All About 2 Stroke Blowdown

Рет қаралды 1,693

Michael Forrest

3 ай бұрын

For more info on this topic go to www.dragonfly75.com/moto/blowdown.html

Пікірлер: 15

@MotorcyclesandArt 3 ай бұрын

Great video

@MotorcyclesandArt 3 ай бұрын

This is one of the better explanations of blowdown.

@MichaelForrestChnl 3 ай бұрын

What I brought new to the topic is the realization that the more you raise the exhaust port the more you decrease the trapped cylinder volume which is the true engine size.

@monster2269 3 ай бұрын

You are a smart Man Michael F. Thanks for the info. Well done.

@MichaelForrestChnl 3 ай бұрын

Thank you kindly. It's nice to be appreciated.

@Iggy900ss 3 ай бұрын

@@MichaelForrestChnl You really are appreciated, Michael! Your analyses, your explanations and your software taught me way more than all of the books I read and the experiments I made

@copisetic1104 3 ай бұрын

I believe that’s why exhaust ports were widened with bridge ports and chamfering to allow exhaust pressure to reduce enough to open the transfer ports.

@MichaelForrestChnl 3 ай бұрын

yes, the wider exhaust ports make it more effective so they don't have to be as tall so the trapped engine volume is greater

@nathansmith3608 3 ай бұрын

I'm pretty sure I remember learning a lot from your site like 8 years ago when I built a gas bike - it's cool to see you're making videos!

@MichaelForrestChnl 3 ай бұрын

I just updated the Porting Calculator to also show a rough calculation of horsepower as well as transfer capacity (delivery ratio).

@mikeeiben3430 3 ай бұрын

I have an oil question. I have an older twin cylinder 4 stroke model airplane engine. It is a glow fuel engine that has been converted to gasoline with spark ignition. Glow fuel is methanol with 18 to 20 % oil and 5 to 15% nitromthane to improve power and ease tuning. Crankcase lubrication is from blow by. Connecting rods are made of bronze and that is the bearing. 20:1 mix ratio was recommended but people had had failures, so now 15:1 is recommended. I was advised by someone with much experience to run 10:1. After reading your paper on 2T oils and watching videos I decided to try Honda HP2 at 10:1. It seemed to be too much and or too thick. There was a nice amount of oil coming out of the crankcase breather tube and I felt that lubrication was superior. More recently I tried Amsoil Dominator at 15:1. It ran much better but I felt like there should be more oil coming from the breather tube. Do you think I am better off with an oil like Dominator at 10:1 that seems to burn off, or a higher quality oil like HP2 or Belray H1R that is ester, but at 15:1?

@MichaelForrestChnl 3 ай бұрын

I'm sorry but for head splitting questions I need some payment. That's work man. Actually you shouldn't ask me because I have no experience with engines like yours. All I can say is to look up the composition of Dominator on my oil page and then you'll probably scratch it off your list. www.dragonfly75.com/moto/oil.html

@matthewfredrickmfkrz1934 3 ай бұрын

Do piston rings next

@MichaelForrestChnl 3 ай бұрын

I doubt I know enough about the subject. All I could say that is informative is that rings are made soft or hard to match the type of cylinder lining. The hard surface of a "chrome" liner needs soft rings to conform to it, and a "soft" iron liner needs hard rings. When you ruin a chromed cylinder and insert an iron liner you also need to find rings that were made to be used on such a liner. I didn't do that when I changed to an iron liner on my KDX200 and had to have it resleeved about every 6 months because it wore down so fast with the stock rings.

@matthewfredrickmfkrz1934 3 ай бұрын

@@MichaelForrestChnl where do you find just rings