From: John De Armond
Subject: Re: AUXILIARY TRANSMISSION
Date: Wed, 29 Oct 2003 13:25:18 -0500
On Wed, 29 Oct 2003 07:46:33 GMT, phil w <email@example.com> wrote:
>I'm considering an auxiliary tranny for my 30 ft. diesel pusher.
>Chevy 6.5 turbo/Allison 4 speed. I'm looking for a little more
>oomph on the hills and on ramps. An old RV hand suggested
>this way to go, rather than chips, boosts, etc.
>Anyone have a history with one? What brand worked the best,
>Gear Vendors or US Gear? Any others? Who best to buy from?
>What say you smart people?
I have some experience with the Gear Vendors unit. I used one on a
street/strip car. It allowed me to run the low gear rear end necessary for
drag racing and then shift into overdrive to achieve gearing suitable for the
the unit performs as advertised and handled several hundred HP without
That said, I think you will get more bang for the buck doing some tuning on
the engine. I have a friend who put one of those engines in an old Suburban,
then did some speed tuning. He does his own "chip" work (actually via a
laptop these days.) He installed larger injectors, turned up the wastegate
and fabricated a better exhaust.
This thing screams. I used it to tow my high performance Caprice to Ohio to a
specialty tranny shop. The Suburban, about 8 guys, the trailer and the car
topped out at about 20k lbs. This thing pulled harder than my mom's small MH
with the big block chevy engine. I took shifts driving but the standard was
'set the cruise on 80 and go". My stint was through Kentucky. Even in all
those hills I don't thing the tranny ever kicked out of overdrive. I could
merge into traffic from an on ramp without using full throttle. Nice.
Diesels respond beautifully to more fuel and air. The added air can come from
a better intake (trading noise for power) and exhaust. Modern fuel injectors
are fairly wide range so reprogramming the computer will handle that. In
fact, if your engine is a late model one, the tuning can be done through the
diagnostic port. No chips necessary.
The Banks system works, though I think it is a bit pricey. The advantage is,
everything you need comes in the box. A local high performance muffler outfit
can make the bigger exhaust and intake. There are a number of people who
provide reprogramming services. But the Banks system has it all in one
package. Time vs money, as usual.
From: John De Armond
Subject: Re: Superchips Micro Tuner
Date: Tue, 09 Dec 2003 02:32:02 -0500
On Mon, 08 Dec 2003 16:50:33 -0700, Vato <firstname.lastname@example.org> wrote:
>What is the scoop on this diesel engine enhancer?
>Does it work?
Can't comment on that particular one but I do have some interesting info.
Last week a friend was in to visit. Until last year he was the chief engineer
for one of the major "chip" companies. We ended up chatting about diesel
truck tuning and he regaled me with trials and tribulations of tuning pickup
diesel engines. Combining what I learned from him with other experience, here
are some thoughts.
There is basically an unusable amount of power available from the engines used
in all three major brands. The tuning has been downgraded for various
mechanical and emissions reasons. For instance, GM had problems passing the
EPA visible emissions test which consisted of an 8 second wide open throttle
run while the exhaust opacity was measured. GM finally solved the problem by
delaying full fueling at wide open throttle for 8 seconds. That makes the
engine feel like a dog and is easily tuned out by the aftermarket tuners.
The problem is, how much power to allow. My friend was telling me about the
problems they had with the early GM diesel which had a weak head gasket. It
would weep coolant into a cylinder, cause it to score and seize, break a rod
and pop a hole through the crankcase. They thought they had a pretty good
tune worked out but when they gave a chip to an RVer pulling a large fiver to
test, disaster. The head lifted during a long WOT uphill pull, the rod broke
and popped a hole through the crankcase, the oil hit the exhaust and caught on
fire and the result was a burned truck and fiver.
The important point is this. If you go with an aftermarket tuner, you can no
longer just lay on the pedal and let 'er rip. The OEMs tune so as to protect
the engine and drivetrain against most any foreseeable treatment. They know
someone is going to load the vehicle right up to the GVW and head up one of
those climbs in the Rockys wide open without a thought or care in the world.
The aftermarket tuners of necessity, have to reduce these safety margins and
sometimes eliminate them. That means that you can break your toy if you're
So yes, the aftermarket tuners do work but you have to be careful.
From: John De Armond
Subject: Re: An old diesel Class A
Date: Sun, 25 May 2008 13:52:42 -0400
On Sun, 25 May 2008 11:26:14 -0500, Bob Giddings <email@example.com> wrote:
>The mileage makes me fear it may be underpowered, which is one of
>the things I'm hoping somebody may be able to tell me. I haven't
>driven it yet.
I've driven a Trek when I was considering buying one new. Can't recall the
year though. That little Izuzu motor isn't going to win any drag races
against those 500 hp pushers but then again, you'll catch 'em as they stop to
put $1000 worth of fuel in their rigs while you motor on by:-) Given today's
fuel prices, I'd consider high mileage, somewhat low power to be a major
feature. After all, who's in a great hurry in an RV? :-)
If it truly doesn't have enough power, there are a couple of things you can
do, either separately or in combination. One is turn up the injection pump
and tighten the turbo wastegate a bit. The other is propane injection. Both
are common and very reliable methods of hotrodding diesels.
I have the larger Izuzu diesel in my MD cube van. It was plenty powerful
enough stock but a guy never has too much horsepower :-) I've given it the
injection/wastegate treatment and have tested propane injection using a 20 lb
grill tank. Both worked as expected. I've acquired an ICC chassis mount
propane tank to make the latter permanent. Propane injection is a popular
power boosting technique with semi drivers and is proven reliable as long as
you don't go overboard.
If you find that you only occasionally need a power boost - climbing a long
grade, for instance - and want to keep the great stock fuel economy otherwise
then propane injection is the way to go. It's typically activated by a button
on the dash or on the steering wheel. All it involves is bleeding some
propane gas into the intake air upstream of the turbo. There are kits
available or you could roll your own for under $50 considering that you
already have a propane tank onboard.
>Run? Just on the basis of the bed? As though it couldn't be
Consider the source. That whooshing sound was the pneumatic blonde
>That sounds like a cosmetic problem, or at least one that's out
>in the open and fixable.
The bed runs on 4 rack and pinion affairs, one on each corner. The pinions
are mounted on two shafts. They all turn together. If you let bed covers get
caught in the gears then yes, the bed can jam. Duh! And I suppose that the
motor could eventually wear out. Other than that, there's not much to go
wrong. Given the huge increase in floor space this bed design give you, it's
a no-brainer to me. If I had a Trek I'd probably investigate installing a
hand crank for in the very rare instance the motor malfunctioned for some
reason. Or maybe not. I suspect that the bed mechanism is highly reliable
after having examined it.