Look forward to seeing the cutout video. Actually being able to see what ports are doing what and when will give amazing insight. It would actually be brilliant to see dyno results when swapping cylinders to see what the differing timings and ports do.
Thanks Rex. This video answered a lot of the questions brewing in my mind. Your videos are an exceptionally Good teaching tool. I have learned so much from watching your videos. It really has increased my Enjoyment of the Hobby. When I see a new video from you I will always find the time to watch it 👍👍👍
What’s always amazed me is the speed with which air and fuel can get in to fill the cylinder. You’d really think there’s no way it would work. I mean a single piston engine running at 36000 RPM is firing 600 times per SECOND!!! How the hell does the air fuel mix fill that fast?!?!? Amazing!
The airstream couldn't do it instantly. It has to accelerate, just as the engine does. Once the airstream reaches the maximum velocity as the engine reaches it top RPMs, it doesn't actually stop and start flowing in between combustion events, inertia helps to keep the air moving. It basically "bunches up", due to the inertia, up against the closed port and "springs" into the port when it then opens. A well tuned intake tract, and optimized port timing, can take advantage of the inertia and the "bunching up" of the airflow to make more power by allowing the air to stack up and then enter the port with force before the inertia runs out and the airflow stalls.
I like how Ron from Werks took his on Toad expertise and incorporated with off-road and took the Werks Motors to a different level! Werks motors are my Favorite till today especially the B2 & B5 and big tracks the B7 is unstoppable!!!
Back then in the late 90s, and 2000s, what determined what was considered an off road engine and an on road engine, was not only just about ports. For example, what was considered ideal for off road applications were 3 to 6 port, along with it being labeled “Long Stroke” for more bottom end, Less rpm’s on the top of the power band. On road engines were anywhere from 7, 8, and 9 ports, and were labeled “Short Stroke” for less bottom end, and stronger mid to top torque on the top of the rpm powerband for faster top speeds, along with turbo heads for use with Turbo plugs. This was the standard for most Picco engines, and Nova Rossi engines, which included the other line up of Nova Rossi engines under the names of TOP, REX, RB Concepts Rody Roem, Collari, JP Racing and so on. Picco also heavily marketed their line of carb that they introduced around 1996 called the Torque Carb, which was a pain in the ass to adjust, and we’re notorious for air leaks around the base of the carb.
How come I never see a comment like this: Hi, my name is NNNNN and I work at Novarossi/Picco/CMB/OS and this is what we do to build fast powerful engines. First we ... then we ... and then we ... and sell the engine for a ridiculous price. I have looked through magazines, engineering papers, books, computer forums, TH-cam, everywhere and can NEVER find anybody who actually knows anything! The progress that 2-stroke engines have made over the years has been phenomenal. Especially RC car engines in the late ninety years. I first started flying with a cross-flow OS MAX 19 that was gutless by today's standards, only 0.45 hp. Now with the same few engine parts, but a better flow design, a 3.5 cc engine can make 3.45 hp! I would love to see a video of the development of two-stroke porting and design over the years, covering the important milestones that have given rise to today's phenomenal power we are seeing in these engines. I would make the video myself, if I could find these designers and get the story from them. Who invented what porting trick? Who legitimately discovered something versus who copied ideas from other engines? Or is it a case of money and Intellectual Property, that the information EVERYBODY wants know, will forever be hidden. Do these designers read the TH-cam comments and say to themselves: Ha Ha, I know the answer you trying to find out but I am never going to say what it is!
LOL Ive sent a few os19 to an early grave due to practice porting a very long time ago. They were so cheap it was worth having a go considering the gains. However once they started making engines for cars that were more than just a head it wasn't worth messing around with that any more. Maybe 1983. If you want to know more look up "Schnuerle porting"
@@TheRwmods Sounds good. I will have to look into measuring that as I just got new calipers. The P5 and the s421 8port blocks were the same part number according to Novarossi exploded veiw. It was an idea. Probably a lil much for a buggy but it be fun.
Doesn't the more ports mean they can all be slightly different heights giving it a more even power band? Also could having more ports improve the fuel and air mixture mixing?
Its not the back pressure so to speak, but the tuned pipe reflective soundwave/ pressure at the correct time causing a back force to push back into the cylinder, the fresh air fuel mixture that flew out of the exhaust port and essentially dynamically super charging the engine. The tuned pipe can take many shapes and lengths to achieve a particular rpm bad for power. Thats gas dynamics folks
I am sure the spraybar location can make a difference but I have not messed with it much. I do think our carbs are kind of primitive. The taper of the lsn really effects fuel flow.
I have found that a carb can flow a touch more with the spray bar just barely protruding into it. However, you will have to retune the engine slightly, because the air isn't moving as fast near the edge of the venturi as it is in the middle.
You should make a video of modding an engine before and after. With drag or track times. I had a traxxas 3.3 modded by a well known guy and not going to lie. But my engine seemed like it lost power.
