Fun with spark plugs

In three words, I don't know.

Ding-dong!  Junior calling

As to your unexpected outcome when coupling the two pumps togther...I'd like to see you do a couple of things. 

Ah, fun with pumps!  Diaphragm style too...hmm.  Another variable I had not considered is diaphragm flex..wonder if the second pump did not have a "variable displacement" based on diaphragm flex at the higher pressures produced.  Well, back to spark plugs!

(By the way, you could also just use a bottled high-pressure gas like nitrogen, argon, C02.  Argon might produce a neat effect...as an inert gas, I'd bet the spark itself would be less diffused and make a sharper, clearer and more distinct image.)

 

So, of course, what you're trying to do is estimate actual cylinder/chamber pressure when spark occurs.  I will offer that this is a very changeable figure, based on many dynamic aspects of the engine, not the least of which is inertial momentum of intake charge at maximum BMEP.  Bear in mind, thinking of the engine's air processing in strictly static terms can fail to take these factors into account.

 

I'll noodle on this a bit and come back with something cohesive.

Would be interesting to see more data off that example.     If your simple add is right, then say he has 300 PSI unboosted pressure.  He still needs 200 PSI of boost!

I found a couple of Thompson Ind. pumps at the salvage yard.  Larger, but don't have enough HP to run in series.   If I use the new Thompson pump as the output stage, I can stall it.    If I take the old input pump (like the one I broke the shaft on) and use it for the output and then drive the new Thompson pump into it, I get about the same results as before, way more than the simple sum of the two pumps.    

If I look at the pressure between the two pumps, it appears the same as if I dead head the input pump.  This is what I would expect to see.    Adding an accumulator between the two pumps has no effect on the output pressure. 

New pumps are similar to other design.  Simple two reed valve design with diaphragm.  

This would make sense with the turbo example that was shown as well.

Simple questions require difficult answers some time.  Can you help me to understand this?

Problem with the CR is that the actual pressure gain can be almost anything.  

I am still thinking gain.  So gain of pump 1 times the gain of pump 2. 

Convert to atmosphere first.  So  take the dead head of the two pumps in PSI, convert to atmosphere then figure the gain.    Multiply the gains and multiply by 1 atmosphere then convert back to PSIG.   Take into account the temperature and I think you would have most of it. 

Hey Matt, your a compressor guru by trade?  Any input on this? 

CR is just the volume ratios, not the pressure ratio.  I can make my engine a very poor pump, or a very good one all with the same CR just by changing the valve timing.   It seems that the dead head is really the number.   But, like Mr. Rice, I don't know.  


For now, lets assume that the pressure with boost is higher than the cranking pressure.   In this next video I am using the new gauge and my new window.   I have the chamber outside the screen so we can get some shots of what I want to show.    This test is with the repaired MC-4, 2 blaster coils, 8.5mm Super Conductor Plug Wire, MSD boots and NGK D9EA gaped at 0.028".  I am using the towers on the blaster coils and have silicone around the boot to increase the  breakdown voltage.   These are the long, straight MSD boots. 

Boots and wires are new, i.e. purchased maybe a year ago and were never installed on a bike.  I keep them for testing only. 

I have not tried this test with the Dyna wires and coils yet, but believe that this video may surprise a few of you.  It did me. 
http://www.youtube.com/watch?v=6qEQzLU9y0c

These pictures show the wires, boots I am using and the silicone on the towers for reference.





Oh, and for Scott, the chamber pressure during this test was around 250PSIG.   I am not sure of the accuracy of the gauge. 

The plugs were cleaned with freon after installing them in the chamber.   

Material contamination in the boots seems possible.  That's a long way for the spark to travel.   Or is it common practice to use corona dope on the boots after they have been installed on the plugs? 

On my bike I have not noticed any misfires while running at the 26-27 PSI.   It seems pretty smooth on the logger.  It may not be enough of a problem.  Or, the boots and wires on my bike are from a different lot.  

The Dyna is a whole different story.  Wires and boots are both a totally different from MSDs.   I am not sure about the energy between the two units.   I can't find any specs on the Dyna, just that its high.   The MC-4 is rated for 190 mJoules (non multi-spark mode).  
  

One things for sure.  Every time I dig into some detail about these motorcycles, I learn something new. 

My bike has the same ignition on it (and same gap).  

Originally posted by geek This test is with ...NGK D9EA gaped at 0.028".

It seems like a friend had told me about problems they had with the boots at one time.  I'll see what they remember. 

I have some other boots that came with the kit that have a different style.    I'll make up a set with them and see what happens.   May try the ones off the other bike too. 

Edited by geek - 09 October 2009 at 12:18am

... Run a dedicated ground from the top of the chamber (same solid piece that the plugs are threaded into) back to the plate that the box is mounted on and grounded to. Btw, what is the box mounted on ?