Speed Density or mass air?

[Topples]

I have a 1987 Lx and would like to start doing some engine mods, it is all stock and I've been told I can't even change the cam because it it speed density not mass air. I know I could do a swap but that is large cash!! how could I get around this problem? someone also told me I could get a tuner. any advice would be great.

[jody]

There is a website 50tech.com :: Home and theres quite a bit of speed density info on there, as well as a list of camshafts that you can upgrade to while retaining speed density. If you read thru there are actually quite a few options for you (I'm in the same boat) you just need to make the right ones

[jody]

Some info I found posted by a SD user:

"......With SD the area you want to watch for is the cam. Once you go over 220* duration@.050, then your idle can become unstable and can start surging etc. SD likes High lift, low duration cams, since it relies on vacuum. Most people switch to MAF when going with much larger cams, but if you stay within reasonable limits, SD will run just fine & hard. My 347 runs great with SD although I have pushed the cam limits a bit far with it, but I knew what to expect and with some fine tuning it's not that bad for ME. With SD, heads, intake, gears, blower, N20, all the goodies can be used and have no problems with it. MAF will give a more precise A/F reading to the computer since it reads & adjusts BEFORE entering the motor where SD reads AFTERWARD'S, and thus MAF gives you just a slight better off idle throttle response, a more precise A/F metering, and doesn't rely on vacuum in the way SD does, but I've also seen many MAF cars encounter surging problems (modded or not), unstable cruising modes etc as well, all the things that many claim is an SD problem. If you have done any in depth research you'll find many people still have SD with blowers etc and have absolutely NO problems. SD has a better fuel curve at higher rpm than does MAF (until MAF is tweaked or modified)

Early 87 5.0's had a little more aggressive cam than what was used in the mid 87-89 5.0's which then were changed again in 1990. If the date code on your 87 5.0 HO is before 4/87, then you have this odd cam. It's not widely known about this oddball cam. The difference being it had 276/276* vs. the later 276/266 cams, plus a slightly more aggressive ramp rate. This particular cam works extremely well with 1.72 RR's, giving you a total lift of .475 and duration@.050 of 209*, and a 115.5 LCA. It pulls very hard right up to 5800 RPM with good exhaust, intake and reasonable gearing (3.55's or better). I am currently trying to find the Ford Part# for this cam as back in 1992 I read in a Ford Motorsport parts book the different part numbers for each cam. The reason I mention this cam is simply because it came only in early SD 87's.

Don't get me wrong now, there comes a time when MAF IS needed, unless you go DFI (Digital Fuel Injection) and with that, you can tune your motor till your hearts desire. I have discovered that having even a basic off the shelf computer chip (Module) help with minor idle issues. Some off the shelf chips will increase your advance rate in the distributor, alter your fuel curve, richen up the motor at WOT as well as add 4* to your total timing which other than a small boost in HP & TQ also allows you to keep your stock setting of 10*, thus making it easier on your starter motor to turn over the motor. I have heard all the rumors about many aftermarket chips doing nothing and being a complete waste of $$. I'm curious if those people who make these claims have actually dyno'd their cars before and after the chip install for absolute verification. Personally, I highly doubt it. I cannot speak for all of the manufactures out there as I have not tested them. I can only speak for the Hypertech Brand, which I personally used for 4 yrs and had the motor & car tested for what changes occurred. This is where my information comes from as listed above. I was pleased with the overall results of the chip, although I think pricing is a bit high for any off the shelf chips.

One key note here, I always recommend a custom cam AND a custom chip when using SD and a moderately modified motor, but it is not necessary with just basic mod's such as intake, heads, headers, gears, exhaust and roller rocker arms. SD also is more sensitive to fuel pressure settings; TPS settings, idle settings, as well as all your sensors, so make sure they all are in good working condition...."

[88-GT]

Speed density can be a pain but on a stock/bolt on modded car they perform really well. My car is SD and with limited mods, mostly just exhaust it runs perfect.

At the begining of the year I always adjust idle, and tps and am usually fine for the rest of the year. Car also makes good power for stock (218HP, 274TQ to the wheels).

That being said the second I decide to go cam I will be going to MAF. It is easy and cheap and when you look at all the hassle just to stay SD over a 1.5hr install and 200 bux of JY parts, I just couldnt justify changing the whole motor setup over a few electronic pieces. Anyways, just my 2 cents.

[The Fox Master]

That article is not exactly correct regarding speed density operation:

MAF will give a more precise A/F reading to the computer since it reads & adjusts BEFORE entering the motor where SD reads AFTERWARD'S

SD doesn't read airflow at all - it relies on a table that contains what ford figured was the volumetric efficiency of the motor. So, at a given load and rpm it would provide X amount of fuel and Y amount of timing. The only compensation the car could make was for barometric pressure and vacuum. So when you radically change the incoming airflow with bigger heads, intake etc, or change the vacuum seen by the MAP sensor with a big cam the computer has no way to deal with and compensate for these changes. Now people have been "fooling" ford SD to working with bigger heads and cams and even forced induction since 1986 by providing enrichment with an increase in fuel pressure, and manually adjusting the distributor for timing. This does work somewhat, but it pretty hokey in this day and age, and does require carefully chosen parts and patient and equally careful tuning of fuel pressure. As said these systems do work very well with minor modifications, and in may ways were more aggressive tunes than stock mass air setups making many 87-88 mustangs a fair bit quicker than their 89+ brothers and sisters stock for stock.

Now Mass Air is a pretty kickass system. It actually reads the incoming airflow as Kilograms per hour and outputs a given 0-5V signal that the computer can then use to calculate a fairly precise fuel delivery. Meaning that this system is adaptable - you could add big heads and intake and the computer would see the extra air incoming and provide the needed extra fuel. Because it doesn't use a vacuum source for calculations a radical cam can be used with minimal tuning and with the advent of bigger injectors and matching aftermarket mass air meters the range of airflow could be greatly increased, as could the fuel output. The result was the highly modifiable and very drivable MAF platform that really put the 5.0 mustang and it's vast aftermarket at the head of the pack.

IMO a MAF conversion is the only way to fly (unless you want to ante up for a nice 2000$ standalone setup). You can pick up a used ECU for 100$ or less, and a conversion does not require a whole wiring harness, only that 4 wires for the mass air meter be run back to the 60 pin ECU connector, and that a few pins be moved around within the harness. Shakes and FXST recently did this swap if you have any questions. The swap kit (minus the ECU) is $39.95 US and available from Interactive Systems & Technologies Mass Air Home Page.

-FM

[ronburgundy]

i would go mass air, it opens up a world of possibilities. if you shop around you can likely come up with the required parts fairly reasonably(used)

[shakes]

I bought the IST kit and it wasn't too bad of an installation thanks to some help I recieved.