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Discussion Starter #1
I am running alcohol thru a Holly 750 double pumper on a 400 SBC. I have noticed something that I am not sure what is going on so maybe someone can help explain. I get the water temp up to 170-180 before I make a run. If I leave the water pump off during my burnout and run down the track, the motor will cut out like it is hitting the rev limiter about 60' before the 660' finish line. It doesn't seem to hurt performance because I actually run 0.03-0.05 faster when I leave the water pump off and it cuts out on the top end. Once it reaches 180 and I do a burn out if I turn the water pump on during my run down the track I don't seem cut out on the top end and it runs 0.03-0.05 slower. Is it leaning out? Why would it run faster cutting out? My temp doesn't seem to register higher on the temp gauge after the run and I turn on my water pump. Any one with an ideas what is going on? What can I do to fix the cutting out on the top end without effecting the bottom end?
 

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not sure about that.I switched to alky this yr, could not keep car warm for nithing going down track. It would loose 50 degrees. started leaving pump off and it helped..I was told real quick not to do that. I blocked cooler off completely and fixed it. I staged at 160 cause I really cant get it hotter then that without burning a lot of fuel
 

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Sorta sounds like a ignition issue....... Why so much temp with alky? You don't need to get it that hot before a run.....get yourself an oil temp gauge and learn to see what operational oil temps are, after initial warm up I'm willing to bet your running excessive heat, your burning out at 180*? My dragster and door car never see those temps, and I warm the motor without the water pump on then let it heat soak, it always retains a little heat, a quick warm up before the run and I pull on to the track at 160* perform my regular routine and stage at 160*-165* depending on the air quality that day, and drive back to the trailer and still don't see 180* how hot is it getting on the pass if your burning out at 180*??
 

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Discussion Starter #4
Sorta sounds like a ignition issue....... Why so much temp with alky? You don't need to get it that hot before a run.....get yourself an oil temp gauge and learn to see what operational oil temps are, after initial warm up I'm willing to bet your running excessive heat, your burning out at 180*? My dragster and door car never see those temps, and I warm the motor without the water pump on then let it heat soak, it always retains a little heat, a quick warm up before the run and I pull on to the track at 160* perform my regular routine and stage at 160*-165* depending on the air quality that day, and drive back to the trailer and still don't see 180* how hot is it getting on the pass if your burning out at 180*??
I was running around 150-160 originally and had several people tell me that was too cold for alcohol. Hotter the better so I started letting it get up to 180 and then I ran faster so it seems to track with what they were saying.
 

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im the same with ken. pull out to do burnout at 160* stage at 165*. and I always run a water pump during the run. car gets to 170* at stripe and car cools back down to 160 by time im back to trailer after a pass. I also got in a habbit of using a block heater on cool days . plug it in and car stays at 140 all day long when not running. but like ken said also you are probably having an ignition problem if its cutting out on a pass
 

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It's about a combination of things. I leave out of the staging lanes with E85 or methanol at about 135 in the summer, 5-10 degrees more as the temps drop in fall and winter. Last weekend I got back to the pits at under 160. The things you need are sufficient ignition, using a plug heat range that is not too cold, keeping the plug gaps relatively tight, .025-.030, and intake that more equally distributes air and fuel, and using a booster that provides sufficient atomization for equal distribution to all cylinders. Distribution is the biggest key, if any of the other areas suffer you have to run more temp to atomize and vaporize the fuel more completely to get the distribution more equal.
 

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I was running around 150-160 originally and had several people tell me that was too cold for alcohol. Hotter the better so I started letting it get up to 180 and then I ran faster so it seems to track with what they were saying.
it might run faster but I would think you are more looking for consistency are you not?
 

