Thread: things to upgrade for high performance

Originally Posted by Dougal

How does a lack of exhaust velocity in a vertical ship exhaust relate to our vehicles?.

re read Bush65 post. And i assume you mean vertical stack and not ship. if it’s a vertical ship i would think there would be bigger problems to worry about.

Originally Posted by Dougal

The presence of a turbocharger, which is a pretty good at stopping pulse reversion from the exhaust, kind of negates the application of that analogy.

Well yes it is rather good at stoping pulse reversion POST turbo, but as it also increases manifold pressure any pulse reversion will have a higher negative effect. Thus increasing the need to manage pulse pre turbo.

I can't comment as I do not know as much as use do about everything ... Im happy to hear everyone's point of view as everyone has had different experiences... So back on topic guys!! 85county you believe it's more to do with valve opening to base tube size on ? I am finding it hard to follow with the pulse converter as it reduces in size but it must be just enough to change pulse but not restrict it to much ...

Turbo chargers , pulse converters . WTF

I love the sound of my NA Isuzu through the stainless snorkel.

Blup blup blup blup blup

Steve G . Now the OE aircon is going back in and the rebuild funds are running out , I may have to look at the remote location turbo option down the track.
I still have the brand new Garrett sitting on the shelf. Not sure if I should soak it in CRC or something for storage

NO don't spray crc on it I would just cover openings and tip some engine oil down the oil inlet then sit it on the shelf...I sprayed mine with crc and it locked it up so it would not turn so I had to sit there and tip oil into the orifice and slowly try and free it up...as for remote turbo option you sure there is not enough room to do it the usual way ?
Hahaha I know the noise you mean from the snorkel on a NA diesel I'm looking for a cheap safari snorkel would have one laying around would you ?

Originally Posted by land864

Turbo chargers , pulse converters . WTF

I love the sound of my NA Isuzu through the stainless snorkel.

Blup blup blup blup blup

Shame about the performance

Originally Posted by rovercare

Shame about the performance

Lol

Originally Posted by 85 county

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

From a little of what you said before and in the last post I suspect you don't understand what the pulse converter is doing. BTW pulse converter is not what I call it (I think the name is misleading), but was used by others.

It has nothing to do with scavenging, or the pulse that travels at sonic speed and reflects from an opening end with the opposite sign (+ve reflects as -ve pressure) and scavenges the cylinder if it reaches the open valve. This phenomenon is used on NA race engines and the rpm and length is critical.

With a turbo in the exhaust, the pulse doesn't reach an opening end.

With a 6 cylinder turbo diesel engine (Cummins for example), it is usual to have a divided turbo with the exhaust manifold divided so the front 3 cyls supply one half of the turbine housing and the other three supply the other half. Now with the spacing of the firing for 3 cyl, at no time is there another exhaust valve still open near TDC for that cylinder with very low pressure when the exhaust valve opens with high pressure (the high pressure pulse) when another cylinder is near BDC. Thus the high pressure pulse drives the turbine.

With a 4 cyl using a divided turbine is not very practical so the problem when the exhaust from the 4 cylinders are joined the with the normal firing order 1,3,4,2 when the exhaust valve for #1 opens, the high pressure of the pulse is lost back down #2 exhaust valve which is still open (near TDC for #2). The so called pulse converter avoids the high pressure from #1 combining with low pressure in #2. This phenomenon repeats with each cylinder in turn.

Note the pulse converter helps to achieve the advantages results that occur naturally with most 6 cyl turbo diesels. This advantage has nothing to do with exhaust cooling, vertical exhausts, or only at 20000 rpm, etc. It simply is a method for improving pressure in the exhaust manifold, with 4 cyl engines and other numbers (such as used in ships) where open exhaust valves overlap adversely.

Look at the graph of the pressure in an 8 cyl engine (the 1st pic that I posted above) to see what happens.

bush65

i agree, you are much better with words than me but i can see it all happening with out having to close my eyes.