The QUIET DEUCE

[houdel]

Will - Radio Shack sells a neat digital sound level meter for $49.95!

BTW, I recently installed a Car Chemistry 3 disk collector insert in my stack. The mfr claims a 5-7 dB noise reduction, I didn't have a sound level meter at the time so I can't verify that but it sounds (pun intended) about right. A 5 dB reduction would be about a 25% reduction in the percieved sound level and that seems to agree with what my ear is telling me.

I have since purchased a Radio Shack sound level meter but haven't had time to run any definative tests with and w/o the insert. Neat thing is it slides INSIDE the top stack, so there is no outward chage to the Deuce's appearance other than the three screws in my stack holding it in place.

I'd like to get the exhaust noise down by 10 dB and then work on non-exhaust noise. The insert came with a set of restrictors (which I haven't used yet) and instructions on how to pack the insert with stainless steel wool for further noise reduction. Preliminary readings with the SPL indicate that at 50 MPH, background mechanical noise (engine, drivetrain, road noise, parts shaking and vibrating) generate nearly as much noise as the exhaust! It would be nice to get the cabin down in the 70-80 dB range, so I can carry on a normal conversation and hear my turbo sing, right now even with the insert the cabin gets up to almost 100 dB when I'm cranking!

I hope to run some tests with the SPL soon to determine just how much noise reduction the insert provides. I didn't notice any seat of the pants performance loss, if anything the Deuce seemed a little perkier. The mfr claims the inserts provide a slight scavanging effect which actually improves exhaust flow, I'm inclined to agree. When I get some definative data I'll put it on the board as a separate posting.

On a related note, does anyone have a simple and inexpensive way to measure back pressure in the exhaust?

Here is a link showing the insert:

http://www.carchemistry.com/shop/in.../20/prevaction/category/previd/1/prevstart/0/

If you click the "Tech Info" tab at the top on the Car Chemistry page you can find a lot more info on the insert. You can buy them from Car Chemistry, JEGS, or Summit Racing, the price is the same at all three. I bought mine from Summit, ordered on a Wednesday, had it Friday, cost me $66.44 delivered, plus they threw in a neat Summit Racing hat, which my wife promptly claimed for herself. If anyone else buys one of these from Summit and doesn't want the hat, I'm looking for another!

 

[cranetruck]

"On a related note, does anyone have a simple and inexpensive way to measure back pressure in the exhaust? "

Why, yes Lee, the tubing connection is shown in the first image, the gauge in the second image just about where the right foot of your passenger would be.

 

[houdel]

Bjorn, you ALWAYS have the answer. What an appropriate range for the pressure range?

On a non-related note - going through some old postings, I noticed you use (or at one time used) a Stellite flip top tote to brew your biodiesel. Did you ever have a problem with the glycerin hardening in the bottom of your tote, and if so how did you get it out? I also noticed on the soap making post that your glycerin seemed pretty stiff.

 

[cranetruck]

My set-up is to monitor the back pressure when the exhaust brake is in use and the range of interest for me is about 0-35 psi.

The back pressure with the muffler will probably need something similar to this air filter canister "vacuum" gauge (image).
The Magnehelic gauges are availabe on ebay for about $10/ea and come in many different low pressure/vacum ranges.

Experiment!

As far as always having an answer, I don't, but I like to play with my big toy.

The Sterilite tubs work great as long as the temperature of the biodiesel/veggie oil is 150F or below.
The glycerin that ends up on the bottom like a doormat, is relatively soft and can be cut into pieces with a wooden spoon actually. It will slide out as one large piece if the tub is tilted.
With the "hard" glycerine it is easy to decant the biodiesel without contamination. Using Sodium Hydroxide makes it this way. The alternate, Potassium Hydroxide makes it stay liquid. I have not tried it.

 

[houdel]

Without using the exhaust brake, what is the aproximate max pressure in the exhaust system at WOT? I'd guess pretty low, 1-2 psi max. I'd probably be better off with a guage measuring inches of water, but what do you suggest as a max scale? From the photo it looks like you brazed a 1/4" flare x 1/4" NPT brass fitting to the stack, does your probe extend into the stack or is it flush on the inside?

 

[cranetruck]

The fitting is stainless steel (as is the tubing) and it was welded.
Pretty much flush on the inside.
The pressure should be very low w/o a muffler. Don't know, but a few inches of water seems about right for a start.