metal head gasket thickness.

[IJ.]

Not enough to make a difference Joel!
that's only 0.15mm.

As an example I'll be running a stock deck height block a 5 thou clean up cut on a new head 104 octane LPG and 30 pst boost.

I haven't run the numbers yet but going by past experience I bought a 3mm Cometic as this "should" put me in the high 7's for comp ratio.

When I get my head back I'll CC it then do the calculations properly to double check.

 

[Joel W.]

been reading your build, sounds like its gonna be a monster... gj.. thanks for the info btw.

 

[IJ.]

Thanks Joel,

It's not rocket science just remember always err on the safe side!

1 bad detonation will ruin your whole day!

 

[Joel W.]

i hear 1 or 2 ping sometimes. is this normal under boost? then the ecu should retard the timing back a bit as needed? i only hear it about 14 psi rarely? i dont like it but have been told its normal... sorry im hijacking the thread...

 

[IJ.]

Doh! sorry I misread one of your earlier posts and didn't realise you were running 14 psi.....

Either run some better gas or back the boost down a touch, you're correct the ECU should hear the detonation and back it down but under certain conditions this all may happen to late to save the HG (Boosting up a hill on a hot day)(good excuse for a bigger more efficient IC)

 

[Joel W.]

with this new 3" dp and exh installed, i have backed the boost back to about 12psi, i retarted the timing to 8 deg. this seems to help. i plan on a metal hg when and if this new stock one blows.. start ordeing parts and put em on the shelf. low budget here...

 

[IJ.]

Good move backing the boost down Joel!

 

[Joel W.]

yeah, ty, the boost creeps up on me now with this setup. like in my (boost creeping ) post so i have to watch it carefully.. should i go back to the 10 deg timing? my hood sticker is unreadable so i dont know if its 10 deg stock or where i should set the timing at with my mods? again im a hi-jacker...:3d_frown: hehe.. thanks

 

[IJ.]

Correct 10 degrees.

I'd even back the boost down to maybe 10 psi in case it spikes on a hard pull.

As I said detonation will kill it so better safe than sorry!

 

[Joel W.]

auzie, auzie, auzie,,,
ahhaha watchin the wsop tourniment finals

 

[IJ.]

LMAO Joel!

The "Gee Whiz" factor of 14 psi is far outweighed by the "Oh Shit" factor of a BHG

 

[Joel W.]

but i secretly in the back of my mind want to blow it, so i can justify the rebuild... :icon_evil

 

[IJ.]

LOL thought you said funds were tight?

Even a basic rebuild on a 7M is expensive Joel

Better NOT to hurt parts before the rebuild.

 

[Joel W.]

ya im not in any hurry. bhg is not bad as long as stop drop and roll.. dont drive it.. happend 26 miles after i bought it lol..

 

[IJ.]

Yep only hassle is our heads tend to anneal when they've been overheated a few times and go soft

 

[Joel W.]

ohh, ya...when mine went, it was like the smoke screen on james bond movie under boost. the car (i had just passed) behind me disapeared instantly... i stopped right there and towed it home.. it never overheated that i know of..

have a good one, gotta go eat turkey....

 

[ronniek]

Finally my supra is back on the road with pwr radiator and cylinder head ported and polished.
Only 1 problem left to fix.The temperature gauge does not work.
I did a compression test when I put the engine together and average cylinder pressure was 150 psi.
Ronnie.