I'm running a fuel cell in my truck's bed at the rear most point to get the weight back there for traction. Would it effect the rate of weight distribution if the tank was mounted on the bed floor vs. under the bed floor ? I'm trying to invision a teeter totter with the fuel cell on the up end, would it make a difference if it was high or low ? The only problem I would have going under the floor would be the pickup port is at the right rear in the normal postion. This would be at right front side if I turn it long ways to fit between the frame rails.
Swade.... If you are looking to lift the front wheels off the ground leave it behind the rear axle and up high. If you want the weight to contribute the MAX amount to traction it needs to be @ the instant center ( the point where the rear suspension angles intersect ). While locating the fuel cell @ the instant center is not really possible because it is somewhere near the drivers seat on your truck I would try and get it as far forward and as low as possible (within reason). If you could put the engine, fuel tank, driver, battery, etc. within a 12" distance of the IC you would have a perfectly balanced , maximum traction vehicle ! Dave
Well if it pulled the wheels, I'd get out and kiss the ground..lol I was thinking of it as a leverage point of view with it being high and as far back as I could go. I've already got everything plumbed where it is now, with braided line and the pump and filter back there too. I'm just about ready to put the floor in it and rethinking it a bit I guess.
Technically, no. Moving it up or down vertically at the same distance rearward will not change the weight distribution. Having it high, like you have it, will tend to make the front rise more at acceleration, lower, less rise. If you change it, I wouldn't have it hanging too low between the frame rails, no tech inspector will want to see that. It does look like you can move it another 6" rearward, that will increase the rear weight bias a bunch.
bitchin truck! Do NOT spin it to have the pickup at the front- keep it at the rear. I know you're at the end of it but if your pickup is in the rr corner, then you've got a circle track tank. Id get a center rear sumped tank.
I've shortend the bed about 8 1/2 inches since that picture, the tail gate will be pretty close to the rear frame rails.
Might help to think of it this way..( Warning, high school physics lesson ) LOL ! Leverage applied via the IC will lift the weight of the vehicle under acceleration. So the basic idea is to use this lifting force to increase traction IE: the more lift created = more traction...The old equal but opposite thing... This is why I reccomended moving it forward. Having it where it is now will not help as much with traction as it will be a pendulum ( hence the wheelie reference ). The last point of reference to visualise is this: Look at a (unloaded) semi truck leave from a stop light. As the clutch is released and power applied the frame rises..and with each gear change the same thing happens..What you are witnessing is the torque being applied to the pavement !! Good luck Dave
You can see the pickup in this picture and I totally agree about the rear deep sump. Since I injured my back I'm on a skinny budget with this thing and I can't afford to buy another. I bought this one years ago because it offered a sending unit and was 16 gallon. I wanted the truck to be a street/strip type deal from the beginning (15 yrs. ago)
well i'd either leave it like it is or put it right behind the cab to put it close to the IC. If you move it up, you could still throw a bag of groceries in the rear of the bed to shut up anyone saying it's not a practical vehicle, eh?
Guess I'll leave it where it is, esp. like the wheelie part, I'll still have the front part of the bed to put my groceries in for the nay sayers. Come to think about it I shop with the t-bucket and there's got to be more room in that bed than in the passenger seat of that thing. Thanks for the replies and advise, I always thought optimum traction would have been placing the weight directly over the rearend. I thought the I.C. was only for conecting the the suspension lines on intersecting points.
Hey Swade. it looks like to me that it can't go much lower then where it's at, and something I think about is how when building a street/strip car or truck is the handling. If you mount everything up high you will have alot more body roll. Like an engine /trans mounted way high or even a 15 gal. tank filled will also put your weight transfer into effect. The truck I'm building now has the engine/trans low enough to where I didn't have to hardly make much of a trans cover. But that's partly because of my size/need all the room I can get, especially in a truck cab. Seen alot of short wheelbase cars get up on two wheels for this reason in a sharp corner or doing a doughnut.
Yeah, I don't think this one will go around the corners to fast and agree with the high weight. The engine sits fairly low so I think I'll be ok about the tipsy turby under reasonable cornering speeds. Here's a couple pictures for reference on engine height, the front suspension is lowered a few inches now so it's not that high in the front anymore either.
Having that type of suspension will make a huge difference, compared to mine/straight axle. I'll probally make a tank to fit between my frame rails behind the rear axle. Trying to keep the bed completely clear, since it's only 40 ins. wide, 5 feet long. Wheelbase at 102"
I pretty much got the bed fabbed up and this is what I'm looking at as far as mounting the fuel cell. The angle iron frame work is the floor support, at this point I can go to the frame with the cell mounts. I think mounting to the floor would be to high, here's a better perspective of where it sits if mounted to the truck frame. What do you guys think about that ?
After messing with it more today, I made a temp floor and sit up there and it's just to high, I'm going to mount to the frame. Isn't there a rule in the NHRA rule book that the fuel cell must be enclosed ? I can't find my book but I thought there was, something about if it's not in a stock postion there must a certain thickness of metal around it. I know it says something about a bulkhead between the driver but what about around the cell ?
just found the regs for fuel tanks but it doesn't say what thickness the metal has to be http://my5ltr.tripod.com/NHRArules.html 1.5 FUEL SYSTEMS Location: All fuel tanks, lines, pumps, valves etc., must be outside of the driver's compartment and within the confines of the frame and/or steel body. Cool cans, in full-bodied cars, must be mounted a minimum of 6-inches (15.2 cm) forward of firewall. Fuel blocks must be located at least 6-inches (15.2 cm) forward of the flywheel/bellhousing area. Tanks: When permitted by class regulations, fuel tanks located outside body and/or frame must be enclosed in a steel tube frame constructed of minimum 1 1/4-inch O.D. x .065-inch (31.8 x 1.65 mm) chrome moly or .118-inch (3.0 mm) mild steel tubing. All fuel tanks must be isolated from the driver's compartment by a firewall completely sealed to prevent any fuel from entering the driver's compartment. All fuel tanks must have a pressure cap and be vented outside of body. A positive-locking screw-on fuel tank cap is mandatory on all open-bodied cars. Insulated fuel tanks prohibited. When used, fuel cells must have a metal box protecting the part of the cell which is outside of body lines or trunk floor, excluding hose connection area in rear. All non-metallic fuel cells must be grounded to chassis.
Maximum possible traction advantage? Cantilevered 18 feet behind the rear axle. Why? Because it would balance the weight forward of the axle, and the weight on that axle would be 100% of the truck weight. Having the weight directly over the axle is less traction, any farther forward is even less. Height: if the suspension didn't move on launch (go-kart, pretty much nothing else) the height wouldn't matter. Weigh up high pivots backward when the nose rises which adds weight to the rear wheels by subtracting it from the front (that's what cantilever does). However, the mass also delays wheelies since it's at rest and needs energy input to move it (if it were centered on the axle, it wouldn't move at all, only rotate). A 10 lb. weight on top of an absolutely rigid carbon fiber tube 100 feet high would prevent the car from wheelie-ing, since the 100 feet of leverage would be more than it takes to bend the chassis (google Archimedes)
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