Retiring the Squirrels

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I have been contemplating a horsepower upgrade for a few months now but had been hoping to put it off until summer.  events from this last weekend have moved Project Hellraiser up to the front burner.

The #4 piston rod is now a 3 piece design.  I am guessing the piston seized in the block, most likely due to lack of oiling or galling caused by a bent rod.  The rod was bent over MLK weekend when the motor was hydro locked after I tried to start it after a flop.  The lesson here is ALWAYS pull your plugs after a roll to clear any oil that has  accumulated in the cylinders (put a rag over the hole and close the hood to avoid spraying oil all over). I had never pulled the plugs in the past but apparently this flop put the vehicle in the perfect position for oil to leak down into the #4 cylinder. I figure I have been driving around on 3 cylinders since the flop, after self clearancing itself the #4 piston probably had close to 0 compression.

I had a lot of time to think about the engine swap on the way home and I decided to wipe the slate clean and consider all my options.  Some factors I considered:

1.  Our wheeling style has changed along with the terrain.  Power to weight ratio was becoming more important than crawl ratio.

2.  My 3 seater wasn't going to get any lighter.  It was roughly 2800lbs with the Toyota axles, I figure I am at 3200-3400lbs with the 60's.   

3.  Rigs with automatic transmissions seemed to handle the verticals easier than the rigs with manual transmissions.  It also seems like you need at least a 6 cylinder engine to have enough power to spin the tires (ignoring the exotic high hp 4 cylinder engines out there).

4.  Transmission adapters add a lot of cost to a drive train.

5.  Any power upgrade would make my Toyota transfer cases the weak link (specifically the rear output). It would be nice to upgrade the transfer case as well to a unit that can handle any power plant I put in front of it. I would also like to add the ability to do front digs.  For those that don't know a front dig is a way of pivoting the buggy about it's rear wheels by disengaging the rear driveline (either in the transfer case or via an adaptor on the rear driveline), locking the brakes on the rear axle and then using the front wheels to pull the buggy in the desired direction. 

6.  It would be nice if the next power plant had an easy upgrade path if more power was needed down the road.

Option 1 - The easiest option was to find a 2.7l from a T-100 or Tacoma and swap it into the buggy.  Utilizing the bell housing from a 5 speed model would allow me to bolt up my existing transmission and transfer cases making for less change over.  The size of the motor was also a plus as it would easily fit into the existing tube work. Downsides were power, I think it would have been peppy but not an eye popping upgrade based on this  96 2.7L Dyno chart I found on Jet Products website.  Stock power is estimated at 150hp and 177 ft/lbs of torque. Future power upgrades would have been expensive (search TRD supercharger) which seems typical of most small import motors.  Lastly these motors are kind of pricey  ranging from 800-$1500 at the junkyards.  I have yet to see a 2.7l float thru the classifieds, I did recently hear about a 2.4l that would have worked (same motor, smaller bore size rated at 140hp, 160 ft/lbs of torque) but again lack of hp at the wheels, weak upgrade path and manual transmission were strikes against it.

Option 2 - A Toyota 3.4l V6 from later year T-100's was also considered.  This compact V6 motor is rated at 190hp and 220ft/lbs of torque so it filled the power requirements nicely and would be capable of spinning an automatic transmission. Strike one was the adaptor needed to use my existing gear driven transfer cases.  Rumors of an adaptor are out on the net but my research revealed Marlin Crawler had some prototypes that are on hold for now.  Even if the adapter existed I am not convinced my transfer cases would have handled the power of the V6. I also did not find any transmission adapters to put a domestic automatic transmission behind the motor.  These motors seemed to go for about the same price as the 2.7l motors in the junkyards.

Option 3 - Chevy 4.3l (or equivalent) with an automatic transmission.  This drive train setup is cheap because the motors were used in a large number of GM vehicles, looking in the classifieds yields a 4.3l powered vehicle being parted out on a regular basis.   The 96+ versions are the most desirable for power output, here is a 97 4.3ldyno chart.  Keep in mind most buggies have all their emissions related stuff removed so that dyno chart would look much better on a buggy-ready motor.  A variety transmissions are available and a Dana 300 or Atlas transfer case can easily be mated to the available transmissions. A wide range of aftermarket parts are available for future power upgrades.  Perhaps the only downside to this motor is it's size, extensive mods would be required to make it fit but to be fair most of the 90 degree V6's will require some tubing rework.  I added the "or equivalent" to the first line in this option because I also wanted to consider some of the other popular domestic power plants you see used in trail rigs ( Ford 5.0's, Chevy 350's, etc).

