Exhaust gas simulation-tubular vs log header!

[turbovanman²]

Found this on a VW forum, pretty damn cool!!!!!

http://forums.vwvortex.com/zerothread?id=3526298

[tryingbe]

I was gonna sell my TBI header, but now I want to keep it. Damn it Simon, it's all your fault.

[turbovanman²]

I was gonna sell my TBI header, but now I want to keep it. Damn it Simon, it's all your fault.

Sorry dude, :(

[zin]

Not sure what it's supposed to mean. The one that has the animation is illustrating velocity, the one below it (not animated) is showing temp (seems kinda high too). Seems like comparing apples and oranges.

[86Shelby]

^^^exactly what I was thinking.

[BadAssPerformance]

The second one is still showing vectors (arrows) of flow and how they collide into each other more.

...maybe I should make a batch of headers this winter :D

[Birddog]

The second one is still showing vectors (arrows) of flow and how they collide into each other more.

...maybe I should make a batch of headers this winter :D

A number of lazy people have been waiting for that......:eyebrows:

When I had the boosted fjords I sprung for a sweet header similar to illustration one (http://www.stinger-performance.com/Pics/SPHeader4Small.jpg)(his current pic not mine). Went from a ported LA3 manifold(log not too different than TM's) straight out and lost all low end performance.

[turbovanman²]

A number of lazy people have been waiting for that......:eyebrows:

When I had the boosted fjords I sprung for a sweet header similar to illustration one (http://www.stinger-performance.com/Pics/SPHeader4Small.jpg)(his current pic not mine). Went from a ported LA3 manifold(log not too different than TM's) straight out and lost all low end performance.

So your saying you went from a log to a equal length type header and lost all bottom end power? :confused:

[Ondonti]

so its still log headers creating more pressure (and reversion) so the turbo starts to spool up faster but maybe 200rpms later the tubular header will already be making more boost and gobs more power because it spools the turbo by maintaining velocity rather then just creating massive pressure behind the turbine wheel. :P

[moparzrule]

I don't think it really matters on our cars, guys that put on tube headers don't really see anymore gains than with something like the TU header. Not sure what it is about our cars but they like log headers for some reason.
I also don't think a TBI header is a good comparison to a tube header.
In those graph's the difference between red a blue is 50 degree's, WTF.

[BadAssPerformance]

Has anyone ever done a back to back dyno test of a log header to a equal length tube header on a 2.2L/2.5L 8v?

Warren Stramer cut off a couple tenths going from a ported stocker to his masterpiece long runner header. A couple tenths in the 10's is a big gain.

[moparzrule]

Who's ported stocker? ???'s flows worse than stock. And a TU header flows a lot better than a ported stocker as well.

[tryingbe]

Has anyone ever done a back to back dyno test of a log header to a equal length tube header on a 2.2L/2.5L 8v?


That question will be asked over and over and it will never been answered, because of the below reasons.

To do a back to back test, you have to have access two both header. Log header is hard enough to get, an equal length tube header will be almost impossible, unless you can make one.

Next, that person will have to be willing to take the head off twice two change the manifolds.

Then, the car will have to be tune twice to maximum the performance.

So, not only you have to have the resources to get both header, able to tune, have the resources to tune, willing take the head off twice, and have the time/money/energy to do this test...

Most, if not all, will just take other's words for it.

[BadAssPerformance]

Who's ported stocker? FM's flows worse than stock. And a TU header flows a lot better than a ported stocker as well.

Warren ported his own stocker, he tends to do all of his own work. I can relate.

I think you are refereing to Vendor A? Those tests were left anonymous for a reason.

Flow measurement in a header is not entirely accurate in determining what is better because it only measures one runner at a time and does not simulate exhaust pulses flowing together. It alaso does not simulate or take into account the 10-60psi of backpressure that the turbine can create.

Dyno or track testing is needed to show true results and benefits of a header.



