top mount vs equal length vs cast manifolds
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Evolving Member
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From: lewisville TX
top mount vs equal length vs cast manifolds
ok, so ive been trying to find something on top mount manifolds.. i have an equal length now. and was just wondering if top mount will help increase spool.
so far in my search everyone has only said topmount increases HP but no one says anything about spool.
reasons??
are there any know it alls out there that might be able to enlighten me what the advantages and disadvantages of the different manifolds?
so far in my search everyone has only said topmount increases HP but no one says anything about spool.
reasons??
are there any know it alls out there that might be able to enlighten me what the advantages and disadvantages of the different manifolds?
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Joined: Jan 2004
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http://www.sae.org/technical/papers/2005-01-3812
It's $15 if you want the truth.
But if you want an unscientific opinion on the matter.......
It's $15 if you want the truth.
But if you want an unscientific opinion on the matter.......
- Shorter primaries are better because they lose the least amount of heat and exhaust pulse energy between the head and turbo.'
- Primaries of relatively equal length are better because they space exhaust pulse 'hits' on the turbine wheel more evenly.
- Cast manifolds are good in that they retain the most heat, but seldomly can they be made to ideal proportions without being unweildly and heavy.
- Short radius turns in the primaries negatively impact pulse energy. Larger, more gentle turns are best, but not always possible due to spatial constraints.
Ideally, one wants a manifold that gives the shortest possible, relatively equal length runners without resorting to short radius bends to do it. With an EVO, the factory turbo placement requires short radius bends to make it work, so there is some compromise there. A manifold with slightly longer primaries but with fewer turns probably represents the best compromise, although it places the turbo in a different location.
Here a good pdf beyond everyones head, reading will make your eye's bleed. But it's free.
1)
"Numerical computations of the unsteady flow in a radial turbine"
http://www.diva-portal.org/diva/getD...__fulltext.pdf
2)
You'll have to search this one out but it's definately worthwhile to read (math is overwhelming throughout though):
"Application of Turbochargers in Spark Ignition Passenger Vehicles"
a thesis presented at Stellenbosch University by Wallace William Bester
enjoy
1)
"Numerical computations of the unsteady flow in a radial turbine"
http://www.diva-portal.org/diva/getD...__fulltext.pdf
2)
You'll have to search this one out but it's definately worthwhile to read (math is overwhelming throughout though):
"Application of Turbochargers in Spark Ignition Passenger Vehicles"
a thesis presented at Stellenbosch University by Wallace William Bester
enjoy
Last edited by C6C6CH3vo; Feb 26, 2009 at 03:27 PM.
Newbie
Joined: Jan 2004
Posts: 88
Likes: 0
I don't know if a genuine 'know-it-all' is really necessary, since the basic strategies are fairly easy to comprehend.
- Shorter primaries are better because they lose the least amount of heat and exhaust pulse energy between the head and turbo.'
- Primaries of relatively equal length are better because they space exhaust pulse 'hits' on the turbine wheel more evenly.
- Cast manifolds are good in that they retain the most heat, but seldomly can they be made to ideal proportions without being unweildly and heavy.
- Short radius turns in the primaries negatively impact pulse energy. Larger, more gentle turns are best, but not always possible due to spatial constraints.
Ideally, one wants a manifold that gives the shortest possible, relatively equal length runners without resorting to short radius bends to do it. With an EVO, the factory turbo placement requires short radius bends to make it work, so there is some compromise there. A manifold with slightly longer primaries but with fewer turns probably represents the best compromise, although it places the turbo in a different location.
- Shorter primaries are better because they lose the least amount of heat and exhaust pulse energy between the head and turbo.'
- Primaries of relatively equal length are better because they space exhaust pulse 'hits' on the turbine wheel more evenly.
- Cast manifolds are good in that they retain the most heat, but seldomly can they be made to ideal proportions without being unweildly and heavy.
- Short radius turns in the primaries negatively impact pulse energy. Larger, more gentle turns are best, but not always possible due to spatial constraints.
