Adding turbo to non-turbo ZX motor?

[inline6]

The point of all this is HP of course. A bump to compression from 7.4 to 8.5 should be worth some HP, increase in efficiency, and thus, gas mileage. I am also wondering if I would get and driveability improvement-- specifically with turbo lag or lack thereof. Is it reasonable to conclude that the bump in compression would give a little better performance when off the boost? Seems like the bigger the turbo (or the more lag), the more the bump in CR would help?

Sounds like the durability of the pistons between the turbo and non turbo are in question. I'll look at them next if I can. Questions would be location on the piston (how far down from the piston tops, and size of rings? Any others? Seems like nissan would use the same blank and machine the dish in the turbo piston for cost, but higher temps may have required a change in those specs.

Thanks for the info, all.

[Gav240z]

I think a C/R around 8 or 8.5:1 would definately help with driveability off boost.

A T3/T4 Hybrid would be good also to keep lag down. Also im sure you know things like BOV's help reduce lag.

[hls30.com]

I am not certian you didn't mean torque instead of HP.

when HP changes-it is due to changes in torque-not the other way around.

Adding HP does not necessarly add to gas mileage-the A/F ratio should be virtually the same in all properly tuned engines, thus a a bigger engine uses more fuel per stroke. A transmission made for a smaller hp motor(a Z transmission) moved between two motors capable of driving it properly (one moderate HP, and one High HP) will get better mileage form the lower HP motor because the # of revolutions the motor has to turn per mile is the same-regardless of the HP-but the amount of air and fuel used is different. The extra Hp will get you to speed faster, but will use more gas to do it, and to keep you there because the RMP between the engines at a given speed does not change.. All engines have one specific speed that uses the optimal resources for the amount of work actually being done. When the gearing allows a transmission to take advantage of or at least approach that speed you have the greatest gas mileage that engine is capable of.

Raising the compression should add some torque and HPand therfor make driveability improvements-there are engine modeling programs (PCDyno) out there that will give some idea of what it should do with everything else constant.

Don't forget the piston/ring land /ring design on the turbo version is not only set up for higher cyl pressures, but is thermally specked out too-get the heat out fast to lower the propensity for premature detonation!

Turbo lag can be tuned out-a modern engine management system can be programmed for supplimental injection to dispose of lag(ad NOS and more gas to intake manifold, or CO2 to the turbo header, and you will spool the turbo up almost immediately at WOT.) or a turbo can be tailored to lower rpm driving.

I think the true limiting factor of the 6cyl L series engine is the Head-that is where all of the current technology has been focussed-cyl wall treatments are virtually the same as they have been, Exhaust technology really hasn't changed, but we have multiple sets of valves per cyl, variable valve timing and more that has been added to the head, That is what is keeping power down in an NA engine, without forced induction, enough air will not move fast enough through the engine. If the head off a 6Cyl Olds Bravada would fit on a 6cyl L series, we would have a great new addition to performance-variable valve timing and programmable injection-I would consider transplanting the whole setup into a Z.

Will

[inline6]

Actually Gav,

I am an old school NA guy that is just getting intrigued about adding the turbo. In the past, wrote off turbocharging as being too expensive and sufferering from driveability issues. I really like power to be controllable and thottle response to be quick. What are BOV's?

My goal for the motor would be minimal lag with moderate power. I autocross from time to time for fun so the idea of a big turbo coming on with lots of boost after lots of lag would be totally unacceptible.

I need to do more research in the archives here on turbo set ups. Obviously there is no shortage of info on the subject. Thanks for the T3/T4 hybrid tip. I'm committing that to memory as I continue researching.

Garrett

[mel marabante]

just now reading this post and i must say i'm astounded on how people respond to a very simple question. inline6, your questions from the beginning are absolutely right on. bottom line is that a turbo that is compatible for higher CR should produce more efficiency. and since the parts in questions are the same with the exception of dished pistons...then why the hell not. i have a 79 280 zx. my set up is good now. why buy a l28t version motor if i can upgrade to a turbo now. i don't get why people don't understand that. the point is simple and dont try to complicate things by writing a freaking novel to showcase your knowledge.

[Mikez73]

just now reading this post and i must say i'm astounded on how people respond to a very simple question. inline6, your questions from the beginning are absolutely right on. bottom line is that a turbo that is compatible for higher CR should produce more efficiency. and since the parts in questions are the same with the exception of dished pistons...then why the hell not. i have a 79 280 zx. my set up is good now. why buy a l28t version motor if i can upgrade to a turbo now. i don't get why people don't understand that. the point is simple and dont try to complicate things by writing a freaking novel to showcase your knowledge.

Um I don't know if you noticed but this thread is ancient. I didn't notice until I'd spent 10 minutes answering some of the misinformation in previous posts

:stupid:

Edited May 14, 2010 by Mikez73
not paying attention

[inline6]

All the same, we get notified by email of new posts to these old threads. And in this case, I'm still alive to see it!

