D Vizard Exhaust Theory, anyone tried it on our I6s?

I have been reading a lot of the David Vizard exhaust theory, and after reading it about ten times, it makes some sense to me. Has anyone here attempted to install a "zero loss" system of his design on our sixes. From what I gather, the size of the resonator necessary for our engines would be relatively small, 200+ ci, and therefore probably doable.

I am thinking of trying this out this weekend, but wanted to see if anyone here has done it so I don't have to completely reinvent the wheel.

Thanks.

If you do a search for vizard you will see his name goes back aways in our forum.

Howdy Buc Fan:

I've been here a while and do not recall reading of anyone specifically trying a "Zero Loss" system. I sure could have missed it along the way, but, I'd encourage you to give it a try. The advantages Visard had were a scientific approach to "Before-and-after" testing and the hardware to do it. IF you have access great. If you don't you can still assess change and results with time testing, MPG, temperature changes, and others. Be sure to write each step and change down and make only one change at a time. I'll be looking forward to reading your results.

Adios, David

Good points, thanks for the information and Advice. Unless its cost prohibitive or has fitment issues for whatever reason, I am planning to give it a go.

Based on what I have read, the system for our I6s could look something like this. Maintain a consistent diameter from the collector to an x-pipe (recommend by both Vizard and CI) as near the header as practical which terminates into two cylindrical or oval resonators of 200ci volume or greater. This entire assembly from header to resonator will, according to his theory, act as an extension of the collector and be anywhere from 24" to 50" (based on his recommendation for street motors maxing out at 4800-5000 rpm) The resonators are intended to mimic the outside air, or end of pipe, and in doing so separate pressure pulses from the remainder of the system.
Now theoretically rendered invisible to the engine the rest of the system is about maintaining flow. Upon exiting the resonators the pipe will reduce to 2" and flow to turbo mufflers each capable of flowing at least 200-220cfm per (again based on his calculation, probably more than necessary right now, but eventually hope to get there HP wise) The pipes would then be routed over the rear dif. to terminate in turndowns at the rear valance.

Sound like a plan?

Thoughts?

do you have a link for the vizard design?

I have this one to popular hot rodding, but gained (I think anyway haha) a little more from his book "How to build Horsepower."

http://www.popularhotrodding.com/engine ... index.html

This article is geared toward V-8 race engines, and some of the calculations vary for 4 and 6 inline motors which he touches on in the book. Though, I must admit, I find his explanation of the use of and requirements for the resonator to be rather vague.

I gather from his book as well that one can avoid the resonator by using an open chambered muffler, such as a flowmaster, right after the collector extension, but I am trying to avoid the drone involved, even though that would be easier and take up less space under the vehicle.

I also called the manufacturer about the flow on the 2" Thrush Turbos. I was told that the Dynomax Super Turbo flows 260CFM, and that the Thrush, lacking the turning vanes, would flow about 10% less, or 230-234. Does this sound right? I was thinking it would be closer to 200-220 cfm. Either way, it is more than enough for this application and may cause it to be a little bit louder.

Finding a suitable resonator is becoming a challenge, any ideas? Thoughts? Suggestions? Criticisms?

All would be helpful at this point.

Howdy bucfan:

I seem to recall a resonator of approximately 267 ci, or 8 times the volume of one cylinders displacement. Did I miss read or am I just forgetting?

I think it will be necessary to make the air box/resonator for two reasons; to get the volume and to build it with a flare on the inside end of the exit pipe. The box wouldn't be hard, but getting the exit pipe right will take a little more care.

Are you planning to install tap pipettes along the system to check back pressure?

Good luck and keep it comming.

Adios, David

Thanks for taking a look at what I have been thinking about so far.

You are correct in that he stated that the box, cylinder or oval (He had stated that the shape doesn't seem to matter as much as the volume and the abrupt change, would have to be 8 times the volume of one cylinder. I took this to apply to V-8s, and that it would vary based on the number of cylinders in the engine. I could be wrong on that point though.

I had not planned on the placing tap pipettes in the system, but it seems like a good idea. I guess the issue here would be whether or not the resonator itself would disrupt flow enough by altering the velocity of the gases to cause back pressure as the flow rates of all of the pipes and mufflers involved are high enough to ensure free flow? Is that correct?

Having trouble finding a suitable resonator, I have been zeroing in on a cylindrical version of 4 x 17, or 213 ci. This could be extended to 22 inches to gain the ci necessary in the 8 x formula. Now, would I have room for it, and would it function properly to dissipate the pressure waves?

