Which head is best..

[Gav240z]

Never even heard of an 05l head before???

I don't know which engine heads the L20 had but I'm pretty sure I recall something about a E30 engine head.

Seems a strange setup is it the L20 six cylinder?

If you going to go with an L24 setup I would change over to a early E88 or E31.

I've learnt the early E88 were almost identical to the E31's.

Also the earliest of the 240z's had about 9:1 compression and the L24 loved to be revved with the 3.9 rear end.

:classic:

Here in AUS anyway.

[HKSZ]

Its a strange one alright.But not the first time I've come across a L20 6cyl, the first 260z I owned had one, the sneaky owner had put a slash above the 0 in the L20 block number making it look like a L26 only when taking the head off and finding coke can size pistons did I know what I had:sick: That head was an e30 but this 05L head has a filled in chamber like the p90 so I wonder whether it would benefit from porting and 280zx valves.

steve

[Caen Fred]

I you shave the head, taking away material, then the total height of your engine will be shorter, right? your camshaft will be lower and your timing chain will slack more putting your timing out of sync... In order to put back your camshaft to the original height, you will need longer cam tower, hard to do ! or you could just put a shim under the cam tower from the same size you took of the head... restoring the right length for the timing chain, voilà !

If only I could speak English...

[hf240z]

Hi,

now i think i understand. do you think replacing the spring for the timing chain tensioner will not be enough or removing a link on the chain will not do it?

thanks,

Originally posted by Caen Fred

I you shave the head, taking away material, then the total height of your engine will be shorter, right? your camshaft will be lower and your timing chain will slack more putting your timing out of sync... In order to put back your camshaft to the original height, you will need longer cam tower, hard to do ! or you could just put a shim under the cam tower from the same size you took of the head... restoring the right length for the timing chain, voilà !

If only I could speak English...

[Royce]

Interesting thought! I have not heard of someone doing this so maybe it would work. I am no expert on this but I am pretty sure removing a chain link or changing the spring in the tensioner will not do it. Maybe because these are not easy ways to fine tune these adjustments. Maybe one link is not enough or too much? How much heavier of a spring do you put in? Getting this wrong could have engine damaging results. I think that is why using shimms on the cam towers and larger spacers on the valve ends is a more prefered method.

Any engine experts out there?

[Royce]

Okay, I was just thinking about this more and think I am getting dizzy! Now, I am thinking that if you take a link out of the chain it would change the relationship between the cam and crank timing. Remember the crank has a small sprocket and the cam is a larger sprocket. They are syncronized so that the crank turns twice in the time the cam turns once. So I would think that removing a link in the chain (or changing the size of the either sprocket) would upset the sycronization between the two.

Does that make sense???

[hf240z]

hi royce,

u r right maybe removing a link will alter the sync, i have another crazy idea, what about if there is a way to snake the path where the chain travel so it will appear like it is travelling in the same distance but actually it was still short distance but re-routed(zig-zag). maybe put a roller on the path...... sorry....just one crazy idea....

thanks.

Originally posted by Royce

Interesting thought! I have not heard of someone doing this so maybe it would work. I am no expert on this but I am pretty sure removing a chain link or changing the spring in the tensioner will not do it. Maybe because these are not easy ways to fine tune these adjustments. Maybe one link is not enough or too much? How much heavier of a spring do you put in? Getting this wrong could have engine damaging results. I think that is why using shimms on the cam towers and larger spacers on the valve ends is a more prefered method.

Any engine experts out there?

[Brett240]

i think if your going for ultimate performance then the p90 will work out best. it has the best combustion chamber shape, square ehaust ports, and the biggest valves.

the chamber shape on a P90 (also a P79) pushes the mixture towards the spark plug on the upstroke, reducing the chance of pinging and allowing more spark advance, i run 18 degrees at idle no problems on mine. in the end it will cost more with the P90 for a non turbo setup to get the compression but for ultimate performance i feel its the way to go. im comparing this to an e88 with similar porting.

[mikew63]

If the engine has an 05L head on it chances are its a full engine relacement from a jap import 1980 skyline 2000, which is one of the few cars I can find to have this combo fitted L20 turbo EFI with this head. I can't find any info on the head ..yet

[jmortensen]

If the engine has an 05L head on it chances are its a full engine relacement from a jap import 1980 skyline 2000, which is one of the few cars I can find to have this combo fitted L20 turbo EFI with this head. I can't find any info on the head ..yet

I haven't seen one in person, but from what I've read it is not a desireable head. Very small ports compared to the rest of them.

[zguitar71]

i think if your going for ultimate performance then the p90 will work out best. it has the best combustion chamber shape, square ehaust ports, and the biggest valves.

the chamber shape on a P90 (also a P79) pushes the mixture towards the spark plug on the upstroke, reducing the chance of pinging and allowing more spark advance, .

Those are all the reasons I would like to go with a P90. I have an E31 on an L28 right now and it works great and I will most likely not change that. I would like to build a 3.2 one day (dreaming probably), I think the p90 would be perfect for a 3.2, It should yeild about 10.5 CR with out any shaving. To make a powerful motor all the heads can work and they all take $ to get them there. So in the end you might as well start out with the best design from the factory and go from there.

[skyline_stu]

For a turbo an N42 will work with the correct piston, but a ported P90 manual lash head is the go. I've made 465rwhp (atleast 550hp at flywheel) on a ported N42, but i'm currently welding up a P90 to improve flow.

On the same note i ran a N42 with about 10.5:1 compression with a low boost turbo (12psi) and that was a great package too. Made about 280rwhp.

Stu: