FrontEngineDragsters.Org Forum
Technical => Spud Miller's Cave => Topic started by: hotrod316 on May 13, 2017, 06:23:09 PM
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Spud,
we took the dragster out today for some shake down runs. we changed lots of things based on your great calculator thanks, it helped alot! But after a semi hard burn out the motor quit reprimed it, fired right back up did a great pass but at the end of the track it died again.
we have two vents, one in the front and one in the back, on the top
7 gal tank with the pickup on the bottom, 1 inch tube, about 8 inch long, with the bottom scalloped
we think the fuel might be sloshing around in the tank uncovering the back of the pick up tube the scalloped part.
our plan before the next test was to put a trap door in side the tank
we would like your thoughts !
is there is something stupid we are missing or over looking
YES the tank was full of fuel !! ;D
we made 3 passes on this motor last year before the cam went south and it did the same thing
so we still have the same issues or some thing still wrong
thanks for your time
steve m
ps is it vacation time yet ?
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Is there baffles in the tank?
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Did you get on the brakes hard after the burnout
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If tank is long and narrow try extending the pickup into the tank about a third of the way. You should be able to do it without cutting tank up.
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no baffles in the tank, the pick up is about 8 inches into the tank, will ask the driver about the brakes
thanks
steve
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First test is to remove tank and fill with water with the outlet covered, remove cover and watch flow, should be a constant streem and not surge, if it surges the there is a vent problem.
Had a similar problem that was pump related, screwed up the endplay an wore the pump cover so bad that it lost pressure at low rpm and coming down after the burnout was not enough fuel to keep it running.
After the burnout, does the rpm rise before it dies or does it just quit???
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we thought one of the problems was the vent,
only had one vent in the back with a roll over, (last year)
we added one more vent to the tank in the front and removed the roller valve.
both vents are # 6
talked to the driver
not to hard on the brakes after the burn out, but harder on them than the other 2 pass. 3 pass when it died.
drive said, he started to back up and it just died, it may have started to lean out but not sure.
on the big in it just died after lifting. does not know what the motor did.
other question
once the motor losses prime, does the pump have have to come to a rest before it will prime again ? to lose the air pocket it cannot self prime ?
will check the pump, we had .007 cam end play between the pump and the cam but that was with the old cam.
sorry this is a bbc injected on non drinkable - safely alc.
with all your help we will find it
thanks steve
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We lost end play when we replaced cam, was a fresh pump and had to turn with wrench, pulled the pump and spun the drive like a top.. that would be my first step based on what happened before
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Didn't mention size of pump
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-1 hillborn
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How big is that in gpm?
How high is the idle?
What dia fuel line and how long? thanks no
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We had the same problem, do the burn out and then brake to back up, the engine would die.
Also have the problem at the top end, make it through the finish line , brake to make the turn of the track and the engine dies again.
We solved the burn out problem by adding a baffle with a flapper that closes when the fuel wants to run forward (Roo Man built the tank).
The top end was no solved by the baffle as that negative g fource last longer.
I added a small tank in the return line and a primer pump that takes fuel from this tank and dumps it into the distribution block.
If the engine starts to stumble I give it a shot from the primer pump and can make it around the corner. I can also start the engine if needed by myself this way if needed.
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thanks Glenn sound just like our problem
what pump did you use?
Bruce 6 gmp
75 inches long tube with 12 inch of #12 hoses
1 inch od
.822 id
we are going to put a baffle with a doors
Does the baffle go all the way to the top of the tank?
we are trying to come after you Glenn and the rest of the pro comp gang :) :) :)
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sorry idles about 1500
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we are going to put a baffle with a doors
Does the baffle go all the way to the top of the tank?
Yes
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thanks Glenn sound just like our problem
what pump did you use?
Bruce 6 gmp
75 inches long tube with 12 inch of #12 hoses
1 inch od
.822 id
we are going to put a baffle with a doors
Does the baffle go all the way to the top of the tank?
we are trying to come after you Glenn and the rest of the pro comp gang :) :) :)
Just got home from Gateway, will look it up tomorrow.
