Looking for directions on my new project

[CPLGDR]

Hey Guys,

 

I believe this is my first post here, so hello to you all.

 

I'll try and keep this brief. I have done my best to search through the forums for answers to my specific questions, but actually, I think I'm looking for opinions rather than specific answers.

 

The situation is this: I have two Z-cars, both S30s. One of them is a 1973 240Z. To summarise as quickly as possible:

 

• Later, flat-top SUs
• 5-Speed Gearbox
• 60A Ammeter (Presumably that means an uprated Alternator
• Excellent condition valvetrain...
• ...yet abysmally poor (and inconsistent) compression
• Fair amount of rot
• Very poor condition interior
• Cracked Brake / Clutch Master Cylinder
• Absolute non-runner
  

 

Then there is the 'replacement' Z, which is a 1972 240Z:

 

• Good engine compression
• Solid Interior
• Very little rot
• Roundtop SUs
• 45A Ammeter
• Very weedy airbox
• 4-Speed Gearbox
• Solid runner - managed an 8-hour journey (over 500 miles) in one day, no problems
  

 

The other backstory - the two cars reside with my Uncle (car fanatic with a HUGE Workshop) in NM, USA. I'm in London at the moment, where I live. I'm going to go and 'collect' the '72 this coming summer.

 

So my question for you experts is: what the hell do I do to it?

I've spend ages thinking and thinking about how to best use my uncle's workshop / time / enthusiasm, but it seems like every option has a caveat! I'd love to chuck in a huge Chevvy V8, but that would cause insurance issues over in the UK, and more importantly, I kind of want mine to stay reasonably faithful to the original. So I really want to stick with the L24, but then I keep waking up in cold sweats at the thought of having just 150HP at my disposal! I'd love to do some 'minor' mods to it, but everyone seems to think that the first step to modding a 240Z is to chuck away the L24, and replace it with an L28E! While this does make good sense, I dunno... I kind of like the L24...

 

So if I had two questions, they would be: 'Is getting rid of the L24 REALLY the only way to make 'more' horsepower?' and 'What can I do to mod the car whilst staying true to its original form?' JDM mirrors?

 

Anyway, sorry for the long post. Here's a picture of the car as thanks for reading all that =P :

[Blown77Z]

If you're going to use the car for drive by shootings then...........

[CPLGDR]

Oh yeah, lol I should explain:

 

That's not me. My uncle sent me an email with 'I've got some bad news, your car was involved in a drive-by shooting'

 

And then I opened it to see that... yeah, it's not... I'm not 'gangsta' or anything lol, he was just screwing around!

[BurnoutZ]

Well you could get some z therapy SU carbs to go on the l24. I would recommend trying to get ahold of an l28 though...

[CPLGDR]

Yeah, I am kind of leaning towards just swapping the engine out. It would be a lot of fun, I do love a nice mechanics project... I guess I could justify it on those grounds.

 

What about a very simple camshaft and valvetrain job?

[BurnoutZ]

With an l24? I mean you could... But you can only do so much with an l24. youll probably get like 175 whp...

 

But with an l28 on the other hand... more potential. If you want alot of power go with the l28et, turbo motor. There is a guy by the name of timz on this forum that managed to get 607 Whp out of his l28et...

[CPLGDR]

OK, thanks. Yeah, I guess I don't really have any problems getting an L28ET, are they easy to find? I had a look around, didn't really have much luck.

 

My only other question would be, obviously it is possible to create your own turbo set up if you wanted to: would it make more sense to do that if you were going to go for a setup that was more powerful than the stock L28ET? Such as an upgraded i/c, megasquirt, uprated injectors, bigger turbo etc. etc? Or is the L28ET ALWAYS a better starting point?

 

I quite like the idea of plumbing the whole thing in myself and the challenge of creating my own build from scratch. I guess either way I'd better go and get that 'Maximum Boost' book and memorise it hehe...

[Challenger]

From what I understand youll have limited time to build the car? If so Im seeing building your own turbo motor may be a little difficult, more leaning towards a stock turbo swap.

 

Also nick whered you get 175 whp? Arent L24's at about 120 stock? Thats a little optimistic for a valve job.

[B00STDZ]

OK, thanks. Yeah, I guess I don't really have any problems getting an L28ET, are they easy to find? I had a look around, didn't really have much luck.

