44 Exhaust

[blueskyracer]

The pipes look great when they are new..What is everyones trick for keeping them looking that way after they have been run?

[Dave M]

Another Source

Cliff Johnson and Eric Vanover manufacture complete systems for the 44 as well. They are the original Obrian type. They work VERY well. Eric won Nat's many years in a row with these systems. I think they sell ready to bolt on systems too, so you don't have to finish machining them. I think they are priced at a real GOOD price point as well. Tough combo to beat.

[Guest]

Pipes

Most of our pipes are stainless steel so they are easy to polish back. Last summer we tried 10 degree cones and they were painted black. By going to the narrower cone you loose a little maximum power but the power band is wider and flatter.This winter I will try to get them plated with nickel which seems to hold up real well on other things that have been done on our engines.

Alan

[boatracer69r]

Does anyone have pictures of the Cliff Johnson or Eric Vanover exhaust systems? Thanks for any help.

Cliff Johnson and Eric Vanover manufacture complete systems for the 44 as well. They are the original Obrian type. They work VERY well. Eric won Nat's many years in a row with these systems. I think they sell ready to bolt on systems too, so you don't have to finish machining them. I think they are priced at a real GOOD price point as well. Tough combo to beat.

[Dave M]

Pics of Cliff's System

Does anyone have pictures of the Cliff Johnson or Eric Vanover exhaust systems? Thanks for any help.

Here is the thread Cliff posted back in October. On that thread the price was listed as $600.00. I am thinking that is considerable less than a comparable system, and it has been proven by winning the Nationals many years in a row. Simply put, it works, and it works well. Proof is in the pudding.

https://hydroracer.net/forums/showthread.php?t=22448

[David_L6]

By going to the narrower cone you loose a little maximum power but the power band is wider and flatter.
Alan

Going strictly by memory here of what I have read but I thought it was the other way around. i.e. Narrow cone, narrower power band. I'll have to dig out my Brinkman's manual (the first one) and see what he said about exhaust.

[David_L6]

Cliff Johnson and Eric Vanover manufacture complete systems for the 44 as well. They are the original Obrian type. They work VERY well. Eric won Nat's many years in a row with these systems. I think they sell ready to bolt on systems too, so you don't have to finish machining them. I think they are priced at a real GOOD price point as well. Tough combo to beat.

Dave is right about the O'Brien system. It works very well. The Parker may work just as well or better. I don't know. Never had one.

I'd guess that I've seen more Bayer systems than anything. Of course, the Bayer systems are manufactured in this part of the country and Kenny Bayer used to rule the 4 cylinder classes down here.

I've seen O'Brien's systems on some very good running rigs. McAfee's for example.

I have an O'Brien system on my 44. I like the fact that the filler block has a water jacket built in.

[David_L6]

The pipes look great when they are new..What is everyones trick for keeping them looking that way after they have been run?

"As cast" megaphones and elbows (like the elbows pictured above) and unplated megaphones are tough to keep looking good. Aluminum elbows and / or megaphones with a smooth finish are pretty easy to keep looking good with Mother's Mag and Aluminum polish and elbow grease.

[Guest]

2 Stroke Tunners Hanbook

Found my copy of Jennings book on 2 cycle tuning. Here are a couple charts that tell the story on cone angle. You can plot a field of curves for cones. The smaller the included angle the flater the curve. The right hand chart tells the story of why we tried 10 degrees. The attached link should take you to an online version of the book. It is worth reading. http://www.vintagesleds.com/library/...20Handbook.pdf
Alan

[David_L6]

Don't want to sound like I'm arguing because that's not my meaning. I don't have the education to argue about something like this....

Throw out all the expansion chamber stuff. We are working with open ended megaphones.

What would a straight pipe do? No megaphone at all. Just a straight pipe all the way back? Seems to me that would concentrate all the energy and make the power band very narrow. What am I missing here?


EDIT: Thinking about this kind of stuff makes my haid hert!

[Guest]

Streight pipes and megs

Hi David,
A streight pipe would sound great but if you used it in a 2 cycle engine you loose the reflected wave that helps keep the new charge in the cylinder and builds a little dynamic back pressure. The chart on the right shows that the energy is being lost as the angle gets smaller and shown by the 6 degree cone plot. Were only talking megs at this time, Chambers are a different story though and a whole new science. Harry Brinkman was playing with a lot of things. I will post some photos when I dig the things out. He had one set of pipes for a 20-H that had a long streight pipe and the a 20 degree cone. I also have all his notes that he did not publish.

Alan

[sam]

No, a straight pipe reflects, it just does not get concentrated ... well not actually concentrated, more like "makes up a little for the weakening due to time and mechanical loss"

Its right there in Jennings' book ... where that graph comes from.

The first 6 carb Merc racers used straight exhaust pipes back around 1970 as did the motor Merten used to raise the ultimate outboard speed record to 136+ mph in 1973.

A straight pipe can work, but there usually are a couple advantages to a cone

[form-e one]

hustler pipes baby,,,, only way to get the hustle on,,,,, ... ie if ya can get them,,,

[Larry M]

Just a quick couple questions..From my observations why do some folks spray water on the exhaust system and some folks do not??

2nd question since my tower is short which makes for great cornering how do I keep the bottom two cylinders from filling up with water when I return to the pits.. It happens most of the time.

We use the O'brien pipes and like them. I really don't think there is much difference in any exhaust system that are fit up right. You need to experiment with the cones. The only draw back I can see for you is the water issue. The Obrien's pipes angle down so they are closer to the water and will be harder to keep dry coming in.

Larry Mac