E88 Chamber CC reduction after a shave?

[Black Beaut]

Hi All,

Does anyone know roughly what the chamber cc will be on an E88 after a 0.030" shave? I need a figure to plug into the engine calculator. I've been guessing at 42cc so far.

Cheers,

Rob

[Gav240z]

I could be wrong but i think you'll find earlier E88's those found on a 72 Z are higher compression than the later any idea which you have?

I wouldn't trust the engine calculator as i believe it's not quite perfect it may give you a correct answer but it has a few bugs.

As for giving you an idea i haven't the slightest idea.

Gav

[MikeW]

Ok, I may be in way over my head here but it seems like you'd calculate it as follows:

Original E88 head volume : 44.7cc

L24 cylinder bore: 83.0mm

L24 cylinder radius: 41.5mm

0.030" = 0.762mm

Cylinder volume = pi * r squared * h

Volume of cylinder removed: pi*(41.5mm)*(41.5mm)*0.762mm

4122.88 cubic mm or 4.1cc

Resulting volume = 44.7cc - 4.1cc = 40.6cc

[Zvoiture]

Ditto...make sure you have verified WHICH e-88 you have.

steve

[Black Beaut]

Thanks guys, I was thinking about working out the volume of a 0.030" high cylinder but wasn't sure what the diameter would've been, 83mm makes a fair bit of sense though :stupid:

Now then on to verifying which type E88 I've got to start with. What are the give away clues? Mine has 42mm inlet and 34mm exhaust valves. Still has brass inlet seats but the head has been given a workover already so they might have been changed in the past already.

Having bought it from the joy that is Ebay, it's origins are a bit of a mystery.

Cheers,

Rob

[Zvoiture]

There is a visible casting difference inside the chamber by the sparkplug. It is present on early e88's and absent on later. There is a good picture of it on Z garage or Zhome...can't remember which.

steve

[Bambikiller240]

The valve sizes are the same as far as I know on bothe early and late E88. Attached pic shows config of Early E88.

[Black Beaut]

Cool, thanks. Here's a couple of pics of my head. That area is clearly less pronounced on mine. What do you think?

Cheers,

Rob

[Bambikiller240]

Doesn't look like the early E88 head to me, unless someone has been "playing with it". What does everyone else think?

[beandip]

send a email to phred , he is a member here . This guy does heads for race z engines .

[Ed]

This head has definately been "played" with. Both the intake and exhaust have been polished, the area around the valve has been unshrouded and smoothed out. To guess the chamber cc would be wrong since the chamber has been altered. The only way to calculate the chamber cc now would be to measure it again.

Find a piece of clear plexiglass that would fit over the entire chamber a 4x4 inch piece would be enough. Drill a 1/4 inch hole in the center. Useing one of those chemistry set glass beakers(sp), one that has measures in ml. Fill it with 50ml. of water. Install the valves with one spring for some tension and a spark plug. Carefully pour the water into the chamber through the hole in the plexyglass. Subtract the difference to find your chamber cc.

Nice work by the way. Too bad they didn't replace the intake valve seat while all that work was being done.

[jmortensen]

Rob your head is definitely early E88. The mods look almost exactly like what I did to my E31, except I have the bigger 280 valves. It appears to me that on your head the valves are unshrouded too, so the headgasket may not seal on an L24 block. It's kind of hard to tell though, just by the pics. Best thing to do is to lay your new headgasket down on the head and see if the fire ring is exposed inside the chamber. The one thing that I think was missed by whoever worked on that head is the threads on the spark plug hole. When the heads are machined they tap the hole and don't stop once they get past the "used area of threads. So you have that triangular patch of threads leading into the chamber that are exposed and have sharp edges. The rest of the chamber's sharp edges are all taken care of. Not sure if that will matter to you or not, but that is a potential source of pinging when you bolt it onto a 280 block, especially with flat tops.

If you are going to put that on an L28 I'm sure that the unshrouding won't matter.

EDIT--just looked again, you can see in the pics where the headgasket sat. If that is really the inner edge of the fire ring on the headgasket, then it looks like you could take some more metal out of there, lower the compression a bit, and get a little more flow.