Popping on alky without knock.

[sixgun86gn]

Does everybodys car pop in the exhaust on alky?I don't know anybody else that runs alky around me.I have pump speed set at the lowest point it actually comes on at (4).I know this because I pulled the up pipe and looked inside.It flowed nothing up to that point on the speed control.I cant set it any higher or it drowns out the spark.Plug gap is set a .030 and boost was 24#.I had no knock at all and was running the 8th mile at 90mph set like this.My exhaust always pops when I run the alky any more and it floods any less and KR.Could it be excess alky burning in the exhaust?My pump setting seems low compared to others .Static fuel pressure is 44# and o2s above 780.It sounds like crap,runs like a demon.Should I change anything?

 

[Turbo__Tim]

I've never experienced that.

Regardless of the 0-2 numbers, it seems more likely that the popping would be comming from un-burnt gas.

Could be one plug, or one plug wire causing that.

If the pump speed is at '4', you might want a smaller jet. Atomization is important. Less likely to douse spark.

If lowering the FP to 42, or changing the alchy to water ratio (to ? ) has no effect, I'd be looking at the wires, or plugs.

Sounds like you got a pretty good handle on it already though. What mixture are you using?

 

[sixgun86gn]

I use mostly just denatured alky,but I added water this time.I would say it was 70% alky 30% water.Maybe more like 50/50 would work better.I dont think it is a plug or wire because it only does it when I run the alky.At low boost on 93 alone it runs good with no popping.Ill try taking out some fuel and see if that helps.

 

[Mr URL]

Mine popped like crazy when I accidently had the plug gaps too tight. Try 0.035 - 0.032.

 

[NC87GN]

Had the same problem on a locals car I tuned. Would reach 3500-4000K pop and then ran like a dream after 4K. Turned out to be too much fuel in the chip. Try bumping the Fuel pressure down but turn the alky on a little sooner. When burning custom chips, with alky, I try to tune the car in pump gas and 16-18# pending on the octane of the gas. Then dial in the boost with alky. Then you can start playing the timing boost game.. With higher timing lower the boost and vise versa. HTH

Mike Banas
87GN

 

[Turbo__Tim]

The popping just happened to me. I was running a 50-50 mix. More details here.

http://www.turbobuick.com/forums/showthread.php?s=&postid=330496#post330496

A common theme to this seems to be the spark getting blown out. Wether from an over rich condition, too 'watery' of a mix with the alchy solution, knock retard, (what happened to me) or just plain weak ignition, all these things seem to cause this...

We are learning!

 

[tyndago]

Originally posted by Mr URL
Mine popped like crazy when I accidently had the plug gaps too tight. Try 0.035 - 0.032.

We had the opposite problem...the gap was too loose and we tightened it up and it got lots better.... Stopped popping and missing.

We went to 50/50 mix , tightened the gaps and upped the boost.... worked to get us into the 11's on pump gas at 2700 feet.