James Rear Mount Equal Length Tubular Headers - Test fitted to car

Re: Tubular Headers to keep turbo in stock location

WOW, there is so much wrong with this post. It is obvious that you arent very experienced in testing and designing turbo systems. I have helped design and build quite a few, and ill give you a bit of advice and info from what i have found over the years.

A good book to find and read is Watson and Janota's "Turbocharging the Internal Combustion Engine". It is a foundational volume. I'm sure that there are others.

There are two Basic Approaches to Turbocharging

What you describe with log manifolds or manifolds with short, stubby runners are prime examples of the traditional Approach to boosting: Brute Force Turbocharging.

With Brute Force, the exhaust gases are forced into restrictive and constrictive exhaust manifolds. And from there, those compressed gases are forced to pass through small turbine housings.

The rationale behind Brute Force is: in order the make the turbine spin, the exhaust gases HAVE to be compressed and forced through. Those exhaust gases need to be as hot as possible also. And the turbocharger turbine housing needs to be small enough so as to force the turbine wheel to spin up faster. [that's the only way to reduce lag, don't cha know!]

Well, that Approach does work. It has been working for years. It is the Approach used on nearly all OEM boosted motor cars for decades.

Brute Force has its drawbacks: greatly elevated operating temps for things like exhaust valves; tremendously increased exhaust reversion back up past the intake valve during overlap; and substantially increased levels of negative work that the pistons have to deal with.

To address those drawbacks, a 'new' Approach to Turbocharging has been showing up. First, in competition motors. Now, a lot more on the street.

Low EBR Turbocharging

With Low EBR Boosting, the exhaust gases are NOT constrained and constricted in tiny little manifolds. Headers are used to let the gases FLOW. Turbine housings are not tiny little snail shells either.

With Brute Force boosting, the EBR....Exhaust Backpressure Ratio…the ratio of exhaust pressure to the intake boost pressure....can exceed 3:1.
[i.e., for 10 lbs of boost on the boost gauge, there is possibly 30 PSI (or more) of exhaust pressure resisting that boost pressure.]

With Low EBR Boosting, the exhaust backpressure may remain less than the boost pressure reading.

[there are some guys in Sweden (the savarturbo boys) running EBRs less than 1:1 on motors that are running over 30 PSI of boost, ON THE STREET. And the output is in the neighborhood of 6 hp per cubic inch of displacement.]

The rationale of Low EBR Boosting is: the energy to drive the turbine comes from the velocity of the exhaust gases. Let the exhaust flow its best. Gather and direct those gases into a turbo that can take the velocity and use it to spin the turbine wheel. Keep the exhaust flow flowing well, so that the motor itself does not have to fight the exhaust gases during the exhaust stroke, or during overlap.

Or, to put it another way: Low EBR Turbocharging is an Approach that uses free exhaust gases to achieve, or exceed, the power output levels of motors with mechanically driven superchargers, but without the parasitic drag of the mechanically driven huffer.

In my own experience, every time I have done something that lowers the EBR, the power output has gone up without raising the boost level.

Heat loss is not the problem often suggested. Watson and Janota cited studies of marine applications trying to determine how much energy was being lost due to the use of watercooled manifolding and watercooled turbine housings. The results showed a less than 5% loss of energy to drive the turbine. An amount of energy that could more than be made up for by better flowing manifold designs.

The other thing, is that the flow in the exhaust manifold is highly unsteady. When the exhaust valve opens, it sends a spike of pressure into the manifold and the turbine bleeds it off. From the engine's point of view, the only thing it cares about is the pressure downstream of that particular exhaust valve at the moment of valve overlap, and at that instant in time, it could either be less than the "average" exhaust manifold pressure (because of constant bleed-down through the turbine) or more (because an adjacent cylinder just opened ITS exhaust valve).

And that brings another point … Picture a 4-banger engine with the usual log exhaust manifold before the turbo. During the moment of valve overlap … the exhaust valve on the next cylinder has already opened (before "that" cylinder's bottom-dead-centre and "this" cylinder's top-dead-centre) and it's in the process of blowing-down, sending exhaust manifold pressure skyward at the worst possible time.

The benefit of a tubular exhaust manifold might not be so much for resonance tuning, but rather to delay the effects of that pulse just long enough so that the cylinder which is just finishing its exhaust stroke, doesn't see it.




