srp

(9000 Rpm) With a 54 stroke its 3189 FPM,58 stroke-3425 FPM,61 stroke-3602 FPM,64 stroke-3780 FPM,68 stroke-4016 FPM. All are safe RPMs. 11300 RPM is 4004 FPM on a stock stroke engine and 14100 RPM is 4996 FPM on a stock stroke. As you can see bigger strokes will raise the piston speed. You would need to have some kind of road racing pipe and porting to get anywhere near redline.

A data recorder with about ten transducers would do the trick.

Our pipes that are tweaked for builders will have a tab with that builders name on it. The builder will know what porting configuration his pipes will work best with. So that information will not be hard to get and our variations will have tabs stating deference's. We will work very close with the builders especially with our drag pipes looking for that last couple of horse-power. Our drag pipes will be four piece stamps just like the inframes making them adjustable at the header and belly.

Piston speed dictates maximum RPM, maximum safe RPM is 4000 feet per minute, absolute max is 5000 feet per minute. Fuel,Air/fuel ratio,compression,exhaust port duration,tuned expansion chamber length,baffle angle and stinger back pressure will dictate what peaking Rpm you actually get from your motor, just as Andy said lots of variables. Lonnie at Sandtrax's said stock ignitions seem to start dropping cylinders at a certain RPM. I would like to know if anybody has experienced this and at what RPM.

You will very rarely see anybody using volumetric efficiency as a way to tune a two stroke mainly because of the returning wave of trapped air being forced back into the motor at exhaust port closing. This raises the delivery ratio to close to 1.4 with a highly tuned pipe, meaning a 350cc engine will burn 490ccs of air/fuel. That is supercharging and the better pipes will have a higher PSI amplitude than a bad pipe will have. Mopedarmy.com has a good animation of this. If I knew how to setup a link to it I would.

Lectrons I have are old and the chokes don't want to stay up and that is not helping things when I have the PVL on the bike.

I can see why they would be good on a flattrack. The light flywheel makes them explosive rolling on the throttle. I have had luck like you on reliability and I really take good care of my stuff.

I agree that they are good and if you can launch in second and not ever bog they are an advantage for the racing we do. If you are getting 6 years out of them you are doing something right. What about starting?

I have been running PVLs for years and have dynoed them against stock ignitions and there is not a nickels worth of difference between them unless you had a problem with one or the other to began with. PVLs have less rotating mass and makes launching in second gear with a lot of paddles difficult. But if you are launching in first they are awesome. PVLs need to have the wires going to the coils supported at the coils to keep the wires inside at the connectors from losing continuity( zip ties work good). Hard to start is a under statement and that is why I am back to stock ignitions. A word of advice if your are running PVLs is to buy one spare primary coil and one spare secondary coil because they do go out regularly.

You are right about volumetric efficiency not being 100%. The only way I know to check VE is to put transducers in the crankcase and in the intake manifold and a MAF sensor connected to a data recorder, then compare the pressures to the atmospheric pressure at your altitude. If you have just a MAF reading in (Lb/Min) and the temperature the day of the test I can figure the volumetric efficiency from math. But seeing the pressures differences between the crankcase and manifold at reed closing would tell me more.

Wow Cam, that is some good data. I will check that out.

Resonance is calculating the larger amplitude oscillations of the air coming down a pipe or manifold to use its useful pressure pulses to help with scavenging and or supercharging ( Ram Air ). When air goes down the pipe it causes a vacuum but after it goes so far it turns around and comes back causing a positive wave and if it is tuned right it can push air into the motor or suck it out. Here's an example... With longer manifolds air is still coming down the manifold after the piston goes past TDC and starts to descend, causing that air to compress into the crankcase just as the reeds close making it higher than atmospheric pressure. That will make the engine lightly supercharged and it is free for the taking. We will offer manifolds in the future that will match up to our pipes. On our very first set of manifolds we gained 4 horse-power without tuning. That tuned intake length was 250mm from the reed tip to the bell of the carburetor at the filter. That info is for anybody wanting to try out some manifolds of their own. Anybody that is interested in this science should Google Hermann Von Helmholtz, Helmholtz resonator, and Resonance for reference.

Thanks for the concern, We can see that an on line company in Canada by the name of Splash'n Dirt was trying to market Power Pro's complete catalog under the name Sniper. We our Sniper Racing Products selling a line of pipes named Assassins. Just to be safe when ordering make sure they are Sniper In-Frame or OOF Assassins. If getting the wrong pipes happens to anyone, we will do what we have to do, so it will not continue. Even if it means changing our name to stop it. I know a little bit about two company's with same name. In our last business we were around 15 years and then a local company changed its name to the same as ours but added ( of Tulsa ) And we couldn't do any thing about it. So everybody can see why we are not going to fight over a name.

