Your thoughts.

[Perfect240Z]

Alright guys,

Here's my situation, it's been awhile since I've posted anything I've been really busy with my slow resto 240z. But here's my question, my 240z came with the e31 block, and someone stuck on an e88 head. The motor needs to be rebuilt anyways. I also have a f54 block that I just picked up, I believe it's from a 280zxt since it has dished pistons on it. That motor also needs to be rebuilt. I have a n42 head that was worked on and only half finished by a Z shop that closed down some years ago, but is pretty clean. Anyways I've read a lot of threads on here saying go L24 vs L28 but my question is what is the benefit? I'll be putting triple carbs, on it anyways. I also didn't know if I should keep the dished pistons from the turbo f54 or replace it with flat tops. I don't make a lot so I'm trying to keep the build as cheap as I can. Any info would be very appreciated.

[jmortensen]

If you're putting triples on it, it's not being restored. If you're hot rodding it, there is no benefit to the 2.4. Worrying about the value of these cars is kinda silly, because a really nice restored 240Z has been about the same price as a new top of the line Civic for about 20 years. It's just not an expensive car. But if you are worried about value, store the 2.4 and that way if you sell the car to someone who wants to restore it, you can say you have the original motor.

If you're looking to make power, the bigger motor makes bigger power. a 2.8 is about 15% bigger than a 2.4, so you'll make about 15% more power. You can do a stroker 2.7L with your 2.4, but for the same money (and with a lot of the same parts) you can stroke the 2.8 into a 3.1 and have about 30% more displacement and power for a similarly built engine than the original.

By the way triples aren't cheap and if you set yourself up with jetting in a couple sizes up and down you'll be in the hundreds of dollars just in jets.

[Zed Head]

The N42 head on the F54 block with the dished pistons will give you an L28 like the 1975 to early 1979 engines. ~8.3 compression ratio.

OR, some people will pay good money for the F54 turbo block. Someone, either here or on Hybridz, was looking for one recently. You might consider selling it and pickup a used L28 engine. Rebuilds are kind of expensive, compared to the extra miles you can get out of a used L28. You'll still need carbs or EFI to get it running.

[Walter Moore]

If you're putting triples on it, it's not being restored. If you're hot rodding it, there is no benefit to the 2.4. Worrying about the value of these cars is kinda silly, because a really nice restored 240Z has been about the same price as a new top of the line Civic for about 20 years. It's just not an expensive car. But if you are worried about value, store the 2.4 and that way if you sell the car to someone who wants to restore it, you can say you have the original motor.

If you're looking to make power, the bigger motor makes bigger power. a 2.8 is about 15% bigger than a 2.4, so you'll make about 15% more power. You can do a stroker 2.7L with your 2.4, but for the same money (and with a lot of the same parts) you can stroke the 2.8 into a 3.1 and have about 30% more displacement and power for a similarly built engine than the original.

By the way triples aren't cheap and if you set yourself up with jetting in a couple sizes up and down you'll be in the hundreds of dollars just in jets.

What he said... If you want performance go big. I rebuilt my original L24, and it runs great, but I have been trying to keep my car sort of "In period low dollar performance" themed. I have an L28 from an 83 ZX sitting the garage waiting, in case I ever decide to go for serious performance.

[Perfect240Z]

If you're putting triples on it, it's not being restored. If you're hot rodding it, there is no benefit to the 2.4. Worrying about the value of these cars is kinda silly, because a really nice restored 240Z has been about the same price as a new top of the line Civic for about 20 years. It's just not an expensive car. But if you are worried about value, store the 2.4 and that way if you sell the car to someone who wants to restore it, you can say you have the original motor.

If you're looking to make power, the bigger motor makes bigger power. a 2.8 is about 15% bigger than a 2.4, so you'll make about 15% more power. You can do a stroker 2.7L with your 2.4, but for the same money (and with a lot of the same parts) you can stroke the 2.8 into a 3.1 and have about 30% more displacement and power for a similarly built engine than the original.

By the way triples aren't cheap and if you set yourself up with jetting in a couple sizes up and down you'll be in the hundreds of dollars just in jets.

