Thread: things to upgrade for high performance

Originally Posted by c.h.i.e.f

I should have also used the words "cross sectional area" and not surface area haha
Personally I am going to use what you and randy have used but I just wanted to question it just incase.
I am going to steer clear from the thinner stuff as I will not trust it whilst under extreme temps,vibration and an expensive turbo hanging from it I would hate it to crack plus the thicker wall will help retain heat which from what I can gather is beneficial in our application. From the bends I have played with they have a wall thickness of around 3mm is this similar to yours John ?
I also do not ubderstand the 20,000Rpm statement ? Assuming when you say reducing the size of the tubes will increase velocity this would be the same as a smaller A/R Exhaust housing I would imagine..

I don't have my pipe catalogues/table with me, but the wall thickness of the lighter 40 NB, butt weld fittings will not cause a problem for you as they are still plenty thick enough.

I don't have my un-finished manifold here, so can't check the wall thickness of the fittings - they are in the order of 3 mm.

BTW, although pipe is sized on the bore, (tube on outside diameter) the outside diameter remains the same for different wall thicknesses, and inside diameter changes (thus the use of Nominal bore. Butt weld fittings are for pressure purposes, thus the need for the different wall thicknesses. The schedule number is based upon a pressure rating, so thickness of, say sch 40 will vary with NB - if bore increases the wall thickness has to increase for same pressure.

Increasing velocity in a manifold branch will not compensate for A/R in the turbine housing as the velocity in the housing is determine by the nozzle cross section area. Some turbo manufaturers don't state A/R, but give the area in cm^2

The reason that the pulse converter has an area reduction to increase velocity is to avoid flow reversal (and loss of pulse pressure) down the other branch.

Originally Posted by Bush65

Oh dear
The pulse converters you are referring to are used on and were developed by manufactures of large marine diesels as used in ships.

Your comment about needing to spin at about 20 000 rpm is way off and very missleading - how do you substantiate the 20 000 rpm comment?

quite simply, but first you have to understand the problems that the ship builders had to overcome.
Big displacement low revving and with a tail pipe about 20 klms long ( usually vertically)
There problem was the gas cooling down becoming denser and not wanting to move, so they used the pulse or sonic pulse to help as well and making the cross section smaller.
in your application i believe that you are looking at this method to overcome or reduce the flow back or the lack of savaging ( for want of a better word) that the turbo produces.
in short the shorter the exorst pipe the higher the revs need to be before realising the benefits. 20000rpm for a 4bd, I was exaggerating, I thought it was funny, you didn’t.

But what’s really funny is, I have posted before about pulses and there benefits and was POO POOed but the so called Isuzu knowitalls. Now it seems that others wish to pursue this topic and those who did the POO POING before now seem to be authorities.

Sounds like an aussie pollies flip flop