Tubular exhaust manifold vs. stock 2g

[jasoncitrano]

which manifold would be better to use, has anybody seen the tubular models on ebay and some other site if you search on ebay for eclipse exhaust you'll see them on there, i was just curious if there was any difference between those adn the stock 2g mani, besides being chrome...thanks
jc

 

[kooka]

the ones on ebay going for about 200 dollars are pacesetter. search here for pacesetter manifolds.

 

[jasoncitrano]

what's the difference though, which ones are better pacesetter or stock 2g?
jc

 

[93formula]

Well, to oppose many beliefs it is mainly heat that spools a turbo, flow does almost nothing to spool a turbo. Cast iron will keep more heat, so it will spool faster with the 2g manifold plus your turbo will be more efficient. Sure it may not flow quite as much on the top end (less than 5 hp on most applications) but will yield better spool. Now you can heat wrap a tubular manifold to retain heat, and that will work rather well. I've never tried a tublar manifold on a DSM, but I have on a WRX and it worked like crap. It didn't spool very well (could even drop boost between shifts) and actually had less power than factroy cast parts on a dyno (386 vs 393).

 

[kooka]

what's the difference though, which ones are better pacesetter or stock 2g?
jc

SEARCH

i just told you how to find your answer. try not to be a complete piece of shit and look it up yourself.

 

[phatTSi]

If you did search you would find a huge thread on reviewing the Pacesetter manifold.
http://www.dsmtuners.com/forums/showthread.php?t=89944&highlight=pacesetter

 

[drk mrk iv]

SEARCH

i just told you how to find your answer. try not to be a complete piece of shit and look it up yourself.

That was useless. The whole idea behind searching is to conserve bandwidth by not posting threads and replies. But since you made such a sorry ass post you contridicted yourself by reprimanding this fellow to search. :thumbdown

 

[LandoAWD]

SEARCH

i just told you how to find your answer. try not to be a complete piece of shit and look it up yourself.

Since you like playing moderator, I bet you know about this text:

Do Not Reply to a Message With the Following:
No "Use the Search" replies - answer the question, link to the answer, or don't reply.

...then again, maybe I'm giving you too much credit...

Play nice, or you can't use the swings when the other kids are on the playground.

 

[GSX_RCR]

Well, to oppose many beliefs it is mainly heat that spools a turbo, flow does almost nothing to spool a turbo. Cast iron will keep more heat, so it will spool faster with the 2g manifold plus your turbo will be more efficient. Sure it may not flow quite as much on the top end (less than 5 hp on most applications) but will yield better spool. Now you can heat wrap a tubular manifold to retain heat, and that will work rather well. I've never tried a tublar manifold on a DSM, but I have on a WRX and it worked like crap. It didn't spool very well (could even drop boost between shifts) and actually had less power than factroy cast parts on a dyno (386 vs 393).

I agree with you on the most part with the heat dynamics. But as far as "highest" output, equal length tubular manifolds are proven to make more HP. Don't get me wrong, most of the tubular manifolds on Ebay are junk. Their collectors are crap, and the welds are questionable. And I highly doubt that they're truly equal length.

A nice quality equal length tubular will help spoolup and outflow any cast manifold. But since we're mostly daily driven, I'd sacrifice a little HP for reliability and stock fitment. I kinda like my A/C during the summers.

 

[L2RTSiAWD]

Since you like playing moderator, I bet you know about this text:

Do Not Reply to a Message With the Following:
No "Use the Search" replies - answer the question, link to the answer, or don't reply.

...then again, maybe I'm giving you too much credit...

Play nice, or you can't use the swings when the other kids are on the playground.

He also might have seen this text in the same area.


2. No Insults and/or name calling - this can get you banned without warning - we don't care how experienced or knowledgable you are, don't be a smart ass!

I mean it's not like it's in red text or anything

 

[Mirage2LTurbo]

If you buy a pacesetter manifold, plan on having it fall apart on you, they are just pure junk. If you are going to buy one, get something worthwhile. On a side note, it is not heat that spools a turbo, it IS EXHAUST flow and the scavenging affect. My manifold was made locally, and while it looks decent, it also comes with a lifetime warranty against cracking. You don't want to wrap your manifold in heat wrap either, that only promotes cracking.

