how much should I get head milled?

[HawaiianBassHead]

I'm planning on buying a p&p head like friday. And I want to get it milled to raise compression for some aggressive cams to have more tq. I know a guy from here locally that has some crower2's 1st gen I think. So I want to get it all done nice for some extra power I may never need. Might just get my old diablo reburnt too or get a SCT and sell the diablo to a friend for cheap. We'll see.

ANyhow lmk how much you think I should mil to get a desirable compression ratio and maybe suggestions on anything else I'll need to know. I'll have a capable mechanic help/do the install. ARP head studs would prolly be nice huh. Any and all help will be appriciated. Hoping to take it to the track once its running good. Thanks,

T

[johnnyboy]

Is this a daily driver? what octane do you use?

[SceviourZX3]

.060 or .070

[johnnyboy]

what's the stock cylinder head volume and deck height?

[d.bluefocus21]

I always thought 0.60 to 0.70 was too much? I would go w/ 0.40, that seems to be good enough.

[dynomyke]

Find out what compression you want and go from there.

[new03zx3]

i was told by ray at mcnews that decking/milling a head .050 will bring compression to 10.8:1 so .050 or so would be about as much as id go.

[Lil_RedZX3]

No, .050 will be more like 11.2 to 1. Mine is milled .045.

[FastFocus02]

i milled mine .085, lol... which puts me at 12.5:1,,, but, im not a pussy like most, and i'll drive a full race car on the street, that camms like a mother and shakes and vibrates like a bitch.... most people cant handle that kind of power/driveability...

[sleeping_focus]

how much power does your car make, you ever run the 1/4?

[Focusedat50]

.040 or .045

[ZX3weasel]

.040 gets you pretty decent performance and drivability. I was very happy with the way my car performed w/ 10.6:1 compression. 163whp and 155wtq is not shabby...

[HawaiianBassHead]

well, seeing as how radical cams lower compression with cams the milling won't have AS high of a copmression. I run 92-93oct only anyway with my chip. and its a ported polished stock head to be getting some 1st gen crower2's for about $200 with cam gears too. so I'm figuring .050 is a good starting point we'll see. keep um coming incase I get a good reason not to mil it. I should be buying it firday or MAYBE next friday if I HAVE to.

[HawaiianBassHead]

daily driven, but I'll run cams that damn near kill the engine just for the caming sound and extra power

[ZX3weasel]

one thing to keep in mind: the higher you bump the compression the trickier it gets to keep the car from detonating. This becomes a bigger concern for people that live in warmer/hot climates. If you have a multi-file chip I would have them make a profile with stock timing for those toasty days.

Higher comp also beats up the engine a bit more... I suppose if this were a concern we wouldn't be pushing these cars to their limits

[JohnsZX2SR]

The table below gives the approximate amount (+/-0.003") you need to mill the head on a 9.6 to 1 Zetec engine to raise the compression ratio. Small manufacturing variations in combustion chamber volume will give some variation in results. If you want to match cylinders you could "cc" the combustion chambers after milling, chamber polishing and doing a valve job.

mill (in) -- CR
-----------------
0.000 --> 9.6
0.018 -> 10.0
0.026 -> 10.2
0.034 -> 10.4
0.038 -> 10.5
0.042 -> 10.6
0.049 -> 10.8
0.056 -> 11.0
0.060 -> 11.1
0.063 -> 11.2
0.066 -> 11.3

I suggest having the head milled between 0.025" to 0.040". Less than 0.025" isn't worth the effort and over 0.040" starts to require better attention to tuning to avoid detonation on pump gas (sepecially if you can only find 91 octane in your area.) While you have the head off, get a nice 3 angle vale job and clean up the intake and exhaust ports.

[FastFocus02]

i have a question,,, hopefully someone knows this... i know really aggressive cams lower the C/R, so... could i run 13.1:1 on 93 octane with crower stage 4 new grind cams? 2nd question is this: i have an svt bottom end, and the head is milled .085" for 12.5:1 C/R on a zetex bottom end,,, if i put that head on the svt bottom end will the svt pistons hit the spark plugs? i really wanna put my old head back on but need to get a thicker head gasket to bring the compression back down to 12.5:1, if .085" on an svt is too much...

[FastFocus02]

oh, and i dont mean to highjack the thread... sorry if i piss someone off for it. lol

[HawaiianBassHead]

FastFocus02 - no big, everyone thread jacks sometime in their life . I'm very intrested in knowing how much to mil for a desired C/R with the 1st gen crower 2's. But I think maybe I should just email crower for that but they might not even know. I think we both need to find someone with alot of experience with crower cams on zetec's to get the clearest answer to the questions we have.

John- I'm getting a ported polished head to mil I'll see if it has a 3 angle valve job done. What are the benefits of the 3 angle?

Thanks all keep in goin til I gain more knowledge to see what the best option for me is.

I'm hoping to get the car faster then run N2O for them track days .