Making twin turbo 240Z - need advice

[280~Master]

EDIT ~~ OK Will, I reread it and get what your saying now.

interesting concept on using the different turbos, is the Z33 ('90-'98) the same?

It is the Z32 and it was made from ('90-'96)

[WingZr0]

It is the Z32 and it was made from ('90-'96)

Thyanks for the correction but it is '90-'98.

There was 2 extra model years in Japan, it was discountinued here in the

U.S. in '96 but survived in Japan untill 1998, just ask Gran Turismo 2 :laugh: !

My fovorite car in that game was a '98 Sonic Silver Metallic Twin Turbo

300ZX Z32 T-top,

outside of the '91 Gun Grey Metallic Skyline Gts-t Type M R32 rear wheel

drive.

~Z~

[sblake01]

For the purpose of this thread (whatever that is) 90-96 would be more accurate.

[WingZr0]

For the purpose of this thread (whatever that is) 90-96 would be more accurate.

Whaat ? Are you sure Blake, I'm pretty positve theres was '97 '98 300ZX.

Heres one of them

http://specs.amayama.com/specs-nissan-fairlady-z-1998-october/23670/

with stats here on the car above

http://english.auto.vl.ru/catalog/nissan/fairlady_z/1998_10/23671/

Scroll down here and see the GT2 car list with four '98 300zx's listed.

The list is from IGN the most respected video game cheat code

and faq website, theres two sections with 300ZX's so keep scrolling down till

you see 'em in the 2nd batch of ZX's .

http://psx.ign.com/articles/073/073087p1.html

And heres other references still

http://www.nissanforum.com/models/300zx/

http://en.wikipedia.org/wiki/Fairlady_Z#The_Fourth_Generation_.28Z32.29:_300ZX_.281990.E2.80.931999.29

I tried to find more precise info but thats all I could get without going on the

Japaness net.

~Z~

[sblake01]

I wasn't doubting their existence, quite the contrary. My point was, no one in this thread so far is from Japan so models not sold here aren't of much consequence.

[red_dog007]

Actually I do believe that you are all wrong. With a little searching I have found that the production ran from 1990 to 2000, not 1998.

Though just for the sake of the forums, we should use only the US run dates to save on confusion which would be 90-96.

[Six_Shooter]

Wow, lots of misinformation and skewed thoughts on twin turbo systems.

For starters some lingo:

"Twin turbo", is exactly that, two IDENTICAL turbos, so you can't have a "Sequential twin turbo", that if anything would be a dual turbo, or better yet simply called a Sequential turbo system.

Some technical:

With a twin turbo set-up both turbo produce the EXACT SAME BOOST PRESSURE, EXACT SAME. What is split between the turbos is the flow, so each flow at half the CFM, of what one larger turbo would flow.

Turbochargers are simply compressors, driven by exhaust through a turbine, but are nothing more than simple centrifigal compressors. Just like running a pair of shop compressors, into one tank, or system, both need to build the same pressure, what doubles is the flow. The difference with shop compressors is that you can run two different sized compressors, due to the use of check valves at the compressor outlet, this keeps the pressurized air from flowing backwards through the compressor. The use of a check valve would be difficult and restrict flow in a performance turbocharger set-up.

A TWin turbo system does NOT require the use of split intakes, in fact it is better to use a common plenum, to combine the output of both turbos and be evenly distributed accross all cylinders of the engine.

KTM, while it seems that HLS30 has read some things about turbo systems, he doesn't understand them like he should, sorry HLS30, but what you said was also pretty misleading. You have some basic understanding, and will be able to pick more up. Don't worry we were all there at some point.

the functionality of a twin turbo system is exactly same regardless of engine configuration, inline, V, flat, radial, it's all the very same principles, just the actual turbo selection will change.

Most inline I6 twin turbo systems I have seen will use two seperate manifolds/headers, using 3 cylinders to feed each turbo. There's a few reasons to do this:

Packaging. It's much easy to take the front 3 cylinders to one turbo and then the rear 3 cylinders to the second turbo

Heat expansion. Like any manifold or header the trubo manifold will expand when it's heated, the difference is that a turbo manifold will usually expand much more due to the higher heat retained in this part of the turbo engine's exhaust system. The turbine itself is a restriction and keeps much of the heat in the header, there is benefits to this, but delves much deeper into turbine theory than we have time for here. With the split manifold, the expansion is shared over fewer cylinders and fastening hardware, reducing overall stress on these parts. If you've ever noticed, good quality headers will usually have the middle port(s) bolt holes as a pretty close fit to the bolt or stud, and as you get farther from the center of the engine, the holes will be slotted wider and wider, this allows for that heat expansion (and cooling contraction). This section could also have "reliability" added to it, as this makes the overall item and system more reliable.

Going back to the cold side, there are a few places to combine the compressor outlets. Most commonly on an inline application there will be a Y-pipe or "merge-pipe" used very close to the compressors, and is probably the most efficiant way to do it. This then reduces to one single (larger) pipe running to an IC or directly to the TB.

You could also run each compressor outlet to a dual inlet IC, whihc then usually has a single outlet to run to the TB.

