Skip to main content ↑ ↓
Topic: Speed Density and Supercharging? (Read 2340 times) previous topic - next topic

Speed Density and Supercharging?

I have a good friend who is preparing to buy a 30k mile Lincoln LSC, completely original, spotless car next weekend. He wants to keep it stock but wants to add a supercharger. In my years everyone always does a Mass air Conversion or stand along, but rarely are these stock engines. He doesnt want to add to the harness, or do anything that isnt easily reversible. My conversion on the t bird for mass air went so smooth, and it idles and behaves so well, but I don't believe I can convince him. He bought one of these new in the late 80's, and after many years and many other projects, I convinced him to go look at this new project. Any thoughts?
1988 LX, 306 with GT40P heads, Downs Upper Intake on Truck Lower, Powerdyne Supercharger and T5 swap.  Scavenger Hunt Build at it's best.

Speed Density and Supercharging?

Reply #1 –
In my honest opinion, there's other things he's going to need to address if he wants to boost it. Fuel pump, exhaust, intake, injectors, EEC, transmission, motor mounts, brakes....


Even though it's a low mile car, throwing a blower on without the necessary supporting upgrades will very quickly leave him walking. Unless he drives like my granny did.

What fun is that? LOL

The exhaust will be the biggest bottleneck, specifically the headers. Easily enough, he can use Mustang shorties and solve that, or at least make it better than stock.
I'd also probably do an aftermarket exhaust, too.

The heads are of course E7's and will be ok to a point, hopefully he doesn't expect to get over 400 horses and still be reliable without some port work, then there's the intake. I'd at least go with a Cobra/Explorer upper and lower, and the Explorer
s 65mm TB.

Sure as hell going to need a higher capacity fuel pump. A Walbro 255 pound/hour is usually considered doable, will get you to block splitting levels, anyway.

The HO cam is good, but there's better, too. If you're gonna do the intake....the cam is not much more work.

That leaves the trans. No witchcraft there, just do the epoxy mod and make sure the fluid stays clean and cool.

4.10 gears will wake it up, too, especially with that AOD.

What kind of power is he wanting? Lots of people have 400 horsepower 5.0s that are reliable, but none of em have stock intakes and heads. ;)
'98 Explorer 5.0
'20 Malibu (I know, Chevy, but, 35MPG. Let's go brandon, eh)

Speed Density and Supercharging?

Reply #2 –
Thundersport what's an epoxy mod?

Speed density is a viable option if you have the right tune in it, mass air is much easier and cheaper to tune though. I assume he probably is aware that he will need a fuel pump,injectors, head studs and the list goes on and on depending on the boost level he is planning. 5-8 psi would probably be fine and still fun.  I daily drive a bone stock 5.0 with E7s and a stock aod. pushing 8-10 psi and the occasional 150 shot of nitrous.Do I think that will last forever? Of course not, but its fun and I have a few extra blocks laying around waiting. I guess my point is most stock engines can handle lower boost levels just fine tell him turbos are more fun than superchargers though.

Speed Density and Supercharging?

Reply #3 –
I would like to see any info anyone has on tuning a ford speed density system for boost. Speed density is great for boost outside of the ford world but the ford system cannot use the map to measure boost level and accurately calculate load.  I’m no tuner but all you could do is pull timing out of the engine and set the fuel tables to a specific operating condition.  Say wot.  The speed density system would not know the load whenever the engine was beyond 0” of vacuum and into boost. Everyone I have seen running boost on ford speed density is doing it crudely and the thing runs rich to compensate for lack of load accuracy.
One 88

Speed Density and Supercharging?

Reply #4 –
In the VE fuel table the Y-axis is Load% and the X-axis is RPM so depending on Load and RPM the computer decides what AFR to run. Load is calculated by quite a bit, for instance Cubic Inch Displacement which can be changed within the computer to help with the tuning process. You can also change the table scalars itself to see higher load ranges because supercharged cars will obviously see load ranges higher than 100% load and the stock setup only goes to 90% load I believe. When you don't change these scales or scalars the computer extrapolates the data from what it has and the result is you're super rich, especially at high load ranges. To tune it correctly you need access to customize these tables among many more like the spark table, and at minimum a wideband and boost gauge that you can data log to see at what load you had what boost and what Afr and slowly but surely build a VE table that works and is more accurate.

Speed Density and Supercharging?

Reply #5 –
Dog is right, its an involved process to tune for forced induction using SD. You're largely building it from scratch and you'd better be putting good numbers in or it'll be the burn while you learn program. To be blunt, unless you have a LOT of spare time, some considerable tuning knowledge, and preferably chassis dyno access, it's not worth installing a supercharger unless a mass air conversion is part of the upgrades.

 Now, lets talk smart vs dumb use of funds and time.  OP's friend will waste his money and time on a centrifugal supercharger in this application in my opinion.  The Mark 7's weight and auto trans lends itself far more to nitrous as a power adder for effectiveness, bang for the buck, and simplicity.

The Mark 7 is a heavy car with a small, slow revving engine that is not at all efficient at high rpm's. And it is backed by a power-sapping automatic with a poor gear ratio spread and a torque convertor horrible for acceleration and high rpm.  Since a centrifugal supercharger's impeller output thrives on engine acceleration and higher rpm, this is obviously a poor choice for a power adder.

The far better choice would be an entry level nitrous system. Wet or dry, doesnt matter at this low of a power level. Either will provide substantial torque gains in the midrange to moderate rpm levels that the engine is actually efficient in.