Ideally, one wants a manifold that gives the shortest possible, relatively equal length runners without resorting to short radius bends to do it. With an EVO, the factory turbo placement requires short radius bends to make it work, so there is some compromise there. A manifold with slightly longer primaries but with fewer turns probably represents the best compromise, although it places the turbo in a different location.
Having a thick walled cast-iron manifold just means it can absorb more of the exhaust energy not less..
That's exactly right. Cast iron absorbs it and retains it, and that makes it better. Ever wonder why tubular steel manifolds radiate so much more heat than a cast iron manifold? Radiated heat is wasted energy. This isn't my opinion. It's common knowledge. Think about it.
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I don't know if a genuine 'know-it-all' is really necessary, since the basic strategies are fairly easy to comprehend.
- Shorter primaries are better because they lose the least amount of heat and exhaust pulse energy between the head and turbo.'
- Primaries of relatively equal length are better because they space exhaust pulse 'hits' on the turbine wheel more evenly.
- Cast manifolds are good in that they retain the most heat, but seldomly can they be made to ideal proportions without being unweildly and heavy.
- Short radius turns in the primaries negatively impact pulse energy. Larger, more gentle turns are best, but not always possible due to spatial constraints.
Ideally, one wants a manifold that gives the shortest possible, relatively equal length runners without resorting to short radius bends to do it. With an EVO, the factory turbo placement requires short radius bends to make it work, so there is some compromise there. A manifold with slightly longer primaries but with fewer turns probably represents the best compromise, although it places the turbo in a different location.
- Shorter primaries are better because they lose the least amount of heat and exhaust pulse energy between the head and turbo.'
- Primaries of relatively equal length are better because they space exhaust pulse 'hits' on the turbine wheel more evenly.
- Cast manifolds are good in that they retain the most heat, but seldomly can they be made to ideal proportions without being unweildly and heavy.
- Short radius turns in the primaries negatively impact pulse energy. Larger, more gentle turns are best, but not always possible due to spatial constraints.
Ideally, one wants a manifold that gives the shortest possible, relatively equal length runners without resorting to short radius bends to do it. With an EVO, the factory turbo placement requires short radius bends to make it work, so there is some compromise there. A manifold with slightly longer primaries but with fewer turns probably represents the best compromise, although it places the turbo in a different location.
There are other reasons cast manifolds are nice, but heat retention is not one of them.
Also I'd add that modern OEM cast manifolds are not cast iron but high nickel steel or austenitic stainless.
Once the cast manifold has been heated, it will no longer be absorbing energy from the exhaust gases. All of the energy is going into spinning the turbine. With a tubular manifold a significant amount of thermal energy is radiating out to the air, reducing the energy of the air prior to reaching the turbine. While the cast manifold may absorb more energy shortly after startup, it will help the exhaust gas retain energy after it has warmed.
Evolving Member
Joined: Nov 2006
Posts: 271
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From: Utah
Where would you find and inconel manifold? That sounds like a it would cost a pretty penny. From what I understand about inconel (other than it being expensive since I work in a machine shop) doesn't it also resist build up and what not on it? I have heard that it doesn't let oils and other residue stick to it once it is heated.
With othe manifolds other than cast how much does a coating help to keep the heat in and not radiating to the outside of the car? Could you technically coat a stock one and have it do well?
With othe manifolds other than cast how much does a coating help to keep the heat in and not radiating to the outside of the car? Could you technically coat a stock one and have it do well?
Here a good pdf beyond everyones head, reading will make your eye's bleed. But it's free.
1)
"Numerical computations of the unsteady flow in a radial turbine"
http://www.diva-portal.org/diva/getD...__fulltext.pdf
2)
You'll have to search this one out but it's definately worthwhile to read (math is overwhelming throughout though):
"Application of Turbochargers in Spark Ignition Passenger Vehicles"
a thesis presented at Stellenbosch University by Wallace William Bester
enjoy
1)
"Numerical computations of the unsteady flow in a radial turbine"
http://www.diva-portal.org/diva/getD...__fulltext.pdf
2)
You'll have to search this one out but it's definately worthwhile to read (math is overwhelming throughout though):
"Application of Turbochargers in Spark Ignition Passenger Vehicles"
a thesis presented at Stellenbosch University by Wallace William Bester
enjoy
