Turbulance and Combustion Dynamics - Part 3

[DavidVizard-GFN]

Originally Posted by hotrod

Just out of curiosity, did you always coat both front and back faces of the intake valve on these valve coating tests?

Larry

Yes, the thinking here is that the air stays cooler and more heat is conducted up the stem into the guide. To test one side coated versus two though is going to rtake some very tight testing and i don't believe my dyno is accurate enough for this.
DV

[DavidVizard-GFN]

Originally Posted by big block fiero

Remember the engine that ran best only when running by large fuel globs rather then A fine vaporizing mist. could it be that ,that engines valves were glowing and the large droplets were fixing the problem? Is it possible that an engine could make more power if the valves were not coated and the glob theory was used instead? Do we now test engines for valves that we can't see by globularizing (new word) the mixture, look for a gain, then if there was A gain pull the motor down and coat the valves? comments?

Yes Matt, I might agree if I really understood what you meant here!! It's been a long day!

DV

[MadBill]

I think he's saying that:
1. Perhaps the Mini 'liked' big droplets because they better cooled the hot valves in the process of being vaporized.

2. By extension, any other engine that responds favourably to large droplets might benefit more than most from TB coating of the intake valves (and logically a subsequent recalibration to finer atomization)

[BlackCat13]

Regarding DV comment on this about Champion plugs being down on power and replaced by Autolites:

quote //So the Champion race plugs were pulled and an equivalent heat range of Autolite race plugs installed.
When fired up the motor sounded no less and no more wicked than before but the dyno numbers were – at 142 hp - nothing short of a techno shock. Although a pleasant surprise it was very much a case of ‘what is the world is going on here?’ This was such a surprise that the Champions were re-installed and re-tested. Same killer sound – just 85 hp! Now I have to tell you that in just about every other Mini application Champion plugs were as good as or better than anything we could find but here was an anomaly. This engine apparently did not like anything with Champion written on it.// end quote

A discussion on another forum about this thread's lead-in story says
quote //
"A fouled plug does not recover once it is fouled.....
If you foul a spark plug, you have to install fresh ones. Those plugs are finished. (carbon tracking)
These are racing plugs, they are very very cold, Easy to foul. (especially with flooding. Once fouled , they do not recover. Even cleaning them will not work."// end quote

Is it true that once a plug is fouled it is permanently ruined??
David, do you have any insight into this for us?

Spark plug choice for vortec heads?

[DavidVizard-GFN]

Originally Posted by BlackCat13

Regarding DV comment on this about Champion plugs being down on power and replaced by Autolites:

quote //So the Champion race plugs were pulled and an equivalent heat range of Autolite race plugs installed.
When fired up the motor sounded no less and no more wicked than before but the dyno numbers were – at 142 hp - nothing short of a techno shock. Although a pleasant surprise it was very much a case of ‘what is the world is going on here?’ This was such a surprise that the Champions were re-installed and re-tested. Same killer sound – just 85 hp! Now I have to tell you that in just about every other Mini application Champion plugs were as good as or better than anything we could find but here was an anomaly. This engine apparently did not like anything with Champion written on it.// end quote

A discussion on another forum about this thread's lead-in story says
quote //
"A fouled plug does not recover once it is fouled.....
If you foul a spark plug, you have to install fresh ones. Those plugs are finished. (carbon tracking)
These are racing plugs, they are very very cold, Easy to foul. (especially with flooding. Once fouled , they do not recover. Even cleaning them will not work."// end quote

Is it true that once a plug is fouled it is permanently ruined??
David, do you have any insight into this for us?

Spark plug choice for vortec heads?

The only comment I have here is that we started and warmed the engine on regular extended nose plugs and then change out to the race plugs ( I have done this a time or too and it is far from my first rodeo) it was not until we had flooded the engine toward the end of our search for the problem (after flooding no attempt to start the engine was made as I was fully aware that in those days cold running plugs fouled easily and would fail to start) that we changed the plugs. However fouling the plugs was not the issue as our Sun scope showed every cylinder (all 4 of them) was firing. Like I said this was something of an anomaly - I have had nothing happen like it before or since!


For what it is worth we have had virtually 100 % success at cleaning race plugs by dropping them in acetone and stiring them around awhile then blowing them off with a 'dry air' air line. I don't know what the poster on the other site was using but by 1966 we were building electronic ignition systems that would fire some pretty disgusting plugs!

DV