Twin scroll vs twin turbo

Nixlimited

Mike@GTM - speaking of twin turbo setups, when are we going to see pricing on the 16/18/20G kits?

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theaudir8fan

Mike@GTM, most of what you say make sense, but i can't help to pose a few questions.
1, on calculation what you say makes sense, but under heat either iron or aluminum is extremely hot, so with the piping being so hot already the exhaust flow should have a minimal reduction in velocity considering the temperature of surrounding pipe is under extreme heat. Also wouldn't this issue be easily addressed by thermal coating and heat warping the said pipe which would prevent the loss of heat.
2, the exhaust pulses that you mention is true, but since the headers aren't equal length, as in the case with your twin turbo kit, wouldn't the pulse from cyl 1 interfere with pulse from cyl 3 as the pulse from cyl 1 travels down the manifold towards the turbo inlet while the pulse from cyl 3 is trying to exist the exhaust valve from the heads into the manifold itself. This logic would also apply to cyl 5 and right bank. So from the turbo point of view, the propeller would recieve one large pulse from the combination of pulses from cyl 1,3,5 and have a long pause until the next big pulse is generated.
Please note that I'm not trying to start a forum war, just trying to learn something, your reply would be greatly appreciated

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Neo187H

+1

Quite curious myself.

SS_Firehawk

Alright, so while at work today I was playing with Visio and had been consuming copious amounts of caffeine. I was in a day dream about my car and turbo's again so I started brainstorming. Unfortunately its difficult to really figure out what will and won't work without having the car in front of me (remember I'm in Afghanistan currently). I didn't want to start another thread as this one will suit just fine. So let me get my flame suit on and tell you my idea and options.

From this thread, you can see I like both twin scrolls and twin turbo's. I also like my headers but every turbo option with the exception with STS requires them to be removed. I understand temps over 1400, mild steel starts to degrade, I'm not looking for an argument on that. Anyways, I thought up of two different ways to get this done, but I can't see how much room I have to work with or if it's even a good spot to put a turbo... or two. I was thinking of putting it a turbo in the drive shaft tunnel. The jpg image I have attached will give you an idea of what I'm thinking. I know I'm missing oil lines and the routing of the pipe to the FMIC, I'm just wondering what you all think.

I would like it to fit between the cross member and the mid pipe. I chose that spot because it's after the header, before the mid pipe, and had what looked like enough room in the drive shaft tunnel. I didn't have any dimension and only had pictures to go by which none did a good job (work proxy disallows vehicle sites). I also couldn't see any additional mounting points either. I don't know what effect unequal pipe length would have and am no expert. I understand that wastegates and recirc piping does better farther away from the turbo, these are just rough guesstimates.

The twin turbo setup would provide better clearance if they can fit side by side. Maybe they can be staggered, idk. They are also more compact so I think they would be easier to fit in front of the mid pipe. The recirc pipes and would continue after the pipe bends towards the turbo, and the wastegate would be at the Y. They would merge after the the twins merge. I don't know if this is an effective way to do it, or if they should merge farther away or staggered. This could also be easily adapted with an X pipe, H pipe, or dual exhaust setup.

The twin scroll is another I drafted up. I decided with the twin scroll because the exhaust piping on each side would merge unequally and would not be able to rely on the long tubes to keep the pulses separate and free from collision. The driver side is a straight shot with a bend while the passenger side has to cross over. The recirc pipes and wastegates would be similar to the twin setup. I don't know if this would maintain clearance, but it may be shorter overall because there is only one pipe coming out of the turbo. This might also work with an X or H pipe config, but not to sure because I don't know how much room there would be left to split the exhaust.

Lastly, I know a lot of you guys are asking... WHY??!!?!?!!
1. Well for one, I'm bored and had time to kill.
2. The shop where my work is done specializes in turbo's; They're willing to design it, build it and install it for under 10k.
3. I'm interested in if you guys seen this done on something else.
4. I'm cold and could use some heat.
5. I enjoy Troll stew.

I'm still looking at what the healthy forced induction market for the Z has available. BP's kit is awesome, GTM's kits are pure bada$$ery, there is Greddy, STS, F.I. (soon), and S&R. I WILL have a turbo next year, so why not research while I wait

Attached Images

TT&TS.jpg (79.5 KB, 54 views)

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SS_Firehawk

Finally able to look at some my underbody pics I had saved on my PC..

I still don't know if either would fit...
I'm definitively no Engineer, mechanic or expert.

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Boosted Performance

Single turbo won't fit, I can tell you that right now. Twins...maybe, and they would have to be the smaller GT28's.

