Head Choice

[76124]

Which head would you choose?

Bottom end is a 1592, balanced, HC Pistons 10:1, crank scraper, lightened flywheel, etc. Fast road is the purpose here.

Head choices are

1.8 - Rebuilt ready to go with a performance intake came, Adj pulleys, performance springs, with a 34/36 DMSA single plane manifold, 4-2-1 OEM cast iron manifold, Crane cams electronic ignition.

1608 - Needs total rebuild, would swap the above performance parts over to it from 1.8 (Yes the front water passage would need to be welded.)

81 FI 2.0 - Needs total rebuild, would swap the above performance parts over to it from 1.8

I am leaning towards the already ready to go 1.8 for both cost and convenience. Not sure the 1608 or 2.0 head would yield enough performance increases to warrant the cost of the rebuild. 2.0 would also lower the CR and the 1608 would keep it close to spot on. I believe the 1.8 head has the same, or similar (lots of factors effect head volume) volume as the 1592 head, so probably no affect on CR there.

Thoughts?

[So Cal Mark]

I'd use the 1800 head, don't really see any reasons to consider the other options

[FiatMac]

The 1800 is your best choice.

The 2.0 liter head will drop compression ratio considerably due to the larger combustion chamber size. You will lose all the compression you gained with the high compression pistons and more.

[76124]

The 1.8 is what I wanted to hear!

Thank you!!

[vortspeloce]

The 1.8 is what I wanted to hear!

I should have a side-by-side photo of an 1800 vs 2ltr head. If you would like to see the combustion chamber differences I can dig out a photo?

[76124]

I have all three sitting here, so I can see the diff. I was just curious more from a flow stand point rather than what it would do to the CR. The domed pistons are at 10:1 so losing some wouldn't be the worst thing for pump gas but not too much to negate them all togther.

[baltobernie]

4mm domed pistons in an 1800 head with two 40/80 cams resulted in cylinder pressures in the 225psi range in my engine. With only one performance cam, your's will be even higher (less overlap). You might want to consider one of Mark's head gaskets for this application, and of course 93 octane fuel.

[76124]

4mm domed pistons in an 1800 head with two 40/80 cams resulted in cylinder pressures in the 225psi range in my engine. With only one performance cam, your's will be even higher (less overlap). You might want to consider one of Mark's head gaskets for this application, and of course 93 octane fuel.

Thank you for that info. I was thinking this was going to push the pressure up pretty high. I am looking at one of Mark's thicker gaskets on this to keep tings together. New head bolts as well. Anyone know of a source for head studs? But then again the head may not clear the firewall with studs for future removal! The 1592 with Jason's lightened and pinned flywheel should really rev quickly for some zippy spring time fun.

[LIQUIDLOUNGE]

If you feel your compression is already too high, going with a thicker head gasket may not be a good way to resolve your issue. A thicker gasket will increase your quench and make the motor more prone to detonation. I do think the MLS gaskets would be perfect for these engines though. I would discuss which gasket to use with Mark or someone who really knows these engines. Isn't the 2L fi head supposed to have the slightly more advanced combustion chambers?

[76124]

I wont know where the CR is exactly until I measure it all but I don't think I will be in trouble. I'll admit I need to read up more on the squelch. This is something a bit new for me..learn as you go as with so many things.

Be happy to finally get this motor in my car after a long time waiting But I want to do it as right as I can. Can't believe I went two summers without driving my Spider. First time in 20 years of owneing it.