@@TheRwmods I can’t remember since it was a while back. I do remember him mentioning the timing on the crank if I’m not mistaken. I would like to say the guys name but I don’t want to give anyone a bad rep.
@@Bang_n_slang It could be that your are using the completely wrong header and pipe for the mods that were done. Your gearing could very well be wrong for the rpm range also. 🤷🏻
It isn't possible to grind another port in an existing sleeve. But it IS possible to change the sleeve out to one with more ports if the replacement sleeve is from the same engine manufacturer, sometimes... Example... My Dynamite .28 Big Red Mach 2 is actually manufactured by SH, and has a 6-Port sleeve in it. Well, it just so happens that an 8-Port sleeve from an SH 8P .28 has an 8-Port sleeve that fits DIRECTLY into my Dynamite Big Red engine. They're both .28's, they're both made by the same manufacturer, and the parts between them interchange just fine. Putting the 8-Port piston and sleeve from the SH P8 into my Big Red engine DOES change the characteristics of the engine, and did give it a power boost and a higher RPM rev range. It was worth the upgrade. The new 8-Port piston and sleeve was $28.99 at A-Main Hobbies, and was a great way to wake up and refresh my tired old Big Red... 👌
The thing is most engines are not drivable. O.s. speed square has been good. Long strokes are okay but if its even sligthly too Lean it revs To sky high and drivabilty is gone. No one needs engine that speeds up at end of straight
6:28 That's not a "3-port exhaust"... Those "ports" are simply supports, to keep the piston from rocking and prevent it from catching on the edge of the port, since it's so wide. That's all they're there for. They don't function as a "port", and are not ports. Sometimes they are called "bridges".
Look forward to seeing the cutout video. Actually being able to see what ports are doing what and when will give amazing insight. It would actually be brilliant to see dyno results when swapping cylinders to see what the differing timings and ports do.
Thanks Rex. This video answered a lot of the questions brewing in my mind. Your videos are an exceptionally Good teaching tool. I have learned so much from watching your videos. It really has increased my Enjoyment of the Hobby. When I see a new video from you I will always find the time to watch it 👍👍👍
Great video and explanation.
Nitro is The Glory !
Thanks for the great video and the great information
This video ROCKS!!! Well done!😃👌💣🌟🌟🌟🌟🌟
Thanks Rex. Top video
You are missed my friend would love to talk to you about some engines right now. R.I.P Rex
What’s always amazed me is the speed with which air and fuel can get in to fill the cylinder. You’d really think there’s no way it would work. I mean a single piston engine running at 36000 RPM is firing 600 times per SECOND!!! How the hell does the air fuel mix fill that fast?!?!? Amazing!
The airstream couldn't do it instantly. It has to accelerate, just as the engine does. Once the airstream reaches the maximum velocity as the engine reaches it top RPMs, it doesn't actually stop and start flowing in between combustion events, inertia helps to keep the air moving. It basically "bunches up", due to the inertia, up against the closed port and "springs" into the port when it then opens. A well tuned intake tract, and optimized port timing, can take advantage of the inertia and the "bunching up" of the airflow to make more power by allowing the air to stack up and then enter the port with force before the inertia runs out and the airflow stalls.
I remember as a kid thinking if I ever got my hand on a 7 port race motor that my nitro rs4 2 (still have it) would break land speed records
I was the first thumbs up. Thanks for all the video an teaching for us racers!
I like how Ron from Werks took his on Toad expertise and incorporated with off-road and took the Werks Motors to a different level! Werks motors are my Favorite till today especially the B2 & B5 and big tracks the B7 is unstoppable!!!
Back then in the late 90s, and 2000s, what determined what was considered an off road engine and an on road engine, was not only just about ports. For example, what was considered ideal for off road applications were 3 to 6 port, along with it being labeled “Long Stroke” for more bottom end, Less rpm’s on the top of the power band. On road engines were anywhere from 7, 8, and 9 ports, and were labeled “Short Stroke” for less bottom end, and stronger mid to top torque on the top of the rpm powerband for faster top speeds, along with turbo heads for use with Turbo plugs. This was the standard for most Picco engines, and Nova Rossi engines, which included the other line up of Nova Rossi engines under the names of TOP, REX, RB Concepts Rody Roem, Collari, JP Racing and so on. Picco also heavily marketed their line of carb that they introduced around 1996 called the Torque Carb, which was a pain in the ass to adjust, and we’re notorious for air leaks around the base of the carb.
Great vid as always rex
How come I never see a comment like this:
Hi, my name is NNNNN and I work at Novarossi/Picco/CMB/OS and this is what we do to build fast powerful engines. First we ... then we ... and then we ... and sell the engine for a ridiculous price.
I have looked through magazines, engineering papers, books, computer forums, TH-cam, everywhere and can NEVER find anybody who actually knows anything! The progress that 2-stroke engines have made over the years has been phenomenal. Especially RC car engines in the late ninety years. I first started flying with a cross-flow OS MAX 19 that was gutless by today's standards, only 0.45 hp. Now with the same few engine parts, but a better flow design, a 3.5 cc engine can make 3.45 hp!