SO, if you feel you can defend your comments with proof and experience, go ahead. I'm pretty sure more z31's would make over 300whp if it weren't for godsend people like you giving out innacurate and unfounded information

Re: Tubular Headers to keep turbo in stock location

Great and educational comment Grr, thankyou. I was hoping someone who actually knew what they were talking about would come along and set the record straight, illinformed negative comment on stuff people are building and taking the time to post up pisses me right off.

Re: Tubular Headers to keep turbo in stock location

[quote]CAG8OR wrote: I'm in right hand drive territory, PM me if you want to sell and ship that setup without the turbo, although going by the pics that turbo flange is skewed so it may not take a GT35. Which I think has a T3 flange.

Re: Tubular Headers to keep turbo in stock location

looks like that setup uses a buick style housing, you can get one of those new or a used one machined for your gt35 for very cheap, or just have a t3 flange welded on it for $30 or so

Re: Tubular Headers to keep turbo in stock location

Yes I am RHD

I would have loved to purchase the Greddy Det Manifolds if i knew they existed in a box somewhere.
CAGOR thanks for your offer > this is the kind of attitude Z31P should be known for

Certainly my half finished example will be finished one day amongst the many things I am trying to do all at once

Re: Tubular Headers to keep turbo in stock location

I am going to go up in the attic tomorrow and find the headers. I will take some new and improved pictures and post them here.

Re: Tubular Headers to keep turbo in stock location

Get an exhaust place to copy, ill buy a set …

Re: Tubular Headers to keep turbo in stock location

[quote]Grr wrote:

Originally posted by NissanXRMA

Wow there is so much wrong with this post.


They will have massive lag because of heatloss and because of the other longer pipes. The rear mount turbo like sts will lag a lot. This is because long pipe from the engine to the turbo, the long intercooler pipe, and the longass pipe all the way to the intake/TB. If you put a Stock T3 way back by the tailpipe with IC pipes to the front with all thelong intake pipes, or put it in the stock location, what will spool faster. The STS will take way longer.

Hitting a wall with a little hammer really fast resembles a little turbo spooling very fast with no lag
Hitting a wall with a large hammer very hard but slow resembles a large turbo that spools much later and slower.

The exhaust gases will not flow faster once there cool down. When there is an increase in heat, there is an increase in pressure. When the exhaust gases cool down, they will not exert more force on the turbine.

WOW, there is so much wrong with this post. It is obvious that you arent very experienced in testing and designing turbo systems. I have helped design and build quite a few, and ill give you a bit of advice and info from what i have found over the years.

A good book to find and read is Watson and Janota's "Turbocharging the Internal Combustion Engine". It is a foundational volume. I'm sure that there are others.

There are two Basic Approaches to Turbocharging

What you describe with log manifolds or manifolds with short, stubby runners are prime examples of the traditional Approach to boosting: Brute Force Turbocharging.

With Brute Force, the exhaust gases are forced into restrictive and constrictive exhaust manifolds. And from there, those compressed gases are forced to pass through small turbine housings.

The rationale behind Brute Force is: in order the make the turbine spin, the exhaust gases HAVE to be compressed and forced through. Those exhaust gases need to be as hot as possible also. And the turbocharger turbine housing needs to be small enough so as to force the turbine wheel to spin up faster. [that's the only way to reduce lag, don't cha know!]

Well, that Approach does work. It has been working for years. It is the Approach used on nearly all OEM boosted motor cars for decades.

Brute Force has its drawbacks: greatly elevated operating temps for things like exhaust valves; tremendously increased exhaust reversion back up past the intake valve during overlap; and substantially increased levels of negative work that the pistons have to deal with.

To address those drawbacks, a 'new' Approach to Turbocharging has been showing up. First, in competition motors. Now, a lot more on the street.

Low EBR Turbocharging

With Low EBR Boosting, the exhaust gases are NOT constrained and constricted in tiny little manifolds. Headers are used to let the gases FLOW. Turbine housings are not tiny little snail shells either.

With Brute Force boosting, the EBR....Exhaust Backpressure Ratio…the ratio of exhaust pressure to the intake boost pressure....can exceed 3:1.
[i.e., for 10 lbs of boost on the boost gauge, there is possibly 30 PSI (or more) of exhaust pressure resisting that boost pressure.]

With Low EBR Boosting, the exhaust backpressure may remain less than the boost pressure reading.

[there are some guys in Sweden (the savarturbo boys) running EBRs less than 1:1 on motors that are running over 30 PSI of boost, ON THE STREET. And the output is in the neighborhood of 6 hp per cubic inch of displacement.]