Torque, and a bunch of it, is what is needed to move a Mark 7 with any authority, and nitrous has an inherent tendency to quickly elevate cylinder pressures upon activation, which delivers the noticeable torque spike between 3K to 5K rpms that creates cheesy grins and has made it famous for years.  Plus, you can keep the speed density, and your hair by not pulling it out fighting your tune for months or years.

Speed Density and Supercharging?

Reply #6 –
If you want to stay speed density get a megasquirt pnp. Also a good turbo setup will hit peak boost far quicker than a centrifugal supercharger.
88 Cougar
88 T-Bird
other cars that don't apply to this forum

Speed Density and Supercharging?

Reply #7 –
Quote from: Moonmount;468447
If you want to stay speed density get a megasquirt pnp. Also a good turbo setup will hit peak boost far quicker than a centrifugal supercharger.

Yes it will. But unless remote mounted turbos are used, it will also be difficult to install in the Marks engine bay while keeping the air ride compressor, the Teves ABS unit, the air conditioning and power steering intact.

 The OP stated the owner wanted something easily reversible with as few changes as possible. Noone that has actually installed a turbo system on a Mk 7 will ever describe it as something easily removed/taken back to stock.  Nitrous and the few neccessary supporting mods is his answer, given the stipulations in the OP.

 I'd wager the number of people, nationwide, that have a daily-driven turbo 5L Mark 7 can be counted on one hand, possibly one finger. The reason? Talking about it is easy and cheap, doing it right is difficult and far more expensive.

Speed Density and Supercharging?

Reply #8 –
Quote from: Vintage;468445
Dog is right, its an involved process to tune for forced induction using SD. You're largely building it from scratch and you'd better be putting good numbers in or it'll be the burn while you learn program. To be blunt, unless you have a LOT of spare time, some considerable tuning knowledge, and preferably chassis dyno access, it's not worth installing a supercharger unless a mass air conversion is part of the upgrades.

 Now, lets talk smart vs dumb use of funds and time.  OP's friend will waste his money and time on a centrifugal supercharger in this application in my opinion.  The Mark 7's weight and auto trans lends itself far more to nitrous as a power adder for effectiveness, bang for the buck, and simplicity.

The Mark 7 is a heavy car with a small, slow revving engine that is not at all efficient at high rpm's. And it is backed by a power-sapping automatic with a poor gear ratio spread and a torque convertor horrible for acceleration and high rpm.  Since a centrifugal supercharger's impeller output thrives on engine acceleration and higher rpm, this is obviously a poor choice for a power adder.

The far better choice would be an entry level nitrous system. Wet or dry, doesnt matter at this low of a power level. Either will provide substantial torque gains in the midrange to moderate rpm levels that the engine is actually efficient in.

Torque, and a bunch of it, is what is needed to move a Mark 7 with any authority, and nitrous has an inherent tendency to quickly elevate cylinder pressures upon activation, which delivers the noticeable torque spike between 3K to 5K rpms that creates cheesy grins and has made it famous for years.  Plus, you can keep the speed density, and your hair by not pulling it out fighting your tune for months or years.


What he said.


Bang for the buck nitrous is better than both and easily reversible.

Speed Density and Supercharging?

Reply #9 –
Quote from: Moonmount;468447
If you want to stay speed density get a megasquirt pnp. Also a good turbo setup will hit peak boost far quicker than a centrifugal supercharger.


Agreed, there is no reason to try and use 30 year old tech when there are so many options nowadays even beyond the ever increasing in price megasquirt.
One 88

Speed Density and Supercharging?

Reply #10 –
Quote from: CougarSE;468466
Agreed, there is no reason to try and use 30 year old tech when there are so many options nowadays even beyond the ever increasing in price megasquirt.

Has anybody here ever used megasquirt? If so, what are the capabilities and how is the tuning software that comes with it? I looked at them back when I started but it was too expensive for me and it looked like a nightmare to set up. I use a Moates Quarterhorse that plugs into the J3 port of the ECU and I run Binary Editor for my tuning software. Cost me a total of $350.00 plus the price of a cheap used laptop, works great for what I use it for. I ended up buying another one to tune my friends cars I also have a chip burner which is handy, I use the Quarterhorse to do the initial tuning then just burn a chip from the saved file on Binary Editor.

Speed Density and Supercharging?

Reply #11 –
I used an early version of it a long time ago on a friends car, it was okay overall but Im sure its been improved since. The setup you have is probably the best bang for the buck for what you're doing.

I'll say this. There is a hell of alot to be said for some brutal honesty in an early weighing out of the benefits/choice of power adder versus the need to tune, datalog, be mindful of seasonal changes in fuel/air temps/density, and keep good records for all of it. Some people are dedicated to it and will play by the rules, some just won't.

All of that to say, in my experience, you can't really advise a power adder or engine mgmt program until you know what kind of owner you have and their expectations.
 

Speed Density and Supercharging?

Reply #12 –
Easily reversible is relative to the skills and resources of the individual.
For example:  I am an ASE Master technician, I have tools, lifts, stands, cranes and keys to the shop.  I'd pull that 30k HO motor and store it, and I'd replace it with a 331 with a twin screw blower, a mild cam, MAF, a Walbro 255, and a tune.  I'd swap the whole exhaust for 2.5" and Magnaflows with large long tube headers.  Why?  Because I can, and if I wanted to put it all back, I could do that, too.
For somebody more normal, nitrous is probably the easiest install/uninstall to offer reasonable gains.