Get flat top pistons or swap motor.

[Go240Zags]

OK, I have an '83 turbo motor with the dished pistons and no turbo. Since it is an f54 block and probably needs rebuilt am I better just swapping for a NA L28 F54 or getting flat top pistons for the engine I have? If I do get new pistons, what would the parts numbers be? Would using the KA24E pistons from a 240SX or the pistons from a 720 truck be a better and less expensive idea? Since I don't have the diesel crank and am not trying to build a monster high octane motor are these other pistons a poor choice? Just want some extra power, kind of a sleeper thing.

I know that's a lot of questions, but I have someone here in Wash. State who wants to trade me a NA L28 F54 engine with dist., etc. for my ugly bodied 1983 2+2 280ZX turbo (sans turbo). I'm having second thoughts, especially after he's made me wait like 8 months before closing the deal and the fact that a cleaned-up Borg Warner 5 speed sold on eBay for over $900 the other day. That's the same tranny this car has got. Decisions, decisions. If I parted out the ZX I should be able to get some cash for the P90A head, B-W Tranny, fuel injection, turbo stuff, etc. and maybe have enough money to do a rebuild on the F54 and install flat top pistons and use one of the early E88 heads and the SUs I already have.

I did do a search for some info on flat top pistons, using flat top and flattop for search words, and although the topic has been discussed I couldn't find much on parts numbers and prices. Just looking for some advice. PS Admin. if I've posted this in the wrong section feel free to move it.

[chickenwafer]

Is the NA L28 engine in running order? Depending on how much work it needs to be in running order, I would think parting out your 280ZX Turbo would be a good idea. Unless of course you really really need a motor. I don't know if pistons from a KA24DE would fit- that's a 2.4 liter in-line 4 cylinder motor. Perhaps the L28 and the KA24DE share the same bore, but the L28 has a stroker crankshaft? Although an extra 400cc would require a larger bore, I do believe, so I don't think the pistons would fit.

Of course, you do have the F54 blocked '83 turbo engine you mentioned, but without a turbo. You could purchase a used turbo from a junkyard or e-bay for a couple hundred or less and be running. Granted it wouldn't be a perfect match but it would get the engine running and working until you can find a decent replacement turbine. Unless you need more than just the turbocharger itself.........???

You will make odolles more power with a turboed F54 block than an NA motor with SU's. An NA motor with SU's, depending on displacement and other variables, won't get you more than 250-bhp if you're extremely lucky. People on the forum here have fully built, fuel injected NA L28's making just north of 220-bhp at flywheel, but a turboed F54 stroked to 3.1 liters and fully built can yield some nice horsepower figures. These aren't the easiest engines to extract power from.....

Just wondering- what car are you planning to dropping the engine in? Your 280ZX or the 240Z in your sig or another car?

Dave

[Go240Zags]

Just wondering- what car are you planning to dropping the engine in? Your 280ZX or the 240Z in your sig or another car?

Dave

Dave, I want to put it in my 71 Series I 240Z. I was just going to find a 81-83 280ZX NA motor when I came across the 2+2 280ZX for $200 (the whole car). I'm not a ZX fan, especially a 2+2 with red velour seats. I just figured I could either A) Find a used turbocharger and swap in the motor to my 240Z; trade for a NA 280ZX with the F54 block or C) Swap the dished pistons for flat-top pistons and trade heads and sell the turbo stuff. My fault, I've been going back and forth on this for over a year now and haven't made up my mind. As I said, not looking for a monster motor or drag racer. Just want something with plenty of streetable power and kinda torquey. I'm also cheap and haven't got tons of cash to invests. Turbo sounds nice, but kind of complicated for my skill level. This is just something I need to make up my own mind about I guess. Thanks for your response though.

[chickenwafer]

Well, if you want good, streetable power NA or Turbo are both fine choices as you know, but if you suggest the turbo is out of your leauge then NA is the route to go. SU's are rather complicated little things so I would stick to fuel injection if you want a daily driver. Any horsepower goals?

So my recommendation is to trade the busted 280ZX for the NA L28 motor. Is the NA L28 motor in running order??

Dave

[Ed]

Gary,

What is wrong with the turbo 280 ZX? Is it just a bad, or missing turbo?

I think that if you did do the N/A thing somewhere down the road you will want to upgrade. More horsepower. More, more, more.

If you have everything except the turbo then I would say go turbo.

