MIAPLAYA

iTrader: (3)

While I agree that the TT is more efficient I prefer the power band of the single turbo setup to the TT. Several others here do as well. That is what makes this a viable option. Its a very good alternative to those who like the Centrifig SC style powerband but do not want the headache of pulleys,belts, and parasitic loss.

Sharif@Forged

iTrader: (92)

Exactly...and if they can launch this thing at a $4000 street price, there would be no reason to opt for the SC, other than smog issues...since cat removal is required...at this point at least.

MIAPLAYA

iTrader: (3)

Yup and Turbonetics is saying MSRP is going to be around 5k which is the same as Vortech. So street price should be the same.

APS

If we're talking about the stock Nissan manifolds or manifold being retained in the turbo system then that's exactly what I'm saying...............the stock manifold simply will not cope with the extreme exhaust gas temperature for any decent amount of time.

Think about it for a moment........... the stock manifolds were designed for N/A exhaust gas temperature which operate at approx 1400 F not 1800 to 2000 F which is common in turbocharged engine operation.

It's obvious that the manifolds are going to fail/crack it's just basic engineering.

I can tell you from my own practical experience (nearly 30 years) that with turbocharging the most difficult aspect in terms of component durability is the exhaust manifolds and transfer pipes that connect to the turbocharger..................if the design is poorly engineered or if incorrect material is utilised in the contruction of the exhaust components you're going to have major problems, it's not a matter of if.......... it's just a matter of when the problem will occur.

There's absolutely nothing wrong with the single turbo approach and Turbonectics are great people..................I'm just pointing out a very real engineering problem that will need to be faced by Z owners in the near future................it's always best to be fully informed so when the problem occurs the forum guys will know how to rectify the problem.

Peter

APS

MIAPLAYA

iTrader: (3)

I thought the most of those failures were due to the proximity of the turbo to the manifold and the fact that that there is the additional weight of the turbo on the manifold. The Turbonetics kit is nowhere near the manifold itself....Furthermore there are countless cars with a supercharger installed on stock or "N/A" manifolds that have not had this problem. Many are boosting well into 9 PSI (more than turbonetics or APS) and have not had any manifold cracking problems. So I guess I'm wondering why the Turbonetics kit boosting 7.5 PSI is going to crack the stock manifold when its placement is the same as all the centrifig SCs. Also the Turbonetics kit is not boosting fully until around 4k (similar to centrifig SCs) However the Roots blown (Stillen) Zs are boosting up to 8 PSI within 3k and holding close to that to redline.

APS

Most if not all exhaust manifolding failures are caused by extreme exhaust gas temperature and constant temperature cycling of the exhaust manifolds (expansion and contraction of the manifolds is what causes cracks and manifold failure) the frequent expansion and contraction of the exhaust manifold is the ultimate cause of premature failure...................this is the reason why the correct material specification is so important in turbo exhaust manifolding.

The stock Nissan exhaust manifold was never designed to cope with this extreme range of temperatures or heat cycling

Exhaust manifold failure has little to do with how the turbo is mounted or not mounted and where the turbo is positioned within the engine bay.

It's all to do with daily temperture cycling of the exhaust manifolds, EG hot..... cold.........hot.......cold......hot......cold....... this continual expansion and contraction is the enemy of long term exhaust manifold life

Peter

APS

MIAPLAYA

iTrader: (3)

So what about supercharged cars...Doesn't the supercharger have the same effect on the EGT. Hot...cold...etc Why is it different for a SC?

APS

The turbo exhaust manifolds are subject to much higher thermal loads due to increased exhaust back pressure between the exhaust ports and turbocharger.

Peter

APS

MIAPLAYA

iTrader: (3)

In a conventional turbo manifold setup I could see that but in this case where there is a good amount of piping in between the exhaust port and the turbine blades wouldn't the additional piping provide a buffer to this. At least in the thermal load department. Wouldn't the additional piping dissipate some of that heat as the increase in backpressure is more focused at the merge area and exhuast housing input tube? Furthermore the increase in surface area of the piping should also spread the thermal load over a greater surface area thus allowing the manifold/piping as a whole to have a lower ambient temperature under high thermal load right?

APS

As I said previously the heat cycling is what causes the damage to exhaust manifolds..................a stock N/A manifold designed for lower exhaust gas temperature will NOT live in a turbo application......................if it would, ni resist castings and inconel turbine wheels would not be required in turbo systems.