The rationale of Low EBR Boosting is: the energy to drive the turbine comes from the velocity of the exhaust gases. Let the exhaust flow its best. Gather and direct those gases into a turbo that can take the velocity and use it to spin the turbine wheel. Keep the exhaust flow flowing well, so that the motor itself does not have to fight the exhaust gases during the exhaust stroke, or during overlap.

Or, to put it another way: Low EBR Turbocharging is an Approach that uses free exhaust gases to achieve, or exceed, the power output levels of motors with mechanically driven superchargers, but without the parasitic drag of the mechanically driven huffer.

In my own experience, every time I have done something that lowers the EBR, the power output has gone up without raising the boost level.

Heat loss is not the problem often suggested. Watson and Janota cited studies of marine applications trying to determine how much energy was being lost due to the use of watercooled manifolding and watercooled turbine housings. The results showed a less than 5% loss of energy to drive the turbine. An amount of energy that could more than be made up for by better flowing manifold designs.

The other thing, is that the flow in the exhaust manifold is highly unsteady. When the exhaust valve opens, it sends a spike of pressure into the manifold and the turbine bleeds it off. From the engine's point of view, the only thing it cares about is the pressure downstream of that particular exhaust valve at the moment of valve overlap, and at that instant in time, it could either be less than the "average" exhaust manifold pressure (because of constant bleed-down through the turbine) or more (because an adjacent cylinder just opened ITS exhaust valve).

And that brings another point … Picture a 4-banger engine with the usual log exhaust manifold before the turbo. During the moment of valve overlap … the exhaust valve on the next cylinder has already opened (before "that" cylinder's bottom-dead-centre and "this" cylinder's top-dead-centre) and it's in the process of blowing-down, sending exhaust manifold pressure skyward at the worst possible time.

The benefit of a tubular exhaust manifold might not be so much for resonance tuning, but rather to delay the effects of that pulse just long enough so that the cylinder which is just finishing its exhaust stroke, doesn't see it.




SO, if you feel you can defend your comments with proof and experience, go ahead. I'm pretty sure more z31's would make over 300whp if it weren't for godsend people like you giving out innacurate and unfounded information

thank youfor a little more technical explination of what i was trying to get across some people here are deathly affraid to think outside the box its rediculous just because the idea isnt decades old dosent mean that it will not work. im a member of several titan boards and there are a few guys running turbos on their trucks and they are all remote mounted and this is not because none of them had the fab skillsor money to build turbo manifolds it is because it is proven to work not clutter the engine bay and add all the extra heat to the engine compartment. one guy in perticular is one of the 2 guys that have made the corvette 90mm tb speak jap to work on the titan when big companies like stillen,bbk,and a few tuner shops cant figure out how to adjust the electronics or wire it so the technical knowledge is there as well as the lack of fear of thinking outside the box. its things like that that get aftermarket parts made for a nameplate there was no interest to make parts for this truck until one guy made headers and now there are 5 or 6 companies that make them there was no interest in doing a TB upgrade either untill 2 guys developed one and the aftermarket saw there was a demand and a decent power to be had now there are 3 companies trying to figure out what they did. point is people like nissanxrma that think if it hasnt been done a million times before it wont work is the reason our cars were completely ignored by the aftermarket face it if a vehicle that has been in exhistance for less than 6 yrs has more aftermarket support than one of nissans icon cars its because of no one showing an interest in trying something different so why would any company spend money developing parts when there is no interest

Re: Tubular Headers to keep turbo in stock location

Sorry for the delay guys, took me a while to find the right box. The process to post pictures here is a PITA, does anyone have storage space that I an upload all of the pics too? Here are a few:

Re: Tubular Headers to keep turbo in stock location

Couple more:

Re: Tubular Headers to keep turbo in stock location

now put them on an engine where they belong :nanan?re

Re: Tubular Headers to keep turbo in stock location

Look pretty good, wonder if they will fit in my engine bay, hmmmm. How much? If you send them overseas by mail they may have to go in two separate boxes, hard to tell, you may want to check with your post office about weight and size restrictions.

Re: Tubular Headers to keep turbo in stock location

Those are for RHD cars, yes? I believe there is an issue with steering column interference on the USDM cars.

Re: Tubular Headers to keep turbo in stock location

I am glad you can read. :nanan?re

Re: Tubular Headers to keep turbo in stock location

I stopped reading this thread because there was to much whining and pissing about using tubular headers with turbos, and the stock location and blah blah blah.

Im just waiting for pic updates so I can compliment him on the work he's doing.