Thanks for that input. It looks like you are on the same page as we are. But many others think different and that is why he is asking. It will show that you, me and Rob are thinking the same when we post some of our OOf drag pipes sheets. We have designed and tested several drag pipes that make peak power 800 rpm earlier than most pipes out now. Our horse-power numbers are 4% stronger than the small bore small flange OOF drag pipes that we test against. We are looking forward to showing off our products at some off the big races. The one size fits all is not our philosophy. We will offer our pipes to builders unwelded to fab and tweak and tune to get the most out of there porting configurations. We feel that most builders theory's are good if they are match up to the right pipe. !!!chrome!!! Does anybody know of a good chrome shop around the Tulsa Oklahoma area?

Thanks for the input. We are in the process of making end caps that will accept Toomey Spark Arrestor's because of the easy c-clip fastener.

Yes we are getting close on are muffler and tail pipe design. We are trying to come in full resonance. If we can it will help with scavenging. On our first test with the trial stampings both setups used the same mufflers and tail pipes to make sure the only thing different was the expansion chambers. We are expecting a power gain with our muffler set up. I don't think some other pipes that used the Sniper name means anything. I never heard of them. Our pipes are In-frame Assassins by Sniper. I would say to make sure somebody didn't get the wrong pipes is to make sure they are Assassins.

We are going to do a electroless nickel plating. It is the ultimate nickel coating. Sometimes cranks and worn parts are electroless nickel plated and then reground. The nickel finish we will use coats the inside of the pipe and will delay carbon buildup.

Thank you for the warm welcome, I was told this is the place I want to be and by judging by what I have seen in two weeks of being a member I agree!!! I would like to tell you a little bit about Sniper Racing Products. We are designers of expansion chambers, Two Stroke Tuning Software and various parts for racing. Everything we do is backed by science and math. Our first product to market is the the Sniper In-frame Assassins, designed on Two Stroke Tuning Software which its self is close to being on the market. We have designed and tested nine pipes that are good enough to clone. Our first line of pipes will be for aftermarket cylinders with the small flange and stock cylinders that are tuned to 10 BMEP. We will be doing an out of frame drag pipe for the same engines after we decide on which pipe we are going to go with. !!!Thanks again!!!

Power valves are OK as long as they don't hang down so far that they put carbon in the transfers. And they open all the way.

I don' t think it will be too confusing at first. We are going to offer three types, One is the standard gas pipe, Second is a alcohol pipe, The third one will be a hill shooter pipe with a 26+ mm stinger all the way out the rear to release some heat off of the engine to help with power fade. This pipe will work with the bigger motors as well. We did test with CPI inframes. The power curve was on top of each other until the CPI's signed off @ 9450. Shoot Jim a pm if anybody wants to test. He provided most of the ported motors I have tested with so far and I did all of the cast cylinder engines.

I can see why some builders feel RPM is tied to duration, Sometimes on some of our stock cylinder engines we are forced to raise exhaust ports to 198-200 @ 76% of bore to reach target BMEP at tuned RPM. Criteria for our pipe is calculated from projected heat and velocity from bmep,calculated kh ,intermediate,belly, stinger factors, blowdown PSI and blowdown duration. All angles are rated bmep and work in conjunction with each other to control expansion and velocity and not lose amplitude @ 15 degrees before the exhaust port closes. Trying not to be too technical here. We will offer a alcohol version because the exhaust gases are cooler and velocity is different .

If you are looking for more power, look at oxygenated fuels and pick the fuel with the highest lower calorific value and the highest stoichiometric ratio. The higher lower calorific value will have the most energy and the higher stoichiometric ratio will burn a largest amount of air. Divide the lower calorific value by the stoichiometric ratio to find the best fuel when comparing fuel brands. You will have to call the fuel company's for this information. This works with or without being oxygenated.

I think from some of the things you have said about your port work. These pipes will match up very good to your motors. We tested many times on a cast cub with the prototype with better than good results on Kenny's dyno. His dyno reads a lower peak rpm @ 9000. That dyno shows 85 horse-power @ 8000 rpm . I have a lot of sheets from that dyno that show close to 100 hp @ 8000 on gas on a ported motor. So from one machine to the other you can lose 1000+ rpm. We are testing pipe to pipe and that is all that maters to me.

If you have a 421 cub on gas that will make 90 horse-power @ 8000 rpm on sandtraxs dyno I will pay for the dyno time????

You are just up the road a little ways. If you have some particular engine cast or ported and or some different pipes to test with. These pipes are available to test.