hey this is cool site !

i worked 180B head on L20b engine that ran on a timing curve like this

http://us.f1f.yahoofs.com/bc/40c02149/bc/Mail+Attachments/gregs_engine_RPMDATA_12675_image001.gif?CCBzjkCBGKJtEK3t

total useless past 3000 rpm with stock dizzy but used to go good with about 25 deg to much advance and never melted the pistons! and what a racket it used to make

in the beging after bolting it down i nearly lifted the roof off the car port

trying to start it then The big bang +flash of light

split the mufflers open like they where wet paper bags

it used to carbon up plugs in about 3 months ,heat range 12 i think

i still have a few of them,the bearings in block lasted less than a year

i later reduced the comp ratio 8 to 1 this brought the total advance back to 22 deg past 3000rpm.

i felt my old engine at 8 to 1 comp had more power than the stock one im running now

i also found that changing the L20 cam to a L18 cam made a slight diffrence the knocking was less with the same timing ,but no recorded values .

here is a graph ,the top 2 points are real the rest a guess at best

http://us.f1f.yahoofs.com/bc/40c02149/bc/Mail+Attachments/estamate_of_compression_ratio.bmp?CCbxkkCBUavaCqTh

sorry this one is 2.1 meg

my mate ......helped me toss the motor out but we didnt rip the head off :eek:

im about to start work/recreate this strange thing again on a 4 cyc head in my bluebird which now has a notebook fitted to control the timing.

this program has taken over 5 years to complete.

i have data recording on accerelation figures on current motor

eg 1st gear is about 13 to 14 rpm increase per pistion firing.

the computer is not that fast only 200mhz but will run a 4 cyc near 10K rpm just

ive got 3 inputs hooked up to change things like vac adv,temp,

revlimiter.

if my new one runs ok i will port the head on 280zx the same way.

does anybody know how many deg overhead is on the L28 dissy?

i need 55 to 60 deg to play with.

can i disconnect the wiring to the dissy and redirect it to my computer or does the efi need this signal ?

Any comments help Appreciated

Wtf....???

ok here are some graphs

http://smokingwheels.myphotoalbum.com/view_album.php?set_albumName=2003

Have been grinding, polishing and flow testing

Had .070 machined off the head (just starting to cut into the bottom of the "nissan" logo now)

Chamber vol 38.5cc to 39 cc

approx 10.5:1 on the compression ratio i think it's my best guess

http://smokingwheels.myphotoalbum.com/view_photo.php?set_albumName=MyEngine&id=head_polished_chamber_by_hand

will have more info soon