Basic engine rebuild and bearing clearances?
05-31-2016, 04:42 AM
#1
Basic engine rebuild and bearing clearances?
Will be pulling engine out for some maintenance, fixing oil leaks etc and painting engine bay. Considering a small rebuild since i will be changing rear main seal etc. i have lots of experience taking the rest of the car apart but have never done internals before.
Car is an 03 g with 66k miles. It has had a procharger kit pushing 14psi on it for maybe 5k miles and has seen 75 shot of nitrous one time before i sold the kit.
Here is my parts list so far:
Eagle/BC rods
ACL race bearings HX
wiseco pistons 96mm 11:1 - bought
ARP main studs - bought
ARP L19 head studs - bought
revup oil pump
HKS HG - bought
nissan oem gasket kit
BC valve springs
maybe tomei 272 cams
Goal is to go nitrous for now and possibly go fi again in the later future. Car is rarely ever pushed hard let alone driven(maybe 1-2k per year in the last couple years). Would want it to handle 7-800 if i do go fi again.
My main questions are bearing clearances - if the journals are within spec do i just put the the new bearings in and torque them to spec? Or is there a lot more complicated measuring involved? Also should i go hx for more oil clearance?
what is a good compression to stick with keeping those power goals in mind, and what is the best safe bore on stock sleeves? not looking to go as far as sleeving as i am not looking to go too extreme at this point.
Any advice on the bearings or on parts missing would be appreciated.
Car is an 03 g with 66k miles. It has had a procharger kit pushing 14psi on it for maybe 5k miles and has seen 75 shot of nitrous one time before i sold the kit.
Here is my parts list so far:
Eagle/BC rods
ACL race bearings HX
wiseco pistons 96mm 11:1 - bought
ARP main studs - bought
ARP L19 head studs - bought
revup oil pump
HKS HG - bought
nissan oem gasket kit
BC valve springs
maybe tomei 272 cams
Goal is to go nitrous for now and possibly go fi again in the later future. Car is rarely ever pushed hard let alone driven(maybe 1-2k per year in the last couple years). Would want it to handle 7-800 if i do go fi again.
My main questions are bearing clearances - if the journals are within spec do i just put the the new bearings in and torque them to spec? Or is there a lot more complicated measuring involved? Also should i go hx for more oil clearance?
what is a good compression to stick with keeping those power goals in mind, and what is the best safe bore on stock sleeves? not looking to go as far as sleeving as i am not looking to go too extreme at this point.
Any advice on the bearings or on parts missing would be appreciated.
Last edited by jdm-v35; 07-13-2016 at 05:41 PM.
06-06-2016, 11:32 PM
#3
350Z-holic
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Ridlin Kids...
cant wait!
cant wait!
06-18-2016, 01:28 AM
#5
Registered User
you can do either std or hx undersize bearings if your looking for extra oil clearance.
extra oil clearance is for safety it doesnt hurt to have extra oil clearance but many people say that is old school thinking. the idea is more clearance means less likely your going to spin a bearing and when your generating tons of heat in a racing engine like 700-800 hp its ideal to have more oil clearance but that was how they did things back in the day.
nascar racers usually seek for tighter clearances because we have full synthetic oil now. the acl standard size bearings which is the ones i have usually give you more clearance to begin with when i checked my clearances it was .002 on the main bearings.
Reducing the oil clearance between the rod and main bearings and the crankshaft has a number of advantages. A smaller gap spreads the load over a wider area of the bearing surface and distributes pressure more uniformly across the bearing. That’s good, provided the bearing is strong enough to handle it. A smaller gap also decreases the volume of oil that has to flow into the bearing to maintain the oil film between the bearing and shaft.