That question will be asked over and over and it will never been answered, because of the below reasons.
...
Most, if not all, will just take other's words for it.

never say never... just needs to have someone with dyno access want to do it.

I rarely take anyone's word on anything without personal investigation.

[turbovanman²]

That question will be asked over and over and it will never been answered, because of the below reasons.

To do a back to back test, you have to have access two both header. Log header is hard enough to get, an equal length tube header will be almost impossible, unless you can make one.

Next, that person will have to be willing to take the head off twice two change the manifolds.

Then, the car will have to be tune twice to maximum the performance.

So, not only you have to have the resources to get both header, able to tune, have the resources to tune, willing take the head off twice, and have the time/money/energy to do this test...

Most, if not all, will just take other's words for it.


I was willing to do it when I had my 8 valve setup but no one wanted to help with the costs or supply a header. :(

I wasn't really going to tune, that way, I think its more of a true back to back test, as long as the boost is equal on both tests and some minor tweaking so the engine doesn't let go.

[BadAssPerformance]

You still got dyno access?

[tryingbe]

I wasn't really going to tune, that way, I think its more of a true back to back test, as long as the boost is equal on both tests and some minor tweaking so the engine doesn't let go.

What's the point if you don't do tuning?

Out of all people, YOU should know better. How many cal did you try with your 16v head?

[BadAssPerformance]

What's the point if you don't do tuning?

Out of all people, YOU should know better. How many cal did you try with your 16v head?

A direct stock motor bolt on with a stock cal would be a great back-to-back comparison. Try each, stock manifold, ported stocker, custom log, custom tube header.

I think your second sentance is why you would not want to change the cals, you want any performance gains to be due to the header swap, not the cal.

[tryingbe]

I completely disagree with you.

If I was doing the test, I want the true MAX performance gain from the header/manifold, not when they are limited by the calibration.

[Speedeuphoria]

Thats where Warren's info helps out, faster w/ the long tube header:thumb:

[turbovanman²]

You still got dyno access?

Where do you think I get my van dynoed, :thumb:

I have no 8 valve cars anymore that run. I have a 91 Shadow I should get running one day.


What's the point if you don't do tuning?

Out of all people, YOU should know better. How many cal did you try with your 16v head?

Your looking for a gain, I think tuning helps mask the gain. I am not saying you can adjust the timing or af at wot but going in and messing with it, I think defeats the purpose plus I don't have that kind of equipment or cal.


A direct stock motor bolt on with a stock cal would be a great back-to-back comparison. Try each, stock manifold, ported stocker, custom log, custom tube header.

I think your second sentance is why you would not want to change the cals, you want any performance gains to be due to the header swap, not the cal.

I agree.


I completely disagree with you.

If I was doing the test, I want the true MAX performance gain from the header/manifold, not when they are limited by the calibration.

See above. I mean if you put it on and gain or lose boost, you knows it done something etc.


Thats where Warren's info helps out, faster w/ the long tube header:thumb:


I agree but his header is pretty unique and of course, a one of unit as well.

[BadAssPerformance]

I completely disagree with you.

If I was doing the test, I want the true MAX performance gain from the header/manifold, not when they are limited by the calibration.

I do not think that you understand the definition of a basic back-to-back product comparisson. The goal of a back-to-back is to see how a specific component change affects a specific setup. The best way would be to do the B2B on each of three setups, stock, mild and wild, to see where the product adds the best benefit.

So if you are doing the test, for a MAX performance comparison, why stop at just changing the calibration for each item compared? Why not also match up the correct turbo, cam, head, intercooler, throttle body, spark plugs, etc for each item compared?

[zin]

I do not think that you understand the definition of a basic back-to-back product comparison. The goal of a back-to-back is to see how a specific component change affects a specific setup.

