the biggest problem with all 4AG's is the crank oiling. nearly every one that comes to our engine shop for repairs, has an identical problem. this can be helped by changing to the latest spec, 3/4 grooved main bearings, as it gives slightly better crank pin oiling.
I have never seen a stock 20V piston fail in a street car, and only once in a race engine.
IMHO the thin TRD head gaskets are just a wank. after you remachine the head and block faces to get them to seal properly, the compresison ratio is raised ever so slightly, and with our notoriously variable, fuels, you can get more detonation problems
PM if you want more detailed info or see .
I also agree that these things are tough as, I revthe crap out of mine every day and its slowly using more oil as time goes on. I had a friend with a 16v that blew a big cloud of some when he accelerated and it was like that for 2 years of high km driving, it never fully died.
So terryo, what do you think of the new race series ACL bearings? do all acl bearings have the grouve you mention? SO can you explain exactly what fails and how it does so?
30kw club
The grooved bearings are more than likely the ACL "race series".
ACL forged pistons are a good replacement piston.
At work when ever we get in a 3sgte / sr20 / ca18 for a stock motor, we'll more than likely use forged ACL pistons in them.
Bearing failure can be due to time, oil starvation and so on...
My AE86 race, street, drift build.
http://www.ae86drivingclub.com.au/fo...ead.php?t=4156
With Super Thanks to AJPS for all your AE86 and BBQ needs.
a couple of people, including ACL, make 3/4 grooved bearings for their "race bearings".
the problems are the same with 4AG & 3S as they both have simialr design faults
case 1) owners let the sump run a bit low, hard cornering causes mometary oil starvation, bearing picks up from metal-to-metal contact.
case 2) owners rev the crap out "old" engine. the oiling design causes momentary loss of oil flow from main to big end (oil flow is cut off due to crank oil gallery design) big end bearing fails from metal to metal contact.
case 3) combination of 1 & 2. this seems to be common on drift car engines
the ACL race bearing helps with case 2 only ,as they allow each big end to be fed with oil from the adjacent main bearing, for a longer time at the critical point. they help stop the flow getting cut off instantly. the ACL bearings are very fussy on size. the tunnels have to be perfect to get the correct crush on the shells.
the factory fully grooved bearings (7A) are another solution, but they have lower load capability.
sorry i dont quite follow,
higher compression along with slightly advanced timing and high octane fuel and the 20v shouldstill run smoothly right?
a slightly higher comp require other modifications???
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