Supercharging & Overdrive

[Kip Woodring]

YIKES!  I just read the spec sheet on the Chevy chassis I've got under my Clipper... 165 measley horsepower from 400 cubic inches of small block!  No wonder it doesn't like hills!

One of my other vehicles is a small block with a Paxton supercharger fitted.  (It's overkill on a 2000 sports pound sports car.) So, I'm seriously thinking of swapping the supercharger to the Clipper where it will do some good.  NOT because I think I need 300 horsepower for an RV... or because I want to drive 80mph... but because the supercharger will mean hill-climbing ability at 10,000 feet (like going in and out of Yellowstone) without slowing to 10mph. And some reserve passing ability.

The other reason is... I'm thinking about putting an overdrive automatic in place of the T350 3-speed.  I've driven a late model Tioga with a Ford V10 and an overdrive automatic, and believe me it's NICE!  Thing is... without enough power, overdrive seems pretty useless.

Where I'm going with all this is:

1) Who out there has experience with installing overdrives on Clippers? (Chevy or otherwise.) Any advice?  Does it accomplish much besides saving a little wear and tear on the engine... or should I save the money for something else?

2) Has anyone EVER supercharged a Clipper?  Any advice on whether or not I should?  Mine doesn't run hot, so I think it can handle the extra heat that might be generated on long climbs where the blower is working hard.

3) Is there any OTHER way (exhaust, air cleaner, cam changes, engine swaps, or WHATEVER to get power levels up to modern standards, and stay smog legal? (Especially in California!)

[Horst]

Many questions here, and I'll give you my opinion for what it's worth.
Overdrive?
I'd go with a U.S Gear or Gear Vendors auxilliary transmission. I believe US Gear makes a unit for your rig, but it may need a pan adaptor. Not 100% sure about Gear vendors.
Read more here
www.usgear.com
www.gearvendors.com

You will have to drive your Clipper for many many many thousands if miles to justify the cost of an auxilliary tranny (gear splitter). But I spoken with a few people who have done it- and they love it. Just don't think this will pay for itself with better mileage (although your mileage will improve)

I would stay away from a super charger.

Finally, be VERY careful about what engine modifications you plan on implementing, especially if you need to pass smog in California.

[EKS]

Your question touched on what I have been researching for weeks.
Regarding the chevrolet engine look at getting the newer heads used in the silverado vortec engine for pickups (I think this is right but research it). I have a friend who is getting 20+MPG and has an incredible amount of power with a 350 4WD pickup. They will help your mileage and power and should smog well. The 400 had cooling problems and the fix is to open up some of the cooling passages in both the block and the head. The 400 is known for having tons of torque which is what you need, not horsepower. If you could get the compression up to around 9:1 that should also help. Once you know what kind of gearing you will end up with and your cruise RPM in and out of Overdrive you can look at cams that will give you the most torque in that RPM range. That should also help with the mileage.
We seriously considered purchasing a Clipper with a Chevrolet instead of the Dodge engine because of the engine performance options and transmission options. Since we pull a horse trailer and info on beefing up the Chevrolet chassis was unavailable we got a dodge.
Regarding the transmission options there are several ways to go. The advantage of the Gear Vendors or US gear overdrives is they just bolt on the back of your existing transmission. They also allow you to chose the overdrive in each gear and some people just leave them in overdrive all the time until they are in the mountains and then they take them out. The Clippers are geared pretty low as is.
The advantage of the Automatic Overdrive Transmissions is you get into newer technology like the lockup torque converters. If you research it there are different Overdrive ratios available.
The Gear Vendor/US Gear ratios are 22% to 28% (don't have my notes with me so check) while some of the automatic Overdrives are up to 31%.
For discussion purposes let's say you have a 33% overdrive ratio. That means for the same number of engine revolutions the vehicle travels 50% further. That means increased engine life and increased life on the alternator bearings etc. A 22% Overdrive means you travel 28% further for the same number of engine revolutions.
The newer technology of the AOD means your torque converter locks up at cruise speed and your RPM drops. That results in less heat generated by your transmission. BUT when you get to a hill you can kick out of the lockup, RPM goes up and your torque converter starts acting as a torque multiplier again. Whatever you do, get a valve body in your transmission that has been set up for towing. That means less overlap in shifting gears (less heat generated) and crisper shifts, higher pressure to the torque converter and several other things (again notes not with me).
It sure seems like one of the big problems with the clipper is heat. Make sure you have a good transmission cooler and consider an external transmission filter (adds a quart of oil which also helps temperature) and temperature guage. For every 10 degrees of temperature rise above 225f transmission life expentancy is halved (there is quite a bit of literature re this on the net).
Keep in mind that only the upper part of your engine has water in it as a coolant. The whole lower part of your engine depends on the oil for cooling so an engine oil cooler also makes sense.
I've started a website www.rvtransmissions.com to document some of this and make recommendations so you might look at some of the info there. IT IS VERY PRELIMINARY but will give you an idea of some of the things to consider.
Hope this helps

[EKS]

Jet Transmissions in Huntington Beach modifies a TurboHydro400 Overdrive so the overdrive acts as a gear splitter to give you a 6 speed transmission. That should give you a gear to fit any need. It is rated for up to 900 HP so that should handle the load of a clipper