Effects of undivided ext. gate spacer on divided manifold & turbine housing

it's not about expansion within the manifold - it's about obtaining the maximum energy differential across the turbine to turn into shaft work. Obviously hotter gases have more energy. this is design theory.

In practice there are so many affecting variables that it's literally a crap shoot to 'have the best setup'. T3, T4, individual runner/equal length, pulse theory, turbine wheel diameter, A/R, Wastegate placement - all these things have to work in concert with one another to hit "the sweet spot"

In my situation, and the point of the thread, was to question the effect of the undivided spacer in a divided system.
 
PASSENGER said:
I was just thinking about your comments a bit more. I think maybe you aren't grasping what I am saying, which is, heat, in itself, does not, drive the turbine. It is merely a by product.
I have a little 2L honda engine I put together and built a turbo system for sitting here. The turbo is a hx52 hotside with an hx55 cold side. At a mere 4000rpm and only 1150* egt I am making 15psi on the cold side.

Think about it, its 1/3 the displacement of one of these cummins, and the egts are anything but hot. So whats driving it? Gas velocity, thanks to good ports and a good tubular manifold.
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So now the temperature of the gas has no effect on the volume and net effect velocity through the nozzle?

Really I want to buy in on this.....just not doing it for me though....
 
Joesixpack said:
So now the temperature of the gas has no effect on the volume and net effect velocity through the nozzle?

Really I want to buy in on this.....just not doing it for me though....
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I never said that, again, you still aren't grasping my point. I never said heat isn't apart of the equation, I'm just saying heat loss isn't worth fretting over when you still have major restriction and flow issues to deal with. Heat is the smallest, and least significant individual factor in driving the turbine.
Of course what I am saying is pertaining to an engine that is producing a complete burn.
 
A little story:

One of the better west coast Cummins guru's installed a equal length header on a heavily fueled, twin turbo Common Rail truck and lost at least 100 hp across the board on the dyno. He quickly changed back to a log type exhaust manifold.
 
WUnderwood said:
A little story:

One of the better west coast Cummins guru's installed a equal length header on a heavily fueled, twin turbo Common Rail truck and lost at least 100 hp across the board on the dyno. He quickly changed back to a log type exhaust manifold.
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Then the header he installed was poorly designed.
 
... for the rest of the "program" because the reduction in turbine inlet pressure (and therefore compressor RPM) resulted in a loss of 100 HP.
 
XLR8R said:
... for the rest of the "program" because the reduction in turbine inlet pressure (and therefore compressor RPM) resulted in a loss of 100 HP.
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Turbine inlet pressure and compressor rpm are not fixed, you can absolutely drop pressure with a change in manifolds and increase compressor speed. Sounds like major design flaws in the manifold you guys are referring to.
 
You can't decouple TIP (drive HP) from compressor RPM.

Will's anecdote infers that no other changes were made.
 
Semantics...
Drive HP is the amount of exhaust energy acting upon the turbine, which is comprised of kinetic (flow or velocity) & thermal (heat or expansion) energy.

Pressure delta across the turbine housing (TIP-TOP) dictates shaft HP, while compressor load determines shaft RPM.
 
XLR8R said:
You can't decouple TIP (drive HP) from compressor RPM.

Will's anecdote infers that no other changes were made.
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When you change volume and flow path, you absolutely can, which is precisely what you do when you change from one style manifold to another.

I've done lots of log to tubular conversions, the tubulars have less pressure, yet spool the turbo sooner, and without heat generation.
 
Forrest Nearing said:
no he/we aren't...

but YOU'RE making it sound like it has ZERO effect on anything, it does
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I'm not exactly sure how you guys picked that up, I said:

PASSENGER said:
Turbine inlet pressure and compressor rpm are not fixed, you can absolutely drop pressure with a change in manifolds and increase compressor speed. Sounds like major design flaws in the manifold you guys are referring to.
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Which was in reference to:

XLR8R said:
... for the rest of the "program" because the reduction in turbine inlet pressure (and therefore compressor RPM) resulted in a loss of 100 HP.
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This manifold that supposedly lost 100hp, was obviously of a poor design.
 
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