Thanks mel marabante. I think a lot of people just default to the ZX turbo motors because they were already turbo. I don't think that is necessarily the smart way to go. If you are going to run the stock efi, then maybe. Others have the experience here - not me.

I have an F54 flat top now and decided to stay NA as I'm not ready to drop the cash or time on all the custom parts that I'd go with if I went turbo. I mean, I'd want to go aftermarket efi, custom intake, custom stainless exhaust, aftermarket injectors, etc. The works! Instead, I'm putting together a tripple 44 mikuni, big cam motor for now. I'd be willing to bet I won't be happy when all is said and done and I'll be pursuing the turbo route I was thinking about in 2004!

[Mikez73]

All the same, we get notified by email of new posts to these old threads. And in this case, I'm still alive to see it!

Thanks mel marabante. I think a lot of people just default to the ZX turbo motors because they were already turbo. I don't think that is necessarily the smart way to go. If you are going to run the stock efi, then maybe. Others have the experience here - not me.

I have an F54 flat top now and decided to stay NA as I'm not ready to drop the cash or time on all the custom parts that I'd go with if I went turbo. I mean, I'd want to go aftermarket efi, custom intake, custom stainless exhaust, aftermarket injectors, etc. The works! Instead, I'm putting together a tripple 44 mikuni, big cam motor for now. I'd be willing to bet I won't be happy when all is said and done and I'll be pursuing the turbo route I was thinking about in 2004!

Glad you're still alive to see it ...wish I'd left my answer now. Bang for the buck go turbo if you want big power. There was some misinformation in some posts. If you ever decide to go turbo repost...although after 6 years you probably know the errors I'm talking about. I got a chuckle out of the "t3/t4 helps with lag" statement

[hls30.com]

... I think a lot of people just default to the ZX turbo motors because they were already turbo. I don't think that is necessarily the smart way to go. If you are going to run the stock efi, then maybe....

It is more a case of one stop shopping and economy. As pointed out earlier in the thread:

Why search for parts and an answer and then have spend time fitting, fabricating, and tuning when with a single $300(what I bougt my last Running 280ZX Turbo for) purchase you can get everything that you need and have it all properly installed in another car and running well in two weekends or less-by yourself?

As an addition, the 280ZX turbo was Nissans reaction to the Crown, BAE and other turbo kits that were built between 1973(the earliest reference to a turbo kit I can find), and the introduction of the 280ZXT for NA Z cars from. I have a COMPLETE BAE kit I pulled from a '80 ZX several years ago.

http://www.classiczcars.com/forums/showthread.php?t=22762&highlight=bae+turbo&page=2 see post 29 for a picture. Getting one of these kits speeds up the process, but they are still certianly more complex than swapping parts-even the manual says that a mis tune coud kill your engine.

I think most people would like to consolidate their efforts and get a working and proven system, rather than piece on together. I am sure a properly designed modern turbo system would be better than what was available in the 80s.

There is a website that explains all about Nitrous, and how to build your own system, it proves that the system it explains is the best out there and why-but people still buy pre packaged kits that are clearly inferior. Why? could be several reason-risk, fear, even convenience...same reasons apply to this thread

Anything is possible with enough time, talent and/or money to pay for them. Some people simply don't have the right combination of all three to get to the place you describe. The factory set up has proven relieable and effective, the aftermarket has been proven to have the ability to be just as reliable and more effective, but it has also proved to turn an L6 into a broken pike of junk very quickly.

L28ET conversion: Low cost, short term project, great performance gain, Proven and long lived results-FSM applies directly to troubleshooting and maintenance.

L28 Turbo Conversion: Much higher cost, long term project, potentially excellent performance gain/dead engine, mixed results. No step by step guide to troubleshooting-mixed equipment means the buck could get passed.

"The smart way to go" depends on the talent/time/money of the one person making the decision.

Edited May 15, 2010 by hls30.com

[Mikez73]

If you can find a good l28et for $300 that is definitely the way to go. Offhand I can't think of many differences in the two cars but sourcing the parts might take some time. Offhand list of parts

1. injectors (cheap, easy to find)

2. exhaust manifold (I'd build one and relocate the turbo)

3. oil pan (drill a hole for the return line)

4. intake (I'd use an ic so that's a non issue)

5. pistons (I'd keep the NA pistons)

6. engine management (I'd want Nistune or MS anyway)

7. oil pump (a new oil pump is a good idea anyway)

8. gas tank (for my 240z anyway)

9. fuel pump

Bottom line is yes if a complete 280zxt parts car is available it makes things easier. Driving z31's for 10 years will give you a more relaxed view of modifying a car. Power adding aftermarket support for the z31 was pretty much nonexistent :disappoin