On his drawing of the system he shows the pipe fluted upon exiting a box, but narrowed via a regular reducing transition when leaving a flowmaster or teardrop chamber. Being cylindrical, I thought the regular transition would suffice. Am I correct?

I gather that the gases will be at velocity x when leaving the header, slow in velocity within the chamber, then increase to a higher velocity than the original x upon leaving through the narrower pipe to the muffler. Is this correct in the way you understand the system?

It would be interesting to run this thing on a dyno with open headers, then headers with extended collectors, then with the full sytem to see what effect it had on the output. I, of course, do not have the funds for it so I guess I will try to use some other method as you suggested.

Ok, so here is the somewhat disappointing verdict. With the holiday season upon us, and with so many other projects to complete on the mustang, i just couldnt justify paying double the amount of the standard system to try this out. I would love to someday, but . . .

I did go with a 2" system to x pipe then to Thrush Turbo mufflers and out to the rear valance. It sounds great, better than I could have hoped really, and the car is really fun to drive. I can really tell the difference from all the modifications that I have completed so far.

In fact, I was really happy with some numbers that were generated on a small dyno cpu last weekend, which many people say are close given that the vehicle data is correct (which it is). Honestly, it read about what I calculated before doing the mods.

Now on to really fun things like floor pan repair!

Resurrecting this thread, and hijacking it , but staying on topic.

I'm presently engaged in designing a no-loss system for my falcon. I have the added complication that the place I'm most likely to want to put my termination chamber is under the passenger's feet, and I have a big ol' cross brace under the passenger's butt, my car being being a convertible.

I have the cliffy dual out header, so I'm going to termitate it with a nice y-pipe (probably from flowmaster) of a size and length calculated to produce the best torque. This will dump into my termination box (roughly 300 to 333 cid, I believe). I may go dual out from the termination box and then run dual 2" or 2.25" all the way to the rear, passing through some suitable mufflers on the way to keep things civilized.

I'm confident this is going to be a huge leap up from my very Ill designed current exhaust system. I've read quite a bit of Vizard, and also looked at numerous pictures of systems fabricated by quite satisfied people on different forums, so I think I have a handle on this. Will keep y'all posted, and welcome you comments, advice, and criticisms.

Cheers!

The BMW E36 M3 seems very similar to what Vizard describes. The M3 produced over 300 naturally aspirated horses from a 200cubic inch (3.3liter) inline six engine. I'd be inclined to mimic much of that approach. What worked for them should apply for ours.

The front and rear pairs merge into an x-pipe, then split back into a resonator. From there, twin pipes go back to a large baffled muffler. The pipes are relatively small, no more that 2", I think to promote velocity.

Lots of pics if you google it.

I have run this exhaust system for years on my six.
Most of the high end imports use this technology. Using this system i was able to pull 145 rwhp through a C-4 trans. See Mikes dyno tests i think mine is #9. Bill

that seems to conform to the vizard approach. looks good, too! havent calculated lengths, but u must be close.

That looks like a very well thought out system. I like.

Vizard's gizmo is, I believe, not a resonator, but a "termination box". He is putting a big empty can where he wants the tuned length of the system to end so that there are no resonant waves affecting the tuned section beyond that point, as if you ran the shortened exhaust system out to the air just behind the front wheels, say. I think he calls for a minimum volume of the box to be 10 to 12 times the volume of a single cylinder; two boxes for dual exhaust. Vizard used to have a great site, Go Fast News, but through some machinations that were never explained there seems to have been a coup, Vizard and company left without a word, and the new hosts proceeded to utterly wreck the site. If you google gofastnews.com and archives and the subject, you might get to parts of Vizard's original tech articles and explanations, with luck. It's a shame, what happened there. I and others tried to get somebody to explain the situation, but nobody would talk. So far as I can tell, Vizard no longer has an internet forum, and seems mainly to be doing live seminars. Any of you know anything more?

Nope, that's about the size of it as far as I can tell. Who knows what politics happened there, but Vizard is no stranger to ruffling feathers; mostly when some manufacturer gets upset for him demonstrating that their stuff doesn't work as advertised. BTW, it is 8 to 10 times the volume of one cylinder. For us 200 type folks, that's between 266 and 333 CI. Flowmaster makes a few suitable candidates for an easy solution.

So, going by Vizards calculations and the dimensions of my Clifford dual out header (which only has primaries) I get the following:

* Primaries are 1.5" diameter and average out to 21" in length measured from the exhaust valve.
* That means my secondaries should be 1.5 x 1.68 = 2.5", and about the same length as the primaries.
* That means my exhaust should be 2.5 x 1.68 = 4" (!!!) and about 36" long, dumping into a roughly 300 ci termination box, and then out to whatever will flow adequately.

