I spun a rod bearing last night. It was on cylinder #1. I switched from my 60-1 hifi to a sc61 on friday and I didn't retune for the increased airflow. My techedge showed from 11.2-12.2 under full boost. It was running its *** off until the 3rd run at 19-20psi on 93 octane ( I know). What besides running low on oil will cause a spun rod bearing? I'm going to throw one of my spare gsr cranks in for now but I'm looking for a sleeved block.

 

that sucks man. Those were some awesome numbers btw.

 

It was very fun while it lasted. I was sure I would crack a stock sleeve before anything else.

 

how did you know you if you spun your rod bearing?

 

There was no mistaken the sound. I pulled the oil pan today and the bearing and crank are both scared badly.

 

is the #1 mains gone as well?

 

Haven't checked yet. I will be changing the cranks and all bearings. Do the mains and rods bearings normally go together?

 

not always but if the #1 mains is out, its usually a sign having to do with your oil pump.

 

Its really hard to spin a main bearing, you would have to be running on almost no oil. You spin a rod bearing becuase the lack of oil caused it to overheat and swell. If it was a freshly built motor it could have been caused by too much oil clearance, which would mean lack of oil. This is a far fetch, but if the oil gallery for that rod got clogged it would cause it. Most likely it was just the lack of oil.

 

I checked teh oil this morning and it was maybe 1/3 qt low. So I don't think that was it. Could it be from running 19psi on my new turbo and just flowing to much air for 93 octane? What can cause a spun rod bearing besides lack of oil? The motor has about 32,000 miles on it. I want to figure out the problem before I do it again. Or will just running lower boost on pump gas solve my problem?

 

You have to understand that when you lean a motor too far it causes detonation. The pounding from the detonation can actually beat the big end of the rod into an egg shape. Once that happens, there is nothing left to hold the rod bearing in place and it will spin.

 

Earl are u guessing the rod is screwed?

 

i think thats what hes saying.
i was kinda wondering how far you would go
if it wasnt for the sc61, youd still be fine
in the end youll be even quicker though.

 

I'm suprised she lasted this long. I have some parts laying around that I never installed because I was scared to change anything. I knew I was running leaner with the sc61. My techedge was showing about .4-.6 leaner everywhere than before but still not leaner than 12.2. The best thing about the sc61 is it spooled up just like my 60-1hifi.

 

So the sc61 spooled just as the 60-1 hifi? When do u start boost and when do u get say 15psi? I'm really curious about the performance of the sc61. Also, sorry about the motor. Paul

 

Rod and crank normally

 

also if the bearings have been in there awhile and the top layer is wearing off, the bearing becomes soft and will catch the crank and spin it. Might check for stretched rod bolts as well.

 

hey sorry to hear about your motor.

earl, i was curious as to what precautions may be taken to avoid spining a rod or crank bearing, damaging the bearings or wearing them out prematurely when using a built motor and turbo combonation??

other than having the oil passages perfectly clean, the oil level correct, the oil pump functioning 100% and the bearing sizes gauged correctly, is there anything else that can be done to a moderate/high boost block?? such as torquing the bolts bolts down more? or gauging the bearings a little on the tight side?

i'm building a turbo motor now and i certainly don't want to spin a rod/main bearing. i haven't had any problems with spun bearings in the past and i'd like to keep it that way, even if i'm running 15-18# of boost. the pumps/gaskets/seals of course will be brand new OEM ones and everything assembled correctly.

 

how'd the sc61 feel compared to the hifi?

 

It was obviously flowing more air

 

Fresh rod bolts and be sure the big end measures perfectly round without the bearing installed. A proper tune-up and good oil pressure will keep it that way. Also micropolishing the crank will help along with a balanced crank.

 

ok, thanks for the reply. i'd never use OEM rod bolts on a turbo block, nor would i reuse old rod bolts unless they were ARP and in perfect shape. i'll be using brand new Eagle rods with my B16A setup, but i guess it doesn't hurt to inspect them and make sure the journals are perfect.

this leads me to a couple other questions concerning my turbo block buildup.
i'm using a B16A block and will be sending it to GE Mfg. soon, maybe this week.
i'll be using new 84mm Ross pistons/rings/pins/locks along with the Eagle rods and ARP headstuds. i also have all new OEM parts (pumps, belt, gaskets,seals) except for bearings.

so what i'm concerned about is: when i send my block and pistons to GE for sleeving and boring etc., would it be a good idea to also include the rods, crank and mains so they can assemble everything for me to spec? i've never sent anything to them before but i hear that normally their work is very good and warrentied.

from experience with GE (if you deal with them) do you think that i can rely 100%on their bearing gauging, ring gapping, rod bolt torquing and assembly??