The third and probably most difficult would be to use dual ICs and combine the outlet from these just before the TB, or if you are using a split plenum, then never merge them, but this seems to be the least traveled path.

There are few reasons and benifits to using twin turbo on any engine:

Spool up time. Using two turbos with a smaller compressor and turbine wheel will have a lower moment of inertia, and spool up quicker than a larger wheel will. The fact that (usually) only half the exhaust gases are flowing through the turbine can have an effect on this as well. Some people have either built or "know someone" who has built a twin turbo system that didn't perform as expected, only to find out that there was very little planning and an improper selection in parts and/or turbochargers was used.

Physical fitment. Even in an inline this can be a benefit. If someone is shooting for a very high horsepower level this will require the use of a larger turbocharger, and one that may not fit in the allotted space, such as between the engine and the struct tower of an S30, also the intake above may be a factor. To get around this, using two smaller turbos that will flow the same but instead of being large in diameter, they fit in the area under the intake, and between engine and frame rail/strut tower, this goes back to packaging.

Price may also be a good reason, especially for someone using junkyard parts. It is generally easier to find two small turbos off another application that uses a smaller engine, such as the Sunbird 2.0L, Mitsubishi Eclipse, etc. These cars used turbos that I would consider too small for a single turbo application on an L24, but as twins could be used to make upwards of 400 HP.

Weight is only a very small consideration.

What I find is that two smaller turbos only might way more than a single larger turbo that would have the same flow. In many cases the weight difference is so small, that not eating that cheeseburger for lunch would have the same effect.

If you're serious about turbocharging read these two books:

Turbochargers by Hugh MacInnes This is an older book, most of the information is from the '60s and '70s, though there are updates in later printings, and is very technical, hard to read, but once you get it, you get it.

Maximum Boost by Corky Bell This is a newer book, first printing in the late '90s IIRC and is geared more towards common enthusiasts that want to understand more, and turbocharge thier rides. The language is much easier to understand than Turbochargers, and has more information to implement in later model cars, such as those with EFI.

[JonnyRock]

That's a great write-up Six_Shooter.

Let me just add that "Dual sequential turbos" are fairly common in the turbocharging world (both production and aftermarket) but I believe correctly matching your (AggieZ) own two of different sizes would be significantly more difficult.

[ktm]

Six shooter, which is why I said "some idea". I really did not want to, nor do I have the knowledge to, post a lengthy diatribe such as the one you posted.

I am not that impressed with Corky Bells book. You have to read it for what it is though.

There are a few great web resources to learn more about turbocharger, one of them being http://www.turbomustangs.com/turbotech/main.htm. Blue's website has a GREAT calculation demonstration mapping the theoretical airflow of an L28 and plotting it against various Garrett turbocharger compressor maps. Its a great resource in understanding how to select the right turbo for your application.

Your post is quite good and has some nice information regarding twin turbos.

[hls30.com]

...

while it seems that HLS30 has read some things about turbo systems, he doesn't understand them like he should, sorry HLS30, but what you said was also pretty misleading. You have some basic understanding, and will be able to pick more up. Don't worry we were all there at some point.

...

There are few reasons and benifits to using twin turbo on any engine:

Spool up time. Using two turbos with a smaller compressor and turbine wheel will have a lower moment of inertia, and spool up quicker than a larger wheel will. The fact that (usually) only half the exhaust gases are flowing through the turbine can have an effect on this as well. Some people have either built or "know someone" who has built a twin turbo system that didn't perform as expected, only to find out that there was very little planning and an improper selection in parts and/or turbochargers was used.

Physical fitment. Even in an inline this can be a benefit. If someone is shooting for a very high horsepower level this will require the use of a larger turbocharger, and one that may not fit in the allotted space, such as between the engine and the struct tower of an S30, also the intake above may be a factor. To get around this, using two smaller turbos that will flow the same but instead of being large in diameter, they fit in the area under the intake, and between engine and frame rail/strut tower, this goes back to packaging....

I appreciate your bringing to my attention that I read and wrote twin turbo, but understood and wrote dual turbo. In terms of misinformation-that does count.

The point I made and posted as my last sentence I don't think you can find fault with.

"If you don't want to do the math, or get someone involved who will, I would choose another way of adding performance. The end result could be bragging rights that reveal a great idea with a bad implementation."

Will

[Mr Camouflage]

A single turbo would be so much easier.

[cpzmanaustin]

A single turbo would be so much easier.

My thoughts exactly.

Aggie Z, what is the budget and power goals for this build? Is it limited to the L24 only or all L-series okay. Turbos have come a long way from where they were 10 years ago in both cost and performance.

If it were me with what limited information was provided I would go L28ET drivetrain (single turbo) with an F54 block/P90 head as a starting point. If you weld a T4 flange onto the L28ET stock manifold your turbo options are numberous. I would stay with 2.8L cylinder bore to keep the cylinder walls nice and thick and spend on power mods elsewhere. Aside from the fuel injection and turbo you basically have a stock L-series configuration.

Just my .02. Good luck.