Well, those are the numbers according to his latest book, although it focuses on 4:1 headers so the extra step is probably throwing me off. My gut tells me this is insanely huge for a 6000 rpm motor, so this is my plan:
*Secondaries at 2.25" and 21" long
*y-adapter 2.25 to either 2.5" or 3" for 36" into the can.

3" still seems really big, although plenty of V-8 run that size and bigger with only 152ci per bank, so... Nevertheless, I think I'll err on the side of small and make my pipe 2.5" into a single-in/dual-out can and then out to dual 2" through some porter mufflers.

As a point of comparison, my current exhaust dumps the header outs into a 2" to 2" y adapter with only 8" of length and then steps up to a 2.25" exhaust about 45" to a turbo muffler. Pretty ugly. I wonder why my new awesome engine didn't make the power I expected. So, I'm going to hand make this intermediate section and have it ceramic coated to match my header. Should be pretty sweet and certainly a better match for my high-revving engine.

Subscribing to this thread and curious if you've made any progress on your design FF? Also, do you have any references (links to vids, clips, photo articles, etc. if available) for any vizzard type designs put into use? Thanks and good luck on your project, I'm interested in your results

A serious no loss exhaust system is going to require some valve event changes to really work well. The inlet and outlet flow capabilities (or restrictions) to the displaced cylinder volume define the overall response to the valve events. Or the flip side (the correct side), the valve events need to reflect the inlet and outlet parameters, in relation to the displaced cylinder volume and desired rpms.

Taking a motor with valve events geared towards a certain amount of exhaust restriction in comparison to the inlet side, and then increasing the exhaust flow percentage (altering the E/I) will loose cylinder pressure and potentially hurt the overlap exchange. This is why adding larger exhaust can decrease the torque, but takes the rpm upwards a little bit. The entire puzzle has to work for their to be gains. It does not matter if its a 6 or an 8 or a single cylinder (4 stroke).

Typically Vizard makes his theories and tests based on certain aspects of an engine build. One of which is a little narrower LSA than might be normally used. He has tests to back it up (and they are good tests- no garbage). But, if the motor's valve events were actaully looking for a little better flow on the exhaust side from too late exhaust activity (narrow LSA), then the tests that enable better flow on the exhaust are definitely going to show more favorable results. Many times this is a product of selecting a camshaft based on cylinder head flows alone, and not the total inlet and exh systems. Therefore, as the exhaust becomes more and more flow capable, essentially matching the cylinder head flow data, the motor will begin working better as it gets closer and closer to original design criteria the cam was selected or calculated for.

I am not saying he hides anything or fudges anything. He doesn't. His tests are 100% valid. However, when looking at his writings and tests/results, there is a whole lot more to it than simply thinking that this LSA is right, or this exhaust system is right. You really have to look at the entire engine combination.

Chances are that if your camshaft has more exhaust duration and is a tad wide on the LSA, that increasing the exhaust flow capability is not going to be productive. If on the flip side, the cam has less exhaust (say equal intake and exh) and narrower LSA, it may really make the engine come alive everywhere.

Well I've bought all the parts for the front half of the system:

2 x 2.25" collector flanges
2 x 2.25" 40* mandrel bends which are 5' long
1 x 2.25" to 2.5" y-pipe
1 x Full Boar brand Flowmaster type 3" in, dual 2.25" out muffler to serve as a pulse wave termination chamber (a bit big at 400c.i.d.) **the 2.5" pipe will extend into the muffler as suggested by Vizard.

I'll build the rear sections once I hear what this sounds like. I imagine it will be loud, so final muffler selection (there will be two, one per side) will be based on my acoustic needs both in terms of tone and volume (quiet but sporty).

I should begin assembly soon (after I finish my quarter panels). The only doubt in my mind is how long to make the two pipes coming off the header. At 60" that seems waaay long to me, but without actual dyno time I guess I could just bank on the "longer is torqueier" theory of exhaust design. LOL. Then some gut part of me says to make them twice the length of the average of the primaries, which average out to about 21", so 42". In the end I'll probably just go with whatever is easiest to build. Since I'll have nothing to compare it to except the cr*p exhaust I have now, I guess I'll never know the difference!

And Buddy, everything you say is true. I will forever regret not putting this engine on the dyno before putting it in the car. I could have set the cam timing and exhaust size and length based on dyno results instead of theoretical mathematics, which I do poorly.