Carbon fiber vs aluminium

[Grimracer]

Larry.. did you get the information you were hoping to get with this thread?

If we would like to open up a dialog on pipe wrapping I can start a new thread.. just let me know. (your thread Larry)

Grim

 

[DPeterson]

I've been reading along and learning. Would like to continue reading on about pipe wrapping. Please do a thread on the subject. I'm a gas guy so I'm hear just to read and learn but I assume wrapping a nitro pipe has a similar outcome to wrapping a gas pipe.

I've been wrapping pipes in boats that have enclosed pipes to keep the inside air temperature down and to protect the cowl from burning. Did not consider any performance factor.

Sorry to highjack the thread. Please start another.

Doug

 

[Jeff Schindler]

Whats the speed of sound? It changes with temperature you know

 

[Jeff Schindler]

By example a 100 F increase in fluid temperature would make the pipe increase its RPM capability as much as making it 1/2" shorter would in Dave's example. See attached calculation showing the time it takes for the pressure wave to return to the exhaust port.

 

[LarryConrad]

Mike,

Some interesting information did come from my inquiry. From reading different posts over the years in this forum i got the impression that racers that used carbon pipes were very strongly biased toward their use much like the racers who own Cooper pipes seem to be. This thread generated no replies from racers using SPP or Gadget pipes though. Although I currently own a vast assortment of different outboard pipes and different power heads and hulls, I’ve never taken the opportunity as you did back in 2005 to do back to back testing. Back when I got started racing tunnels in 2006 I started with a MAC power head on a K&B lower, with a Irwin muffled pipe pushing a TopSpeed 2. Shortly after the engine was broken in the hull was replaced with a XTR-21 Leecraft which I raced for two seasons. During the second season I changed to a Silver Bullet HP pipe with no noticeable change in performance. I had similar results during the same time period with my 45 tunnel. Axe Rossi River King/K&B lower/muffled Irwin, on a XT 460 Leecraft, then switched to a Silver Bullet pipe. Prop changes have shown me larger performance gains or losses and also some require the boat setup to be adjusted.

 

[LarryConrad]

I would definitely like to know more about pipe wrapping.

 

[Grimracer]

Do you want us to keep it here?

Grim

 

[LarryConrad]

I don’t have a problem with that.

 

[Grimracer]

Jeff,

Cool stuff.. I am not discounting it as fact.. I am pondering how to tune with it. I have found great gains in the proper pipe length during launch.. how do we account for that. Just thoughts going thoughts my head.

The last thing I want it a larger spread in optimized lengths...

Grim

 

[HTV Boats]

So is it a "sound wave" or a "pressure wave". There are a lot of factors here beside length that affect the reflective properties. Consider an outboard pipe is pretty much hanging in a stream of cooling air. Well most of it especially the 180 turn then the converging cone is in disturbed air behind the head button in most common pipe configurations. I imagine there are a range of temp differences in an aluminum pipe. Hence CF or a wrapped pipe would keep the exhaust a little more constant. I have wrapped pipes around the 180 turn for years.

Other considerations are anodizing which I have not tried to stiffen the surface. Or Powder coating which I have done and noticed that I had to richen my needles after. More heat better burn. This is a glow diesel motor and managing heat is as important to me as trying different lengths. Then the stinger exit diameter and length come into play. Too big a stinger just lets that heat out and lowers fuel pressure from the pipe. I don't worry about what length it should be. Start long and shorten till lap times fall off. Then consider too long will finish the race and too short might go fast till you become a turn pin. Theories are great guidelines. Test and make changes is what counts. Don't rely on the "butt dyno", use a watch like Mike did in his tests. Radar and GPS give nice to know info but the watch doesn't lie.

Mic

 

[LarryConrad]

Mic,

What do you use to wrap your elbows? Do you also wrap the header?

 

[HTV Boats]

Larry,

I have used plain old fiberglass cloth with a little epoxy to keep it from unwinding, covered with foil duct seam tape. I now am going to 1" header tape as it is neater. I don't do the header and wrap from the coupler to the converging cone.

I do like powder coat. It cost me $100 to batch 10 pipes. Every set up lowered the tune number on my flow meter. More heat burns more fuel. Rather than lean a motor out to get on pipe, don't starve it, feed it and use controlled heat to burn it. I have gone to a lot of air cooled finned Aircraft heads to keep heat rather than water cooled. Where your at with water temps rarely over 70 degrees that cold water circling around a head button is not even heat. You can pre heat head button water with a couple coils wrapped around the header.

Sorry for getting away from alum vs CF but a balance of heat is relevant. CF should keep more heat in the pipe. I just haven't found a CF pipe I liked.

Mic

 

[LarryConrad]

I’ll have to give the pipe wrapping a shot, and then maybe I can try the air cooled heads again. Rod Garaghty turned me on to restricting the water flow at the water jacket using a tiny exit hole allowing the engine to build more heat than it would with the cooling water freely flowing through the water fittings. With more heat I can run richer needle settings and the engines make more power. When I tested with cut down buggy heads on my MAC’s I had issues with the engine falling off the pipe in turns and wasn’t able to find a tune that ran as consitantly as running restricted water flow.

 

[LarryConrad]

Mic,

When you have your pipes powder coated, do they use a temp resistant color coat or a ceramic heat barrier coating like used on automotive headers and turbo housings?

 

[HTV Boats]

Talking to the shop that powder coated he used a black high temp coating. Not sure if it was ceramic. I would think ceramic would be best. It would be interesting to try Mike's radar gun theory before and after to see if it stiffens the pipe at all.

You can take a small plastic water fitting "T" and put a 440 bolt in it and make a cheap variable flow device and creep down on water flow. I have used Rods method also. I like the header water pre heat idea as warmer to the head button is like a thermostat if you regulate it.

Mic

 

[LarryConrad]

There is a powder coating shop in Elk River, I’ll swing by with a box of pipes and get an estimate. I’m going to give the pre heat coil idea of yours a try this spring when testing resumes after ice out.

 

[michael faszcza]

Wonder about powder coating a can muffler like on a os ?