Jump to content

IGNORED

Making twin turbo 240Z - need advice


AggieZ

Recommended Posts

I am going to make a twin turbo for my 240Z.

I have considered all options for upgrading my engine/tranny and have rejected them. The reason is I feel that if the 2.4 liter engine is taken out, it is no longer a 240Z. I'm just ol' school. I fully understand this route will cost extra money. I'm not worried about that.

PLEASE ADVISE.

Did you consider Nitrous Oxide?

it is pretty much the only cheep way to be fast occasionally, and retain all of the characteristics of the car(when the switch is off).

Will

Link to comment
Share on other sites


To make up a twin turbo for the L24, you've have to make seperate intake and exhaust manifolds for the engine, and not to mention that you would lose power with a twin turbo setup on an inline. I've seen someone try this, and had nothing but bad luck with his inline. And I'd have to agree with red_dog007 about picking up the RB26DETT.

Justin

Link to comment
Share on other sites

Really? there is 1 fast z with a twin turbo setup (but his has a custom dual overhead cam setup and a 3.1l)

I think you can do a twin turbo setup if you use the right combination of parts.

he wants to keep the L24 engine, so dropping in the RB (while a nice fast engine) is out of the option.

it will be a lot of work, and you might not get as much power as you could with different setups, but i think it might be neat.

Not sure what you mean by losing power in the L6 with a twin turbo setup. the RB is a twin.

maybe you mean in the z engine? I think if the turbo's were sized properly you should be able to make the same power as a single setup.

Link to comment
Share on other sites

...

Not sure what you mean by losing power in the L6 with a twin turbo setup. the RB is a twin.

maybe you mean in the z engine? I think if the turbo's were sized properly you should be able to make the same power as a single setup.

The point of a twin turbo setup on an inline engine is to have two different sized turbos that are tuned to different positions on the engines power curve to broaden the area of added power. In a dual turbo application on an inline engine both turbos share the exhaust and the intake of all cylinders. This is not the same functionality of a dual turbo system on a banked engine like the RB, where each bank gets an identical turbo.

Turbos usually have a sweet spot in the engines rpm band where they function most efficiently. Adding a second turbo to an inline engine would be done to make additional power over a part of the powerband the first turbo did not address with a slight overlap. With a larger area of added power from properly adding a second turbo, gearing can be used through more of the powerband instead of the "bump" in power usually generated by a single turbo, meaning a larger area of effectiveness in the entire drive train, and more flexibility in the shifting of the car.

As I understand the physics of the design of an inline engine dual turbo system it functions like a 12db per octave crossover, tailoring the output curve of a smaller turbo to match the output curve of a larger one so that the areas of power overlap slightly, making a larger area of more power. Using two turbos the same size on an inline engine means both were two small to be effective in the first place, and added more weight and complexity than a single turbo system properly mapped for the engine(twice the tubing). Adding them such that they operate on cylinders excluded from each other says exactly the same thing as far I have read.

A dual turbo setup on an inline engine done to maximize performance takes lots of information about the engine, the turbos, the fuel curves, the plumbing before, between ,and, after, and the cooling system. It is not horribly difficult to just add a second turbo, but adding one to maximize performance adds complexity and weight to the complete engine system.

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

Link to comment
Share on other sites

I get what you saying Will for the most part but get lost, I'll reread your post but

before I lose my train of thought....

Out the block (figure of speach), It seems like forged mechanicals would be the way to go is it not?,

but would the block (engine) hold up and up to how much power with what kind of

gaskets and head studs strong enough to handle it?

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?

Link to comment
Share on other sites

Only one person in this thread has some idea of what they are talking about, and that is HLS30. Please, if you do not know for 100%, don't spread wrong information.

To the original poster, if you truly want to TT your L24, you have a LOOOOOONG road ahead of you. Everything will be custom fabricated and you will need to do A LOT of reading and research. The fact that you are posting here HOW to do this indicates that you are no where close to being ready to undertake this project.

Link to comment
Share on other sites

I am going to make a twin turbo for my 240Z.

I have considered all options for upgrading my engine/tranny and have rejected them. The reason is I feel that if the 2.4 liter engine is taken out, it is no longer a 240Z. I'm just ol' school. I fully understand this route will cost extra money. I'm not worried about that.

PLEASE ADVISE.

Did you consider Nitrous Oxide?

it is pretty much the only cheep way to be fast occasionally, and retain all of the characteristics of the car(when the switch is off).

Will

If you are hung up on the 2.4 liter displacement thing, here is an option. There is a RB24SOHC engine that Nissan exported to the Philippine auto market. This motor uses a RB25 block with a RB20 crankshaft.

Just throwing this out because I like to be different. I agree with your sediments about the thought of it no longer being a "240Z". Sticking to the 2.4 liter displacement with newer technology would have a cool retro effect.

Link to comment
Share on other sites

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

Yes. Same with the TT Supra Mk IV of the same era. There's a reason they are both holding their value and considered "super cars" by many. Gobs and gobs of consistent power.

As for a TT build on an L6 not setup for it to begin with...monster job. Get an RB and you have Nissan power at least. I've even heard of some guys dropping a Supra 2JZ engine into for monster hp but if your not careful, the torque will pretzel the car.

Dig around on HybridZ. It's all there. Good luck.

Link to comment
Share on other sites

I think that he would be better off with a pimped out L24. Cam, diff, tranny, ect.

That is basically what my goal is as I want to keep the same L24 under my hood. Thought of a turbo, not worth it imo, when this thing can still be a monster N/A.

About the turbos, parallel twin-turbo both have their own exhaust manifold, and push the same boost. This setup basically takes the work on one turbo and splits it between two turbos evenly.

The BMW 335 uses this technologly and does it good. Extremely low pressure (only 6psi, so 3psi per turbo) No lag, tons of low end and midrange power and effectivly N/A up top.

Then there is seqential twin-turbo which share the exhaust manifold and there is one small turbo and then one large turbo.

Vertially all V shaped engines use parallel just to make plumbing easier, but inlines can go either way fairly easy without too much plumbing.

There is also another type of system that can be used, but it rarely seen at all.

Link to comment
Share on other sites

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~

Link to comment
Share on other sites

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~

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

...

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

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

Come on guys. This is obviously some youngster's pipe dream. The first post in this thread is the last time he posted on this site to date. Not one answer from him on any of the suggestions/opinions etc. Maybe he took the advice and went to HybridZ.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy and Guidelines. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.