SOHC V6 Supercharger

The purpose of this thread is to discuss the design and possible development and installation of a supercharger for my 2000 Sport SOHC V6 engine. I have no first hand experience with forced induction systems and want to learn from forum members that have them on their vehicles. While I don't plan to implement a turbocharger system, there are many problems common to all types of forced induction systems.

The easiest and least expensive solution would be to modify a Ranger SOHC V6 Banshee kit and purchase a used Thunderbird supercoupe positive displacement blower. However, the kit makes no provisions for an aftercooler which I think is beneficial even with only 5 psi of boost.

The Explorer Express supercharger kit includes a quality looking manifold but one is very difficult to obtain.

Once again, there are no provisions for an aftercooler.

I suspect the best solution for me would be a centrifugal supercharger with a water aftercooler. With my oil coolers and remote filters I have very little room in front of the radiator for an intercooler. I am interested in a boost in the range of 5 to 8 psi - enough for a significant performance increase but not so much to adversely impact reliability and require beefing up of engine internals or the transmission/torque converter.

Procharger sells a kit for the 2005 - 2010 Mustang V6.

But the Mustang configuration is opposit to the Explorer - intake on left and battery on right. Also, there is a lot more room between the engine front and the radiator rear on the Mustang than on the Explorer.


Vortech also makes a kit for the Mustang but there are the same problems.

The logical location for a centrifugal supercharger is the same side as the air filter box and intake manifold inlet port. Unfortunately, that is where the alternator is located. I'm investigating the possibility of replacing the belt driven power steering pump with an electric motor driven pump and then relocating the alternator to the old power steering pump location.

 

[jd4242]

Thanks for posting that link. It looks like the plenum bolts directly to the heads.
View attachment 69440
If so, then what about the knock sensor and the injector wiring harness?
View attachment 69441
A new injector wiring harness could built but I would hate to lose the knock sensor - it is even more important with forced induction.
View attachment 69477
From the above photo it looks like there is no problem with the knock sensor because it is lower than the head ports.
From the photo in the first post it looks like the Explorer Express phenum allowed retention of the knock sensor and stock injector wiring harness.

I bet you if you split that harness open there is two main groups of wires in there.one per side or bank.if so there is no point of having it grouped together in the middle.just split it and run one on each side of the sc mount.my buddy has a ton of harnesses for sohc including some from a ranger,ill ask him when he gets home and check it out

 

[jd4242]

here is the reply to the email i sent rpcaster.so i was right you can spit it and put it on the outsides

''Sounds like you might have an Explorer?
I does mount to head. You can open loom and move injector wiring to outside "like Ranger" and other can mount below in void area. Check out website bansheesuperchrger.com visit "customer rides" click on the year link below explorer and I believe you will find add'l info.

- rpcaster''

 

[2000StreetRod]

belt slip

One concern for belt driven superchargers that is not an issue for turbochargers is drive belt slip on the supercharger pulley. Higher boost is achieved by decreasing the driver pulley to make the supercharger spin faster. The faster the supercharger spins the more force required to drive it. A smaller pulley reduces the contact area between the drive belt and pulley increasing the chance of belt slip. Unfortunately, the SOHC V6 (unlike the V8) has an integrated harmonic balancer/serpentine belt pulley. It is impractical to add a dual belt pulley to the harmonic balancer. Therefore the supercharger must be driven by the serpentine belt that drives the rest of the accessories. It looks like the Explorer Express kit replaces the stock idler pulley with a dual idler pulley and snout support bracket.

This configuration would provide about 180 degrees of supercharger pulley wrap (almost the maximum).

I wonder what boost (smallest pulley) can be achieved without belt slip.

 

[Dono]

http://www.pulleyboys.com/store/product.php?productid=35&cat=9&page=1
I'm not sure, but see Rockets postings on efficiency of the m90. Also, I haven't heard of anyone complain of belt slip. You could be right though.

 

[2000StreetRod]

Fuel efficiency

It may seem inconsistent to discuss supercharger fuel efficiency but when gas prices approach $4 per gallon it is something to consider. Eaton superchargers are positive displacement air pumps. That is one reason they produce boost at low engine speeds. When a blower is producing boost it is performing work which requires energy. An Eaton supercharger is ideal for accelerating a heavy vehicle from rest or from upshifts for a transmission with wide spaced gearing. Boost is probably not required at idle, normal cruise speeds or deceleration.

The chart below posted by Rocket 5979 shows the inlet flow vs supercharger rpm which is quite linear.

One article I read states the airflow of a centrifugal supercharger increases proportional to the square of the rotation speed. If 8 psi of boost is produced at 6500 rpm engine speed only 2.8 psi of boost is produced at 3250 rpm engine speed.

I think centrifugal superchargers "slip" more than positive displacement superchargers at low engine speeds. Consequently, they produce less boost but require less energy. Accordingly, a centrifugal supercharger may have better fuel efficiency than an Eaton supercharger for a daily driver. On the other hand, for a heavy SUV the lower speed boost provided by an Eaton supercharger will make the engine displacement seem significantly larger and much more responsive. More torque at low engine speeds could reduce average engine speeds and improve fuel efficiency. Since vehicle manufacturers incorporate positive displacement superchargers much more frequently than centrifugal superchargers I suspect they have already determined which type is most fuel efficient and driver satisfying.


