Sometimes, it is good to sit on a school bench. VVT refresher course.

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
10,004
Likes
180
Points
63
Location
St-Hyacinthe, Quebec, Canada
#16
Not the one on comp designation. 1st ducor mean.

Anywho, gotto go gf is scrapping the covers, time to get off the net.

BTW, if you work in a high volume shop, this tool will save time, and $$$$

http://www.theinductor.com/induction-heating-products/mini-ductor/models/md-700-110v


As usual, a useless tune.

The system is broken, up to us to fix it. Then our children, no other way.

 

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
10,004
Likes
180
Points
63
Location
St-Hyacinthe, Quebec, Canada
#17
@Bill, some of the equations are done in mv. The rule of thumb seems to be 1 mv = 1 psi.

But that depends on VE test. That is when graphing get long for the un initiated.
 

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
10,004
Likes
180
Points
63
Location
St-Hyacinthe, Quebec, Canada
#19
Fun was graphing fazing cam hazers out of whack. :beer::beer::beer::beer::beer::beer::beer::beer:

Listening to heavy metal, my mind is not on scope stuff, but I hope I helped in the placement of transducers for your question.


 
Last edited:

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
10,004
Likes
180
Points
63
Location
St-Hyacinthe, Quebec, Canada
#22
This guys accent is impossible for me to get, but he seems to show what I was learned.

For me, not the teacher I would have wanted. Thanx I got a real french guy, so the matiere stuck.
 

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
10,004
Likes
180
Points
63
Location
St-Hyacinthe, Quebec, Canada
#25
@billr

Hello bill, happy canada day.

I want a little favor of you today or whenever you got time. Can you please view this video. I am currently, as you know, looking into this. I even might want to make one, but this product looks hopeful. But I know your better at scopes and associated peripherals than I am.

What do you think, is this a justified buy for a guy like me?

 

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
10,004
Likes
180
Points
63
Location
St-Hyacinthe, Quebec, Canada
#28
Because in the courses this last week, we had two available, the teacher, Dany Labrie said having two of them is most helpful. That would bring my tool investment to 2 grand. Quite a substantial investment, so before I shell out that cash, I need insight. I also invite others here to advise.

In my car career, I know when to cheap out on a tool, and when to spend a few extra bones, to save my bones from arthritis and such, but this tool is a first investment for me. I am probably answering my own question, but that scope 1 kit sure looks good.

Obviously the pico one is light yrs ahead, but 500$ ahead? I don't know?
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
6,521
Likes
83
Points
48
#29
Well, to me, "light yrs ahead" sounds like much more benefit than the cost increase from $500 to $1000; that is only double.

However, I think a key question is how much diag work you think you will be doing with VVT? That is the only function I see this being really great at. All other uses it is touted for can be handled with simple mechanical gauges that you already have. If it provided readings for the whole cycle, including combustion, it could be very useful for performance research/tuning; but I'm thinking that is not your present or intended business.

I have to admit, I didn't study the manufacturer's info assiduously, so if you think I am missing a feature/benefit please advise so we can discuss further.
 

billr

wrench
Staff member
Joined
Mar 12, 2007
Messages
6,521
Likes
83
Points
48
#30
Some more comments...

I could not find a spec for the response time of the Comp-Peek, but it seems like both units probably use the same class of transducer, because they both have the transducer buried in a box with amplification separate from the basic transducer. Those transducers are about $60, so you could make this a DIY project building your own amp and using a GP scope fairly cheaply. There are transducers with built-in amps, for about $75, but their response time is about 1 msec vs. the 100 usec of the Pico (and C-P, I think); 10x slower. The transducer shown in the video of your reply #23 is probably the slower "self-contained" type.

What makes the Pico so much better, is it the software? If so, then forget the DIY approach; anything you do with a GP scope is probably going to seem cumbersome in comparison to SW specifically for this purpose; would probably seem "light yrs behind" even the C-P.

None of this is a new concept, of course, I have a 1930s textbook showing similar "indicator cards"; but they also include the combustion pressure to get the whole cycle.

There is often discussion on performance sites (like Megasquirt) about using transducers to show the whole cycle (combustion included), and I have toyed with cheap ways to do that, like a specialized spark-lug or thin "banjo" fitting/gasket under the plug. However, pressures in the cylinder doesn't tell the whole story. You have to integrate the pressure over all the crank/rod angles to determine net torque at the crank, and account for the varying friction from side thrust on the piston. I think it is far easier, and more accurate, to just go to "the bottom line" and measure torque with a dyno.

Again, for diagnosing VVT, I can see that seeing those pressures, even without combustion, can be quite valuable. Maybe for variable inlet runners, too, but I think effects there will be more subtle and harder to see.