More headwork Fail questions.
 

Paul and everyone's 99 motors seem to be running really well.

We all know you really want to go lower compression on a build for boost. But the 99 seems to be holding up great at 9.5:1 compression ratio.

My brothers S/C car is the old style. The nose is not upgradeable. But we found away around that. The JR1.8 version had a smaller pulley. Something like 67.5mm I think. Bam 2psi. YAY!

And if we get the crank pulley 2more psi, for hopefully 8-9psi.

Head milling question

We thought about milling the head on his car some. Since he will never be high boost, we would like to gain some compression. 9.5:1 would be great, if there is enough clearance for the valves. Otherwise, whatever is safe for the valve clearance.

I know it isn't going to be crazy power, but the 99 is holding great with up to 14psi on 9.5:1

What do you think about this. Milling is cheap, and we are not going for stupid compression. Just somemore responce and low end. All for $20 milling from a family friend, gasket, and time.

do it.

Considering the 1.6 was actually 8.8:1, you're not going to get 7/10 of a compression point out of milling the head. I had a head decked once and noticed no difference on the butt dyno. However, I'm a bitch.

One thing to keep in mind about milling an aluminum cylinder head is that once you remove material from head it will not be able to deal with overheating situations as well as when it is at it's normal deck thickness. Mazda recommends a new cylinder head if it is warped by more than .006".

Take it for what it's worth.


Tony

Hmmm.............. We'll probably just go a head and get the crank pulley.. And save that thought for when he is tired of the new found power.

Is there a stronger material, but thinner head gasket?

Dyno's sometimes read different from week to week, and place to place. I had a GSXR1000 read 143 hp one place and 153 another. But I did think it gained some power after 7000 miles.

Hustler could you feel any difference?

The 1.6s were 9.0s. Only 94-95s had the flat-topped 8.8 pistons.

If it were me, and I was going to have a reason to pull the head other than to mill the head, I would do it while it was off. I wouldnt remove it just for that reason though. Im quite glad I did mine though, since I think higher compression will be helpful since I only have 8.8:1, and dont plan to do over about 8-10psi on a 2554. I had .015 removed from mine, and will probably have another .005 removed when I bring it to the machine shop again to remove some minor dings in the surface from sliding it on a table top. Though a whole different animal, I had the head from a Honda Prelude milled .020 years ago, and did notice a slight seat of the pants gain(very slight, maybe). It was n/a though, making maybe 160-170whp, already at 10.5:1 if I remember correctly, so it may have gone up to upper 10's or low 11's. Not sure that you would be able to tell a thing with an over 200whp s/c car though, not likely.

its useless and unsafe. dont do it.

Why do you say it is unsafe?