I think the point Tryingbe is trying to make, is that he would be interested in the max potential of this component when applied in appropriate circumstances. Doing a B2B test of a race cam in a stock head wouldn't reveal the true potential of that cam, just as testing a log vs header might not be representative of either piece's potential if not mated to the right combo of parts or tune for a given condition/application. That's one of the reasons these simulators exist, to test a given scenario and adjust it to the application.

I fully believe that a properly designed tubular header would kick a log's azz, but there are limits on space/expense that cause manufactures to compromise. Bottom line is a poorly matched/designed piece will have predictable results.

My .02

[turbovanman²]

I think the point Tryingbe is trying to make, is that he would be interested in the max potential of this component when applied in appropriate circumstances. Doing a B2B test of a race cam in a stock head wouldn't reveal the true potential of that cam, just as testing a log vs header might not be representative of either piece's potential if not mated to the right combo of parts or tune for a given condition/application. That's one of the reasons these simulators exist, to test a given scenario and adjust it to the application.

I fully believe that a properly designed tubular header would kick a log's azz, but there are limits on space/expense that cause manufactures to compromise. Bottom line is a poorly matched/designed piece will have predictable results.

My .02

That is also a good test but not really a true B2B test, if your changing tons of stuff. If you simply change the manifold and see a change, then you know its working better or worse, then you can tune for max potentional and go from there.

Thats usually the issue, we change tons of stuff but never just one thing.

[tryingbe]

The whole debate is pointless as nobody has what it takes to test the all three set ups right now.

I'll be sticking with my TBI header in my Omni and a ported unit in my Daytona.

[BadAssPerformance]

I have a stock manifold, several ported manifolds, an equal length tube header and access to a cast FM turb header, all I need is cheap dyno time.

http://www.badassperformance.com/mstore/bap_parts/header/header_01.jpg

[tryingbe]

Call Chris to get a group dyno going in your area.

[BadAssPerformance]

Probably easier/cheaper to call a local dyno shop myself.

[8valves]

For those that think that a true header "just isn't a big deal on our cars" is probably the same person who thinks that just because one person has gone XX.XX @ XXX mph that it is the best possible ever.

How long did it take for people to finally realize that a one piece ISN'T a good performance intake in stock form. How about throttle bodies? My car loved having a 58mm on it, and I'm sure it will enjoy the 70mm now.

Setups are so case dependent it's difficult to nail things down to one single part, even if it's only one part that changed. One car with a fantastic head might really show gains from a one off, different runner configuration, injector angle, and plenum style intake manifold. Someone who is just forcing 30+ lbs down it's throat may not see the same gains. Who's do you go off of then?

I am with the camp on a vehicle needs to be tuned accordingly for a change. Keep timing at a constant, and keep boost at a constant (because it WILL change), and modify the tables to keep AFR's at a constant between the two at a safe level.

You wouldn't put a cam in that is supposed to be at straight up and install another at straight up, but is supposed to be 3* advanced. To compare them like that would obviously be incorrect, but that is tuning of the cam timing.

[BadAssPerformance]

I am with the camp on a vehicle needs to be tuned accordingly for a change. Keep timing at a constant, and keep boost at a constant (because it WILL change), and modify the tables to keep AFR's at a constant between the two at a safe level.

You wouldn't put a cam in that is supposed to be at straight up and install another at straight up, but is supposed to be 3* advanced. To compare them like that would obviously be incorrect, but that is tuning of the cam timing.

So if one manifold vs. another with everything else being the same (including cal) frees up an extra 3 psi of boost, you would de-tune that to match teh first manifold?

Don't get me wrong, I agree 100% that each item needs to be accomodated for with proper tuning, my point is just that for a direct B2B for manifolds A to B should be just that, direct.

And cams are a different animal, that is like comparing one cal to another...

[turbovanman²]

So if one manifold vs. another with everything else being the same (including cal) frees up an extra 3 psi of boost, you would de-tune that to match teh first manifold?

Don't get me wrong, I agree 100% that each item needs to be accomodated for with proper tuning, my point is just that for a direct B2B for manifolds A to B should be just that, direct.

