IronMan

Thanks TG.What do you think if there is a tunable tune pipe.Someone from this forum ever mention about making this type of pipe.Lets say I shorten or lengthen it by about 10mm to 20 mm.What difference does it make?

modellor

Increasing the length of the pipe will help produce more power at the top end while shortening the length will produce more torque.

But with the .12 engines the differences are barely noticeable unless the engine is really tuned to perfection.

stefan

Sorry, but my experience is that the longer pipe gives you more torque while the shorter on gives more rpm's.

EVOLUTION

I too thought it was the other way around.

afm

Sorry, but I agree with Modellor, lets not confuse header to pipe lenght, which gives you what you are saying. Actual pipe size goes the way Modellor says. My experience with Picco and Sirio engines, which are a mid-lenght conrod engines and so have a bit more torque, have their pipes very long (difficult to fit in most cars) because they try to enhance top-end. I remember that the Picco pipe was the hot ticket for the Mugen MT12 engine (long conrod).

AFM

Manticore

http://www.rbproducts.com/rbww/faqrb...erformance.htm

read it carefully and check out what does "pipe length" mean there.

afm

Manticore, that's what I was trying to set clear, i totally agree with you, and if we go to:

http://www.rbproducts.com/rbww/pipe_...foldlength.htm

It tells you how to measure that lenght, and in their pipe product description it tells you the min. and max. lenght suggested for each pipe. But what Modellor and I are trying to explain is that on the pipe's designed size by itself, Longer = Top end, Shorter = Torque.

AFM

x_man

I thought it was the other way round, where longer pipe will gives more resonating volume, lower resonating time(lower pitch sound) and backpressure, shorter pipe will have less resonating volume higher resonating time(higher pitch sound) and less backpressure hence better reving engine(top end).
These pipes of course, that i am comparing are with the same stinger outlet diameter.

GoldFinger

I thin you were addressing to the divergent cone shape.
So maybe you can not state it longer and shorter (pipe length terms), just different language problem i guess.

afm

For everybodys benefit go to the following web pages, which in my modest opinion have the most complete explanation on Tuned pipes. Eventhough they are from planes and boats, the theory is the same for all 2 storke engines. After reading them things will be as clear as water.

http://www.bolly.com.au/book/Book.js...er=6&Section=1
http://www.hpt-sport.com/direct.htm (go to pipes)

Hope it helps

AFM

afm

Pipe design is complicated by the many variables. The art of pipe design is to combine the lengths, angles and diameters of the pipe to suit the characteristics of the engine, especially the exhaust timing and end use.
Some examples are;
Small volume - high heat - narrow operating range (peaky)
High volume - lower power (if too big) - broad range
Steep angles - 'peaky' - high power
Shallow angles - broad range - moderate power
Smaller or larger diameter stinger - lower or higher pressures and heat.
There are a multitude of ways of quoting pipe length. The most accurate method (and most rarely used) is to quote the distance from the piston face to the Mean Reflection Point (MRP). The MRP is the average point of the reflected wave forces. Many people quote a length of plug to the high point, which is easy when pipes have a clearly defined high point ... most modern pipes have a flat or mildly curved center section which is used to "tune" the operational power band..smoother, wider etc.etc.

AFM

EdwardN

iTrader: (1)

Why don't we read agian articles on the web sites I posted on the beginning of this thread.
Generaly-longer pipe kick in earlier and give us benefit at lower RPM, but it will not bring us to highest possible RPM. Short pipe will ki9kck in later at higher RPM range will give us much higher topr RPM level, but engine first has to reach that leve when pipe will start making charging ( resonance effect).
At any lenght of pipe, it will not start working till engine reach RPM on which pipe is tuned. If engine isn't able to reach that level, pipe will never bring any benefits ( resonace charging).

Start from longest possible pipe and run it, after that start shortening it, till you will find the best effect-don't forget at differnt load engine will go to level differently-more load takes more time to get there.

modellor

That is correct. This arguement is my fault. Typed my first post back to front and didnt realise.

Sorry everyone.

afm

Totally agree with that TG, that is why there are so many pipes out there in the market, and each manufacturer and it's different models of pipe try to enhance different "power bands", but if you don't tune them correctly to your engine and application, they are worthless.
But lets not confuse the pipe's lenght by itself with total exhaust lenght, that is why i think that the best explained method is the one given by RB Products and it is called "pipe to manifold lenght", which will give us the effects you so well explained.

Sorry if i got confused between those two concepts that started this argument (pipe lenght vs total exhaust lenght), that in the end has been very productive for everyone.

AFM

EdwardN

iTrader: (1)