61
Front Engine Dragsters / Re: FED bounce problem.
« on: June 22, 2020, 02:47:23 PM »
Frame is wider style with diagonals so it should be relatively stiff chassis. That is part of reason I am reluctant to just start adding more bars.
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62
Front Engine Dragsters / Re: FED bounce problem.
« on: June 21, 2020, 05:11:00 PM »
It is bouncing some during the RUN under power! And you could see the flex in the chassis when front wheels are in the air. Now the shut down area is a different issue and yes easing into the brakes or throwing parachute out helps.
I can deal with the shut down area but I want it to hook good on any track any time and right now it is not. I suspect it is too much flex in the chassis allowing it to bounce under power. I want this car to be best performing car out there to carry me when driver is not on top of his game. Lol.
Another thing I do not mind adding more bars to stiffen chassis thing is I want to find a way to verify that it will help it before I do it.
I can deal with the shut down area but I want it to hook good on any track any time and right now it is not. I suspect it is too much flex in the chassis allowing it to bounce under power. I want this car to be best performing car out there to carry me when driver is not on top of his game. Lol.
Another thing I do not mind adding more bars to stiffen chassis thing is I want to find a way to verify that it will help it before I do it.
63
Front Engine Dragsters / FED bounce problem.
« on: June 20, 2020, 07:15:28 AM »
I have a 225 inch FED runs 4.90-5.0X and I am having a problem with it. Data logger is showing some bounce / tire spin down rack. Last race I took the wheelie bar off and weight out of nose to be able to run index in high altitude bad air. I THINK I know what the problem is but want some input on how to resolve it. Mind you it is not bad but I want this car to get down any track under all conditions as close to perfect as possible.
Last week in final round saw a video that kind of affirms my thoughts. The car took off at the hit and pulled front wheels up about 8 inches and carried them out about 60 foot and then set them down nice and smooth. That is more than normal but no big deal. What I saw that was interesting is a lot of chassis flex in the middle and what I think is happening is with the long car it is flexing and causing bounce down track. I understand some of that flex helps it hook but I think it is too much here.
I THINK stiffening up the chassis will help it hook better and smoother in the shut down area to. Several tracks we run at is rough in the shut down and it will get my car bouncing. I have also done a lot with tires and tire pressure but this is more than tires now.
My question is how can I test and verify my thinking on stiffening the chassis? Was thinking about tying the chassis with cable under tension to see if it helps and verify it is right direction to go. Something where it attaches in the front and back and goes over middle bar on top to limit downward flex. Then if it works could go in and add more bars to stiffen chassis. I want to do it right but want to verify it is heading in right direction and not making it worse before I do a bunch of major chassis changes.
Last week in final round saw a video that kind of affirms my thoughts. The car took off at the hit and pulled front wheels up about 8 inches and carried them out about 60 foot and then set them down nice and smooth. That is more than normal but no big deal. What I saw that was interesting is a lot of chassis flex in the middle and what I think is happening is with the long car it is flexing and causing bounce down track. I understand some of that flex helps it hook but I think it is too much here.
I THINK stiffening up the chassis will help it hook better and smoother in the shut down area to. Several tracks we run at is rough in the shut down and it will get my car bouncing. I have also done a lot with tires and tire pressure but this is more than tires now.
My question is how can I test and verify my thinking on stiffening the chassis? Was thinking about tying the chassis with cable under tension to see if it helps and verify it is right direction to go. Something where it attaches in the front and back and goes over middle bar on top to limit downward flex. Then if it works could go in and add more bars to stiffen chassis. I want to do it right but want to verify it is heading in right direction and not making it worse before I do a bunch of major chassis changes.
64
Front Engine Dragsters / Re: Finally taking the digger out on Sunday
« on: March 10, 2020, 06:45:49 PM »
It is an adrenaline rush, that's why we do it.
65
Front Engine Dragsters / Re: Finally taking the digger out on Sunday
« on: February 29, 2020, 09:10:55 AM »
That is part of the fun of it. Have fun.
66
Front Engine Dragsters / Re: Humidity & Water Grains
« on: February 06, 2020, 06:02:02 PM »
That far off I would say check for clogged nozzles.
67
Spud Miller's Cave / Re: nitro mixture with 02 aensor
« on: January 11, 2020, 04:26:38 AM »
I run 8 O2 sensors and sometimes run up to 8% Nitro and I use the gas scale. Can not tell any difference on O2 when using some Nitro. Now those are small percentages in fact usually 2% or less.
I think the O2 sensor is measuring burnt Oxygen or lack of so perfect mixture burns all of the Oxygen no matter what fuel. Those sensors read the same and sends SAME signal to the controller where it uses what scale you want but the O2 in the pipe is the same no matter what scale you use.
I think if you are running a carb then 2 O2's one on each side is enough. But if you are running mechanical fuel injection where you put the fuel into each cylinder then you need to measure each cylinder. Every race day it tells me something that could save a burnt piston or worse. I have an 8 cylinder motor and each nozzle is different size to match the needs of that cylinder. Then use main jet for weather changes. Hundreds of people have ran injection for years with no problems but then once in a while people burn pistons and do not understand why or how it happened.
With a carb if it is getting air it is probably getting close to right amount of fuel. With injection your air and fuel are separate. With a carb it works by having some vacuum to draw the fuel out with venturi effect. With injection it does not have that so it allows motor to draw in a little more air giving it the "Potential" to make more power if it gets right fuel mixture.
I think the O2 sensor is measuring burnt Oxygen or lack of so perfect mixture burns all of the Oxygen no matter what fuel. Those sensors read the same and sends SAME signal to the controller where it uses what scale you want but the O2 in the pipe is the same no matter what scale you use.
