Turbo Minivan performance tips

While the go faster! page gives great step-by-step instruction on how to make your turbo minivan faster, there are a number of small, inexpensive, simple upgrades you can perform at any time. While any individual tip offered below might not make a huge difference on its own, they will combine to have a real impact on your van's performance. When combined with the mods on the go faster! page, the effect will be even larger still. So the next time you're at home with some free time on your hands, why not do a few of the following?

Manual fan switch

There are times when it is handy to force your radiator fan on (like when you're idling in the staging lanes at the drag strip). While numerous gearheads have come up with bizarre ways to accomplish this, there is a very simple and elegant solution: do it just like the computer does. In order to energize the fan, the computer simply sends a ground signal to the fan's relay... so all we need to do is tap into that same wire and send a ground signal as desired. Now when you flip the switch, the fan kicks on. Turn your switch off, though, and the computer is in complete control just like before. The best part is we didn't mess with voltage wires, and we don't need some high amp switch to handle the load. Here is a helpful picture:

Find the fan relay underhood; it's with the other relays next to the battery. The relay has two connectors--one with three wires, the other with only one. The input ground wire is blue and it's all by itself in the one-wire connector. Unplug this connector and graft in your extra wire here. Be sure to solder this connection! After it cools, cover it with electrical tape or heat shrink tubing and plug the connector back in. Now run your new wire through the firewall, then connect it to one pole of a toggle switch. With a seperate wire, connect the other pole of the switch to any grounded bolt or screw under the dash. Mount the switch in a convenient location and you're done!

Gauges

Any driver who is serious about power will want to keep tabs on his engine. If your van has the no-frills instrument cluster (no tach, no temp gauge, etc) then you ought to upgrade it. Just find the better one in a junkyard--it'll bolt right into your van. You will need to upgrade from a coolant temp switch to a coolant temp sensor, but this is a simple operation also.

Now that you've got all the gauges possible from the factory, time to add in the aftermarket ones! A boost gauge is mandatory, as is some sort of air/fuel readout; an EGT gauge is highly recommended provided you can drill into your exhaust manifold to install the probe. Where should you mount all your gauges? It's up to you--there are tons of possibilities thanks to the acres of flat interior space. Here is one picture with some interesting ideas:

Spark plugs

Back when new, our engines left the factory using Champion RN12YC plugs. Over the years the OEM-equivalent plug has stepped up a temp range to the RN14YC. Higher temp plugs are more prone to detonation, which is bad, and higher boost pressure also promotes detonation, which is bad. To help counter this, simply run colder spark plugs. I strongly recommend two temp ranges colder than our originals--Champion RN9YCs. These plugs are inexpensive and available nearly everywhere.

What about platinum plugs? In a word, DON'T! Back in the early '90s it was shown that the tips on Bosch Platinum plugs could actually break down under higher boost pressures, resulting in pieces of metal bouncing around inside your combustion chamber. While I've not heard of it happening with other brands of platinum plugs, why take a chance? Steer clear of the platinums and go with Champions.

Balance shafts

Since four cylinder engines are not naturally balanced, they tend to create quite a bit of secondary engine vibration--these are the vibrations you feel inside the car, making the rear view mirror vibrate slightly and so on. The vibrations are compounded as the displacement of the engine grows, and 2.5L is actually pretty large for a four cylinder. To offset these secondary vibrations, Chrysler equipped the 2.5L TurboI with a pair of counter-rotating balance shafts. Think of them as tiny crankshafts--carefully weighted sticks--which cause their own vibrations that, through the miracle of physics, actually counteract and reduce the vibration you feel from the engine. The result is a vehicle which feels smoother... and a happier John and Jane Customer. The downsides are parasitic drag on the engine and extra weight you have to haul around.

Is there anything we can do? You bet--take them out! You can remove them right there in your own driveway; just drop the oil pan, remove a few bolts, cut a chain, plug an oil feed hole, and reinstall the pan. Depending what you read, removing these shafts will free up 5-10 horsepower at 5000 RPM. Not bad for a free mod, eh? Better yet, it's a completely invisible upgrade... and turbominivan.com is all about stealth.

But what about the secondary vibration? Yes, you'll feel a bit more than before but it doesn't hurt the engine at all. Really! Don't be alarmed: this is NOT a harmonic balancer. The engine itself doesn't need these shafts for proper operation and removing them will not compromise its long-term durability in any way. If you are worried, though, install new motor mounts just to make sure everything stays where it should. You'll be fine.

Still not convinced this is a safe mod? Then go do some research. Once you learn the difference between a harmonic balancer (which must be bolted directly to the snout of the crankshaft in order to cancel damaging torsional vibration) and a balance shaft (which is installed underneath the crankshaft to cancel harmless second order vibration), you'll see that removing the shafts will not compromise engine durability in any way.

Weight

Weight is the enemy of vehicle performance. A heavier vehicle takes more power to accelerate, requires more distance to stop, consumes more fuel, puts more stress on its transmission, and more. An old racer's rule of thumb says tossing 100 lbs of weight will drop your ET by a tenth of a second. What's the easiest way to lose 100 lbs? Look for 1600 places to lose an ounce!

With a FWD vehicle, the further rearward the weight the more detrimental it is to a good launch. Start with the obvious: remove both bench seats. In the hatch, toss the rear wiper motor and related hardware (don't forget the washer bottle) and the rear stereo speakers. Under the van, remove the spare tire, the tire carrier, all the brackets and hardware which hold the tire in place, the black air dam attached to the bottom of the bumper, the bumper rub strip, and so on.

You can go ahead and gut the inside of your van, but for one reason or another you might not want to. If that's the case, go for stealth: unbolt and remove both front seats; set them aside. Now remove the carpeting. Under it lies the heavy sound deadener--get rid of it! Then turn the carpet over and carefully peel off all the insulation which is glued on. Now replace the carpet and no one will be able to tell anything was ever removed. Another great idea is to unbolt the interior side panels and carefully remove all the insulation glued to them, the heavy sound deadener on the wheelwells and all the foam insulation stuck into the body panels (it's the stuff in the sealed black plastic bags).

Now just keep moving forward, removing everything which is not essential for proper vehicle operation. This is free speed, so don't hold back.

Thermostat

Our vans use a 195^ thermostat as original equipment. Horsepower makes heat, though, so it will be an advantage to switch to a colder thermostat. The best way to go is with a 180^ unit; they are inexpensive and available at parts stores everywhere. You may also see colder ones (such as 160^) but you should avoid them; going lower than 180^ will cause excessive piston ring wear and will shorten the life of your engine.

For those of you living in the snow belt, 180^ is still sufficient to warm the van during winter driving. No worries!

Automatic Transmission

The vast majority of Dodge/Plymouth turbo minivans have automatic transmissions, so I'll assume that's what yours has. These came with a seperate trans fluid cooler, which is good. However, extra horsepower puts more stress on the transmission, so an extra capacity cooler is a wise upgrade. Which one should you choose? Simple: as big as you can find! Seriously, I go to an auto parts store and get the biggest one on the shelf, usually labeled for use in big block V8 RVs. Heat is the number one killer of automatic trannies; your trans fluid can never be too cool.

While you're at it, another insurance item you can add is an inline fluid filter. There is the filter "sock" inside the trans, yes, but your fluid can never be too clean, either. Trust me, the $10 you spend on the filter is easily worth the extra protection. Be sure to replace it once a year.