That’s also good, provided the oil is thin enough (low viscosity) to flow well into the bearing. This also reduces the amount of oil pressure the engine needs, so some extra horsepower is gained by reducing the load on the oil pump.
you cant really go wrong with either std or hx, hx usually lets you run higher grades of oil and that can be good in many ways especially when your running turbo where you want to be able to run a higher grade of oil to help keep things really well lubricated within the turbos.
extra oil clearance is for safety it doesnt hurt to have extra oil clearance but many people say that is old school thinking. the idea is more clearance means less likely your going to spin a bearing and when your generating tons of heat in a racing engine like 700-800 hp its ideal to have more oil clearance but that was how they did things back in the day.
nascar racers usually seek for tighter clearances because we have full synthetic oil now. the acl standard size bearings which is the ones i have usually give you more clearance to begin with when i checked my clearances it was .002 on the main bearings.
Reducing the oil clearance between the rod and main bearings and the crankshaft has a number of advantages. A smaller gap spreads the load over a wider area of the bearing surface and distributes pressure more uniformly across the bearing. That’s good, provided the bearing is strong enough to handle it. A smaller gap also decreases the volume of oil that has to flow into the bearing to maintain the oil film between the bearing and shaft.
That’s also good, provided the oil is thin enough (low viscosity) to flow well into the bearing. This also reduces the amount of oil pressure the engine needs, so some extra horsepower is gained by reducing the load on the oil pump.
you cant really go wrong with either std or hx, hx usually lets you run higher grades of oil and that can be good in many ways especially when your running turbo where you want to be able to run a higher grade of oil to help keep things really well lubricated within the turbos.
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06-18-2016, 08:32 AM
#8
thanks! im planning to go HKS HG. and will need to look more into bearing sizing! did you actually need to measure the clearance? or did you just plastigauge then torque to spec if it was within tolerance?
Last edited by jdm-v35; 06-18-2016 at 08:42 AM.
06-18-2016, 12:34 PM
#10
Registered User
you can use either plastigage or buy 500 dollars worth of tools like a dial bore gauge and a micrometer to measure it.
i used a plastigage the factory service manual say its ok and i spoke to many machinists and they said plastigage will be fine. plastigage cost like 5 bucks at autozone.
the way it works is you put a piece of wax on the crankshaft journal then torque it down to spec dont spin the crankshaft....then untorque everything and match it with the size that you see on the paper to make sure everything is within proper tolerance. if it isnt than you need to figure out why. maybe faulty engine parts or improper assembly.
i used a plastigage the factory service manual say its ok and i spoke to many machinists and they said plastigage will be fine. plastigage cost like 5 bucks at autozone.
the way it works is you put a piece of wax on the crankshaft journal then torque it down to spec dont spin the crankshaft....then untorque everything and match it with the size that you see on the paper to make sure everything is within proper tolerance. if it isnt than you need to figure out why. maybe faulty engine parts or improper assembly.
Last edited by Justin100; 06-18-2016 at 12:36 PM.
06-18-2016, 08:56 PM
#12
Thanks for all the info! It will be a long road for me to finally collect all the parts, but just want to be prepared to do so. I will probably go the plastigauge method.
I am still undecided on sleeving or not. Looking at that RJM block I am not sure if its any better since it just appears to have the top welded and decked. It doesn't look to have stronger sleeve material.
I am still undecided on sleeving or not. Looking at that RJM block I am not sure if its any better since it just appears to have the top welded and decked. It doesn't look to have stronger sleeve material.
06-19-2016, 04:06 PM
#13
Its a machined like that. Better than sleves but not as good as billet. They said its seeing 1400 but they belive its good for 1600. No idea what vq has 1400 but still better than the 7-800 stock can handle.
Last edited by Conway_160; 06-19-2016 at 04:08 PM.
07-13-2016, 05:40 PM
#17
Just FYI I looked more into how that closed deck block is made.. it basically just has a more precise CNC machined block guard. It does work and has been done on hondas and subarus a lot. It is a cheaper alternative to darton sleeves though.
I am probably going to end up going that route when the time comes.
I am probably going to end up going that route when the time comes.
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