Popping fire while building boost at the line???

Blackbumper

Blackbumper

Could be worse!
Joined
Dec 30, 2006
Messages
364
We watched this truck a couple of times this weekend and are trying to figure out why he is popping fire out the exhaust when he is building boost at the line. He said it was because he has a bad cylinder that only runs good after it gets hot I find that a little hard to believe. Do you think he is adding something in the fuel or what are your opinions?

http://video.competitiondiesel.com/video/bcfb6099-45bc-4a6c-9e65-99600112a942.htm
 
Hard to say what it is (cough nitrous), but a bad cylinder could be ruled out I'd say.
 
What engine?? Sounds "Cummins like," but not quite right!

It's not uncommon for an engine with LOTS of timing to bark a little flame. In part, he is right...the cylinder isn't hot enough to fire, so the fuel doesn't ignite until it enters the hot exhaust from the other cylinders. Once he gets some heat built, it's fine!

Not that it's right, but it's not unheard of!
Chris
 
That truck used to or maby still does belong to Craig Mackelfresh (sp?)
BTW my dd will do that with the big injectors in it.
 
Mine has shot flame from the downpipe when the timing was screwed up. Mine also makes a 18" torch cone out the stack at night but I think that's a different issue. :hehe:

brandno.
 
Sounds and looks like exhaust ignition. Timing and fuel will do exactly that everytime.$.02
 
SuperSonic said:
That truck used to or maby still does belong to Craig Mackelfresh (sp?)
BTW my dd will do that with the big injectors in it.
Click to expand...

I'm not sure what his name is but I think he lives by St Joe,MO. Seemed like a nice guy I just had never seen a truck run like that the officials at the track were all looking at each other wondering if they should back away or shut him down.

As for the question "does it sound like a 466" no it doesn't but it definetely has a different sound to it for being a cummins. The truck runs hard and has made some nice passes so we are looking forward to seeing him again.
 
Yes, that is Craig's truck, one of the nicest guys you'll ever meet. He was more than willing to give me some pointers after I blew my rear yoke apart last night.
 
I saw the title of this thread and immediately thought of him, yup, try standing behind it and next to the sled while it does that, that pop is freakin' loud.
 
ambient air temp is too cold or cylinder temps are not hot enough, see it on pulling tractors tons of times, also happens with high timing.
 
I talked with Craig last friday night at the Platte City, MO Pull. He said timing, fuel, and the bad cylinder were the cause. Anyways he pulled in the street diesel class and made it over 300' (308 I think?), then he put the nitrous bottle back in the truck and pulled with me in the Open class. I pulled 292 for 4th place, he pulled 288 I think for 5th place (Crowder, Ingram, & Painter were the top three). Then he took the bottle back out and pulled in the street diesel pull off at the end of the night (around 14 trucks in the pull off). I can't remember his distance (over 300) but he ended up breaking the rear driveshaft at the slip yoke. Splines were twisted around the shaft pretty good.
 
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