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[Air Assault]

from Dave Buschur

My tube chassis car has a tubular header on it that I built. On the flow bench this header acted like a damn suction machine. The head was so much faster (better flowing) than any cast piece we tried that it wasn't even funny. To give you an idea with the HKS manifold on the car and then switching to the header I built was the equivalant of adding .250 lift to the exhaust cam. That is huge.

On the dyno the gains weren't nearly as noticeable, as a matter of fact if I remember correctly we didn't measure any real gain at all. On the track, if I remember correctly the car was faster/quicker. Confusing stuff.

any more questions?

 

[GSX_RCR]

On a side note, it is not heat that spools a turbo, it IS EXHAUST flow and the scavenging affect.

You don't want to wrap your manifold in heat wrap either, that only promotes cracking.

Heat Energy is what drives the exhaust flow. So basically, it's the heat that spools the turbo. Exhaust scavenging effect has a small role in turbo applications since we're already cramming X amount of atmospheric pressure into the combustion chambers. We need to concentrate on exhaust flow, not only to help spoolup, but to also prevent intake contamination, which can lead to knock and detonation.

I do agree on the header wrap though. While you may be able to keep the heat energy within the manifold runners, you lose the ability to "cool" down and that can ultimately lead to cracks. It's not the heat that cracks/warps the metal, it's the inability to cool down proportionately enough.

 

[Mirage2LTurbo]

Heat Energy is what drives the exhaust flow. So basically, it's the heat that spools the turbo. Exhaust scavenging effect has a small role in turbo applications since we're already cramming X amount of atmospheric pressure into the combustion chambers. We need to concentrate on exhaust flow, not only to help spoolup, but to also prevent intake contamination, which can lead to knock and detonation.

I do agree on the header wrap though. While you may be able to keep the heat energy within the manifold runners, you lose the ability to "cool" down and that can ultimately lead to cracks. It's not the heat that cracks/warps the metal, it's the inability to cool down proportionately enough.

That, and also it holds in moisture, which is never good.

Yes, heat is energy, and that drives exhaust flow for the simplest definition. Exhaust scavenging affect has a HUGE role in any motor application, n/a or f/i. If you bolt on a manifold with 3in diameter runners, it's going to affect spool drmatically. Same goes for equal length manifolds.. they "theoretically" flow more top end because of less turbulence, but spool is worse.

What is intake contamination? You mean exhaust still being in the chamber going into the next cycle? Back pressure is not good on *any* engine, you never want it. Be sure to distinguish between back pressure and the scavenging affect, as they are completly different.

Maybe we're on the same page, if not were close.

 

[GSX_RCR]

Maybe we're on the same page, if not were close.

HaHa! Close enough! :laugh:

What I meant was that to create an effective scavenging effect, you need to carefully time the exhaust pulse that creates the low pressure wave to draw in the fresh intake charge. But in turbo applications, there's 2 things that you need to keep in mind.

#1) A turbine spinning @ 80k-110k+ rpms is going to cause some disturbance, before and after. It'll be difficult to try and calculate anything with a huge fan spinning at the end and throwing off your values.

#2) Boost. You're already cramming up to twice or three times the atmospheric pressure into those chambers. You don't necessarily need any more help with that aspect. What you should concentrate on more is improving ways to efficiently expell the spent exhaust gases and help drive the turbine. I totally understand if you're talking about N/A applications. But that's a totally different topic altogether.

But I still contend that a properly designed equal length manifold with a quality merge collector will help spoolup and outflow any cast manifold. Let me dig up some dynocharts showing the difference between a log type cast manifold and an equal length tubular.

