Getting the most power

[AndysPlit]

Eventually I would like to rebuild the stock L28 motor on my 78. There are some performance mods I would like to consider like a lighter flywheel, cams, maybe a bigger throtttle, headers, etc. However, I am trying to stay away from anything like throwing in a turbo, nitrous, or swapping out for a V8. Mind you, all those are exciting mods, but they are just not for me.

My attempt is to get the most power out of that staight-six without going over the top. I am asking 4 things:

1. What upgrades are recommended from you guys?

2. Is it possible to get the car in the 5 second range (0-60) by doing it this way?

3. What is the calculated top speed?

4. What's the most horsepower I could get?

Thanks!

[hls30.com]

1) You have limited your upgrades to those that are slightly effective(10% claimed increase), big bucks(head work aint cheep) or are trial and error for a diyer. After a used 4:11 swap, Nitrous is without a doubt the biggest bang for the buck at retail. I am sure some of the seriously into Engines/racing guys will chime in here with some viable upgrades for you.

2)With enough money and time, anything is possable.

3) Depends entirely on the tranny and differential you end up with-there is a link to a calc floating around somewhere-I'll post it when I find it, but top speed and low 0-60 figures are pretty well mutually exclusive unless you swap the 5th gear to something really really tall...

4) see number 2 and read it twice!

My answer isn't to be flippant, it is just to point out that almost everything in the automotive world is a trade off-you can't have a gain in one specification with out a loss somewhere else, and most of the time that translates to mean you can't have an older car that does everything well.

Will

[beandip]

I agree completely with what Will just said. If you do a rebuild , replace your dished pistons with flat. Have the head gone over , ported ,milled valve work and the compression raised to 9.5 - 10.0 to one or higher if racing is for the car. Install a cam with a grind suited to the sort of driving you intend for the car. Road racing then a hi-revving cam. Street use then one that will build power at lower revs like 2K to 5500. The 78z is a fairly heavy car compared to a series 1 so overcoming the power to weight ratio will come into this. Building the car for top speed will greatly impact the lower speed performance . As Will stated using a low rear end gearing will greatly improve the off the line performance but will lower the top end speed. Everything is a trade off, it all depends on how fast you want to SPEND . Gary:rambo:

[Arne]

Is it possible to get the car in the 5 second range (0-60) by doing it this way?

However, I am trying to stay away from anything like throwing in a turbo, nitrous, or swapping out for a V8.

As Will said, anything is possible if you throw enough money at it, but I think it will be VERY difficult to achieve 0-60 in less than 6 seconds without the things you list as "not for you".

[240ZMan]

As someone who has a similar desire to keep the L6 and not go to forced intake or nitrous, I can relate to your goals. I've been gradually building up my L28 to the point where I now have:

N42 block bored .020 over

Flat top pistons

N42 head with mild porting

Header + 2.5" exhaust

Stage III-equivalent reground cam

Triple Webers

MSD ignition

Lightened flywheel

5 speed

4.11 LSD

The car is blast to drive and makes useful power up to 7k rpm. I'm in the process of converting to FI and will dyno it after that so can't tell you the power right now.

BUT....

If you want to build a reliable 5 second 0-60 car, then you should be looking at a V8 conversion or turbo L6. Assuming you don't want a turbo, then focus on a V8. Done right, the weight will be about the same and you'll spend about the same amount. Plus, if you want to go faster still, you'll have lots of options available to you.

I realize that what I'm saying could be considered blasphemy, and a few years ago I couldn't even imagine it. If you're like me and you like to wrench on your car and enjoy the learning that comes with it, then I'd definitely recommend going down the L6 route and enjoy the process. But if you want to straight to a 5 second car on a reasonable budget, then you should think about the V8.

Just my $.02.

[240ZMan]

Another thought: build a 3.1 stroker. It would let you keep the L6 and should get you to your performance goals.

BUT...

It's not cheap at all. In fact, from what I've read in multiple places, you'll likely spend MORE than a V8 conversion with comparable power.