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SS_Firehawk

I'm assuming not enough clearance? Thanks for the reply, at least there is some feasibility to it and I don't look entirely retarded. I miss my car...

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Boosted Performance

Correct, there just is no room on the HR and VHR cars. The 03-06 350z's do have a lot of room back there, in fact I took advantage of it a long time ago:






The 350z's however had a large opening on the passenger side for some reason. You can see it in this picture. There is a decent amount of room, and I am able to fit a 76mm (1000hp+) turbo under there without too much trouble.

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SS_Firehawk

Thanks for sharing the pics, ill go back to being bored now. The Marines now blocked yahoo, Bing Ange Google cached pages, vehicle sites, entertainment, finance, living, weapons, shopping, newsgroups and forums, chat, social media, streaming media... This list goes on... FML. This torture only has one remedy. A combination of alcohol, sex, and forced induction for my Z.

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Cell

Holy shiet... the military deprive you guys of all that?

gbrettin

SS_Firehawk - I think it's awesome you are striving to be a well-informed buyer and also the sellers are stepping up to assist.

It's great information for potential purchasers of F.I.

I certainly appreciate it anyways.

SS_Firehawk

Thanks for the comment. I just want to make sure I find the most effective way to go forward. GTM will always be tried and true as there is more than enough data to show they have a damn good thing going on regardless if it's TT's of SC. BP also has a great alternative that turned out better than I think anyone anticipated for a very competitive price. Then my shop believes they can build FI around my headers, but they said they really need to look under the vehicle to see how much room they are working with. every option sounds great to me. The cheapest, easiest install and most complete would most likely be BP's, the one and only downside is the cost to get the headers removed and stockers reinstalled. GTM's will hit low and hard, the price is fine for me, but the install cost would hit harder than those turbo's. Lastly is the shop option which I have no idea what it would be, only that it would run $7-$10,000. I would have to buy all the parts, they design and fabricate the piping and of course tune. It is by far the riskiest, it's unproven, it can be disastrous, and at worst, I would be buying a new motor. The up shot is they would design it with the headers which can be a performance booster and big cost savings. I can also make decisions based on budget and performance on the fly as it's being built. By next year, I'll know what I'll be doing and will order one of these options. It will be installed while I'm away. That would most likely be the start of a build thread.

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fuct

whos to say you wont blow the motor with GTM and BP? sheit happens

SS_Firehawk

Yes, but with something that's already been tested and documented, it reduces the risk.

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Dustin@Z1

I'll toss my 2 cents in and try to help out if I can.

In response to question #1: Thermal coating and wrappings are beneficial in keeping the heat where you want it. The problem is that tubing cannot hold the heat in as well as a cast manifold. Simple thermodynamics will prove that the pipe, given the material and wall thickness, will cool much more rapidly and will radiate heat at a greater rate than a cast pipe. The cast manifold has a greater density and can both insulate and maintain the temperature in a much more stable way. Cast manifolds can also handle the stresses imposed by heat cycling far greater than SS piping which can grow/stretch at different rates depending on pipe and weld quality. As long as the casting is done properly, the rate of growth and expansion can be predicted. Another point I would like to make is that thermal coatings are expensive by them self and heat wrappings are notorious for contributing to a higher rate of rust/corrosion.

Cost is also a HUGE, unmentioned (as far as I could tell) part of this equation. Building a proper set of manifolds whether tubular or cast is expensive from a production point of view. Creating a proper cast manifold like what GTM or Greddy uses is far more cost effective when pricing a kit out, not to mention reproducible time after time. Everyone has to make money and I am sure GTM and Greddy did their cost analysis to realize that doing a true tubular manifold would have probably priced their kits outside of an acceptable price point.

Even with jigs, fixtures, pre-bent sections and so on. Tubular manifolds are expensive to create and require a skilled welder/fabricator hours and hours of time welding. For sake of argument, even if a machine was employed to weld the hundreds of welds, the cost of the machine itself would have to be absorbed into the production costs of the manifolds themselves.

In response to question #2: There is way more science here than I can explain. The pulsing is not as severe as you make it sound. There is also something to be said about how the ports are designed in the manifolds and how each cylinder's exhaust gases are introduced into the exhaust stream. Smoother transitions and alignment will lessen the pulsing that you are referring to even in a log type manifold. Something else to keep in mind is that being equal length by itself IS NOT ENOUGH and the end of the equation in an equal length manifold design inorder to have proper scavenging. Other critical parts of this includes: pipe diameter and the way the collector is designed. A great "appearing" set of manifolds with an improperly designed collector or pipe diameter that is too large will null any gains made due to the fact that the exhaust stream will stall out and will not merge together efficiently.