after over 600hp daily use,i move to mobil 15w50 and engine didnt want to shutdown oil light after first start,after starting and shuting down for 5 times,i decide to let it run and after 5 seconds oil pressure come up.after running 30 miles a slight knocking noise, i remove the crankcase and the Cosworth bearings was smashed.crankshaft is ok. now im wondering to keep using 10w30 or run looser clearances? any experiences with this?

 

your engine builder should have reccomended what oil to use most of them use thicker oils when running high boost.

i even have a couple local customers that sware by 15-50 and thats on stock engines still.

 

Depends on how "loose" you left the clearances. If they are a little looser than you should be running a thicker oil.

I dont know of too many people that build real high HP 4G's and run real tight clearances, maybe some do just not most I have seen.

At least the crank is ok.

Mitch M

 

Well the op built his own motor. So he should be able to tell us his clearances. Well thats what I got from his signature, built and tuned by manny. The several motors I have built I have never been so tight that a 50wt oil couldnt have still worked. You must have been sub .0015 clearances. In some honda's I built I ran some .0018 clearances and ran 50wt making over 600whp and never had a bearing issue. I see the 4g's like it a little looser, right around the .0020 mark with some 40wt or 50wt should have no problems.

 

so was this do to mechanical failure or oil failure
im at 418 hp on pump gas and i used cosworth race bearings i use 5w 50 molbil one syntetic is this good or bad choice for my evo 8???

 

Hate to say it--but that crank needs to be turned if it had a bearing failure. Replacing the bearing alone will get you the same result. Sounds like you had bearing issues prior to you oil change to heavier weight if you had an oil light on at start up. A bad bearing will show a pressure drop for oil, especially at idle hot or cold.

 

Def sounds like prior bearing failure, I have quite a few miles on stock motor w/ Mobil 1 15w-50. Sorry to hear this...

 

well ,i build the engine,clearance was .0015,my speed shop have some ALC bearings with a looser clearance than stock.im thinking to get this one and check clearance in the .002 side instead. the issue is i install a 65mm throttle made by my friend and ported matched the intake manifold to the head just like buschur.when he was doing this i remove the crankcase to take a look to the bearings,everything was like first time install,i put everything back,only thing i change was oil type to 15w50.when i crank the engine i notice what i say before about the warning light.will check oil pickup for cracks or any sign that wil delay oil suction.i have use 15w50 and 20w50 in all my old school engines with out problem,but now im afraid in the Evos.

 

Mandy it sounds odd, one would not think that just by pouring higher viscocity oil and then starting the engine and all of the sudden boom an issue arives,,, ver odd maybe a 40w instead of 50w i know you are down in the island and those high temps and turbo charged cars get pretty hot

well good luck, if we can help with any oil needs let us know.
hablamos espanol tambien

 

i forgot to mention i change the headgasket to EVo9 cause a slight water consumption after a run with the Water inj hose popoff.will install new bearings and check clearance and try again 10w30.if startup problem persist ,time to new oil pump.

 

i use 5w 50 molbil one syntetic is this good or bad choice for my evo 8???
i live in a hot area

 

Hey thats cool man. I was doing 600whp daily too. I switched to Mobil 15w50 and the next day I spun a bearing too..lol How sweet!!!