And cams are a different animal, that is like comparing one cal to another...

Exactly, :amen:

The same could be said for cylinder heads, if you install a ported unit and keep the other variables the same, you will notice a change, either good or bad.

[8valves]

So if one manifold vs. another with everything else being the same (including cal) frees up an extra 3 psi of boost, you would de-tune that to match teh first manifold?

Don't get me wrong, I agree 100% that each item needs to be accomodated for with proper tuning, my point is just that for a direct B2B for manifolds A to B should be just that, direct.


More than likely, a good manifold change will show a drop in boost from what we've seen.

Theoretical: No boost controller changes or cal changes.

Test A: log manifold, 300 whp/ 300 wtq at 20 psi.

Test B: tubular manny, 296 whp/289 wtq at 17 psi.

So the tubular is worse than the log right? See what I'm saying? That manifold likely achieved a 30+ whp gain, but it didn't show unless the boost was equalized.

Theoretical Part II: If the electronic controller controls boost the same...

Test A: Log manifold, 300whp/300wtq at 20 psi, 10.2:1 AFR

Test B: Tubular manny, 311whp/309 wtq at 20 psi, 11.0:1 AFR

Where did the gain come from? Is it because the part is better, or is it because it leaned it out? What would have happened if it was kept at a 10.2:1 AFR with the tubular? What if the log were at 11.0:1?

You're not directly measuring the gain of the part if the tune is different/subpar to begin with, or after the matter.

[BadAssPerformance]

Theoretical example A should have use a WB A/F gauge as well, and then it can be predicted if 3 psi would make a positive or negative difference in hp/tq. ;)

So, why will boost change? The delta P between the 2 manifolds should affect this, however, using an intake manifold pressure activated spring type wastegate actuator it should be fairly consistant, especially if using an external actuator, right?

[8valves]

Theoretical example A should have use a WB A/F gauge as well, and then it can be predicted if 3 psi would make a positive or negative difference in hp/tq. ;)

So, why will boost change? The delta P between the 2 manifolds should affect this, however, using an intake manifold pressure activated spring type wastegate actuator it should be fairly consistant, especially if using an external actuator, right?


You would think so, wouldn't you?

If you can visualize in your head, or even using the diagrams this all started from, the way I justify it is that less time the exhaust gas spends trying to be forced straight and through the turbine wheel, the less pressure buildup. Therefore, with the header giving a hopefully more stable and true path for the gasses to make it into the turbine volute uninterrupted they stack less, causing less backpressure, therefor lowering boost overall as it is taking more cfm to create a certain PSI in the intake, since th exhaust flows so much better.

That might be a bit confusing, but overall you're making the VE of the engine better, so more cfm will be required to achieve your desired boost level.

Sometimes I've found that MBC's are rather innacurate, especially with weather changes. A cold night MBC car sometimes will boost 2 psi higher with no changes. That's not good on some cars... ours might not care.

I often wonder if placement of the vacuum line to the MBC can affect accuracy as well. The size of the line being restricted, and if it were in the direct path of airflow, say at the end of a plenum, if it would read a higher pressure at the valve's seat compared to inside the plenum.

Random thoughts, sorry.

Back to topic, most cars we've tinkered with loose boost when we do a nice tubular manifold on them... but they usually pick up power at the same time :p

[BadAssPerformance]

Interesting example, and I'm sure your dyno experience tells the tale for sure. Got any specific examples on B2B turbo manifold tests to share? ;)

I agree that a vacuum MBC is very dependant on the atmosphere, but for a theoretical lab test we could assume constant barometer and a spring type actuator.

So, I need to talk thru this so I understand what you are saying...