Most people would have upgraded the turbo or replaced it by now anyway.

You could sell your N/A stuff from your car and use it to finance your rebuild. The new turbo will cost some $$ but if you save your pennies now it won't be such a shock.

Go to the HybridZ.org site and search their forums. They have sooooo much engine info you will be reading for days.

[beandip]

For one thing the P-90 head is a great one to run on the F-54 block with flat top pistons. You will need to do some work on the head like haveing it milled , but if you are going to build an engine this is something you would do anyway. The head has the good shaped combustion chambers , at least this is what the builders claim. Plus they flow and you dont need to change to larger valves. It is as good or better a head , as anything else you can find. Using pistons from a truck ingine or some other application , is not something done by just the bore size . There are many other measurements to take into concideration . I am going with SUs on my '82ZX flat top motor . I gave away all the injection parts. I dont find the SUs complicated at all , in fact they are so vary simple it is amaizing . I am after a strong engine but simple and easy to maintain. Sounds like you already have the parts for the build accept for 6 pistons. The 2+2 has a larger clutch which is good . Have a look at geocities.com/zgarage2001/engine.html Good info on just what you are looking to do. Gary :rambo:

[e_racer1999]

also, the KA24DE pistons have a HUGE bore difference...

[chickenwafer]

also, the KA24DE pistons have a HUGE bore difference...

That's what I thought.

I didn't mean SU's were seriously complicated. Compared to normal Holley 4bbr carbs they are amazingly simple. But, in my mind, fuel injection is easier to work with. Maybe it's just because I'm still a youngen :lick:

And I agree with Ed that you will want more power after your upgrade. Sure, you will be satisfied with your initial power, but after a few months more power will be the only thing on your mind. And the only way to get that is to go turbo. Turbo engines can push some serious horsepower.

A little off-topic here, but I wonder what the highest horsepower L-series NA engine is and the highest horsepower L-series turbo engine is? Something tells me there would be quite a difference.

Dave

[e_racer1999]

^^i think the highest HP N?A motors are probably max 300, and the highest HP turbo motors are around 450... just a guess....

at any rate, turbo vs NA is a complicated topic. the application of the car is going to be the determining factor. granted the turbo is going to have the potential for higher HP, but at what cost? the NA motors have reliable (no that a turbo's going to break, but turbo lag, etc, is an issue) power all through the power band. turbos' power comes in a big surge.

[spudea]

full on racing N/A motor ~350rwhp. Turbo motors in japan have 600-700rwhp.

[chickenwafer]

I know the application is the determining factor. It all depends on what you want. Truth is, however, that a turbo motor will yield the great horsepower-per-dollar ratio 99% of the time.

And I'm not so sure about an NA motor being more reliable than a turbo motor. Most of the time turbos handle abuse for over 200K miles, so unless you're road racing your turbo beast you shouldn't have any conflicting issues that you wouldn't run across in an NA motor. And, NA motors need a higher compression ratio to kick out extra power, thus increasing the chances of knocking and pining, which mandates a higher octane fuel thus generating more money. And because the NA motor will have to be stroked and bored to get more power, along with the high compression, it's fuel milage will probably be worse. I agree, it's all in the eye-of-the-beholder, but you can't overlook a turbo for the pure "cheapness" of it.

I mean, if you spend $2,000 on an NA L28 and $2,000 on a Turbo L28, the turbo L28 is going to have more power- no bones about it.

And thanks spudea for the info. I thought turbo motors would make more than 450 ponies. Of course, in Japan they can get more and better performance parts to wring more power out of their L-Series blocks than we can here in the USA. I want to goto Japan!!!!!

Dave

[e_racer1999]

^^ i figured that i was low-balling the guesses... anyway, when i said "relaible" i didn't mean the engine was gonna blow, i meant that NA always has the power on demand... with a turbo, you have to have a properly tuned turbo for the application. there are lag issues, and sometimes one can be without power for some time. sometimes, if a car is course driving, the turbo car may be a complete dog because of the odd areas of the powerband that a turbo car has. for example, a car could be on a course with a lot of twisties and never make it into a proper RPM range to get decent power.

anyway, i do agree that you can get more HP for the $$ with turbo, but to be honest, in going all out you will pay more with the turbo. my reasoning is: all of the tuning you will be doing to the NA car will have to be done to the turbo car as well, and then you don't have to worry about the cost of the turbo(s)