doing mine right now and it cost me about $250 US total. I am sure it can be done cheaper as well because I paid a little too much for my computer. One other thing that I always hear people saying about speed density is that their idle is erratic and stuff like that but my idle has always been good with no problems at all. Well that is my thought on the situation, hope it helps you come to a decision but I am sure there are plenty of other comments coming your way.
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1988 Mustang GT - 331, hand ported Twisted Wedge heads, TFS Stage 2 cam, R-Series intake, 1 3/4 long tubes, dual 3" exhaust, tko 600, Zex 100 shot, ect.
357 rwhp/ 361 rwtq on motor
428 rwhp/ 484 rwtq on 100 shot
12.48 @ 111 mph on motor (2200ft + elevation)
11.7 @ 120 mph on 100 shot (2200ft + elevation)
...but I am sure there are plenty of other comments coming your way.
lol maybe not? Thanks for the info. I had two 5.0 mustangs I was looking at but they both are out of my range. Tried negotiating and nothing worked, so no fox for me... for a while. I mean the cars are in good shape but $5500 (went down from $6500) for a bone stock 90 GT and $7500 (firm!) for the 86 LX are kind of high prices. I know a lot of people want them, but geez! Help the man out, here!!! lol. I wouldn't modify the car much, except for exhaust and other little things, so I would not even touch the S.D. system in the car for a while. Te GT was MAF so it was all cool there. Anyway, thanks again for the info:thumbsup
i have a speed density car. doesnt bother me one bit. from what i understand, MAF cars get better mileage, but hey, im not driving a 5.0 for its economy.
its an easy swap to MAF. if you like the car, dont let the SD system stop you from buying it.
That being said, i think $5500 and $7500 are outrageous prices for 80's mustangs.
3 grand more and you can get a 2000 GT with like 30,000 miles on it around here.
i paid 1500 bucks for my LX, and would never pay more than 3 grand for a fox body from the 80s
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1965 Mustang Coupe Project: 1965 Mustang Inline 6 (For Now) Coupe, New Floors, New Quarters | Ford 9 Inch Rear, 11" Rear Disc Brakes, 3.50:1 Gears | Control Freak Front U/L Control Arms, Global West Adj. Strut Rods | KYB Gas-A-Justs, Grab-A-Trak 620 Coils & Mid-Eye 5-Leafs | Global West Tubular Subframe Connectors | Addco 1-1/8 Front Swaybar Kit
I have an 86 GT and the speed density is fine; I have no major mods though. From what I have read, it's when you start adding heads, cam, intakes, headers, or forced induction that you reach the limitation of the stock speed density. I have also read that you can have your car tuned to run well with these mods. I don't know for sure and will probably have to cross this bridge someday myself.
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1986 Mustang GT - BBK Cold-Air Induction - Flowmaster American Thunder aftercat system - Steeda Tri-Ax Shifter - Summit Racing High Flow Water Pump - 160 Degree Thermostat - Sony MP3/CD Player - Otherwise, All Stock and Loving it.
i have a speed density car. doesnt bother me one bit. from what i understand, MAF cars get better mileage, but hey, im not driving a 5.0 for its economy.
its an easy swap to MAF. if you like the car, dont let the SD system stop you from buying it.
That being said, i think $5500 and $7500 are outrageous prices for 80's mustangs.
3 grand more and you can get a 2000 GT with like 30,000 miles on it around here.
i paid 1500 bucks for my LX, and would never pay more than 3 grand for a fox body from the 80s
Yeah, I won't even think about it. I already have an 89 which I tried getting rid of, but the prospective buyer backed out... so back to square one. He even said he wanted to get his money back from when he restored it. Thanks for the help anyway!! Now I really won't think it twice if I see a sd car in good shape.
I have an 86 GT and the speed density is fine; I have no major mods though. From what I have read, it's when you start adding heads, cam, intakes, headers, or forced induction that you reach the limitation of the stock speed density. I have also read that you can have your car tuned to run well with these mods. I don't know for sure and will probably have to cross this bridge someday myself.
That's what I heard too, but I wasn't planning on modding it until a few years down the road. Thanks for the input!
How does speed density work?? 
Thanks for the help anyway!! Now I really won't think it twice if I see a sd car in good shape.