I agree that a better flowing header will allow for less back pressure, but wouldn't the exhaust restriction (turbine) determine the exhaust manifold pressure. So if an exhaust manifold flowed better, the result would be higher CFM thru the turbine at the same pressure? Higher CFM thru the turbine would equal higher wheel speed resulting in higher compressor speed resulting in higher CFM on the intake side. Assuming the intake/induction system was not a restriction then the manifold pressure (that open the wastegate) would be reached sooner.

So on a dyno at a set RPM, the boost should be the same between manifolds if the boost control system and barometer are the same, but during a WOT dyno pull, the time to get to a set boost level affect peak boost reached?

And with all else being equal, if a better flowing manifold produces less boost, is it only due to the lower back pressure causing less spool yet higher CFM, or is it potentially due to a restriction on the induction side?

[8valves]

H-wow!

Let me make this simpler. If the exhaust gas trying to get INTO the turbine volute is already smooth and straight, it doesn't back up pressure trying to take time to get in line if you will. It won't delay so much to make it's way through the turbine wheel.

Your turbine wheel speed should be dictated by your wastegate, not your manifold. A huge firggen wastegate can sometimes offset a piece of junk manifold design. A huge wastegate with a really good manifold leaves you with all kinds of opportunities :)

If the turbine wheel/housing was the ultimate effect/element on possible cfm flow, then a big --- box with a turbo on the end of it should perform the same as a beautiful header does.

But it doesn't, does it? That's why I don't neccessarily agree with manifolds being evaluated on a basis of cfm. In reality, what are you showing me? Sure, it has it's merits, but it doesn't really tell you if one is better than another. Same with cylinder heads, really.

As far as backpressure being equal outside of WOT. I can't say for sure really. But I do know that a good change to a car will change it's fueling all across the band, not just at WOT.

[turbovanman²]

I said you could make minor tweaks, IE AF at WOT and equalize the boost, so if you had 20 before, you are allowed 20 after the part change. I think that will give you a true back to back test.

So example A-log header at 20 psi, 200/200, 11.1 af.
Example B-equal length at 20 psi, 230/220 11.1 af.
Example C-equal length at 20 psi, 190/180 11.1 af.

That way, your testing the manifold, not the tune.

[Speedeuphoria]

But I do know that a good change to a car will change it's fueling all across the band, not just at WOT.


Thats why I dont see a "true back to back" as a good option. It deff going to change the fueling requierments on the engine and possibly the boost pressure. If you dont have the same a/f on both tests(which would require some tuning) then what exactly are you proving

^Simon posting at teh same time w/ similar idea^

[8valves]

Please re-read post #32. I'm fairly certain that's exactly what I was saying.

[BadAssPerformance]

Let me make this simpler. If the exhaust gas trying to get INTO the turbine volute is already smooth and straight, it doesn't back up pressure trying to take time to get in line if you will. It won't delay so much to make it's way through the turbine wheel.

betetr flow and velocity should spin the turbine faster & sooner... more boost, but you say no? I think manifold volume comes into play in this correlation too.


Your turbine wheel speed should be dictated by your wastegate, not your manifold. A huge firggen wastegate can sometimes offset a piece of junk manifold design. A huge wastegate with a really good manifold leaves you with all kinds of opportunities :)

A external wastegate is a spring with a piston so (exhaust) manifold pressure v.s intake pressure signal should determine when it opens, so, the turbine wheel speed is a direct result of the manifold pressure and CFM... I think we are saying teh same thing but different.


If the turbine wheel/housing was the ultimate effect/element on possible cfm flow, then a big --- box with a turbo on the end of it should perform the same as a beautiful header does.

But it doesn't, does it? That's why I don't neccessarily agree with manifolds being evaluated on a basis of cfm. In reality, what are you showing me? Sure, it has it's merits, but it doesn't really tell you if one is better than another. Same with cylinder heads, really.

