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High-Horsepower Hybrid
Question:
Along the lines of the diesel-electric Chevette mentioned in your July '10 editorial, I've been thinking about making a diesel-electric VW pickup. Because the VW is front-wheel drive, you can leave the entire powertrain alone but simply add a live rear axle with the differential facing up into the bed, where it could connect directly or through a gearbox to an electric motor. With the 6-foot bed there is plenty of room for batteries and whatever other electric equipment is required. I would be aiming for upward of 150 hp and lots of torque in a 2,000-pound truck-it should move alright. I'm also hoping to get upward of 60 mpg. I think it'd be pretty straightforward; my biggest problem is finding an electric motor. Know where I could get one?
Kevin Kosinski
Middletown, Rhode Island
| We did some math, and even if we added 800 pounds of weight to our '82 Chevette, it would still only weigh 3,210 pounds with driver. Based on its weight and horsepower, that would give us a theoretical quarter-mile time of 12 seconds or better with a 400hp electric motor-if we could get the traction.
Answer:
Future highways could definitely be populated with biodiesel hydraulic-electric hybrids, but if you're not willing to wait for the future, there are options now. Vehicles like our '82 Chevette diesel are great on economy, but short on fun. In our minds, there are two ways of doing a diesel-electric hybrid. The first plan would involve a small electric motor used to help around-town acceleration, but the diesel engine would still be the primary steady-state engine. The second type would be to add a large electric motor for short-range driving that would also provide rapid acceleration. Freeway fuel mileage would probably be a little lower or unaffected, but daily commuting would go up dramatically. If the vehicle was plugged in at night, it could be used purely as an electric during short drives and still have the diesel engine for road trips.
Here's how we'd do it: First, we'd establish a primary focus-in the case of the smaller electric motor: fuel economy. Electric motors are very good during low-rpm, torquey situations because most commonly available electrics are used in forklifts and golf carts and such. Under light-load conditions at about 40 mph, a light diesel car's fuel economy could be as high as 60 mpg, but during acceleration it might only be 20 mpg. If fuel economy is a main concern, then a small (or two small) electric motor(s) could be used to accelerate the vehicle up to speed, thus conserving the diesel fuel for light-load, constant-speed situations. Our Chevette only gets about 37 mpg in stop-and-go traffic, and this figure could be substantially improved upon with the addition of a small acceleration motor. Electric motors, such as the now-defunct Briggs and Stratton Etek, or the new-and-improved Perm 132 and ET-R motors, all make about 20 hp at peak amps and 72 volts, with a flat torque curve. Electric motors can only be run at peak amps for 10 to 20 seconds, however, or they'll start to overheat. This type of hybrid is what we would consider an electric motor-assist setup and would mainly be good for improvements in fuel economy. We'd expect this type of conversion to cost about $2,500 to $5,000 depending on your fabrication skills. If you do decide to go the route of a 50hp diesel hybrid, you're not in it alone. Companies like Cloud Electric (www.cloudelectric.com) and Thunderstruck Motors (www.thunderstruck-ev.com) can help with the electric side of the project.
In our second hypothetical hybrid, we'd focus on performance. This would mean it would be time for a large electric motor-something like the motors built by Net Gain Motors. If you're going to go this route, why stop at 150 hp? Net Gain markets electric motors that can make more than 400 peak horsepower, run hundreds of volts, and be used at insane amperage levels (1,400 amps!). The controllers for these motors can be expensive but are readily available through Net Gain Controllers (a sister company), which are sold through EV America (www.evamerica.com). All in all, we'd expect to pay $7,000 to $8,000 for the motor, controller, and basic lead-acid batteries (which, by the way, will weigh about 500 to 800 pounds). While that may sound expensive, it's virtually impossible to add that kind of horsepower through modification of most small diesel engines, and adding that amount of power to any vehicle usually isn't cheap. Personally, we like the thought of a 400hp VW Rabbit hybrid pickup.
6.5L Diesel
Cranking Compression
Question:
I am currently working on a 6.5L Chevy diesel that has 18:1 compression pistons and was wondering if 300 to 325 psi is what I should see on a compression test. I heard 400 psi was normal for a stock 21:1 compression 6.5L engine.
John Joling
-via email
Answer:
It's hard to say how much dropping compression in a diesel will affect cranking pressure, but 300 to 325 psi sounds pretty close to us. To double-check, we called Bill Heath, our go-to 6.5L guru, who said that sounded about right (he also said that 380 to 400 psi is a good stock reading), although he did suggest that lowering the compression on a 6.5L might not be the way to go, since it will reduce engine efficiency. Heath said he runs 22.5:1 compression and 30 psi of boost on his race truck (up from about 21:1 stock) because fuel from the injection pump is the limiting factor, so the engine needs to be as efficient as possible.
6.4L Power Stroke Swap Question: I have an '03 Ford Excursion with the 7.3L Power Stroke diesel. I have some performance products already on it-an upgraded turbo, Edge chip, 4-inch exhaust, and 6.0L intercooler. The truck has a little more than 130,000 miles on it. After installing the upgraded turbo, it was running great, then it seemed to lose power. The CCV and exhaust is more smoky than usual. I have been looking at rebuilding the engine, but with the cost, I'm wondering if the 6.4L with the 5R110 will work in my truck. The cost of a wrecked 6.4L with the transmission would be about the same as rebuilding my 7.3L and 4R100. What would the swap entail, if feasible at all?
Scott Hepburn -via email
| Brian Jelich proved that 7.3L trucks are no slouches when he got Fourth Place at this year's Diesel Power Challenge with his 800hp '00 F-250. While it takes quite a bit of money to get this type of power out of a 7.3L Power Stroke, it's still cheaper than buying a new $50,000 truck and modifying it.
Answer:
We get this question every so often, and the short answer is: Yes, it can be done-but it would be one heck of a headache. There are no stand-alone electronics to run the engine and transmission, so that's why 6.4L engines and transmissions can be picked up for dirt cheap. The cost of piecing together a wiring harness, computer, and all the needed sensors would be very high, and extremely difficult. An easier route is to find a wrecked 6.4L-powered diesel truck that still has the engine, transmission, and all the sensors. We'd expect to pay about $10,000 for this type of vehicle (check out www.copart.com). Even after you've found the right truck, you'd still need lots of custom parts to make it fit: engine mounts, exhaust, transmission, crossmember, etc. The only person we'd expect to take on a project of this nature would be a very experienced fabricator, and he or she would still have $15,000 to $20,000 in it-not counting any aftermarket parts.
First and foremost, we'd suggest looking into why your 7.3L engine lost power. It might be something simple. At 130,000 miles, your engine shouldn't need a rebuild. Even with the powdered metal rods your truck has, it should live a long life at 300 to 400 hp, as long as the tuning is conservative. With a 6.4L swap you could have 600 hp, but is 200 extra horsepower really worth $20,000? We'd say no, and we'd suggest you take your 7.3L to a reputable shop in the area and have them take a look at it. If you feel the need for more power, check out the "7.3L Power Recipes" article we did back in our Aug '09 issue.