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Discussion Starter #9
im the same with ken. pull out to do burnout at 160* stage at 165*. and I always run a water pump during the run. car gets to 170* at stripe and car cools back down to 160 by time im back to trailer after a pass. I also got in a habbit of using a block heater on cool days . plug it in and car stays at 140 all day long when not running. but like ken said also you are probably having an ignition problem if its cutting out on a pass
I think it is a fuel problem that is causing the cutting out because why would running the water pump which keeps it cooler cause it to not cut out but leaving it off which would let it run hotter cause an ignition problem. If it is an ignition problem where do I start looking?
 

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Discussion Starter #10
it might run faster but I would think you are more looking for consistency are you not?
It does seem to run consistently either way as long as I do it the same either way. Just trying to figure out why I am getting the two different ets when water temp seems to be the same with only difference is whether the water pump circulates during the run or not. If I leave off the pump is it possible I am getting hotter temps around the cylinders than what the temp gauge reads? If hotter is not better why does it run faster?
 

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I was actually talking with a friend who's been helping me tune my Alky combo in and the first thing I asked was pre-burnout temp, stage temp. He's run Alky for 20 years and told me to go into the burnout box at 160*, stage at 165* and its probably going to 170* through the traps. I've also got a big aluminum rad, with 2 12" fans. I noticed when I crank my car up I don't even use the fans at all. Open my lean out valve for 3-4 minutes at its at 160*.

Going this weekend Saturday to get some 1/4 data for the YB nationals! I also dropped from a 5.14 gear to a 4.56. Hopefully that will tame it down enough.
 

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I think it is a fuel problem that is causing the cutting out because why would running the water pump which keeps it cooler cause it to not cut out but leaving it off which would let it run hotter cause an ignition problem. If it is an ignition problem where do I start looking?
Im not normally one to comment on electrical stuff because I'm still learning, surly enough the water pump wouldn't cause a voltage drop??
 

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Discussion Starter #15
maybe the water pump has a short or something in it. if the voltage drops under a certain point it will start to cut out
Maybe I didn't say it correctly but it cuts out when the pump is off. If it did it when the pump is on I would say yes. My uneducated guess is when the pump is off the water temp around the cylinders gets hotter then when the pump is on and that is causing some sort of leaning out which is the cutting out. Is that plausible?
 

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You can fight it all day and say that you think it's a fuel problem but in reality if the car is running and pumping fuel to the motor the only thing that'll make it shut down momentarily is IGNITION!! It takes fuel and spark to create combustion, loose fuel and it'll run until it Empty's the fuel bowls, lose ignition it'll cut out instantly, is there a bump on the track? You could have a bad switch or terminal.... Don't eliminate possibility's because you think that one action of turning the water pump on or off has made a difference in performance....something is causing the car to cease to run, never seen a car that didn't sputter when running out of fuel, which would be a clear indication..... Ignitions cut out!! Unless you're not explaining properly, you have an ignition problem you need to find... Hope this helps!
 

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Our Jr. on Alcohol was cutting out like an electrical problem. bypassed the kill, changed the plug, wire, coil with no fix. I ended up finding out the needle and seat in the carb were all gummed up from the alcohol. SO I would clean the carb out real good.
 

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You can fight it all day and say that you think it's a fuel problem but in reality if the car is running and pumping fuel to the motor the only thing that'll make it shut down momentarily is IGNITION!! It takes fuel and spark to create combustion, loose fuel and it'll run until it Empty's the fuel bowls, lose ignition it'll cut out instantly, is there a bump on the track? You could have a bad switch or terminal.... Don't eliminate possibility's because you think that one action of turning the water pump on or off has made a difference in performance....something is causing the car to cease to run, never seen a car that didn't sputter when running out of fuel, which would be a clear indication..... Ignitions cut out!! Unless you're not explaining properly, you have an ignition problem you need to find... Hope this helps!
I am not ruling anything out. Just seems odd that it if it was electrical that it would only ever do it near the finish line. It doesn't even do it all the time. I a run uploaded a video of when it did it. If you listen to the motor right before the finish line you can hear the motor waver. Let me know what you think.

http://youtu.be/vua0PfXFlnA
 
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