CFM is great to compare intakes and head ports, and I agree that it does not accurately represent header function and this is in part due to not being able to flow test cylinders firing in sequence at 7000 rpm ;)


As far as backpressure being equal outside of WOT. I can't say for sure really. But I do know that a good change to a car will change it's fueling all across the band, not just at WOT.

steady state = steady state so it should equal out, but who races at 1/2 throttle anyways!? LOL

[Speedeuphoria]

Please re-read post #32. I'm fairly certain that's exactly what I was saying.

I know, I was agreeing w/ you

[8valves]

I know, I was agreeing w/ you


Ah! My mistake. I was starting to think that people were skimming through the lengthy posts, in which, I don't blame you!

[Speedeuphoria]

From what I understand, and what Aaron was saying.

Basically boost is due to restriction. If the head is restriction you will need more psi to make a certain HP, same for the header, if it flows better(less backpressure and reversion) then you should flow more air at a given psi. Now how that relates to turbine speed, well cant quite explain that

[BadAssPerformance]

Thats why I dont see a "true back to back" as a good option. It deff going to change the fueling requierments on the engine and possibly the boost pressure. If you dont have the same a/f on both tests(which would require some tuning) then what exactly are you proving

^Simon posting at teh same time w/ similar idea^

I think it comes down to point of reference.

Is a manifold being purchased with the goal of being a stand alone 'bolt on' for a power gain like most enthusiats view mods? Or is it as part of a maximum output race motor for the hard core performance mongers that are able to tweak their own cals. This is why I suggested the stock, mild, wild comparisons. So best would be to monitor resulting boost and A/F for each setup and then adjust boost, A/F is needed... who's got a couple weeks of dyno time available? LOL

[zin]

I think it comes down to point of reference.

Is a manifold being purchased with the goal of being a stand alone 'bolt on' for a power gain like most enthusiast view mods? Or is it as part of a maximum output race motor

I think this cuts to the core of the debate. What makes a part better than another and what makes a good test of those parts is relative to it's intended use. Its not fair to compare a Clydesdale to a Quarter Horse!

[turbovanman²]

I think this cuts to the core of the debate. What makes a part better than another and what makes a good test of those parts is relative to it's intended use. Its not fair to compare a Clydesdale to a Quarter Horse!

No, but most of us are going for WOT gains, so a headers intended use is WOT, ;)

[moparzrule]

I think you are refereing to Vendor A? Those tests were left anonymous for a reason.


Not really I already knew my manifold flowed better than ''vendor A'' and didn't need steve's flowtest to show me that. I could have picked out who's vendor A was without even knowing. My own personal experiences with my car show me that as well, and if you ever look at one in person you would think WTF just like I did. One other thing I also already knew that it flowed less than a stocker based on a leaf blower test that a friend did for me.
If a vendor's manifold is worse than stock I think it deserves to be called out so people don't waste their money with it. I understand what yo uwere talking about flowtest VS real world but I have had one on my car and compared to mine I had 300 RPM slower spoolup and less power all around.

[BadAssPerformance]

Your ported stocker does flow well, and that is great. You sell it for a fair price too. :thumb:

We just try to eliminate all possible forms of vendor drama around here.

[moparzrule]

Understandable I guess, but I would still rather not see people getting ripped off.

[Pat]

You would think so, wouldn't you?

If you can visualize in your head, or even using the diagrams this all started from, the way I justify it is that less time the exhaust gas spends trying to be forced straight and through the turbine wheel, the less pressure buildup. Therefore, with the header giving a hopefully more stable and true path for the gasses to make it into the turbine volute uninterrupted they stack less, causing less backpressure, therefor lowering boost overall as it is taking more cfm to create a certain PSI in the intake, since th exhaust flows so much better.

Back to topic, most cars we've tinkered with loose boost when we do a nice tubular manifold on them... but they usually pick up power at the same time :p

The stacking in the restrictive manfold you are talking about would be happening before the gasses entered the turbine housing. I'd say that the build up of backpressure at the port entrance into the manifold would be higher, but the backpressure at the turbine wheel would be the same given an equal CFM flow through it (assuming equal boost level, rpm, etc).

