3VZ-FE Head Skimming & Compression Ratios

[headcase]

I got some on my 3vz
:-)

[cdwood2010]

Nice. Did you make those?


c.

[headcase]

No I got these of Jeff about 3yrs ago now :-)

[cdwood2010]

Very cool. Got some flanges here, might be worth a looksee!

:)

[AlunJ]

In either case, supporting mods would make the best of it. I think a good intake on an N/A is always a must, but both would benefit from decent headers. Most people use the stock 3VZ pig iron headers, but what it really needs is something like Goukys headers......

For N/A tuning it's all about smooth flow so headers certainly wouldn't hurt. It's certainly about the supporting mods too, with intake, cams and headwork to make the most of it. The 3sfe / 3sge differences show a fairly good example of the differences that can be made. Wonder if a couple of sets of triumph throttle bodies could be used for an intake setup? Because.. well because throttle bodies :icon_biggrin:

The whole thing with piston compression is interesting. Forced induction cars run a lower piston CR because their on-boost CR is significantly higher than an N/A engine. An NA engine at 10:1 has a compression pressure near 10 bar. A FI car with 8:1 piston compression (when boosted to a bar and a half) has a compression nearer 20 bar. Lower compression ratios for FI are an exercise in detonation control at the cost of performance. There are some situations where raising the CR for a forced induction engine to N/A levels is beneficial too.

[adamh]

if you can find a machinist they can make the hole a radial slot fairly easily.
its not a great amount metal in a pulley, if you machine a symetrical pattern on the same radius opposite to it (other side of centre bore) it would be better than not doing it. if you d.i.y with a dremmel then work out the volume of metal removed and pop a hole through, or a series of smaller holes with a drill on a scribed arc, the same volume as what you took on the opposite side of the centre. it wont be too different.

Might pinch some off you. Dunno if they need to be balanced though?

[wood_patrick]

Probably a better idea to get them done properly somewhere in hindsight then, better to be safe rather than risking damaging the bearings or cams.

Might park this till a later date and can always swap them over again. :-)

[cdwood2010]

You might need them.

If taking 0.5mm of the head shifts the timing, which it must, then a cam adjust may be essential.

I'm not sure how much of an impact the skim will have.

Also have a chat with Sean Hurley, he may well have something already that could be adapted.

:)

[wood_patrick]

Yeah but dunno how accurate the cam timing is to start with. :-/ Plus it's not much different than someone using a bi-metal headgasket, Im just doing it the cheaper way. :-)