The rotation speed and boost of a turbocharger is more dependent on engine load than either of the above types of superchargers. As exhaust flow increases so does the turbine speed and associated boost.

 

[boominXplorer]

All the newer 01 newer sohc's (except explorer) have steel fuel rails instead of plastic and have the wiring harness on top of the fuel rails. They also use plastic valve covers with the pvc valve on the drivers side instead of using the box thingy in a freeze plug in the valley of the block.

 

[2000StreetRod]

fuel rails & injector harness

All the newer 01 newer sohc's (except explorer) have steel fuel rails instead of plastic and have the wiring harness on top of the fuel rails. They also use plastic valve covers with the pvc valve on the drivers side instead of using the box thingy in a freeze plug in the valley of the block.

Thanks, Chris. That could be very helpful, cost and labor saving information.

 

[2000StreetRod]

Gearing & engine performance

The formula for vehicle speed vs engine rpm is:

mph = (rpm*tire dia.)/(ratio*336)

My BFG P235/75R15 tires have a diameter of 28.86 inches
My rear axle ratio is 3.73:1

1st 2.47*3.73=9.21 @ 6,000 rpm = 56 mph
2nd 1.86*3.73=6.94 @ 6,000 rpm = 74.3 mph
3rd 1.47*3.73=5.48 @ 6,000 rpm = 94 mph
4th 1.00*3.73=3.73 @ 6,000 rpm = 138 mph
5th 0.75*3.73=2.80 @ 6,000 rpm = 184.5 mph

A graph of the above shows the change in engine rpm when shifting from one transmission speed to another for any vehicle speed.

For example at 60 mph an upshift from 3rd speed to 4th speed is an engine speed change from approximately 3800 rpm to 2600 rpm.

At lower engine speeds the torque converter increases the overall gear ratio increasing the engine speed for a given vehicle speed. This can be seen on a datalog of a WOT test from rest in 3rd speed.

The bold line represents engine rpm with its scale on the right of the graph. The other line represents vehicle speed with its scale on the left of the graph. The time scale is on the bottom of the graph.
The vehicle speed increases while the engine speed remains constant (@75 secs) or even decreases (@76 secs) as the torque converter ratio decreases to 1:1.

Below is a copy of my stock engine performance after the throttle cable modification in transmission selector "2" or 3rd speed.

Selecting a supercharger that broadens the engine torque curve will result in the most satisfying driving experience.

 

[Ronin8002]

Like you said, it all depends on where you want that extra power. With a centrifugal you're going to get it at the top of the RPM range/WOT usually. With a positive displacement you get it down in the lower RPM range and the ability to build some boost at part throttle.

Having run a Vortech centrifugal on my 91 4.0 OHV, I personally feel for a truck or SUV it's better to get the power down low (positive displacement) since accelerating from a stop is where these types of vehicles need more power.

I guess if you're racing you might want power at the top end/WOT. But if that's your goal then maybe you could just run nitrous oxide injection and have a less expensive setup that is only "on" when you want it.

The formula for vehicle speed vs engine rpm is:

mph = (rpm*tire dia.)/(ratio*336)

My BFG P235/75R15 tires have a diameter of 28.86 inches
My rear axle ratio is 3.73:1

1st 2.47*3.73=9.21 @ 6,000 rpm = 56 mph
2nd 1.86*3.73=6.94 @ 6,000 rpm = 74.3 mph
3rd 1.47*3.73=5.48 @ 6,000 rpm = 94 mph
4th 1.00*3.73=3.73 @ 6,000 rpm = 138 mph
5th 0.75*3.73=2.80 @ 6,000 rpm = 184.5 mph

A graph of the above will show the change in engine rpm when shifting from one transmission speed to another for any vehicle speed.

At low engine speeds the torque converter increases the overall gear ratio increasing the engine speed for a given vehicle speed. This can be seen on a datalog of a WOT test from rest in 3rd speed. The vehicle speed increases while the engine speed remains constant or even decreases as the torque converter ratio decreases to 1:1.

Selecting a supercharger that broadens the engine torque curve will result in the most satisfying driving experience.

 

[2000StreetRod]

no racing

. . .
Having run a Vortech centrifugal on my 91 4.0 OHV, I personally feel for a truck or SUV it's better to get the power down low (positive displacement) since accelerating from a stop is where these types of vehicles need more power.

I agree. Thanks for posting your first hand experience with a centrifugal supercharger.

I guess if you're racing you might want power at the top end/WOT. But if that's your goal then maybe you could just run nitrous oxide injection and have a less expensive setup that is only "on" when you want it.

I have no interest in racing. Almost all of my driving is in the city. I just want to enjoy the responsiveness of a larger engine without performing an engine swap to the 5.0L V8.