If you're seeing a boost level drop when going to a tubular header, I'd argue that it's the reduction of heat at the turbine wheel. A restrictive manifold with poor flow characteristics would cause a build up of heat (or less dissapation of heat) from the exhaust port to turbine housing where a smooth flowing, less restrictive tubular set up would more than likely shed more heat as the gasses pass through the header and enter the turbine housing. Less heat, less energy, less cfm, less turbine wheel velocity, less boost (depending on compressor wheel). But, you also get less backpressure between the exhaust port and turbine wheel, better engine flow efficiency. Actual CFM may go down due to the reduction of heat (gas expands with heat), but more densely packed combustion exhaust so to speak. The mass of exhaust gas would be higher since you'd be making more power, but the volume of gas may be lower since it's not as hot (due to expansion).

Ever measure EGT at the port vs at the turbine when doing these swaps?

[8valves]

The stacking in the restrictive manfold you are talking about would be happening before the gasses entered the turbine housing. I'd say that the build up of backpressure at the port entrance into the manifold would be higher, but the backpressure at the turbine wheel would be the same given an equal CFM flow through it (assuming equal boost level, rpm, etc).

If you're seeing a boost level drop when going to a tubular header, I'd argue that it's the reduction of heat at the turbine wheel. A restrictive manifold with poor flow characteristics would cause a build up of heat (or less dissapation of heat) from the exhaust port to turbine housing where a smooth flowing, less restrictive tubular set up would more than likely shed more heat as the gasses pass through the header and enter the turbine housing. Less heat, less energy, less cfm, less turbine wheel velocity, less boost (depending on compressor wheel). But, you also get less backpressure between the exhaust port and turbine wheel, better engine flow efficiency. Actual CFM may go down due to the reduction of heat (gas expands with heat), but more densely packed combustion exhaust so to speak. The mass of exhaust gas would be higher since you'd be making more power, but the volume of gas may be lower since it's not as hot (due to expansion).

Ever measure EGT at the port vs at the turbine when doing these swaps?

About the backup in the manifold, precisely. It's the ability of the manifold/header/whatever to get the gasses into the turbine volute in a orderly manner if you will. You described it very well.

The heat thing is an interesting point! We have wondered about this to a certain extent, then come back to the fact that the cars usually spool better with a nice long tube setup on the car. If it's a divided tangential setup, even more so.

I've never done the multi-point EGT measuring. That would be neat to take a look at some time.

Most of the headers we do are either coated or wrapped, sometimes both. Not to mention they are very thick stainless; so we do what we can to minimize the loss of heat.

[Pat]

About the backup in the manifold, precisely. It's the ability of the manifold/header/whatever to get the gasses into the turbine volute in a orderly manner if you will. You described it very well.

The heat thing is an interesting point! We have wondered about this to a certain extent, then come back to the fact that the cars usually spool better with a nice long tube setup on the car. If it's a divided tangential setup, even more so.

I've never done the multi-point EGT measuring. That would be neat to take a look at some time.

Most of the headers we do are either coated or wrapped, sometimes both. Not to mention they are very thick stainless; so we do what we can to minimize the loss of heat.

Coating and wrapping certainly would help to keep the heat in, but if you have a smooth, orderly flowing header, you reduce backpressure build up due to friction within the manifold/header itself, which equals less heat production.

Port to turbine EGT's would definitely be an interesting test. Your car is apart now, isn't it? ;)

[8valves]

Port to turbine EGT's would definitely be an interesting test. Your car is apart now, isn't it? ;)


It surely is. Sadly enough, the header needs to be sent to be coated now, and I don't have any EGT bungs off hand. It's not that big of a deal, I can add them at some later point in all honesty.

You'll actually see the rolling chassis I was going to use up for sale in the next 30 minutes or so. I need money to move to FLA for my new job, and a car will have to wait.