 

[Mirage2LTurbo]

Damn, someone with some common sense.. you must be a wiseman

I agree that tubular is better than just some cast manifold, but AFAIK, there have never been any conclusive tests done with tubular vs. equal length tubular. It's been my understanding that it's all theory and preference. However, I'd love to be proved wrong there and see some good testing done

 

[ITSME4G63]

If you buy a pacesetter manifold, plan on having it fall apart on you, they are just pure junk. If you are going to buy one, get something worthwhile. On a side note, it is not heat that spools a turbo, it IS EXHAUST flow and the scavenging affect. My manifold was made locally, and while it looks decent, it also comes with a lifetime warranty against cracking. You don't want to wrap your manifold in heat wrap either, that only promotes cracking.

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why is that turbo facing the other way!

Tubulars are nice, but For the price I dont think you can beat the sbr one? no?

 

[Mirage2LTurbo]

why is that turbo facing the other way!

Tubulars are nice, but For the price I dont think you can beat the sbr one? no?

Only way I could fit it in there.. we had a few complications, but the end result it what you see. I think it works better for a few reasons

http://www.kydsm.com/gallery/showgallery.php?cat=509

 

[GSX_RCR]

Damn, someone with some common sense.. you must be a wiseman

I agree that tubular is better than just some cast manifold, but AFAIK, there have never been any conclusive tests done with tubular vs. equal length tubular. It's been my understanding that it's all theory and preference. However, I'd love to be proved wrong there and see some good testing done

Well, I'm not a DSMTuner wiseman, but I've been in the game long enough to absorb a little information here and there.

As far as the comparison between different manifold types, HERE is one test between a log type manifold vs. a true equal length, merge collector manifold. Same boost pressure, same tune. It's not a DSM, but we're talking performance, so just look at the data.

 

[93formula]

I will agree to a point that flow of air will spool a turbo, but I ask you according to any physics teacher or turbo designer (whom I have spoke to many guys at garrett through my school and all of them say tubular is a bad idea for turbos unless it is heat wrapped to keep in heat, why would everyone that races imports professionally do it this way?) with 600 cfm of 30 deg air or 600 cfm of 500 deg air, which one will have more force? Ask any teacher or designer and they will say the 500 deg air, it is just simple physics. Now if you keep the tubular as hot as the cast, then the tubular will win in power because of flow, I understand that, but for most cars the amount of flow difference will make very little difference because of the turbo restriction. So, if heat is equal, then go tubular. Also, it was brought up that cast iron might lead to higher detonation I think, correct me if that was not in this post. But the exhaust air that gets back in would be hardly different at all, because they both have the same restricion stopping the gas, the turbo, but I do see what you're saying. The main factor in detontaion prevention is the quench area, as a rule of thumb the smaller the better actually below .004 is hurtful but that is almost impossible to get. For instance, I built a V8 musclecar that was a 408 SBC that had 11.5:1 compression that ran on 89 octane because I paid so much attention to the quench area, and it made more power (about 12 if I remember right) than a friends similar 408 SBC with 13.5:1 on race gas.

 

[93formula]

Sorry I just caught that last post with the log vs equal length, and that is what should happen between the two, but the log was not a cast iron unit, and looking at it, it looks like crap, our 2g manifolds look a lot better than that when ported. 2G manifolds are rather close (rather being a very relative term compared to the log used in the test) to equal length.

 

[Mirage2LTurbo]

I will agree to a point that flow of air will spool a turbo, but I ask you according to any physics teacher or turbo designer (whom I have spoke to many guys at garrett through my school and all of them say tubular is a bad idea for turbos unless it is heat wrapped to keep in heat, why would everyone that races imports professionally do it this way?) with 600 cfm of 30 deg air or 600 cfm of 500 deg air, which one will have more force? Ask any teacher or designer and they will say the 500 deg air, it is just simple physics. Now if you keep the tubular as hot as the cast, then the tubular will win in power because of flow, I understand that, but for most cars the amount of flow difference will make very little difference because of the turbo restriction. So, if heat is equal, then go tubular. Also, it was brought up that cast iron might lead to higher detonation I think, correct me if that was not in this post. But the exhaust air that gets back in would be hardly different at all, because they both have the same restricion stopping the gas, the turbo, but I do see what you're saying. The main factor in detontaion prevention is the quench area, as a rule of thumb the smaller the better actually below .004 is hurtful but that is almost impossible to get. For instance, I built a V8 musclecar that was a 408 SBC that had 11.5:1 compression that ran on 89 octane because I paid so much attention to the quench area, and it made more power (about 12 if I remember right) than a friends similar 408 SBC with 13.5:1 on race gas.

