ive bin searching the net for days now....ive got a 4age bluetop tvis map sensor motor in an ae 82 rolla and im starting to hear the infamous knocking noise (however cant complain got the car for $1500 bucks from a wrecker).
from what ive read....i got a few options...
newer 4age smallport head transplant
4agze transplant
4age 20 valve transplant
and i dont want the hassles of engineering/changing computers/harnesses or the thought that i might be buying a grenade
so i decided to re-build my 4age...
now i was thinkin to get some 288 cams with about 8.0 mm lift not too much lift still wanna use the shim over bucket set up.
(some people say big duration and stock computer no-go and i
read that if i bump compression up at the same time i might be ok...so im a little confused there)
and i know i need more compression for the cams....this is where i cant find any good information on the net...i know u can get thinner head gaskets....but my stock compression is 9.4 and im looking to go to 11.0 or there abouts...will a thinner head gasket do enuff?
im guessing not. Im thinkin ill have to shave the head...but can i shave it much...Am i gonna connect valves to pistons/pistons to combustion chambers? ive heard about bottom end realiability problems with shaving head and thin gaket...how is this?
i will need to do to get that 11 to one compression ratio tho...wanna keep stock pistons if possible to keep costs down. got two cousins mechanics so labours cool just need to pay the parts....dont have much cash want to try to maximize it where i can...and im gonna do the exhaust for sure (one day).
if nyone can give me any info on these things or help or comments feel free to write something!
Location: Redbank Plains,near Ipswi...
Registered: May 2002
Re: 11 to 1 compression on bluetop?
Wed, 02 June 2004 22:08
that compression requires better than our premium unleaded--forget it.
i have billet cams available but only a few are OK with stock computers. your comment is basically correct
anything above about 9.8:1 is a custom piston. you need to know if you have 19 or 20mm gudgeon pins.
you cant really shave the head much as it hits the valve edges. compression is raised by piston design.
Location: Redbank Plains,near Ipswi...
Registered: May 2002
Re: 11 to 1 compression on bluetop?
Thu, 03 June 2004 10:34
the combsution in the 16V engines is heavily disturbed by high dome (high compression) pistons. The 20V does not have this problem. Also, it has a knock sensor to help manage this problem. You cannot just compare CR's . There is experience that shows cutting the crowns on hi-comp 4AG 16V engines stops some detonation
I see...
i got the cams wrong (soree)...they were 280 degrees and 8.0 mm lift...a lil bit more sedate.
oh my engine does have knock sensor...i found out when i put the dizzy timing too high..
im wondering whether u think these cams are a possibility on a stock computer...i can put up with some roughness...how do u think these cams would make my car run? would it be totally useless?
or maybe with a piggyback fueller....
am i right in thinking higher compression will be better for the cams tho?
Wed, 02 June 2004 17:18
