How much clerance do you run on you MAIN's and ROD bearings ?

[Master Chief]

This is what the Manual says for the S14 SR20DET:

Main bearing clearance: Standard 0.004 - 0.022 (0.0002" - 0.0009")
Limit: 0.05 (0.0020")

Connecting rod bearing clearance: Standard 0.020 - 0.045 (0.0008" - 0.0018")
Limit: 0.065 (0.0026")

Now i want a motor capable of a safe 400-500HP, to be used daily on LOW boost , and a safe 8000-8500 RPM limit.

I intend to ocasionaly DRAG/DRIFT the car.

What clerance's should i look for ? What do you guys run ?

I have TOMEI's Microfinished bearings for the ROD's, and Meaby i'll stick with OEM or NSIMO's for the MAINS - as i dont see any other brands have all the diffrent grades, and i dont want to grind the crank unesecary.

Thanks.

[EAT Motorsports]

yeah get the numbers off your crank and block and go from there tomei rod bearing are good, and go with nismo for the mains, dont go with a brand that doesnt have the grades.. bad times..... but either way start with the numbers on the crank and the block to find out what grades you need.

[!Zar!]

This is the first thread that isn't typical zilvia crap in a long time.

[Master Chief]

Glad to help, Mel, but doesnt seem to help me back...... ;)

I know how to select bearings, according to the Nissan Manual - But that is good for a standart spec engine.

Runing higher power and revs, requires higher clerances on the bearings.

I am wondering, what others with these Power Levels, run.

Thanks.

[Unit-121]

Wat i can do is ask my tech teacher on engine performance tonight and ill have the specs for ur main and rod bearing clearance by 1030 and ill post it back in your thread thats if no one has answered it yet

[Master Chief]

The more opinions, the better ! I'll be looking foward to you'r post.

Thanks.

[Sileighty_85]

www.RHDJapan.com (http://www.RHDJapan.com) has Tomei, Nismo, and now Power Enterpirse, They have many sizes availible, I ran with the Nismo Mains and they're working great.

I used the FSM Bearing Specs, I DD/Race/Drift mine no problems takes 7,500RPMS like a champ

[Unit-121]

Alright for the main bearing u have to go all the way to the limit 0.05 (0.0020) and the rod bearings the same all the way to the limit wich is 0.065(0.0026). In order to have these numbers u have to polish the crank all the way to this number specs. Why the limit? because the looser the clearance it makes it allot easier for less friction and because of thermal expantionit opens a little more clearance for your rod and main clearence. Bacause u wanna keep it nice and steady revs were u want them ur gonna have to use a high volume oil pump. HOPE this helps

[koukimonster139]

This is the first thread that isn't typical zilvia crap in a long time.

seriously i was suprised


thought it was gonna say "how much clearance to fit Z brakes" or some shit

[Master Chief]

Sileighty85 - What power are you runing ?

Unit121 - I never heard of SR20DET RWD, high volume Oil pump. Do you have a link or something, to something like that ???

Thanks.

[Unit-121]

well i would say a high volume oil pump only because of the fact that u said drag, allot drag cars carrie high volume oil pumps so i would assume thats what the sr should run if they make those type of pumps for the the motor i will try and research some more about it and post it back up on the thread really good question

[RedtopTech]

