Question for two stroke experts regarding port height and jetting

[AZMIDLYF]

Camera work is terrible but....that sound!!!



Enough hijacking....

[FMP]

That camera work has me sick. When it warmed up and started to motor , that sounds so good.

[Chaz]

I don't think even the Lake Tarpon Test Center bouyyyyzzzz , could get away with that for more than a lap or two ...

http://www.supertrapp.com/product_se...t.asp?CatID=36

[Mark75H]

Camera work is terrible but....that sound!!!

https://www.youtube.com/watch?v=NNPxRvdAusA

Enough hijacking....

I believe that one is just a 60ci ( 1 liter) engine ... he also has a 1600cc handmade version of the same thing

[FMP]

Mercury V6 Pipe Project - An Experiment with a New Approach
Article by John Lentzkow
Forward by Greg Terzian
Scream And Fly presents to you the results of John Lentzkow and his Team's three year effort. Although Mr. Lentzkow by no means feels that he is "reinventing the wheel" with regard to this project, this is a notable achievement that we feel is worthy of the Lentzkow Team's efforts. Different? Definitely, and we applaud Lentzkow Racing for taking on a project of this magnitude. It is important to note that Mr. Lentzkow is not trying to redefine the Lake Racer, rather, this was an experiment for his own gratification. We thank the Lentzkow Race Team for sharing their efforts and ideas, and for using Scream And Fly as a forum to express them.


35 pounds of of excitement...

I have toyed with the idea that the exhaust system in the Mercury could be improved. After all, I was at a point where it seemed that there was no more horsepower I could gain from my Pro Gas motor. I decided to use my race block, and design an insert that would fit in the exhaust divider plate area that could be removed and still use the standard tuner. When I began this project, the rules stated any engine modifications allowed, except that no nitrous and normally aspirated motors. Since there were no restrictions on weight to displacement ratio, I elected to run the standard 3.5 inch bore engine, and play with the exhaust. Little did I know at that time that the rules would be changed to not allow expansion chambers. When this ruling was made, I lost interest to pursue this project and further my development. I shall provide you with the project to date and what was involved.
Jonathen mounting the support struts while I finish up the coil bracket.


First of all, if anyone had intentions of taking on such a project, don�t! You may be a candidate for AA meetings. I have spent the last three years on/off working on these pipes with my goal to build something different. I had played around with some megaphones, but they did not seem to offer enough backpressure. They were loud, but the performance was not there. Since my son and I have been involved with bikes and snowmobiles all our life, we knew the performance gain these chambers were capable of.

The first stage was to set the block in the mill and machine the exhaust cavity area to clean up the casting draft to accept an insert. This area was machined perpendicular to the divider plate surface. Next an impression was taken and a wood pattern made. Many hours were spent here developing the shrinkage rate to allow for material in the casting for machining to fit the cavity. A casting was made and cut to fit, using die ink to show high spots, and machined for a slip fit. The exhaust ports were scribed and cut allowing for a smooth transition and maintain exhaust flow runner length. The real problem is # 6 bore which had to be directed in a different fashion because of its location in the lower portion of the block. Two plates were made to block off the normal flow to the stock tuner and mounted in the block. I have not described how you block off the downward port runner in the block. This is the meat and potatoes of this project, and if you figure it out without a lifeline, and can make it, you deserve to be sitting across from Reggis on his show.
Lentzkow's shop - the spawning ground for his creations.
Certainly provocative, this creation will make anyone think twice before challenging it.

Next the flange plate was made matching the exhaust ports to the insert. All mounting holes were transferred from the block and drilled and counter bored. I made a tool to hand form exhaust tubing to make the transition from oval to round. These were then carefully tig-welded to the flange plate at angles to allow for the pipes when mounted to clear the waterline during an in gear idle start.
Although performance figures are not available yet, the initial tests prove very promising.

The chambers were designed using an old snowmobile formula and a software program. The cones were formed and tig-welded straight to allow for later development in case a section needed to be altered. A simple bracket design enabled the pipes to be supported by the steering arms using adjustable struts, yet provide some flex to eliminate breakage. Coils were mounted on a special bracket on the side of the block. EGT fittings were welded on and spring clips were also added. I matched the ports and machined a copper gasket for the flange plate.


Trying to convince OPBA vice president Paul Freeman that these are not much different than a stock S3000 Drag Tuner.

So how do they work? Well the first time we bolted the system on, we were in the middle of the race season, and elected to be conservative. We fired it in the shop and knocked down everything on the walls due to sound percussion. The neighborhood really loves me.

We were asked to make an exhibition pass in Jasper, TN. with Speedvision using an onboard camera to film this controversial bolt on part. The idea was to show the rules committee and also to add some spice to their ODBA show. Are they loud? Yes. Do they work? Yes. Do they need more development? Yes. The head pipe and the stinger need to be downsized for more bottom end punch. We turned the motor 10,200 RPM with the ECU box set rich. Some of the bottom end and mid-range response was due to driver error. I forgot to flip the vacuum switch to allow the ECU to go full rich. Doh! I was so nervous with the crowd I even forgot to put the boat cowling on when we went into the water. But we went to the water knowing that everyone was watching and hoped they appreciated all the work that went into this project. At least we had the courage to try it.
The start of a revolution? We think so, and a very loud one at that. John Lentzkow's project sends a very clear message: There are always new ways of improving the performance potential of drag rigs.

John ran bracket races at New Athens, Il. this summer and turned 9.371 @ 116.788 mph in the 1/4 mile. That is on gas and no nitrous. "Even if I can not get the motor to respond to low end punch,
these pipes should work great for rope racing starts, and I think it will
turn in the low nine second or even high eights.", John reports.
We just got word John did win the APBA National High Points in Pro Gas this year. That makes it his 6th APBA National High Points title plus four TDBA High Point titles for a total of ten High Point Championships.
So there you have it. Its been a fun project and I am thrilled to share it �with you all� (that�s southern talk) . Please take it easy on me boys. If you like it, great. If you don�t, well at least I tried something you did not. And to set the record straight, I did not steal this off an old combine here in Iowa. My thanks to Chad Mc Koskey for his help in the pipe software development, and my son Jonathen who inspired me to do something beyond my comprehension.

Respectfully,

Kurcz Triple Pipe , claim they work better than chambers by still providing the pulse stuffing from tuned pairing. OMC

[Mark75H]

Kurcz Triple Pipe , claim they work better than chambers by still providing the pulse stuffing from tuned pairing. OMC

From seeing them in person I would not say they absolutely work better than chambers, but the Kurcz and Runne internal tuned set ups work better ON THE BOAT in circle competition. Sled Runne's internal manifold might be better than Tim's.

[FMP]

Lots of good reading . Came across a frequency port shape thread .