 

My only other question would be, obviously it is possible to create your own turbo set up if you wanted to: would it make more sense to do that if you were going to go for a setup that was more powerful than the stock L28ET? Such as an upgraded i/c, megasquirt, uprated injectors, bigger turbo etc. etc? Or is the L28ET ALWAYS a better starting point?

 

I quite like the idea of plumbing the whole thing in myself and the challenge of creating my own build from scratch. I guess either way I'd better go and get that 'Maximum Boost' book and memorise it hehe...

It's depending on how much work you wish to put into the car. If you put a v8 or sr20 or rb26 in it, it will take alot longer because there is alot of custom fabrication involved.

 

As for 175 whp, sorta optimistic. Porting, bigger intake valves, aggressive cam, triple carbs, race gas..

[JonnyRock]

Also nick whered you get 175 whp? Arent L24's at about 120 stock? Thats a little optimistic for a valve job.

 

The L24 came rated 150hp from the factory. It's even stamped on the tags.

[blue72]

The L24 came rated 150hp from the factory. It's even stamped on the tags.

 

They were talking about wheel horsepower. Assuming an 18% loss, 120whp is right on target for an engine making 150 crank horsepower.

 

Back on topic though, do you have a budget in mind CPLGDR?

[Daeron]

An L28 is an L24 with a different crankshaft and rods (shorter rods, longer stroke) and a bigger bore. Not THAT much bigger in any dimension.

 

People "shy away from boring out L24 blocks" but only in the sense of boring it out for a ma displacement L-6. If I am not mistaken, the P30 block that is in the 73 car could be bored to 280 spec safely, and with the L28 pistons, and the crank and rods from an L26 (I could get the crank/rods for you, we have two L26 engines we were discussing stripping and junking today) you have a 280 motor.

 

But that is all displacement. The BIG difference between the turbo motor and the earlier NA Z motors is the shape of the combustion chamber in the cylinder head.

 

Have you read through the stickies regarding different cylinder heads? The P90 and P79 that came in the 280Zs (P90 being turbo and 79 being non) have large displacement (~53cc) quench style chambers, where the later 240 motors, 260 motors, and the 280Z-no-X motors had open chamber heads. EARLY 240Zs with the E31 head have a quench-type combustion chamber similar to the P-series heads. This is ALL a GROSS SUMMARY of things you need to know more thoroughly yourself before you make your decisions.

 

The combustion chamber on the E31 head is smaller than the P-series, which means that the E31 out of the box would give you higher compression with the same bottom ends. (by the way, with either of these heads in an NA application you will want to be using flat top pistons, not the dished used in the early L28 motors (Z no X) and the turbo L28s.)

 

So, in the end, my point is that there is no real serious difference between an L24 and an L28e.. nothing magical except displacement, and slight differences between the interchangeable cylinder heads. Some choose to take a P90 head and shave 0.080" off of it, using N-series valves and cam tower shims to fit the valvetrain geometry, and not need to bother replacing valves with larger than originals (something you would want to do on a stock E31 head. The later head also has hardened valve seats that tolerate unleaded fuel; pre-77 heads all had bronze seats.)

 

But a motor with fairly high compression (9-9.5:1), an electronic ignition distributor from an early 280Z, (search) your round top carbs (ACTUALLY I just heard that the needles from your flattops, can be swapped into the roundtops, for a good street performance needle) and an appropriate cam will deliver you plenty of oompah for your little old Z car.

 

Never forget: 200 horsepower is ALOT of power for a 2000 pound car. Yah, the Z isnt THAT light... but you aren't talking about a Cadillac here. Once you get to a point with carbs, a cam, and good spark, you can turn your attention to improving your car's handling and get alot more driving fun for your dollar than you will by going all the way to 2, 250, 300 horsepower on stock rear diff and suspension. Ask anyone with a 250 horsepower dyno sheet: they burn tires! Personally, I've always been happy with a motor that delivers a satisfying *barK* from the rear tires shifting hard into second and third; if I had to exercise utmost control to shift into third gear, I wouldn't be having as much fun.

[CPLGDR]

Sorry for the slow response. Forgot about this thread!!

 

Anyway, thanks for the great responses. I don't know what my budget will be (come summer), although I can be pretty sure it won't be more than $6000 - and that depends entirely on the exchange rate.

 

And thanks Daeron, that was enlightening. Your point about suspension is very true. I understand that the stock gearbox and clutch are good for a fair bit more than the 150 SAE HP that the engine can deliver, but I shall definitely do some work on the suspension. I just want to budget that after I budget the engine work... which is probably a huge mistake.