If this engine was built for race only you would want to go pretty loose on the bearings but all the way to .002? I dont think so. If you are already at max clearance this wouldnt allow for ANY wear. Not that there should be any contact between the bearings and crank but it happens everytime you start the engine.
Also bearing clearance plays a major factor in oil pressure. On a street driven engine i prefer staying to the tighter end for higher oil pressure and longer engine life. I set all of my Mains up at .0009 and rods at .00011.
Engine makes great oil pressure at idle and a lot of the little noises in the top end are gone after the rebuild. Ive now got about 3300 miles on my fresh engine.
The most important part of your rebuild besides blue printing and assembly is the break-in. Use 5-30 dyno oil and start the motor up. Some people crank the motor for extended periods in order to build up oil pressure before allowing the motor to start. This sounds like a good idea however during cranking everything is kept seperated by the assembly lube which is easily squeezed out of small clearances. You want the engine to start quickly. After the engine started raise the rpm to about 2000 and hold it there till the engine warms up to operating temp. You should have someone check for leaks at this time. next shut off the engine and change the oil. next start the engine again and take it out for the first break in drive. I prefer to drive about 5 miles on the first run. during that run its important to put a load on the motor in order for the rings to "properly" seat or wear into the cylinders. I generally keep the revs below 4500 on this run. Next bring it back home and change the oil again. I am meticulous about changing the oil so often to ensure that all break in particals are flushed out. Next drive the car again this time with a little more load. I prefer 3rd gear pulls from 2500-5000. WOT is not needed.
On every break in run it is also important to allow the car to "engine break" This helps to evacuate crankcase pressure and also helps the rings to seal.
After about four runs and oil changes i perform a leak down test on all cylinders. My goal to determine when an engine is "broken in" is 10% or less in each cylinder. After the rebuild, before the engine was first started i had 18-16% leak down on all cylinders which isnt to bad for an engine with 100k miles on it. After my fourth break in run i had 11-10 percent on all cylinders. After a week of driving to and from work (lots of load and engine braking the whole time" The engine was down to 6% leak down on all cylinders. These numbers are nearly unheard of. Most engines are considered "good" with under 20-15%! I believe it was the meticulous break in procedure that aloud the rings to seat the way they did. Also keep in mind that i went wide on the ring gaps because of my ocassional use of nitrous.
Good luck buddy!

[Sileighty_85]

Sileighty85 - What power are you runing ?



300ish (for Now) Lots of Internal mods but only running a T-28, for the moment. Im hoping to find a TD06-20G at UpGarage.

[Master Chief]

RedTopTech, i assume you meant - 0.0011" on the rods, and not 0.00011".
These are basicly , the Recomanded clerances, in the Manual.

I used a bit difrent Runing in procedure, but allso got about - 5-6% losses on leak down test.

Anyway, not sure what power are you runing, but the question here is what to set the clerances for about 450-500 HP !

At 300HP, i trashed the car for about a year, but what went at the end, was a rod bearing. The OEM tight clerances, might have had something to do with it - when the car ran of the limiter, during a drift sesion.

[Unit-121]

Master Chief heares a link were i found a high volume capasity oil pump might give u some ideas http://www.justjap.com/parts_nengine.htm hope this helps bro

[Master Chief]

Thanks, I had a look, but what they have there is for the RB26, and my SR, is not an RB yet.

As far as i know, no one makes a High Volume PUMP for the SR20DET.....Meany there is a reason....

[Unit-121]

I guess u can upgrade more on a bigger oil pan thats all i can think off .

[Master Chief]

Done that , long ago !!!

[infinitexsound]

This is the first thread that isn't typical zilvia crap in a long time.

isnt that the truth!

eh, just measure od,id... and refrence the fsm for tolerances... basically if u really didnt cut that much off the mass.. you really wouldnt need to run oversized ones... when u do rebuild the motor i highly suggest pre lube... something like redline assembly lube is one of the best out there on the market.. i highly suggest picking up a can cause its fairly cheap like around 6 bucks...

[Master Chief]

Have that, did that....

Allso, iam not asking about OEM specs, iam asking what would be recomanded for 500hp and 8000RPM.

[RedtopTech]

tight side of factory spec! how many times does it need to be said? there isnt any single magic #. The factory gives you an operating range spec, stay within spec. These are the best clearances for engine life and performance. Youre making big power and high rpm- you need good oil pressure, keep it tight!

[Master Chief]

"The factory gives you an operating range spec" .... Thats good for a factory engine. Not one that pushes twice the power, and more revs.

Anyway, I heared alot of opinions about this, and allso some from Top tuners like Mazworx, NorrisDesigns etc..... All say to go loose. i will be trying to get to the MAX values and hope for the best !

Thanks to all, for the help.