Could the engine take it?

[WishN4DaZ]

Lets say i took a 75-76 280z, with its N42 cycl head and on re-build i threw in some flat topped pistons to raise compression to approx. 10.4:1

#1 would it work

#2 would the engine just go boom

#3 what kind of performance gains could i expect if it did work

Now i assume some machine work wouldn't have to be done to the head the strengthen it a little, but the thought still stands.

Matt

P.S i chose the N42 over the N47 becuase of the square exhaust ports.

[Phacade]

1. Maybe

2. Maybe

3. While the old school of racing seemed to believe that higher compression = more horsepower this really is not necessarily the truth. It COULD mean more power, maybe a little more torque. If you wanted to run flattop pistons, why not just go for a F54 block out of a '81-'83 280ZX. You can slap your N42 head on top with no mods and have the same setup pretty much. Carbs or EFI at this point are your call.

[WishN4DaZ]

The reason i dont just get an F54 block is because i dont REALLY want to do an engine transplant, and i'm not a fan of the ZX bodies for some reason ( dunno really why, but not a fan )

The style i like the most is the red car on the front of MSA's catalog ( don't know the exact year so if you know it would help )

The other idea i had was an E31 head with 280 valves stuck onto an L28, that would put the compression pretty much as high as i can get it on a Z block without doming the pistons and running octane booster with every tank.

What do you think of that?

Matt

[Phacade]

Dunno. Personally I think that if you are going to go with all this trouble that a transplant is just the sme amount of effort if not less than leaving the lower end of your engine in the car. Two motor mounts, two transmission bolts, crossmember, drivelive and a bunch of wires and hose is all that is keeping you from getting a cherrypicker and rebuilding a GREAT Z engine. My dad always used to say that if its worth doing, its worth dong right.

Then again in retrospect, I am really not sure Dad said that. Good advice anyway.

[WishN4DaZ]

The way i saw it is this.....

if i re-build the engine thats already in the car it saves me from having do do the computer switching stuff...

i was going to re-build the engine of the car i bought anyway, so why not switch the heads to better ones while their off...

Why not throw in different pistons...

I could go to a turbo engine but then im looking at a whole new group of problems and confusions, i dont know much ( actually anything ) about the electrical systems of cars, and switching a newer system into an older car would simply just be to much for me to handle, im not much of a car mechanic and this project will be my first which is why i want to do some performance, but nothing to difficult.

Switching the dished to flat-top pistons would be the quickest and easiest way to add performance, but why not change to a different head while their off...thats the only reason im changing the head, becuase its going to be off anyway =)

So basically what i'm trying to say in that jumble of words is that i want to go fast as easy as possible.

Matt

[Phacade]

Here is the problem. Well not actually a problem just a pain. To change your pistons you of course need to rmove the head which means you need to remove the front end of the engine (ie water pump, dist, etc). Now you need to remove the oil pan from under the still mounted block. Possible I am told while still bolted but I have not tried it. Assuming you are able to remove the pan then you need to remove the rods from the crankshaft (because you are not going to be able to remove the pistons from the top). Once the rods are unbolted you can remove them from the top. Installation is reverse. The pain is that it will take you twice as long while still in the car.

If you are going this far IMHO I would go ahead and jerk the block and either have the block work done to it or at this point drop a F54 block in. They are the same size deminsionally and no wiring modification is necessary.

[WishN4DaZ]

The difference between doing that and using the block already installed is simply this...

$$$$$$$$

i'de have to buy an F-54 block, cost is also an issue for me....

Now if i found an older car with an F54 block already installed, maybe with a blown head gasket ( which would be great cause im re-building the engine anyway ) i might just buy that and stick the head on.

And as i said before, a main reason i dont want to switch blocks is because wouldnt you have to switch the wiring harness/computer from the year car you took? and as i said, i can't do electronics stuff...

I look at the wiring diragrams in the Haynes i got and just go "WHA?":confused:

and thats a major problem for me...as i said this is my first re-build so if you have any helpful tips or info please let me know.

P.S a website with DETAILED info, like first take out this bolt then take out this bolt would be great ( already did datsun garage )

Thanks

Matt

[Phacade]

You do not have to touch the wiring. Leave it. You could swap the block out and then slap your head back on it and then put all the injection and wiring back where you found it. Will work fine. I swapped a F54 block with a P79 head into my '73 240Z and had absolutly no problems. Changed very little of the wiring. Of course I went to electronic ignition so you will not have to do that. Basically all you have to worry about is the mechanics of this. Believe it or not, its basically a big jigsaw puzzle. I recomend a few good books like the 'how to rebuild your OHC datsun engine. I can't remember the author's name. Remember: new seals, rings, pumps, and pre-lube is a must!

[WishN4DaZ]

thanks alot i appreciate it.

Matt

[McZ]

The book Timberwolf was talking about is How to rebuild your Nissan & Datsun OHC Engine by Tom Monroe. You can get it from Amazon.com. Another good one to go with it is How to modify your Nissan & Datsun OHC Engine by Frank Honsowetz.

[WishN4DaZ]

thanks