how far can i go with my speed density (building a motor soon)

Bump, Im interested in this too as a fellow 86 owner.

As far as you want. Just keep the stock cam .

Go to 5.0tech.com and look at their SD cam page. I just put a set of P heasd form tri state with 1.7s, stock cam and a cobra intake my little brothers 119k mile shortblock and the thing runs AWESOME! Seriously, his car is way faster than mine, and hes only got 2.73's

talk to T-moss, he has done a fair amout of stuff with SD

I am putting together a SD combo for my 88lx right now that I am hoping to be within spitting distance to 300 rwhp NA and I will spray it up to 400-450

well ive played with the s/d system for sometime now.

my current combo is 180k mile shortblock
old styler performer heads with 1.9 valves
crower 15511 cam and 1.6 rockers
performer intake , 70mm tb

got the other normal bolt ons exhaust and pullies and what not

c4 trans , 10 inch converter and 4.10 gears

in a 3250 lb car ive been 12.40 at 108 but im now fighting some hot weather issues and cant get out of the 12.60 range .

the car runs great strong throughout the rpm range and the only time it gives me fits is in reverse and on cold starts .

speed denisty isnt as bad as people make it out to be like stated just watch cam choices

1988 302 block new pistons and rods, windage tray, oil pan and fasteners (about 9.5-9.6:1 CR)

Gt-40 heads ported, valve job, Trick flow valve spring/retainer/locks kit (part number TFS-2500100),

1.6 Roller rocker arms

Professional Products intake manifold and 70mm TB

24 lb's

Factory HO roller cam reground to Comp cams XE grind

NX plate system

3.55 rear gears

Full length headers 1 5/8 primary 2.5 collector, with no cats, x-pipe, 2.5” exhaust pipe and I run cutouts at the track (the cutouts are after the x pipe)

and a few other top secret tricks I have up my sleave.


I am hopeing to run mid 12s NA and low 11's on the bottle


also talk to stock50lx, he had a 87 speed density car that he was running mid 12s with stock bottom end, gt-40ps and 3.55's

Only answer that really works is...maybe. Maybe the car will work OK with a cam swap...lots do, lots don't. Should the car become a headache to drive (unfortunately I know what a pee'd off SD car runs like) you can then switch over. No two cars will behave the same to changes so no one can really answer your question.

Joe ran his super charged with speed density..

yeah I think vortec and paxton still make the check valves and such to run uner boost

i've always heard SD takes mods well. Just will act up with a camshaft. But intake and heads it will run fine i am told....

With the mods you are planning you should be fine, it wont like a letter cam though. You should get a speed density computer from an 87 or an 88, even on a stock 86 you will pick up some power from the ECU swap.

you can also get a vacume reserve can or tank for when at idle....

here is some good info

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.