[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

16v head on a 1.7L engine



>     Umm, scott, the only reason compression goes up with 1.8 head + 2.0
> block is that the 2.0 block has less area with piston at tdc than the 1.8
> block does. The 2.0 head has more area under the valves than the
> 1.8.

Er, Allyn? You're incorrect, bud. :^) First of all, it ain't a 2.0l versus
1.8l issue. The combustion chamber shapes are different from 8v to 16v
motor. Just look at the head and pistons. The 8v has a relatively little
volume in the head itself but the pistons are dished. Whereas, the 16v has a
near hemi-spherical combustion chamber and the pistons are flat. The only
exception that I know of is the oldskool 8v "Heron" head which also had flat
pistons.

If you install an 8v head on top of a 1.8l *or* 2.0l 16v bottom end, the
compression ratio will shoot way up (makes for a nice NA race-only motor).
And, if you drop a 16v head on top of a 1.8l *or* 2.0l 8v block, the CR will
drop. These are facts!

> P.S. is that your gti that shows up for like 1 second in those
> rally videos?

I'd have to guess not. The footage in that flick was taken up in Canada. To
date, I have never rallied up there. I was planning on gettin' sideways up
there this season, but... well... you know the story. :^)
--
Scott F. Williams
NJ Scirocco nut
Golf GTI 16v rollycar
Mazda 323 GTX turbo assaulted vehicle
'99 Subaru Impreza 2.5 RS (coming soon)
ClubVAC: "Roads found. Drivers wanted."

Check out our rally team's website!
http://www.usrallyteam.com