 

[2000StreetRod]

ultimate supercharger

In my opinion for my driving the ultimate supercharger would be one with instantaneously available variable boost appropriate for engine load and user requested demand. The variable boost would be PCM controlled and the requested demand would be reflected by the depression of the accelerator as reported by the throttle position sensor. One method of providing nearly instantaneously available variable boost is by driving a supercharger with a variable speed electric motor. Unfortunately, an appropriate capacity motor (10 hp) normally requires a 24 volt or greater supply to reduce current flow. That would mean another 12 volt battery and alternator (heavy and space consuming) in additional to the electric motor.

The next best alternative seems to be a positive displacement blower. While not providing a user requested variable boost, at least the boost is fairly constant throughout the normal power range of the engine. I will investigate the various types and brands of positive displacement superchargers. One other advantage could be a less cluttered engine compartment.

 

[CDW6212R]

Hi Dale, I see that you are well on your way to figuring out the best path for your truck.

I suggest the Eaton style over intake PDB, with an intercooler underneath if possible. Fuel mileage may suffer, but there is one simpler possibility than the variable boost/pump etc.

I saw a car show recently which advertised an aftermarket cylinder cut out device for EFI vehicles. There were no real details or price, I didn't catch a brand name, but it appears it would work for any OBDII vehicle. That may be an answer to a vehicle that has lots of low rpm power and drag, during light throttle.

Good luck there, and don't do anything without addressing the weak 5R55E trans. It's fine for a stock engine, but above that it needs all the little things done that are available. If I boosted a SOHC vehicle, I would first build and install a spare 5R55E with everything done to it. Work out the kinks with that, and then put the boost to the engine.

 

[2000StreetRod]

5R55E upgrade

. . . don't do anything without addressing the weak 5R55E trans. It's fine for a stock engine, but above that it needs all the little things done that are available. If I boosted a SOHC vehicle, I would first build and install a spare 5R55E with everything done to it. Work out the kinks with that, and then put the boost to the engine.

Thanks for the good advice Don. I'm surprised that Jake's transmission has lasted so long with the turbocharger.

 

[jd4242]

Thanks for the good advice Don. I'm surprised that Jake's transmission has lasted so long with the turbocharger.

You want a surprise, i still run a A4ld! probably not much long though, i plan on doing the 2.9 5 speed swap.but not because the a4 is failing,i want that lower first gear of the 2.9

 

[2000StreetRod]

back & knees

You want a surprise, i still run a A4ld! probably not much long though, i plan on doing the 2.9 5 speed swap.but not because the a4 is failing,i want that lower first gear of the 2.9

I've had numerous vehicles with manual transmissions: Alfa 2600 Spider, Jaguar E-Type, BMW 635, Volvo 544 & 142E. I eventually learned that a good automatic could shift faster but doesn't have as much control (engine braking, downshifts, etc.) Now I'm lazy with a bad back and knees so will never have another manual.

 

[jd4242]

I've had numerous vehicles with manual transmissions: Alfa 2600 Spider, Jaguar E-Type, BMW 635, Volvo 544 & 142E. I eventually learned that a good automatic could shift faster but doesn't have as much control (engine braking, downshifts, etc.) Now I'm lazy with a bad back and knees so will never have another manual.

O i hear you.i love my auto but i want that controll like you said and that lower first gear.i run BIG 36x14.50 and 4.88s.i wish i went 5.13 for sure as this is mostly a off road truck.ive hear those 5r can be pretty strong with some mods.

 

[rocket 5979]

Thanks for the good advice Don. I'm surprised that Jake's transmission has lasted so long with the turbocharger.

Proper tuning and band adjustment are key to keeping those transmissions alive. Got those down pat and as long as the transmission was in good mechanical shape beforehand they will be able to take a little bit of power. Your tuner might just know a thing or two about that.

 

[2000StreetRod]

band adjustment & tune

Proper tuning and band adjustment are key to keeping those transmissions alive. Got those down pat and as long as the transmission was in good mechanical shape beforehand they will be able to take a little bit of power. Your tuner might just know a thing or two about that.

Thanks for reminding me that I still need to perform a band adjustment. When I purchased my Sport I couldn't tell from driving it whether I had a 4 speed or 5 speed trannsmission because the upshifts were so soft. James did an excellent job adjusting the transmission shift pressure and timing.

 

[rocket 5979]

James did an excellent job adjusting the transmission shift pressure and timing.

I bet he did. I tune all of my own vehicles myself but when I wanted a tune for the Green V6 Explorer I didn't even bother with it because I knew James can tune it better than I could because of all of his experience with the 4.0 SOHC and 5R55E. Why mess with perfection and reinvent the wheel when I have a friend who is likely the best V6 Explorer tuner out there?

 

[2000StreetRod]

Roots blowers

The Roots type blower (Eaton M90) is very efficient (90%) for low rotor speeds and low boost (1.5 psi). The efficiency decreases slightly (80%) at mild rotor speeds and boost (5 psi). For medium boost (8 psi) and rotor speeds the efficiency drops to about 73%. The efficiency at 15 psi of boost is only 58%. For any given amount of boost a larger rotor will be more efficient than a smaller rotor because the rotor speed will be slower. The output of a Roots blower is pulsating rather than continuous.