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thanks all cutter her up this am :-*
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This is what I started out with. The pump was later replaced with another one as this one did not have enough power.
(https://www.lever-family-racing.com/wp-content/uploads/2015/02/DSC_1512.jpg)
I put the small tank in stream in the return line to the tank. That way once it has been started the first time at a race it is always full until you empty it at the end of a race.
(https://www.lever-family-racing.com/wp-content/uploads/2015/02/DSC_1511.jpg)
(https://www.lever-family-racing.com/wp-content/uploads/2015/02/DSC_1524.jpg)
The feed to the pump comes off the bottom of the tank.
(https://www.lever-family-racing.com/wp-content/uploads/2015/02/DSC_15181.jpg)
The line from the pump goes into the distribution block for the injectors, with a check valve.
(https://www.lever-family-racing.com/wp-content/uploads/2015/02/DSC_1532.jpg)
Now I can give the engine a shot of alcohol anytime I need to.
I cannot find a shot of the pump, I will have to go over to where the dragster is stored and get a shot for you.
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thanks Glenn :)
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Gimmicks, lots of cars dont use that--whats so different??
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Gimmicks, lots of cars dont use that--whats so different??
I believe what causes my problem with the engine quitting is the shape of the tank.
Being long and narrow causes the fuel to run away from the pickup with negative G's.
Not a gimmick if it solves the problem.
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Built correctly and there wouldnt be a problem.
Had an oppertunity to play with "fluid motion" graphics program, played with size, shape, volume, and forces, It can be made to work
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Glenn, I think you are right about the fuel tank shape. When Dave Tuttle build our car in 1997, he asked about what Bud wanted for a tank, and we were going to race the car and not build a show car, Bud wanted a tank that would not die after a burn-out or after the finish line, he built a kinda tall tank, it's a 4 gal tank that is 10" tall, & 16" long, with a baffle/shelf about 3" from the bottom, and about 1" open on each end of the tank with one hole under the fuel cap so the tech guys can do the fuel check [ must be pure alky], no hinged baffle. We have never had a problem with fuel supply.
BTW, if you'll notice the big show cars have tall tanks. Now when I had my nitro JrFuel car in the 60's, we made a cute little tank no higher than the top frame rail, and widge shape, BUT that was during the time of no burn-outs, just push start from the big end, change lanes behind the start line, and go with a flagman and smoke the tires about half track, no VHT.
Glenn I know you may not like our tank design, because of your full body, but a 10" tall tank has worked perfect for us.
I hope this helps.
Jon
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I have no choice if I want to run the full body, which I do.
With the new tank having a baffle and trap door the engine no longer dies after the burn out.
The primer pump solved the problem up on the big end. I can now make the turn of the track under power.
Glenn
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Burnouts without a problem
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Nice article here: The Perfect Fuel Tank (http://www.fuelinjectionent.com/perfectfueltank.php), by Spud (our sponsor).
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left a lot out of the artical
5052 H32 aluminum because its very corrosion resistent , this material was created for the boating industry.
.080 in this material is hard to work with using hand tools and to form radius edges for the edges to ensure proper welding. .063 is a little easier to work with but a little harder to weld than .080.
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.080 5052 aluminum is a little more effort to work, but worth it in my opinion. Polishes a bit better than 3003 alloy for sure! Spud's article has a lot of ideas on tank design, and he's a down-to-earth good guy to work with as well.
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In you opinion, what reason do you give for .080 over .063??
I have made many using both thickness, but also have heavier duty equipment to work the thicker material
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I have equipment that can handle the thicker material as well so I try to go with the .080 5052 on a fuel tank. I use a radius brake for the largest section, a Pullmax to form the ends, and a Eckold machine to shrink where needed. I figure the heavier wall may hold up better for a longer period of use, so I feel I might as well go with it when I can. But then for something smaller and not carrying weight like a puke tank, I would go with a lighter thickness. Around what time did 5052 first come in to use anyway? I still much prefer using annealed 3003 H14 for deep shaping, but only if corrosion resistance and polishing are not required.