I would love to see a video of the development of two-stroke porting and design over the years, covering the important milestones that have given rise to today's phenomenal power we are seeing in these engines. I would make the video myself, if I could find these designers and get the story from them. Who invented what porting trick? Who legitimately discovered something versus who copied ideas from other engines?
Or is it a case of money and Intellectual Property, that the information EVERYBODY wants know, will forever be hidden. Do these designers read the TH-cam comments and say to themselves: Ha Ha, I know the answer you trying to find out but I am never going to say what it is!
Those companies are NOT goimg to freely give away their secrets to making incredible engines. Would you if your bottom line depended on it?
LOL Ive sent a few os19 to an early grave due to practice porting a very long time ago. They were so cheap it was worth having a go considering the gains. However once they started making engines for cars that were more than just a head it wasn't worth messing around with that any more. Maybe 1983. If you want to know more look up "Schnuerle porting"
Great info. Loving these engine videos. What you think about putting that 8port rossi sleeve in a P5 crankcase with a 15007T crank.
Should be fine as long as the block isn't in the way of any ports. Always check compression height when using different parts in a engine.
@@TheRwmods Sounds good. I will have to look into measuring that as I just got new calipers. The P5 and the s421 8port blocks were the same part number according to Novarossi exploded veiw. It was an idea. Probably a lil much for a buggy but it be fun.
I really Enjoy it.
One question the Transfer porch and timing. How you know how much to cut.
Thanks
Bobby
Knowledge, a bunch of math, and experience. There are 200+ page books on the subject, and it's WAY too much to explain here..
Doesn't the more ports mean they can all be slightly different heights giving it a more even power band?
Also could having more ports improve the fuel and air mixture mixing?
Could be true on both points. I do see some offset exhaust port heights but not on intake much.
@@TheRwmods ok. Idk anything. I just guessing
That's what they're there for....
Its not the back pressure so to speak, but the tuned pipe reflective soundwave/ pressure at the correct time causing a back force to push back into the cylinder, the fresh air fuel mixture that flew out of the exhaust port and essentially dynamically super charging the engine. The tuned pipe can take many shapes and lengths to achieve a particular rpm bad for power. Thats gas dynamics folks
Does polishing the outside of the piston sleeve help anything?
Hurts more than helps.
I saw that video too. Hilarious!
Do you still rebuild nitros engines that people can send you? If so I have 2 mach 427 and a 26. That needs to be done
Yes, my adress is on my site, just send them and I will let you know what they need.
Explain spraybar location and how that affects fuel flow into the case
I am sure the spraybar location can make a difference but I have not messed with it much. I do think our carbs are kind of primitive. The taper of the lsn really effects fuel flow.
I have found that a carb can flow a touch more with the spray bar just barely protruding into it. However, you will have to retune the engine slightly, because the air isn't moving as fast near the edge of the venturi as it is in the middle.
You should make a video of modding an engine before and after. With drag or track times.
I had a traxxas 3.3 modded by a well known guy and not going to lie. But my engine seemed like it lost power.
There are a few well known modifiers that do not change timing. They just do some Dremel cuts and polishing.
@@TheRwmods unfortunately timing was included.
@@Bang_n_slang What timing did they change?
@@TheRwmods I can’t remember since it was a while back. I do remember him mentioning the timing on the crank if I’m not mistaken. I would like to say the guys name but I don’t want to give anyone a bad rep.
@@Bang_n_slang It could be that your are using the completely wrong header and pipe for the mods that were done. Your gearing could very well be wrong for the rpm range also. 🤷🏻
It isn't possible to grind another port in an existing sleeve. But it IS possible to change the sleeve out to one with more ports if the replacement sleeve is from the same engine manufacturer, sometimes...
Example... My Dynamite .28 Big Red Mach 2 is actually manufactured by SH, and has a 6-Port sleeve in it.
Well, it just so happens that an 8-Port sleeve from an SH 8P .28 has an 8-Port sleeve that fits DIRECTLY into my Dynamite Big Red engine. They're both
.28's, they're both made by the same manufacturer, and the parts between them interchange just fine.
Putting the 8-Port piston and sleeve from the SH P8 into my Big Red engine DOES change the characteristics of the engine, and did give it a power boost and a higher RPM rev range. It was worth the upgrade. The new 8-Port piston and sleeve was $28.99 at A-Main Hobbies, and was a great way to wake up and refresh my tired old Big Red... 👌
Your opinion matters bud u been doing this for a long time
The thing is most engines are not drivable. O.s. speed square has been good. Long strokes are okay but if its even sligthly too Lean it revs To sky high and drivabilty is gone. No one needs engine that speeds up at end of straight
My mean it's! Not too' mutch port's.
6:28 That's not a "3-port exhaust"...
Those "ports" are simply supports, to keep the piston from rocking and prevent it from catching on the edge of the port, since it's so wide. That's all they're there for. They don't function as a "port", and are not ports. Sometimes they are called "bridges".