ompression test high, why?

[shift_down]

Ka24de
Turbod
91 octane

I ran a compression test before I blew my hg and I had 180 across all cylinders. I got my head milled and now is 210psi on all cylynders. Could this be because of milling the head? And is 91 octane good enough to not worry about detonating at a high compression?

[di-devol]

The throttle wide open when taking the test? How much did the shop take off the head?

[Croustibat]

Ka24de
Turbod
91 octane

I ran a compression test before I blew my hg and I had 180 across all cylinders. I got my head milled and now is 210psi on all cylynders.
Could this be because of milling the head?

Of course it is. When milling a head, use a thicker headgasket to compensate... even more when you are going turbo, as you need lower compression.


And is 91 octane good enough to not worry about detonating at a high compression?

No. Not even sure 93 octane would be enough with that pressure ratio.

High compression would work wonder with e85 though.

[shift_down]

Alright, thanks for the input. I might switch my tune over to e85. Thanks for the help.

[Croustibat]

The simplest would be to just fit a thicker HG, because e85 conversion requires bigger injectors, remap ... and a supply of e85.

If you are ready for this, go ahead, you wont regret it (esp with a turbo engine)

[feito]

Same thing happened to my brothers 13 after refreshing his ka. I even made a thread too, guess it just proves how naive we are, even when it comea down to basics. The more material u remove from a head when resurfacing it, the smaller u make the combustion chamber, thus increasing the compression. It also throws off mechanical timing on ohc engines such as ours.