[AndysPlit]

Right on. I will consult my garage (Sunrise Z) to see what we can do for my car in the future. Your recommendations sound quite similar to what they have mentioned. I really want to keep the straight-six, even if I I'll never get a 5-second or car without the turbo. Keeping with what came from Nissan will automatically override any lofy (maybe laughable) expectations I may have had.

Yeah, the V8 conversion can be cool, but I decided not to go down that route. I love my six! Maybe, I'll consider the turbo afterall. I guess I haven't really thought about what I am more willing to sacrafice: acceleration or top end...............As I have understood from other posts I need to think about that. Hmmm......I don't think top end will be my specific goal now that I think about it. I live a long distance from the Salt Flats anyhow!

So far all I have is a 2 1/2 turbo muffler as far as performance mods go. I have a ways to go, even after owning the Z for 10 years. How many horses would you estimate your car has?

Thanks guys. I'm open to more advice.

As someone who has a similar desire to keep the L6 and not go to forced intake or nitrous, I can relate to your goals. I've been gradually building up my L28 to the point where I now have:

N42 block bored .020 over

Flat top pistons

N42 head with mild porting

Header + 2.5" exhaust

Stage III-equivalent reground cam

Triple Webers

MSD ignition

Lightened flywheel

5 speed

4.11 LSD

The car is blast to drive and makes useful power up to 7k rpm. I'm in the process of converting to FI and will dyno it after that so can't tell you the power right now.

BUT....

If you want to build a reliable 5 second 0-60 car, then you should be looking at a V8 conversion or turbo L6. Assuming you don't want a turbo, then focus on a V8. Done right, the weight will be about the same and you'll spend about the same amount. Plus, if you want to go faster still, you'll have lots of options available to you.

I realize that what I'm saying could be considered blasphemy, and a few years ago I couldn't even imagine it. If you're like me and you like to wrench on your car and enjoy the learning that comes with it, then I'd definitely recommend going down the L6 route and enjoy the process. But if you want to straight to a 5 second car on a reasonable budget, then you should think about the V8.

Just my $.02.

[zbane]

I really want to keep the straight-six, even if I I'll never get a 5-second car without the turbo. Keeping with what came from Nissan...snip...

...I love my six! Maybe, I'll consider the turbo afterall.

How about this-find yourself an L28T from a later model year 280zx. Sure, it's a turbo, but it is a Nissan L28, and before you go and drop it in, you can do all the work you want to it, all the while driving your Z...

[AndysPlit]

I thought about that in the past....and it sounded like a cool idea. But for some reason I seem to be on this kick of keeping the original motor. Basically I want to finish the job Nissan started years ago with that very engine.

How about this-find yourself an L28T from a later model year 280zx. Sure, it's a turbo, but it is a Nissan L28, and before you go and drop it in, you can do all the work you want to it, all the while driving your Z...

[hls30.com]

I thought about that in the past....and it sounded like a cool idea. But for some reason I seem to be on this kick of keeping the original motor. Basically I want to finish the job Nissan started years ago with that very engine.

One more thought, the L28ET was the final evolution of the L24!

Granted it isn't your original engine, but it is in the original vein!

[240ZMan]

How do you define "that very engine"? At the risk of playing with semantics, if you define it as the block, pistons, and crank, you could swap to a P79 or P90 head, turbo it, and have a pretty robust engine as long as you didn't go crazy with the boost. Leave it at the factory levels of boost and that engine would live a long and happy life

Please keep in mind I'm not trying to push you into a turbo, just making sure you know what your options are. I'm not a fan of turbos for performance cars, although my daily driver is a turbo volvo. I don't like the delay between pressing the gas and feeling the torque. But that's just me. Lot's of people find the extra hp worth the slight lag.

Choices, choices, choices ...

[AndysPlit]

Yeah, tell me about choices. If only I had the budget to aquire a few Z's and try different things on each of them. At any rate, I suppose I would define "that very engine" as the block. The pistons and such I would like to upgrade. I'm still trying to decide if I want to bore out the cylinders.

By the way, does anyone know how far the cyliners can be bored to on an L28?