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My guess is the first time the the boating industry started using alu to make boats out of.
You have the equipt and I have the equipt, the average guy/girl that wants to try and do it themselves prob do not have access to. So to keep fustration down and to be able to use simple forming tools to work the 5052, giving up .017" in thickness to learn proper construction methods and increase welding skills, I feel holds a little more weight to the discussion. Most of the tanks discussed here will be small in volume vs a big show top fuel or funny car that using the thicker material is a general must use, and those will be made by the likes of you and me, and not the home builder. The last home built tank I saw run in a funny, blew up and burned the car down, used .080 but did not roll the edges and split across seams
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Thanks for the info, drerace !
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Well that did not go well! went testing last week
almost lost our new fed.
car made a very hard right turn! even the tower said that was a great save.
original fix
baffels in the tank?
we put 4 baffels in the tank.
1st problem,
it blow fuel out the rear vent, right onto the right rear tire, never done that before! thanks to (go pro)
fix?
going to tie front and back vents together and put them into a vented punk tank not going to do that again you say heart attack!
SECOND PROBLEM IS STILL THE PROBLEM TRYING TO FIX. SECOND PASS THE MOTOR DIED AGAIN AFTER THE BURN OUT, BAFFLES DID NOT FIX THE PROBLEM.
FIX
WE PUT THEM IN THE WRONG PLACE.
IT'S NOT THE TANK
QUESTION SPUD
IF YOU REMEMBER WE ARE RUNNING THE MAIN BY PASS OFF THE PUMP ( PIC IS ON HERE UNDER PUMP I THINK, REMOVED ALL THE INTERS)
COULD THIS BE THE PROBLEM, CAVITATING IN THE PUMP
FUEL TANK TO FAR FROM PUMP.
FUEL LINE, IS 1" ALUM TO 10" OF # 12 HOSE TO PUMP
GOING TO CHANGE THE MAIN BY PASS TO RIGHT BEFORE THE BARROW VALVE TEE OFF.
PLUG THE PUMP
IT SOMETHING STUPID I KNOWN!
AS ALWAYS THANKS FOR YOU TIME
STEVE M :D
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Liquid under the tire at launch is no fun.
I almost collect the wall at gateway last year when we were held at the line for a track problem and the engine got hot and water from the expansion tank escaped right in front of the right rear tire. No one noticed the water.
People tell me they do not know how I did not touch the wall, myself I do not remember coming that close, it was just reaction instinct that saved me.
This problem has been addressed and will never happen again.
Sorry the baffles did not solve you problem. The description exactly fit the problems I had at Epping before we install baffles
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THANKS GLENN WE ARE GOING TO MOVE THE MAIN OF THE PUMP AND TRY AGAIN
WE HAVE ONE MORE TEST BEFORE THE NEXT NDRL RACE :)
STEVE M
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Are you going to Norwalk?
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that was the plan! but if we can not find the gremlin no!
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What are the butterflies set to? If they are too tight...when you snap the throttle closed they might be cutting off air for just long enough to stall. open them up a few thou and try it....you will have to readjust the barrel valve.
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thanks Steve will try that.
went testing Saturday, stayed off the brakes longer, motor did not die after the burn out, but still die at the big in
and yes it a PIG!! 5.30, 5.30 5.31 5.30 131 or 132 mph IN THE 1/8, now I have a driver! Richard Lawson, now can we just get to a race?
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What are the butterflies set to? If they are too tight...when you snap the throttle closed they might be cutting off air for just long enough to stall. open them up a few thou and try it....you will have to readjust the barrel valve.
Just screw the stop a little bit , no need to mess with the BV, Its alcohol! as long as it comes off of idle clean and sharp the BV is fine.
Fuel volume reacts to "G" force. 1g will move the fuel to fill the void at a 45* angle at the tail. If you are not carrying enough volume the fuel will move away from the pickup, and is quite common with the chute hit.
Racing is too expensive to have problems, really need to have somebody build you a tank that works correctly