If you want to believe ( I used to believe this also many years ago) that the stock N/A manifolds are going to live in Turbo system applications that's fine with me..............you'll just find out the expensive way and then have to have custom inconel or 321 stainles steel exhaust manifolds fabricated when the stock manifold fail.

Ideally cast ni Resist manifolding would be the ideal solution as this alows for the optimum manifold design and profile to be utilised whilst delivering long term manifold durability.


Peter
APS

MIAPLAYA

iTrader: (3)

I'm not saying I dont beleive what you are saying. I just find it hard to believe that as knowledgable as you and I both know Turbonetics is that they would not have already known this or had a solution for it. I'm sure they thought through all of this when they designed their kit. I'm sure Brad could chime in here with some info on that...

APS

I think the answer is very obvious and this is no disrespect to turbonectics..................the decision to utilise the stock manifold in any turbo system is based purely on cost and I understand this decision only too well as it's very expensive to design and produce exhaust manifold tooling to cast turbo manifolds.

It's an indisputable engineering fact that turbo exhaust manifolds need to be cast in the correct grade of ductile iron (ni resist material or better) and that fabricated turbo manifolds need to be produced in either 321 stainless steel or some high grade of inconel for turbocharger exhaust manifolds.

Hope this information helps you to better understand turbo exhaust manifolds and what's required for long term manifold component durability.

Thanks

Peter

MIAPLAYA

iTrader: (3)

It does and I will pass along my questions to Brad as well to see what their perspective is as well on this...As I'm sure you know Turbonetics has a very large R&D budget and is fully capable of designing a manifold in the manner that you described. I don't think the cost of design was a reason they chose not to go with new exhaust manifolds. I'm sure the have a very good reason though and I think that Brad could much better explain it then I.

APS

There is no other practical or logical explanation other than production and tooling cost savings.................I'm sure that Brad well knows that ni Resist iron is required for this turbo manifold application as they would cast many turbine housings in the same or similar material.

Speak to Brad via pm I'm sure he will agree with me that turbo manifolds and turbine housings for gasoline applications require ni Resist castings or even a higher material specification.

Thanks

Peter

APS

sorry double post...........damn computer.

Peter

little_rod

Interesting, love to get turbonetics to chime in on this trend, although since it is not a turbonetics trend, don't know if they would even see it.

With my engineering degree in my hand, I would still like to understand how the exhaust temperatures are different from an SC to a turbo (a turbo setup like this on where the turbo is not on the manifold). With exhaust flowing through the system of a turbo, it can increase it some, but the main thing that is unclear is with the turbo in the same location as an SC, with both compressing air, is the turbo that much hotter on the exhaust side than the SC to cause this problem with the manifolds?? Also makes you think twice bout turboing if it is so.......as there seems to be no such problems with the manifolds in SC applications and all the extra heat does for an N/A stock engine is wear the engine even more.

Hopefully Brad will chime in, cause it is a pretty big issue if the stock manifolds will breakdown, and there is no replacement that can adequately handle the heat. The difference in what materials can handle is easily understood by me, and cost would be the only reason for a shortcut.

You have to respect Peter for being straight forward and pointing this subject out, cause he didn't have to and it could get sticky. You see any other issues?? Would love to hear from people like Crawford to see what temperatures their headers can take, cause they are being used with SCs already.

g356gear

iTrader: (12)

I wonder how ceramic coating will impact this issue. Should extend the life of the exhaust and provide some more protection.....you would think.

mudger

So APS. Are there any manifolds that we can go out and buy, that are resistant to cracking?

keeptrying

iTrader: (5)

I would also like to hear from Brad. Peter has made some good point, but so has Miaplaya.

APS

Thanks and all I was wanted to achieve was to help out forum members with information which has been learnt the hard way by myself over many years of turbocharging.

There's nothing more frustrating than running into a manifold and turbo connection pipe failure (constant cracking and warping of manifolds/constant exhaust leaks) and not knowing how to solve the problem..............this drives the owner insane..............I know this from years of personal experience.

There is no subsitute for high quality ni Resist manifolding on turbocharged engines.

If you take short cuts with turbo manifolds you will end up paying for it big time................eventually you will either give up on the turbo system or spend a small fortune on custom built inconel or 321 stainless steel manifolds.

I just hate to see turbocharging get a bad name through an unfortunate experience............when it comes to turbocharging this is one area that you need to thoroughly investigate before parting with your hard earned money.

Thanks

Peter