So the search was on.  The night we arrived back from Mammoth I started browsing E-bay and the various 4x4 classifieds sites I frequent trying to get an idea of going rates and what was available.  One particular motor had caught my eye a month ago and I noticed it was still for sale: a supercharged 3.8l found in a 1999 Pontiac Grand Am.  I started doing some research and discovered this motor had quite a following on the various message boards and good aftermarket support. Here is some good information on the GM 3800 series engine I found on Wikipedia.

Stock specs were 240 hp and 280 ft/lbs of torque (non-intercooled), the dyno chart shows the real world numbers at the wheel.  Being a blown engine means added performance is a blower pulley away, from what I read 300hp is possible without an intercooler, more if you run an intercooler. Note on the dyno charts above and the ones I linked; I believe they are all done in second gear and started at 45mph to show peak hp and torque.  Unfortunately this method doesn't show us the low end hp or torque which would be far more useful for us rockcrawlers.  It is fairly safe to assume the torque and hp will fall of as the rpm's decline so the higher the start reading the better. 

Here is a really helpful page that has dyno charts of this motor with various upgrades: www.intense-racing.com, Project 8 Ball.

Along with the motor came a built TF904 transmission and a Dana 300 transfer case.  The TF904 isn't the strongest transmission out there but with stronger parts it should not be the weak link in the chain.  The Dana 300 is a great choice in transfer cases, lighter than an Atlas or Stak box but requiring output shaft upgrades  to survive what I plan on putting it thru.  The Dana 300 already had an optional clocking ring which allows you to rotate the transfer case up for maximum belly clearance.

Update 4-2-06 - This motor has been used many times in various competition buggies so little of what I am doing here is new but this will be the first time all of the information will be in one easy to find spot. Here is some additional background information  that may be helpful if you attempt to use this motor. I found this information on various internet forums and from individuals who have used this motor before.

From Tony K. at Rock Equipment - A 700r4 from an S-10 that had a 2.8 V6 bolts right up. The converter will need about a 3/8" spacer built for each lug. And that case can be updated with all the later 700r parts. The S-10 trans was garbage stock. You can also use a 904/999 case. You will have to notch the bellhousing on the drivers side for the starter and you should tig a support ring around that area.

In regards to the PCM - If you are using the 98 and older harness and PCM, then you use can use the parts as is but need to add an anti theft module from Speed Scene Wiring.  If you use the 99 and newer harness and PCM, then you can send the computer to Jim at Jim's Performance and he can flash the correct info for you. He's done several for us over the years.

Here are some links to sites that carry performance parts and/or have forums related to the L67 motor:

3800 Performance - Performance parts for the L67 Motor

West Coast Fiero - Look under "Engine Hardware 60" for some useful custom parts.

Club Grand Prix - forum devoted to the Pontiac Cars.

L67 Swap - a great website dedicated entirely to swapping this motor into all sorts of vehicles. Check out the RWD swap forum

One of the club members has a brother who runs this motor in his sand car so we went out to take a look.  The motor seems more compact than a 4.3 on initial observation.  The only points of concern are the exhaust manifolds which dump straight out from the sides and the intake which will wind up at the rear of the motor, possibly in the cab.   I think a set of headers will make the exhaust manifold a non-issue and some cab modifications will be required to make room for the intake.  Beyond that I believe positioning of the drive train will be dictated by how far back and how low I can get the automatic transmission. All lights looked green so I bought the 3.8l drive train and am awaiting it's arrival in the next few weeks.

When checking out the 3.8 powered sand car I took some measurements and have found some tubes that need to be moved to make this drive train fit so modifications will begin shortly on the chassis.  Let the fun begin.

Update 3-6-06 - Still in the process of tearing down the buggy and selling off the old drive train parts.  The motor came out last week and I was able to get a better view at the carnage.