I think if you are running a carb then 2 O2's one on each side is enough. But if you are running mechanical fuel injection where you put the fuel into each cylinder then you need to measure each cylinder. Every race day it tells me something that could save a burnt piston or worse. I have an 8 cylinder motor and each nozzle is different size to match the needs of that cylinder. Then use main jet for weather changes. Hundreds of people have ran injection for years with no problems but then once in a while people burn pistons and do not understand why or how it happened.
With a carb if it is getting air it is probably getting close to right amount of fuel. With injection your air and fuel are separate. With a carb it works by having some vacuum to draw the fuel out with venturi effect. With injection it does not have that so it allows motor to draw in a little more air giving it the "Potential" to make more power if it gets right fuel mixture.
68
Front Engine Dragsters / Re: Potential FED Build
« on: January 11, 2020, 04:05:26 AM »
I have learned a lot with my 225" front engine dragster and few if any are the same. Part of the reason for that is the length of the frame, how it is braced in front and the flex of it. Tire choice, tire pressure may not work on two different ones that appear very similar.
Most of the Rear Engine Four link dragsters have become pretty generic and others can get you a close set up on them. There is NOTHING Generic about a front engine dragster, they are like women and have multiple personalities. Some of those are not pretty and hard to tame.
My dragster is working good now but it was a fight and she did not give in easily. When I throw more horsepower at it we may be in for another fight.......
Most of the Rear Engine Four link dragsters have become pretty generic and others can get you a close set up on them. There is NOTHING Generic about a front engine dragster, they are like women and have multiple personalities. Some of those are not pretty and hard to tame.
My dragster is working good now but it was a fight and she did not give in easily. When I throw more horsepower at it we may be in for another fight.......
69
Front Engine Dragsters / Re: stage rpm vs stall and wheel speed
« on: December 08, 2019, 07:21:34 PM »
Well raising engine up helped some it was too far down. Started working with tire pressure and that did not do much. Moving some weight back helped more and working with the tires helped a little more. I have had my battery in the nose of the car, raised engine and moved battery to the rear, those two things helped and it hooked up better but was pulling big wheelies. Put battery in nose again and it stopped the wheelies but was still not working back tires right. Put the battery in the middle and now working with tires to get it right where I want it.
Each change has helped but there is no one thing that made it work and it is still not perfect. My altered rarely if ever had an aborted run or traction problem. My dragster has been a fight but it is getting better and data logger verified it. I suspect if car lost 100 Lbs or got 100 more HP I may have to start all over to tune it to work right. In my opinion it is a balancing act to get weight and performance just right on these things.
Each change has helped but there is no one thing that made it work and it is still not perfect. My altered rarely if ever had an aborted run or traction problem. My dragster has been a fight but it is getting better and data logger verified it. I suspect if car lost 100 Lbs or got 100 more HP I may have to start all over to tune it to work right. In my opinion it is a balancing act to get weight and performance just right on these things.
70
Front Engine Dragsters / Re: stage rpm vs stall and wheel speed
« on: December 05, 2019, 05:28:26 PM »
I got it and only way to know is to get out there and run it. Make changes and see if it is better or worse. Most everyone else is running a rear engine four link dragster with big block Chevy and most even paint them the same but they know what it takes to make it work because everyone else has similar. Trust me ours does not respond the same as the other guys and one of those guys can not say Just put a little preload in the anti roll bar. You do not have one. You can not just make a shock setting change. You do not have shocks. Our tires and weight distribution does not work the same as those guys. None are like yours. None. Any input those guys give you most likely will not work on your car. All you can do is go out in YOUR car and make changes to see if it makes it better or worse and keep making changes until it works. Even what works on mine probably is not same on your car. But I have had to make massive changes and 18 months until I was able to get it to work good. With a FED it is a balancing act between horsepower, torque converter, weight, traction, weight distribution, Tire compound, tire pressure, correct tire stiffness, chassis stiffness or flex and more.
Data logger and good slow motion video can help you narrow down what is happening and which direction to go to fix it. I actually had to change my engine angle to make it work better among many other changes.
Data logger and good slow motion video can help you narrow down what is happening and which direction to go to fix it. I actually had to change my engine angle to make it work better among many other changes.
71
Front Engine Dragsters / Re: stage rpm vs stall and wheel speed
« on: November 24, 2019, 03:18:21 PM »
Never going to know until you get out and run it. depends on stall, power curve, tune up, weather etc.
72
Spud Miller's Cave / Re: Not seeing any gains !
« on: October 28, 2019, 01:45:05 PM »
I do think the Nitro gains would be at lower RPM and tighter stall may help with that. With your motor turning lower RPM than it was before I suspect something else may be going on. What kind of injection you have?
73
Front Engine Dragsters / Re: Bent chassis
« on: October 19, 2019, 06:59:44 PM »
With those bars so close together and no uprights and diagonals it is going to be very flexible.
74
Front Engine Dragsters / Re: Fed build design ?
« on: September 08, 2019, 07:09:43 PM »I’m not to big, 5-5 170, what’s the reason for shoulder hoop width?
Build it as big and wide as you can, you can always use extra padding to raise you up but if cage is too small you can not ever sell it unless they are smaller than you. I am 5'11" and I built my dragster to fit anyone up to 6'3" or maybe more. If you are 5'5" and you build it to only fit you then you would never be able to give the car away. And you need room for padding, helmet clearance.
75
Front Engine Dragsters / Re: Fed build design ?
« on: September 05, 2019, 02:00:58 PM »
If you are limiting it to 150 inches or so then I would say drop the idea of a front engine dragster and go with an altered roadster. You can make a good altered really work but I think it would be difficult to make a 150 inch dragster work in the 7's. Not impossible but would be a pain. Buy or build a Spitzer type design and it would work.