I've read your post 4 times now, and I an't follow your train of thought. Tubular is not going to retain heat as well as cast, correct, because the material is not as thick. You do NOT want to wrap your manifold in that heat wrap shit, as it will cause your manifold to crack. The real question is, how much heat do you think your manifold is going to lose between the head and the turbo, maybe 12 inches max, probably more like 8. Let's talk about exhaust gas velocity.

Exhaust gas moves extremely fast. I once talked to a machine shop owner who specialized in domestics, and he said that on a new LS1 engine, exhaust moved at around 50ft/second. I wouldn't expect that to vary much for our 4 cyls. So for argument's sake, let's say our exhaust moved at 15 feet per second. That still means that cyl 1's pulse is going to be well through the exhaust, before it could lose much heat. Considering most 4g63's operate around 1500deg t the combustion chamber, I don't think the amount of heat you would lose between tubular or cast is even worth talking about.

Now let's talk about flow differences. I don't think there is much discussion here, tubular is going to flow better in just about every case.

 

[GSX_RCR]

with 600 cfm of 30 deg air or 600 cfm of 500 deg air, which one will have more force?

Yes, the hotter exhaust gas will carry more energy. That was my point.

Also, it was brought up that cast iron might lead to higher detonation I think, correct me if that was not in this post. But the exhaust air that gets back in would be hardly different at all, because they both have the same restricion stopping the gas, the turbo, but I do see what you're saying.

If you're talking about the exhaust reversion contaminating the intake charge, then it's slightly different than what you're saying. I mentioned that instead of trying to create a scavenging effect in a turbo application, we should concentrate on exhaust flow. That would encourage quicker spoolup and prevent backpressure which can lead to reversion.

The main factor in detontaion prevention is the quench area

I agree. But that's a totally different topic that merits it's own 10 page discussion. But since most of us are daily, street driven...we tend to keep some parts somewhat stock and sane. Work with what you got, that's what I always say.

 

[CanadianTalon]

http://wakesports.com/full-race/index.php?act=ST&f=2&t=249&st=0#entry875

Equal Length Merge collector mani vs. Typical log mani. The results speak for themselves. 48 WHP and 44 WTQ ONLY changing the manifolds on a mild 350 horsepower honda. Reason enough for me to go with a good tubular.

 

[kpt4321]

All this talk about heat providing spool, or flow providing spool, or whatever, is a bit silly.

The turbine wheel requires ENERGY to compressor the charge air, end of story. Energy comes in many different forms, and the turbine wheel uses more than one of them.

Heat is the primary energy source to the turbine wheel; however, hot air alone will NEVER spool a turbo, no matter how hot it is.

In order to put the required amount of energy through the turbine wheel, so that you can achieve a desired boost pressure and airflow on the cold side, you need to put a certain amount of total energy through the turbo in a given time period; "heat flow," if you will.

As such, the number of heated (and therefore highly energetic) molecules that pass a turbo is just as, if not more, important than the temperature. This is why flow matter just like heat does.

A lot of the properties that effect the flow characteristics you require (low turbulence, high velocity, etc) will also require the heat loss in the manifold, which may be one reason yu are equating heat loss with slower turbo spool. Heat loss will slow the turbo spool, but as Mirage pointed out, there simply isn't a whole ton of heat loss in the sytem.

Mirage, on the other hand, I think you went a little too far in the other direction. Yes, the exhaust is in the system for a very short period of time. However, keep in mind that th delta-T from the manifold to the engine bay is VERY high, therefore making the situation conducive to conductive heat transfer. Simple things like a ceramic coating on the manifold can raise the internal gas temperature by an appreciable amount.