Well I mean restore as in I'm fixing everything on the car. Welding, replacing back to stock on items I can get online, re paint the car, as far as motor I'll have that stuff for if I were to sell the car. I was just referencing a thread I read earlier between someone using a 2.4 or 2.8. I have both, both need rebuilding. And in that thread someone said the L24 is very peppy and you didn't need the L28.

And I know the triples are expensive, thats the one thing I'd be willing to spend a little money on after rebuilding.

Well should I still use the stock dished pistons even though I'm going for carbs? I was going to use flat tops, but I heard that I'm going to get detenation. Anyone have pros or cons on that? I won't be using a after market cam or anything else really for performance till later on when i recooperate more funds after the finished product.

[Perfect240Z]

What he said... If you want performance go big. I rebuilt my original L24, and it runs great, but I have been trying to keep my car sort of "In period low dollar performance" themed. I have an L28 from an 83 ZX sitting the garage waiting, in case I ever decide to go for serious performance.

Both of my motors need rebuilding so it's not like I'd be spending any extra, unless people say I shouldn't use the dished pistons with carbs since its from a turbo.

[jmortensen]

I ran a dished L28/E31 setup for years, ran great with a .490/280 cam and SUs' and then later triples. I ran the same head with flat tops and it pinged like crazy, had to mix race gas, basically became undriveable as a street car. 8.3:1 is lower compression than you would ideally like to have, but it's MUCH better to have lower compression and be able to run the appropriate amount of timing than it is to run too much compression and have to back the timing way back to make it run. If you are buying pistons anyway, you might see if there is a piston with a shallower dish or one that has a half dish.

[Perfect240Z]

I ran a dished L28/E31 setup for years, ran great with a .490/280 cam and SUs' and then later triples. I ran the same head with flat tops and it pinged like crazy, had to mix race gas, basically became undriveable as a street car. 8.3:1 is lower compression than you would ideally like to have, but it's MUCH better to have lower compression and be able to run the appropriate amount of timing than it is to run too much compression and have to back the timing way back to make it run. If you are buying pistons anyway, you might see if there is a piston with a shallower dish or one that has a half dish.

I don't know if these are considered deep or not, but these are the pistons.

[jmortensen]

Unless someone swapped them out they're going to be dished pistons you might find on a 280Z or ZXT. I suggested you see if you could find dished pistons with less dish, but I didn't mean to look in the the block.

[madkaw]

E-31 block? What year is your car? It should be a P-30 block and the e-88 might be the correct head for that block. And if it's a early e-88 head it will be almost the same as having an e-31 head. How bad is the engine since you say it needs a rebuild. Bottom ends are very tough, maybe you could just get away with a top-end rebuild.

If your looking for a peppy L engine the L24 with an early head will be peppy. The compression will not be that much of a factor if this an original pairing of p-30 and e-88. So go whatever route is cheapest-I think you'll be happy either way.

Edited January 1, 2012 by madkaw

[Perfect240Z]

E-31 block? What year is your car? It should be a P-30 block and the e-88 might be the correct head for that block. And if it's a early e-88 head it will be almost the same as having an e-31 head. How bad is the engine since you say it needs a rebuild. Bottom ends are very tough, maybe you could just get away with a top-end rebuild.

If your looking for a peppy L engine the L24 with an early head will be peppy. The compression will not be that much of a factor if this an original pairing of p-30 and e-88. So go whatever route is cheapest-I think you'll be happy either way.

I have a 1970 240z #979 She should have a e31 block with a e31 head. But I'm guessing the previous owner who had it in new Mexico swapped it out? I don't know which e88 I have, it's still attached on the engine stand, I was going to get a e31 later on and install it to my e31 head to make it period correct. I might be able to get away with getting the top end redone. It didn't really smoke or anything when she ran. Just never ran past 40mph. So I don't know what was up with the motor/fuel issue. But if I have a bigger displacement motor I might as well use it if I want some fun till I can make my car period correct when I'm older and want to sell her.

[madkaw]

might want to take a minute and rethink this. You have a motor in the car that might not need to be rebuilt. The fact that it doesn't go past 40mph tells you NOTHING! Do a compression test, look at the plugs, pull the dipstick and smell and look. Pull the valve cover off and look inside-what do you see. You might have something that has already been touched up, but right now it's not running good. Seems to be a lot of unknowns to base decisions on. You seemed to have made cost a priority, so I would work with what you have first. You might have some gold covered in grease!!!